Rear Parting Tool Holder For Your Lathe - A Little Performance Analysis

[@terrycannon570]

Excellent demo Mark As an added comment I always love your shots of the Ausie wildlife around your home. Beautiful

[@EDesigns_FL]

You might be able to reduce play in your tool holder by relocating the flexure from the top to the bottom. In it's present configuration, the flexure/clamping screws have to resist the cutting force imposed on the parting blade. If the arrangement was flipped, these forces would be imparted on a more rigid fixed surface. Just a suggestion.

[@ADBBuild]

That's a really good point. You could have all the rigidity in the world and you would still be limited to the rigidity of the flexure, which is intentionally not rigid! If the slot for the parting tool is in the center of the holder, all you would have to to is flip the holder over to fix it.

[@Preso58]

I have had many people make that same suggestion and I do need to make a new tool holder for the insert blade so I will investigate if I can incorporate that feature into the new tool holder. Regards, Mark

[@sparkiekosten5902]

I'm not gonna lie....Watching that parting off was a joy to watch!

[@Preso58]

I know! I am almost relaxed with parting off operations now. I did have a brief scare the other day when I got a bit too relaxed and forgot to add some cutting oil while I was parting off some 6011 aluminium. The cut must have been a bit dry and the heat made the blade expand sideways in the cut. You can hear it when disaster is about to strike but I got the blade out before that happened. A few sprays with WD40 did the trick though. Regards, Mark

[@kentuckytrapper780]

If that tool lifts any at all it would destroy your parting tool. It is cutting great in my opinion, wish my lathe tooling cut that good. Great video, keep'um coming..

[@1962clarky]

I think I'll make one for my lathe. Thanks for the series Presso...

[@somebodyelse6673]

Thanks for doing the tests! It's gratifying to see actual measurements that show the design idea isn't plagued by excessive lift or flex. You've probably convinced some people they should add a new project to their list.

[@nunosantiago2273]

I'm certainly convinced. I also own a Colcester Student and parting is something I never look forward to.

[@Preso58]

Thanks. I am very keen to see if someone else runs with the idea. It won't suit every lathe since many like the South Bends don't have a machined cross slide but I can carry out the parting operations now without the usual anxiety. Regards, Mark

[@TheAyrCaveShop]

Thanks Mark, Enjoyed the testing....Clock spring chips nice side effect !

[@Preso58]

I must say I was totally surprised to see how those stainless chips had formed. Certainly a lot easier to dispose of than the birds nests I get from 6011 aluminium! Regards, Mark

[@camillosteuss]

Ayy, nice seeing that update/refinish! All the best!

[@MattysWorkshop]

Gday Preso, that’s a really solid result, I use the same parting blade setup that you’ve ordered, there not bad, thanks for the update, cheers

[@Preso58]

Thanks Matty. You tend to work with much larger diameters than I do and I have always been impressed with how well your lathe handles those big chunks of steel. Regards, Mark

[@soundmaster1966]

Mark, as always the birds were lovely. Happy new year. Stay well. Cheers Ulf

[@russtuff]

This is a fantastic result.

[@RB-yq7qv]

Hi Mark I would be more then happy with the results you are getting.

[@bulletproofpepper2]

Thanks for sharing you videos, I have been chasing for more rigidness in my hobby lathe. I think mine goes deeper into way it was constructed. I think nothing on my lathe is flat, square or parallel. Thanks for sharing.

[@MrLukealbanese]

Excellent video Mark, happy new year mate 👍👍

[@HM-Projects]

Sold, I'm going to try making one for my small bench lathe. Thanks for the update and testing, very helpful.

[@grahamlucas6033]

Nice result Mark that is a very rigid set up and works a treat, parting can bring such sorrow 😃happy new year mate

[@dizzolve]

the whole project is very nice looking -it came out great. Love how the chips stay out of the way too. I bet the whole thing feels safer too

[@Preso58]

Yes. it's a joy to use. However I know I will still jam up a tool at some point. The chances of calamity are lower but they are never zero! Regards, Mark

[@learningturningmetal]

Great result - thanks for sharing. Cheers Andrew

[@Preso58]

Thanks Andrew. It has given me a lot more confidence when parting off. I recently added two carbide insert tools, a 3mm and a 2mm and dedicated tool holders. They are much better for doing large diameter work since they don't rub so much on the side of the cut. Regards, Mark

[@Lesfac]

I made a rear part off holder that transformed the ability of my Chinese lathe and ordered the same type of carbide part off you have. In testing and frankly abusing the set up, it performed very well but the pressure opened up the slot that the insert fits in by bending the bottom down. (Down because I run in reverse for parting). I was able to add a support under the blade but in hindsight I would get a blade where it is taller giving more strength to resist the bending pressure. I did see the taller type.

[@Preso58]

Thanks. I was a bit reluctant to order a cheap import parting blade for the reasons you have given. I also considered a much deeper blade but when I modelled the tool holder in my CAD software it started to get a bit chunky. If I can part off stock up to 50mm diameter I will be very happy though. Regards, Mark

[@AmateurRedneckWorkshop]

That is a very nice parting tool. I think you are in danger of testing it beyond reasonable limits. Thanks for the video keep on keeping on.

[@somebodyelse6673]

That's where you find out what the limits are, yes? Keep measuring until its all well inside the tolerances you need, then you know for sure.

[@Preso58]

Thanks Harold. I am getting set up to use the clamps on an actual milling operation and I want to try to pull a job out of the clamps to see how much holding power they have. I just have to work out a way of doing it. Regards, Mark

[@ianaristotlethompson4186]

I would say what a very nice setup. Even so vibration in the blade will make the pattern on the job. Excellent, I would be happy with that, primarily when parting the finish is second consideration.

[@Preso58]

Thanks, as you point out, I am less interested in the surface finish. I just want to be able to part off without anxiety. So far it is working out quite well. I haven't smashed a tool yet! Regards, Mark

[@larrysperling8801]

very nice build. i might try one of these on my 13 in grizzly.i'm a coward when it comes to power feeding a cutoff tool in a lathe like mine. i will be very interested on seeing how your insert tool works i have have broke three of them (bangood) all in the same spot just under the blade. my hss works just fine and leaves a very nice finish. i use the multifix tool post . your video's are first class and always interesting. too many of my favorite you tubers are going the infommertial route. stay the course mark, i think you are what us home shop guys really enjoy.

[@Preso58]

Thanks Larry. Generally, I am not a fan of insert tooling. In my view, it is more suited to repetitive production work where cycle times need to be short. I find it hard to get the sort of finishes that big heavy lathes can produce with high spindle speeds and fast feed rates. HSS tools can be made very sharp with very little effort and they are cheap and adaptable. I am happy to be proven wrong though. I will try the insert tool but at least I can go back to the HSS tool if it doesn't work out. I must say it is very tempting to "sell out" and start accepting overtures from vendors who only want you to say nice things about their products but it's not for me. There are no plans to change! Regards, Mark

[@blfstk1]

Good Show Mate: As per normal. Happy for you that deduced the problem and came up with a solution that works.

[@jasonhull5712]

I just made a rather elaborate version for my lathe, it’s a odd dovetail type and it’s not as simple as just bolting it down to the cross slide unfortunately. But it did turn out great. And rear mounted parting is the ONLY way to go for me from now on. What a satisfying experience! I made a block that clamps down on the cross slide using the dovetails that now accepts a CXA size QCTP vs the BXA size that’s on the top slide. It’s so nice having the versatility of tool post mounting and rear turning and parting options.

[@Preso58]

Thanks. I love the design of the old Myford lathes that had tee slots on the back side of the cross slide. I don't know why all lathes don't have that feature. I have found that hand feeding the rear mounting parting tool can still be a bit hit and miss. If I just engage the auto feed and keep the cutting oil fresh it always seems to cut without issue. It's really counterintuitive but it works. Regards, Mark

[@Steviegtr52]

Hi Mark. I think the cuts are fine. I have been using the one i made quite a bit with the making of the Hemingway kits lathe steady rest series. It has been flawless. No worry of a jam up any more. Totally agree the insert holder, although works well , does need a hefty push to cut. As you say they have a pretty blunt profile. All we get in the garden is pesky pigeons & Starlings. Regards. Steve.

[@Preso58]

Thanks Steve. I have been using the parting tool a lot lately and it is such a pleasure to be able to run the cuts under power feed. I had started out being quite conservative with my expectations but so far nothing has gone wrong. I did take delivery of the two insert tools and I have designed the tool holders for them but it's not been a priority since the HSS blade is working well enough. I will do an update later on. Regards, Mark

[@michelecrown2426]

I think your design and concept are spot on. The only difference I would try is, the grind on the parting tool be at a slight angle instead of straight.

[@Preso58]

If you mean having some front clearance, there is about 5 degrees but no top rake. The geometry of the tee type parting blades means that you cannot grind any clearance behind the cutting edge. Regards, Mark

[@bigbattenberg]

Cool. I decided to go all the way and build a 4-way indexing rear tool post using GG25 for the riser block and GGG50 for the indexing tool holder. Using GG25 for the riser block is because of availability and it's less stressed as well obviously. Just ordered the materials yesterday. Because of course there is no compound slide I can use 25 mm tool holders instead of the usual 16 mm on the front tool post, do have to get LH tool holders though. Because the compound slide overhang over the left cross slide guideway (25 mm) is also eliminated the setup will be as rigid as can be. Main goal is perfect parting off and stable roughing. A bonus I think might be better visibility in boring operations. I have a smaller Boley RD42 turret lathe which runs in reverse by default, took a bit of inspiration from that. Not having chips flying in your face is probably not bad either.

[@my1956effie]

Great result Mark,nuthin scarier than front post parting.

[@Preso58]

I agree! I almost feel relaxed with parting off operations now. Maybe I will be able to sip a chardonnay and do lathe work at the same time😁 Regards, Mark

[@neffk]

I recently made a solid carbide parting blade which seemed better than the HSS and even a Shars carbide-insert tool. Given the deflection was almost 0.002 in and most of it was in the blade, a solid carbide blade might be the way to go. Thanks for sharing your build and test results.

[@Preso58]

I did not know you could purchase a solid carbide parting tool! I would like to build a low speed diamond lapping tool like the one that Stefan Gotteswinter has. I think I would like to be able to put a razor sharp edge on the carbide inserts sometimes. I find that the commonly available inserts have too much edge radius on them for small work. Regards, Mark

[@joell439]

Fantastic results 👍😎👍

[@Preso58]

Thanks. I must say I was pleasantly surprised at how well the whole build turned out and so far it has been a joy to use. Regards, Mark

[@jsteifel]

great job Mark, I think you are chasing your tail looking for perfection, that looked and sounded great parting. Love seeing the cuckatoo, beautiful bird.

[@Preso58]

I think you are probably correct. I do want to try out the 3mm carbide insert blade though. It turned up in the mail today so I just have to make a tool holder for it. I will do a bit of a follow up when I have it ready. Regards, Mark

[@2lefThumbs]

If the marks are radial, it suggests that whatever is happening does so in sync with the rotation of the work- since you're power feeding, I'd investigate what effect using different gear ratios has (ie does the angle between tge radial lines vary with gear ratio? Presumably hand feeding wouldn't give waves as there'd be no relationship between chuck angle and infeed if you're winding by hand)

[@darrenconway8117]

Make sure you lube the SS thread to prevent galling of the thread. The galling will lock up the bolt. Wear on the flanks of the HSS blade will make it tapered when looking down in plan view. Eventually it will wedge into the cut and then BANG. Carbide insert tooling is much safer.

[@macw2234]

Good show squire. Greetings and salutations from a gloomy Schoondijke in the Netherlands.

[@Preso58]

Thanks. I just checked out Schoondijke on Google Maps and you have a windmill! So cool! We have a sort of rough itinerary to travel to the USA, Canada and Belgium/Netherlands later this year. We are very keen to see your part of the world. Gloomy or not it's still exciting to be travelling again. Regards, Mark

[@JoseSilveira-newhandleforYT]

Thanks for clearing the doubts about the wavy pattern. I didn't expect the parting blade to be out of square, but that meets my idea that there was side flexure (wish you had placed the indicator on the blade side as well). Despite the minor imperfections, it's just parting, not facing - wish I could do close to your worst result 🙂 Lovely cockatoo in your garden. I have a parrot by the side of my desk, and it behaves exactly the same. Just wish it didn't make such a mess, but I can't bring myself to place it in other room - I got used to its crazy mimics of speech and sounds. It also interferes with all my phone calls, saying hello repeatedly and ringing like a phone 🙂

[@Preso58]

I will be doing some more tests with the indicator and I will try to test for side to side deflection. I suspect that all I will see is some flutter on the indicator though as the frequency or resonance will be quite high. Those cockatoos are quite entertaining to watch. We get to see them quite closely from our kitchen window. Regards, Mark

[@JoseSilveira-newhandleforYT]

@@Preso58 You are quite right - resonance plays an important role in these small imperfections and, if frequency is high, it's hard to see deflection (would need a vibration monitor), although with the misalignment in previous video, I'm convinced it would be visible. You have the best solution - watch cockatoos in the garden and keep the mess outside 🙂

[@doppelraab]

A happy new year to all

[@whiteblock8]

i went for the 32 mm deep parting blade, as there is a lot more meat behind the blade , i have used it on my seig sc4 with great success ( upside down on front)

[@robertwalker7457]

Great job, I winder if eccentricity of the 3 jaw chuck contributes to the pattern. Perhaps a collet may make a difference?

[@Preso58]

I think that there is some sort of harmonic vibration going on but I am not the guy that would be able to test for that. I took delivery of two insert parting tools today. One is 2mm wide and the other 3mm. The type I have should not make any contact with the sides of the groove apart from right at the cutting edge. I am keen to see what sort of finish I can get with them. However, If I can part off without smashing HSS tools I will more than satisfied. Regards, Mark

[@inspector1794]

Compared to my mini lathe your lathe is large, heavy and rigid. 😀 I was wondering how this would work on a lengthwise cut, would it reduce chatter. Happy New Year and thanks for sharing your work with us.

[@Rustinox]

Indeed, nothing to worry about. Now I know I can go ffor it too :)

[@Preso58]

I can honestly say that it was totally worth the effort. I no longer fear parting off! Regards, Mark

[@glennbarker222]

Working pretty well, guess if you are some kind of perfectionist (which you clearly are - so waiting on part 2), then you can work out where and what you need to machine off the back of the tool holder to correct the slight misalignment. Operationally though, it's a none issue, that tool is cutting as well, probably better, than any other parting tool I have seen in action, seems to be a lot of rigidity there, which is paying dividends. Lovely job and thanks for the update. PS - have you checked the lathe spindle for run out under load?

[@somebodyelse6673]

Just as a general issue, I've more than once wondered how much good it does to show off fantastically low spindle runout with no cutting load. I haven't thought of a good setup to measure it while actually cutting, though.

[@samrodian919]

@@somebodyelse6673 the easiest way would to turn between centres and carefully machine the headstock end concentric with very light cuts, then put an indicator on the concentric part and take a heavy cut on the rest and see what if any runout you can detect.

[@somebodyelse6673]

@@samrodian919 - If you're putting the indicator on the workpiece, how do you rule out inconsistancies in the workpiece material? Just buy something expensive and hope it doesn't have non-uniform stresses being released, hard spots, soft spots, etc?

[@Preso58]

Glenn, I will do a follow up when I get the two carbide insert toolholder made. I bought a 2 and a 3mm version and I have designed the toolholders for them. I just need to do the machining and try them out. The HSS blade is working well enough that it doesn't warrant any further tweaking. Regards, Mark

[@brenwyattm0rij909]

Mark, my lathe hates 500rpm. The harmonics are terrible. It shakes like a dog having a … All other speeds are fine. I power feed part off at 300 and its a pleasure. The other thing, if you put an indicator on any cutting tool, it will move. Keep them coming !

[@Preso58]

That's interesting! I recently changed over the motor in my lathe from a 1kw single phase motor to a 2.2kw three phase. I also fitted a new lower pulley and two new matched vee belts. It may be just my imagination but the surface finishes I am getting now seem to be much better. I had read that single phase motors tend to suffer from "cogging" which is a sort of induced vibration in the power train. Plus, more power! Regards, Mark

[@steejans]

I wish my lathe would work with this tool! Next lathe I'll definitely make something like this!

[@Preso58]

You do need to have a lathe with a machined surface on the cross slide which does rule out the South Bend and Hercus lathes. The good news is that having the rear tool post and an inverted tool means that it will work with a screw on chuck. Regards, Mark

[@AlbiesProductsOnline]

I think the pattern on the old piece looks cool so if you find out how to make it then that’s a good trick to add to the bag of tricks

[@Tensquaremetreworkshop]

Fantastic project. The one missing test is to measure the deflection of the tool holder- this would answer the many that posit the clamping screws would be better inverted. I do not believe this to be the case (clamping force is equal and opposite) but it would prove the point. Is the tip ground square or with a slight tilt to one side? The radial pattern may be due to a 'wandering' of the cutting surface, which is normally prevented by that tilt.

[@Preso58]

I did check the grind on the cutting edge and it is square or at least as square as I can check it. I may need to break out the digital microscope to have a good look. That was one thing I suspected as a cause for the wavy pattern but until I can get the insert tool I won't be able to compare it with anything else. Regards, Mark

[@fristlsat4663]

I wondered as you made this, a tool holder for the front side of the lathe is solid in the direction of the force from the cut, and the clamp is on the "unloaded" side of the tool. Your rear tool holder (Which I plan to emulate) is carrying the force on the clamp of the tool holder, and the three set screws in the tool post. It apparently does not make a significant difference, at least that I could see from this video. The tool holder could easily be modified and flipped over, just need clearance on the rigid side for the wider cutting edge. I haven't yet managed to imagine a way to put the clamping screws on the bottom of the tool holder that is not clumsy and inconvenient, still pondering that one. I suppose if you controlled the size of the clamping tang on your tool holders carefully you could make a wedge style clamp that pulled horizontally into the tool post below the tool holder.... Hmm, I see an interesting project here, but I doubt it would actually perform better in any way that I could measure. Maybe in wear on the set screws/top of tool holder if it were used a lot, but the whole point of this was for smaller lathes in hobby shops, which generally don't get used a lot, at least not in my hobby shop.

[@Preso58]

The design I ended up with was really a compromise between having good rigidity and ease of access to the clamping screws. For that narrow blade, I think the arrangement is adequate. Certainly, it would be more rigid with the clamping screws underneath. The original Colchester rear parting tool post had slots for both conventional and inverted tools and the set screws were underneath on the slot for the inverted tool holders. It had clearance all the way down to the riser block. I am just going through the design for the tool holder which I need for the 3mm carbide insert tool and it will have the set screws underneath and the flexure slot close to the bottom edge of the tool. I think for that tool it will be necessary since it will be taking wider and deeper cuts than the HSS tool. Regards, Mark

[@fristlsat4663]

@@Preso58 From the way it works I think you are correct about it being sufficient for the cutoff blade. When I make mine I will be making it to hold more than just cutoff tools, because any form tool has the same issues that plague cutting off on smaller machines. I have a Clausing 11 inch, which is actually just a rebadged Harrison M250, with a 1.5 HP motor, so form tools or cutting off will chatter or even stall the lathe if I run higher RPMs to improve surface finish. I am hoping a rear mount will give me a little more capability . The complication of making it general purpose instead of just cutoff/grooving is that it needs height adjustability to accommodate hand ground form tools that may at times be a little clumsily ground so will not always have the cutting edge on a plane with the top of the tool blank, but at worst case it won't be any worse than shimming a 4 way toolpost. I may just put tools directly in the post, have slots in 3 sides of it appropriate for 1/2, 3/8, and 1/4 inch tools, and just use a holder that fits in the 1/2 inch slot for cutoff tools.

[@TgWags69]

You might be able to mill in a shelf with a ramp on it for the tool holder so when you tighten the set screws it pulls in tight to the block. Similar to a post and beam construction. Sometimes the set screws on a flat surface have enough push as they turn to allow the part to walk out slowly. If that isn't the problem then maybe setting up a fly cutter in the lathe and machining a skim cut in-situ to make it perfect with the ways on the lathe may be a good option???

[@Preso58]

I recently bought two carbide insert tools and they have a raised vee profile in the top and bottom edges of the tool body. I guess the idea is that the matching toolholder has a corresponding vee profile to align the two parts accurately as you clamp it. It's a good idea but it wasn't something that I could easily machine in the top and bottom surface of the slot of the toolholder that I made. I sort of lost interest in tweaking the performance of the HSS tool since it works well enough that it doesn't really bother me. So far I haven't had any breakages or dig ins so unless that starts happening I think I will take this version as a win! Regards, Mark

[@shiro-r4m]

Congratulations on parting stainless, it was indeed missing from your last demonstration video. I consider it the real proof of a solid setup, being able to cut stainless. A small bit about metal strengths: the steel bolt you were using could be up to twice as strong as the stainless steel you switched to. While stainless steel is very tough to cut, the more common grades don’t have a very high tensile strength. Steel bolts on the other hand do. I’ll assume it was an 8.8 grade bolt, pretty standard stuff: that would have around 800N/mm^2 minimum tensile strength which is twice as strong as mild steel.

[@Preso58]

You are correct about the high tensile bolt. It would indeed be stronger than the stainless that I used. However if I ever do stretch or break that stainless bolt I will have done something really stupid. Regards, Mark

[@gregfeneis609]

Interesting. Appears most of the sun ray effect was just due to alignment. I was wondering if it might help to capture the cutoff tool in a V slot instead of a square (flat surface) slot, which could help resist side to side flexure.

[@Preso58]

At the end of the day, I am not really concerned about the surface finish. It is almost always necessary to do a facing cut to get rid of the little pip in the centre of the cut off part any way and I am just grateful that I can part off stock without having to worry about the tool digging in and damaging either the tool or the part. However, after using the tool more I have been able to reduce the sideways chatter by tweaking the spindle speed and the feed rate. Regards, Mark

[@mrc1539]

Mark, I think the majority of us would be tickled pink to get those results . But I can appreciate your quest for perfection 😉. Love the view of the bird, the only birds I see out my window are sparrows and buzzards .

[@Preso58]

I do think that I may be splitting hairs to go after better results and I have taken delivery of the insert tools so the next step will be to make up tool holders for them. We do like observing those big cockatoos. They are generally right outside our kitchen window during the day. They are actually quite big birds and they have very powerful beaks. Regards, Mark

[@warrenmaker798]

Hi Mark, WOW, what a great series and expertly covered thank you . May I ask the name of the firm you purchased the Dura-Bar from please. I am guessing you are in QLD from hearing the parrots in the background. You have inspired me to attempt it myself, but I am struggling to find a slug of steel that size. After having forked out over 8K for a 1336 lathe that is touted as being "Euro Precision", sadly I find no matter what I do it will not part off. For a lathe weighing over 600KG and costing that much, needless to say I was gutted. I have stripped it down to the main bed and redone all the Gibs and re-adjusted the entire machine. It's better, but not much. I would have sent it back but the one saving grace is the spindle has 0.005mm runout. I have never had a lathe spindle that accurate. Also, the 3-jaw chuck is 0.05 runout. So its biggest Archiles heel is it won't part off. Thanks again.

[@Preso58]

Unfortunately, the company I bought the durabar from has folded. It was called Mancave Metals and the guy that ran it was based here in Australia. I don't know what happened but his website is now closed. However you can buy short lengths of durabar from www.edconsteel.com.au/store/products/steel/cast-iron/round-bar/3d They do sell in cut lengths and the prices seem OK. I have also bought large pieces of steel and other metals from Offcuts Galore on Ebay. www.ebay.com.au/str/offcutsgalore He sells aluminium, brass, steels and sometimes cast iron. It is a bit of a lucky dip and his stock changes regularly. If I am looking for something in particular I have contacted him and he will keep an eye out for me. The base of the rear parting tool doesn't need to be cast iron. Steel would be fine but cast iron does have some internal damping properties. For what it's worth, I have some carbide insert parting blades which fit the rear parting toolpost but they need a lot of tool pressure to work well and I find that using a manual feed is a bit precarious. You just have to bight the bullet and use power feed and they seem to be fine. HSS is more predictable and leaves a better finish on soft materials but the carbide is great for stainless and harder steels. Good luck with the lathe. Regards, Mark

[@sheph7]

WOW, the "problems?" are sooooooooooooo minor I call this a major win both design and execution

[@bostedtap8399]

Positive result 👌, definitely a much needed feature to any lathe, well worth the time and material. Possibly the radial lines are from spindle bearings, or chuck jaw jaw/belling out?, though as you say, harmonics, finding the source, or sources would be very difficult, but it doesn't detract from the finished article. Do you get the same when facing conventially, or when facing using the rear tool holder?. Very nice through experiment, thanks for sharing. Regards John

[@samrodian919]

Any harmonics will be directly related to the stick out of the tool from the holder. Shorten the overhang and the harmonic will either go up in pitch or go altogether sometimes only moving the tool usually inwards even two or three millimetres will stop that from happening.

[@Preso58]

Generally I get fairly good finish on facing cuts. Certainly as good or slightly better than the last part shown in the video. I think that getting rid of the out of square alignment has made the biggest improvement to the performance of the parting off blade. I am still keen to see how the insert tool goes since it's geometry eliminates any side contact during the cut. Regards, Mark

[@bostedtap8399]

@@Preso58 Using a narrow HSS blade at its inception, possibly exacerbates any inaccuracies in the set-up, Possibly using an insert type parting off tool would have masked this, or generated a whole set of different results. Really enjoying this treatise on machining. Best regards John

[@bostedtap8399]

@@samrodian919 I think changing the stick out of both part and tool are a subset, the whole machine, and it's reaction to the floor should be considered.

[@dizzolve]

Just a thought and it might not even make a difference but if you beefed up the top portions of the tool holder and tool post (which should never be in the way, maybe you could reduce upward movement of the tool itself. I know you're going to try the 3mm wide part tool so that should reduce too. Just 2c

[@Preso58]

I think for that narrow HSS blade, the tool holder is about right. I just took delivery of the 3mm wide carbide insert tool today and I will fit the flexure slot and the set screws underneath since it will be taking much wider and heavier cuts. Another update coming soon. Regards, Mark

[@CraigLYoung]

Thanks for sharing 👍 are you going to parkerize it?

[@37yearsofanythingisenough39]

Always parkerize. It is the fastest way to a rust resistant surface. Remington, Winchester, & etc. knew about this before WWII.

[@Preso58]

Yes, absolutely. However, I need to finish off some other projects first since it's better to do a lot of parkerising all at the same time. I am part way through making a Hemmingway knurling tool and I will be doing a whole batch of tee nuts, some finger clamps and some Mitee Bite style clamps all at the same time. I hate rust! Regards, Mark

[@bradthayer6782]

Have you put an indicator on the side of the blade to check for horizontal vibrations? That’s my guess. Not sure that has anything to do with whether the parting blade is on the back or front though.

[@Preso58]

Brad, I have not checked for sideways movement. I suspect there will be some vibration and flutter there but since I realigned the parting blade it has been cutting a lot better. I have the two insert type parting blades and I just need to make up the tool holders for them. I will probably do another follow up when they are completed. Regards, Mark

[@davidmott2090]

Very nice. If those chips are any indicator of quality it can't get much better. Cheers.

[@simonbirt6121]

It works in practice, now all you have to do is make it work in theory.

[@Preso58]

I am going to use that! Great way to confuse your critics! 😁 Regards, Mark

[@opieshomeshop]

*_Wny did you make the tool holder right side up? Seems like that too should either be upside down or why not integrate the blade directly into the tool post instead?_*

[@Preso58]

I have had a lot of suggestions to integrate the parting blade directly into the tool post but I wanted to be able to swap out the HSS blade for a couple of insert style parting blades I just purchased. I have a 2 and 3mm wide insert type and they are much deeper. To be as versatile as possible it was necessary to have a tool holder for each style of blade. I can also incorporate things like form tools as well. Regards, Mark

[@Warped65er]

👍 Thx for the vid.

[@ncktbs]

belt flat spot? making the speed varying?

[@Preso58]

I have recently fitted a brand new 2.2KW three phase motor and two brand new vee belts and a lower pulley to the lathe so it's unlikely. I still think that I need to check the main spindle bearings and check for end play in the spindle. Regards, Mark

[@cloneit3dengineering437]

Mark, I am making one of these and will mount a BXA quick change holder. I am curious if the orientation of the slot in the mounting block has any significance?

[@Preso58]

I hate having to align the parting blade if you take it out to sharpen it. If it is even slightly misaligned (more or less than 90 degrees to the spindle axis) it will bind as you go deeper into the cut. My aim was to have the components self align. The down side is that it's not so easy to fit general tooling like form tools or a general purpose turning tool. I did consider fitting a regular QCTP so it would accept BXA tool holders though. Regards, Mark

[@cloneit3dengineering437]

@@Preso58 Now I am thinking of streamlining the project more and just mount the quick tool changer right to the block without a slot cut. Save some machining. Thoughts on why that would not work and so on.? Thank you

[@cloneit3dengineering437]

Mark, I made one of these units but with a quick change tool holder and I had the same issue I have in the front so I am now thinking it is something to do with the quick change unit so now I will see if I can redesign what I have started.

[@ericbrackenbury]

How do you adjust the height of the cutter 🤔

[@Preso58]

I can't really. I can put a very thin shim under the block that fits into the solid tool post but I figured that I would not be swapping out tools and that it was only ever going to be used for one style of parting blade so I just machined everything to put the blade tip on the centre height of the lathe. Regards, Mark

[@ericbrackenbury]

Thanks Mark, I will figure something out like shims maybe.

[@MyLilMule]

I've never had much success parting off. And unfortunately, with the way my South Bend is constructed, making a rear parting tool attachment isn't an option. I'd have to replace the whole cross slide.

[@Preso58]

I know what you mean. We had two Hercus lathes at the school where I used to teach. The Hercus is a clone of the South Bend and they had the same cast, round surfaced cross slide. Myford had the right idea fitting a long tee slotted cross slide to the Super 7 lathes. Maybe there is a good market out there for an aftermarket machined cross slide for the South Bend community? Regards, Mark

[@douglasbollinger8678]

@@Preso58 For your US viewers with small SB lathes (9A & 10K like mine) you can buy a T Slot cross slide casting and also a rear mounted toolpost casting for a parting tool. Search MLA toolbox. I have both in raw form in a box in the closet. The "problem" for me is that I don't have enough issues parting to go through all the work of machining another cross slide. I also use a carbide parting blade almost exclusively as well. I can't explain it either.

[@rory1344]

Given the descrepancy between your new back post, and the tool holder.. would it be worthwile 'final' milling it in situ with the lathe chuck holding the tool.. this then is to your saddle's travel/angle😎 exactly. (also an opportunity to show milling in the Lathe for us poorer folk who are mill-less.)

[@Preso58]

I am considering re-milling the slot in the tool holder while it is clamped in the riser but I will probably do that in the Bridgeport. Trying to do it in the lathe will almost certainly lead to more inaccuracy since it would be necessary to pack it up on shims or lower the tool holder in some way to get the cutter to engage where it needs to. Regards, Mark

[@malbirrell]

You could put an end mill in the chuck and face the blade holder dead square

[@chrisquinn3751]

Hi Mark, quite a few of us seem to be concerned about the direction of the load on the flexure holding the tool. It occurs to me that turning the tool upside down and running the lathe in reverse might yield some data on that one?

[@samrodian919]

Chris Quinn, running in reverse means you have to have the cutting edge uppermost, as I have in my rear parting toolpost. Otherwise the tool will just rub and not cut. It's exactly the same if you put the tool upside down in a normal parting off situation and run the lathe in the forward direction.

[@chrisquinn3751]

@@samrodian919 Yep, daft suggestion. The cutting edge of the blade would be way too high and it's non-adjustable. I should have drawn it out before making the suggestion - Sorry!

[@samrodian919]

@@chrisquinn3751 we all have brain farts occasionally!

[@Preso58]

Chris, I have had several people question the arrangement of the clamping screws which lock the toolholder in place. Many have suggested that the screws should be clamping on the unloaded side of the toolholder i.e. underneath. That way the tool holder is held up tight against a solid steel surface instead of the three point loads of the set screws. In fact, the original Colchester rear tool post had that provision but I am not sure it's an issue. It also makes it a lot harder to tighten the set screws that way. I also wanted to have the tool function without having to reverse the spindle direction and being able to part off immediately after a drilling or facing operation is great. Also, if you have a threaded on chuck it makes it possible to part off from the rear tool post whereas reversing the spindle would "unloosen" the chuck😁. Regards, Mark

[@Watchyn_Yarwood]

When you do part off a piece of stock, don't you normally face off the cut anyway rather than accept the cut as a finished face?

[@Preso58]

I would normally face off the outward facing surface and then part off. So generally one face is better than the other. If it can be gripped easily I would then face off the parted surface but for thin discs it would mean mounting it in some sort of fixture. I do have a very nice Flexi Chuck with machineable aluminium spigots for that sort of thing. Regards, Mark

[@mikepearsall9387]

Useful to get a good parting off finish when making washers & the like. I have planned to make a rear toolpost as it also avoids having to change tool holders in my QCTP when making multiple equal parts when repeating turning & parting off. Mike

[@thisnicklldo]

It looks very good. A lay view: I don't see how the sort of play you are looking at can possibly cause the radial pattern. Whatever causes it, it is happening at the exact same angular position of the workpiece, on every revolution of the spindle, or at least at some small integer multiple of the the number of revolutions. I'd be looking at the train between motor and workpiece, not the workpiece to saddle part of the mechanism. Say one of the gear teeth in the power train has a slight malformation, then every fixed number of revolutions the workpiece may speed up minutely, causing a tiny cosmetic effect on the cutting action. Or a pulley is slightly out of round. Or something like that. I wouldn't think such minute variations in workpiece speed could ever be totally overcome by even more rigidity. Anyway, you are getting fine results from a beautifully made tool, so no worries.

[@Preso58]

Thanks. I am still going to investigate the preload on the main spindle bearings. I can tweak that a little to see if the pattern goes away. When I first purchased the lathe (used) it had fallen off a truck and the cross slide feed screw had been slightly bent. It would leave regular bands in the faced off surfaces. I was able to straighten the bent section of the screw and problem went away. As you say, I am probably chasing my tail somewhat. Regards, Mark

[@MrZX1206]

If I wanted the tooling to be square to the chuck, I would figure out a method of holding an endmill with the chuck and cutting the tool holder in place. It seems like it is good enough so it probably isn’t worth redoing it.

[@Preso58]

Good idea. I do have a right angle head for my Bridgeport and I can mount the whole malleable iron base in the milling machine and indicate it square. It would be a simple matter to just take a light cut over the pocket where the blade is clamped. I also have an ER40 collet chuck that could be mounted in the lathe but the vertical alignment would be a bit more difficult doing it that way. I would like to have it dead square so I can take the parting blade out for sharpening without having to worry about tapping it back square again. Regards, Mark

[@Mr7yhnmki8]

Will you be getting a better camera in the future? I’M NOT COMPLAINING, just asking. I’ll be updating my lathe as you have done. Seems like an easy decision to make. Well done BTW. I’m always amazed those birds don’t bite off the tips of their tongues! I can’t eat a peanut without shedding some blood. Cheers, Gary

[@Preso58]

I am currently using a Sony HDR CX625 Handicam. It's a bit of a compromise but I am not a fan of using DSLR cameras in the workshop. They are big and heavy and expensive if you knock them over. I know a lot of people use an iPhone or a Samsung phone but I don't have a spare one for that. One thing I have done is to ditch Movie Studio in favour of DaVinci Resolve for editing. Once I get used to the workflow I think it will be a big improvement and I can take advantage of a higher frame rate and increased resolution. It is interesting to watch the cockatoos manipulating their food with their tongues. They are also very good at standing on one leg and eating at the same time! Regards, Mark

[@Mr7yhnmki8]

@@Preso58 thanks for your reply. I understand your approach regarding video recording. You’ll work it out I’m sure.

[@bobweiram6321]

Do people capture the bird as pets?

[@Preso58]

I think not. Most native wildlife is protected here but they could be bred in captivity. Maybe some unscrupulous types capture them as wild birds and there is a lucrative trade in native wildlife being smuggled overseas. Sadly, there are some cases where people are stopped in airports with native Australian reptiles and birds strapped to their bodies after being on a 12 hour flight. Most die in transit. Regards, Mark

[@guilriss]

Hola, muy interesante , pero me parece que la base magnética debería estar apoyada sobre la bancada directamente , no sobre el mismo carro, saludos.

[@Preso58]

Gracias por ver. Tiene razón y debería haber mostrado más pruebas con el indicador, pero después de usar la herramienta de tronzado trasera durante algún tiempo, puedo decir que ha funcionado muy bien y todavía no he roto ni una hoja de tronzado ni un inserto. Las piezas también salen limpias y, aunque el acabado de la superficie no es perfecto, al menos puedo tronzar diámetros grandes sin tener que preocuparme por las herramientas atascadas y rotas. Regards, Mark

[@Freetheworldnow]

It is not good practice to lift the tool post versus pressing down. You are going against gravity. The gibbs will suffer. But most importantly, the machine ways are designed to support and absorb the machine loads and cutting forces. Building a rear tool post is an excellent idea but with the tool pressure force going down. Also, your build has not enough rigidity. Especially having the parting tool outside of the tool post creating unnecessary oblique forces against the center post. I enjoy your videos Mark! I also enjoy the nature aspect of your content. Thanks for sharing!! God Bless.

[@Preso58]

The existing holes in the rear of the cross slide were for a factory original Colchester rear tool post so I am guessing the engineers at Colchester had considered the upward vertical load on the cross slide and the gib. At least, I hope they did. I couldn't detect much vertical movement with an indicator during a cut but the real issue would be how much load is transferred to the gib if the tool dug in or crashed into something like a chuck jaw. Regards, Mark

[@stefankrimbacher7917]

I think threading from behind would also be an advantage.

[@c00lamah]

Tut,,,,you Aussie's showing of again with your spare cockatoo's in your back gardens!!!

[@Preso58]

Those parrots and their smaller cousins, the short billed Corellas are considered pests in some areas. They can be seriously noisy and the Corellas can strip fruit and grain crops in no time. The down side to having them in the Macaranga trees is that they spread the seed and we have new trees popping up everywhere in our garden. Regards, Mark

[@c00lamah]

@@Preso58 Hi Mark. I neglected to say, I have watched every video you have made. I find them inspiring and I love your sense of humour. I thank you for the time and effort you put in to their creation. Jerry UK.

[@metalworksmachineshop]

👍

[@kimber1958]

That machine is tight. I would be afraid to put indicators on my tool post , I think it would be all over the place.

[@Preso58]

Thanks. I must say I was very surprised at how little movement that was evident. Like all older lathes, the carriage runs very smoothly in the middle and gets tight towards either end but I have tightened all the gibs so that they are "right" in the middle where I do most of the work. Regards, Mark

[@Stefan_Boerjesson]

It's a known way to part off, running in reverse, having the cutter up side down. But making a special tool post for that feels as too much when a partial part off and the bandsaw does the job. Checking my min lathe, it has no room, no height, for an up side down blade Anyway, thanks for the video.

[@Preso58]

I do have an inverted parting tool that mounts in the front tool post and I have a keyed spindle mount for my chuck so I can safely run the lathe in reverse. Unfortunately, a lot of folks have screwed on chucks so running in reverse is out of the question. Even with the inverted tool that I have for the front tool post, it's still not as good as the rear tool post since the compound slide is way less rigid than the solid post at the back. As you have found out though, it's not something that can be implemented on every lathe. Regards, Mark

[@wernerpfeifer]

Now you can make dollar coins yourself soon... ;)

[@markowen7164]

F.A.B.

[@garychaplin9861]

I am following your investigation with interest but no compliments, I still have not forgiven you for that Maccareindder thing.

[@Preso58]

Ahh... I can see I have blotted my copybook somewhat! 😁 Regards, Mark

[@bigbattenberg]

As i have mentioned before, boring the jaws while preloaded is an absolute must and it has been covered in great detail recently by none other than Robin Renzetti. I have taken a very interesting idea in a comment on one of the other videos on this subject and put it into a proper design. The concept is presented in my wordpress site blog 'rndproductietechniek'.

[@Preso58]

I just quickly read your blog and I noticed the ring design. I had made a similar part for a 4 jaw chuck. It was cast in aluminium and machined on my small CNC mill. Steel would have been much better but I don't think my little mill would have been up to it. I ground the jaws with a pneumatic die grinder held in a tool post. It sort of worked but I need to revisit the process. I almost purchased an 8mm carbide drill bit today with the idea of drilling the ends of the jaws on my big 3 jaw chuck so I can fit dowel pins and clamp down on a hardened steel bearing race. I baulked at buying the drill since I still have a ton of other projects to complete first. Regards, Mark

[@bigbattenberg]

@@Preso58 Thanks. The intention is to have these preloading rings laser cut, I regularly buy laser cut materials, combining this with some customers orders keeps the price down. I first contemplated drilling the jaws for pins, in fact some of my chucks (like the Forkardts) already have holes. But the preloading ring is much easier and I like to keep the boring bar as short as possible. I will go ahead with this soon and let you know how it worked out.