HS250 Line boring a thread - experiment

I made a tap to cut 5/8 5tpi to make a new saddle nut for my surface grinder. A viewer suggested I could line thread the nut, saving time and effort. This is an experiment to see if I could make the technique work.

[@raymondmarteene7047]

In the Model Engineers Workshop manual by GH. Thomas, there a good article on line boring bars where he put the tool bit at 45deg to the bar instead of 90 deg as you had done. Gives more length for the tool bit and keeps the strength of the bar by having the hole at a more linear angel to the length of the bar. He also had a 2 grub screws behind the bit for adjustment and locking, there were some maths calculations about the pitch of the grub screw and the 45deg angle to set the depth of cut. It’s worth buying the book and having a read. Cheers.

[@FCleff]

Three cheers for the BRILLIANT GH Thomas!

[@HaxbyShed]

Hi Raymond, that sounds interesting thank you. Cheers

[@bostedtap8399]

Procedurally very involved, certainly an excellent insight to utilising a small line boring threading tool, fantastic work Paul 👏. Thanks for sharing 👍

[@HaxbyShed]

Hi John, for all the complexity with the boring method I think I could cut the thread quicker than making another 5/8 5tpi tandem compound ACME tap again 🤪 That was a right marathon, with a lot of risk of wasting a lot of hours in the event of a mistake at any stage. Cheers

[@Preso58]

I read an article in the Model Engineer magazine describing a method for precision setting of line boring bits. It used a detachable micrometer head to push the bit out of the bar. I think it was shop made and it had a vee in the base to allow it to be clamped to the bar. I'd be trying to add a guide bush to keep the bar centred but if you could feed the bit with small increments it might not be necessary. I bought a Vertex brand "K type" vice. Basically a Taiwanese Kurt knockoff but it was about half the price of a genuine Kurt in Australian dollars, and it has proven to be very good. Regards, Preso

[@raymondmarteene7047]

Hey Preso, I think Hemingway’s have a kit for that, micrometer adjustment for line boring bars. Cheers

[@HaxbyShed]

Hi Mark, thanks for the suggestions. I looked up the Vertex K-Type and I have a vice like those (assuming I found the right one) but I thought mine was Indian. There is no name on it and it may be a copy of a copy anyway. Cheers

[@petermcneill80]

That was a great video , liked the modus operandi to quote 1 of Fred’s sayings 👍🏻 Enjoy Saint George day tomorrow 😁

[@HaxbyShed]

Thank you Peter 👍

[@peterhadfield873]

Hi, you can reduce the flex by adding a travelling steady or if your really flash a travelling steady each side of the job. Re setting the tool, I think that the hemmingway boring bar kit has a gizmo for doing just that - looks like bit like a 3 point external micrometre. Cheers.

[@HaxbyShed]

Hi Peter after your comment I looked at the kits and I see what you mean. Cheers Paul

[@larrykent196]

Very good approach, nicely done both the tap and the line bore method. If I may suggest possibly key the chuck end to repeat loading it in the same place, and just back off the tail stock remove the boring bar crank the part into place reload rinse and repeat, I have never threaded like that however, just a thought. In the past doing something similar only boring I made gauges that fit the shaft with a c/bore such it enabled me to size the tool to it. A few of them out of alum to get me close and a steel finish one for accuracy. I have a line bore job to setup this week, it will be done in the lathe too. The Lathe is such a versatile tool, Cheers!

[@HaxbyShed]

Hi Larry I think those suggestions are good, and would lead me to a workable repeatable solution. Cheers

[@TheAyrCaveShop]

LOL 20:37 There is a gravitational force that draws any part especially small ones dropped from a workbench or table to the most inaccessible location possible. This has been confirmed many times in my shop.

[@HaxbyShed]

Dean I think it was transmuted to parallel universe and emerged back into the Shop through that wormhole under the Rapidor. I always thought there was something strange about that machine ..... 😬

[@Warped65er]

Interesting threading technique, thx for the vid.

[@HaxbyShed]

Still more to do to perfect it but I think I could make it work with a couple of modifications. Cheers

[@stephenperry5849]

The line boring tool on Hemmingway Kits has a removable measuring tool, couldn't hurt to take a look and do something similar! Thank you for the video, it's a really interesting experiment.

[@HaxbyShed]

Hi Stephen I just looked at the Hemmingway kits and it looks like a good method for setting the cut. Thanks for the suggestion. Cheers

[@alanremington8500]

Good going, my brave friend !!

[@HaxbyShed]

One of those things you just have to jump in and try because no amount of thinking about it will tell you if it's going to work, or can be made to work. Cheers

[@TheRecreationalMachinist]

Great stuff Paul. A technique to mentally file away, ready to use should the need arise in the future. Thanks for sharing 👍

[@HaxbyShed]

Yes Matt, for when you have to cut 6mm pitch two start trapezoidal thread for a 16mm diameter screw into a nut blank 75mm long through a 10mm hole. (I can't think what machine would need that but it sounds challenging - no point giving an easy example 😁). Cheers

[@ThePottingShedWorkshop]

Great experiment! Results were very encouraging for a first try. Couple of suggestions. Your first cut was bending the bar, so doing repeated spring passes would have helped. Secondly, whenever I grind up little cutting bits like that, the first operation is always to put a flat on the top which acts as a reference for any mounting or future sharpening. Once you get your SG up and running life will get a whole lot easier making things like this.

[@HaxbyShed]

Thank you. I am just begging to think about simple jobs for the SG. Simple because I am a beginner - never used an SG before. So I may start by sharpening tools like chisels and a plane blade to understand the best setups for angles etc. Cheers

[@TheAyrCaveShop]

Interesting experiment...seems easy on paper until tried.. Enjoyed , quite the effort Cheers....

[@HaxbyShed]

Dean it did leave me feeling "why am I doing this?" but it was a good feeling when it almost worked (and I think could be made to work). Cheers.

[@jonsworkshop]

Good proof of concept Paul, you are a braver man than me. These type of setups at this size are in the book of "well, we have tried everything else and have run out of options". But it's good to prove that where there's a will, there's a way. I think with some further modification and iteration, you would be able to make this work. A valuable reference for others, so well done for making this video! Cheers, Jon

[@HaxbyShed]

Hi Jon, I hope all is well. I think I could make it work by 1) putting a hex on the chuck end of the bar so it can come in and out without losing registration; 2) using a bar which is the same size as the hole in the (to be) nut I want to thread but cut a scrap channel along the bar in line with the cutter for the swarf to exit. I'd put a 99% chance on that working. The rest is just care in setting/advancing the cut depth. Cheers

[@lv_woodturner3899]

Very interesting experiment. Thanks for sharing. A LOT of work to try this out. The result was better than expected based on the awful noise. Very well done. I have a lot of wild life roaming across our property. Just before watching this video I looked out the window and saw a red fox running across the lawn with something it caught in its mouth. Most wildlife is during the night. Back in late Feb I saw some unusual scat (animal poop) so purchased a trail camera which takes pictures based on motion detection during the day or night. For night it has Infrared LED's to capture the pictures. These are black and white but very clear pictures. Daylight pictures are normal colour. My friends assure me the scat was black bear scat, but so far not signs of bears, just plenty of does and a young buck. I know we have other animals such as possum, raccoons, skunks etc. but so far they have not triggered the trail camera. Interesting to see the thermal camera showing the roosting bird. Dave.

[@HaxbyShed]

Hi Dave, around here the wildlife is limited. Pidgeons and garden birds. Hedgehog maybe. The occasional mouse. Might hear an Owl sometimes. Plenty of domestic cats. The threading bar sound was awful wasn't it. I got a sickening feeling at that point but all you can do is let it run to the end and check the damage afterwards. Cheers

[@TheKnacklersWorkshop]

Hello Paul, A really interesting experiment. Enjoyable viewing, thank you. Take care. Paul,,

[@HaxbyShed]

Thanks Paul, hope all is ok. Cheers

[@TheKnacklersWorkshop]

@@HaxbyShed All good thanks...

[@pvtimberfaller]

I can see a couple things right off. The small dia. bar doesn't bother me as much as the length, I think you might be able to use a larger dia. on the chuck end and neck it down. The thing about hardening the bar to get a better grip on the tool is total BS, if anything it will make it easier for the tool to slip out and your heat treating technique is pretty much guaranteed to make it warp. the only advantage is it might be stiffer and it will wear longer. your drawing shows the cutting edge of the tool past the center line, it must be on center when cutting threads. Look up Dave Gingerys book on building a metal lathe for a depth setting jig for the tool. When using the boring mill at work I just leave some drag on the tool and gently tap it out using a dial indicator. Cheers

[@HaxbyShed]

Hiya pvtimberfaller, I like the idea of necking the bar. If I were doing it again now I would use a bar the same diameter as the hole but cut a scrap channel along the length to extract the swarf. That way the nut supports the bar and stops it flexing. I tend to agree about the hardening myth. Silver steel is pretty strong untreated and the heat treatment just gave me distortion. And yes tool point height was too high - agree it needs to be close to the centre line. 3/16 tool dia is 'large' in a 9mm dia bar so I would have to get the C/L height set in the tool grind geometry. I'm 99% sure I could get it to work next time. Maybe have a roughing tool bit then a finishing tool bit. Sounds like a lot of work but it would be less work than the darned tap I made! Cheers

[@coplandjason]

Very interesting Paul and you certainly proved the concept, with jobs allowing a thicker bar there could be room to perhaps allow a grub screw behind the end of the cutter to better control depth of cut but otherwise just measuring the stick out is probably all you can do.

[@HaxbyShed]

Hi Jason, I think I'm 80% there with it. A couple of mods and I think I would make it work reliably. Cheers

[@spikey2740]

To reduce bar deflection, consider using a sleeve/collar to barely slip over the bar from the lead direction and small enough to pass through the workpiece. It won't get in the way of the shavings if used only on the lead end. Glue it on to make for easy removal when done. As for the collar exiting the workpiece ahead of the cutter, I'm not sure how to keep the bar from deflecting as cutting continues. Workspace is very tight, or I'd suggest a steady/follower rest if that's possible

[@HaxbyShed]

Thanks Spikey, these suggestions added to my data bank. Cheers

[@dougl892]

Very impressive experiment. With all the boring bar work I have done, I did get to thinking if threading was viable. I believe you have proven the concept. I completely get the challenges of hand grinding such a small tool and heat treating your boring bar for improved stiffness. More success was only limited to available equipment, and wouldn't we all like better equipment in our home workshops !!

[@douglasbollinger8678]

From what I've been reading, the Young's modulus (elasticity) of the metal doesn't change with heat treating while the hardness does change. I'm assuming that deflection via elasticity is what we are most worried about with a boring bar.

[@dougl892]

@douglasbollinger8678 ah yes, thanks for that.

[@dougl892]

My apprentice master always claimed that surface hardening improved torsional resistance, but of course I was always too intimidated to ask how ha ha. Please persist if you are able, because I feel you are close to a good answer.

[@HaxbyShed]

Hi Doug, I think I could make the method work with some changes people have suggested. I won't try just now but if a suitable project comes up I may put the time in to get it working fully. Cheers

[@kcraig51]

What about heat shrinking a bushing on the bar in front ( or behind?) of the cutter .001 or so smaller than the bore to ride the minor diameter to reduce the flex?

[@HaxbyShed]

Hi Kcraig, yes a bush may help but there does need to be a way for the chips to get out. I'm thinking a thicker bar with a scrap channel cut along the length maybe. Cheers

[@kcraig51]

@@HaxbyShed bushing in front. The chip will stay behind. Blow out after each pass.

[@jonedmonds1681]

For a lower tpi I would not cut full width, I would cut the right hand side surface, then advance z until width is cut. Use topslide parallel to bed, (using a narrower than full profile cutter). Also you need more clearance on top of cutter if you center it in the bar, rather than having top surface on centre. Hope that helps.

[@HaxbyShed]

Hi Jon, I think you are right. I could just about cut 8tpi in that nut with a 1/16 cutter going straight in but there would be no chance with a bigger thread like 5tpi straight in. Cheers

[@kooldoozer]

Very very very interesting video. Thanks. ----Doozer

[@HaxbyShed]

Thanks Doozer, bit of an unusual technique but has possibilities if the nut you want to cut is very long. A viewer mentioned he needs to make a new nut for a 1inch screw, 2tpi, 2 start, 10in long. But I guess maybe with a 5/8 or 3/4 diameter boring bar it may be rigid enough for that extension. Cheers

[@kooldoozer]

@@HaxbyShed You know, some HBMs have threading capability. I guess this is pretty much the setup they would use. ---Doozer

[@HaxbyShed]

@@kooldoozer Took me a minute there Doozer but I've got it now - Horizontal Boring Mill. I've seen them on videos but never got up close to one in person. They look like a very interesting machine, and yes I understand your point thanks. Cheers

[@Koptokaf]

Introducing the tedium and terror of line boring threads! Sweeping the tip of the cutting bit with an indicator and tapping in the depth of cut is the common practice for this sort of operation. It works quite well, to be honest, but having a threaded advance (your first concept drawing) is much more controlable. A tip for this approach: Choose the finest thread you possibly can for the cutter advancement screw. It helps with making fine adjustments, obviously, but the hidden benefits are myriad. The integrety of threaded connections is generally assured by the engagement of 3 full threads, for example. Thus you need less material on the back of the cutter for the screw to function properly. Anyway, loved the experiment. All the best /G

[@HaxbyShed]

Hi G, the great thing about KZbin is no matter how unusual the idea somebody will have experience to share and help. Thank you. 👍

[@roylucas1027]

You’re like an English Mr. wizard. Thank you.

[@HaxbyShed]

Hi Roy I had to look up Mr Wizard - interesting guy. I take it as a compliment, thank you. 👍

[@henrikhv5084]

Hey Paul. According to, at least one former US president. You do the best you can, with what you got, were you are, at the present time. (I hope, I got that right). So a kurt vice would be nice to all of us, you dont got one, and neither do i, but we get along. And you, my freind, you do very well, if i may say so 🙂 thank you, and cheers from Denmark

[@HaxbyShed]

Hi Henrik, thank you. In my observation some people become paralysed by an imperfect situation. "I can't do it because I don't have this or that, and then this might happen, and somehow the project will fail, and it will be like I never should have started". I think it is best to just do something, and learn something, and then somehow the job just gets done. Cheers

[@philhermetic]

Hi Paul, I think that would improve no end as the thread diameter, and thus the boring bar, got bigger in diameter. That worked, but without a method to put on a max of 2thou cut it is too much for the diameter of the bar, even if hardened full length. In a factory setting a tapping machine would be used, with a graduated tap similar to the one you made! That was an excellent proof of concept though, and a good result, and an enjoyable watch! Always liked Sony gear and two cameras linking up like that is ideal. When I used the GoPro it could be controlled with a smart phone which was good, but that is much better! Phil

[@HaxbyShed]

Hi Phil, the Sony cam can be controlled through a smartphone app but in a limited way. The disadvantage is it causes the camera screen to blank so you can't see yourself in selfie mode on the cam screen (you can see what you are videoing on the phone but not from the inverted cam screen). When talking into the cam you want to be looking at yourself and not looking down at your phone screen. Cheers

[@georgegeorgakopoulos5956]

Tried this some years ago,making a cross slide nut for my boxford lathe. First try was a disaster. Then i tried to do it in steps,first cuts with 60° tips,last cut with the trapezoidal tip. Turned out to be a good fit,but the time i spent i could have made a trapezoidal tap...

[@HaxbyShed]

Hi George, if you watch my videos making a 5/8 5tpi RH tandem compound ACME tap (vids HS238-240) you may reconsider whether it would be quicker. 😁 Cheers

[@PioneerRifleCompany]

Make two brass or, preferably, oil-lite bronze bushings that go directly before and after the tool bit. Those bushings need to be wide enough to span three threads. Their I.D. should be snug on bar, with an O.D. about 0.001" under the minor diameter of of the internal thread you are cutting. Those bushings keep the bar centered and reduce chatter. You can use bearings if your internal thread dimensions match up to a commercial spec. If the bushings don't fit snug on the bar, you can always cut snap-ring grooves to hold them close to the bit.

[@HaxbyShed]

Thank you 👍

[@graedonmunro1793]

G'Day Paul ,,, i thought this was a good effort and worked well!!

[@HaxbyShed]

Thanks Graedon. I'm pretty sure now I could make it work properly with just a couple of refinements. Cheers

[@davidmartin3080]

We were taught to use a DTI on the tip of the tool when line boring. It's messy and frustrating but works.

[@HaxbyShed]

Hi David I can see that would work, with care. I would improve the method to maintain the index so I could take the bar off the lathe to set the cut on a surface plate or similar. Cheers

[@peternedsmith]

I bought one of those 6" vevor vices, wasn't expecting too much, had to scrape the bottom and top rails flat, fortunately the fixed jaw was at 90 deg, but on first use I was surprised it produced a square block, you can steal a tip from a kurt, if you machine the bottom of the moving jaw near the front for two 12mm O rings, one either side, leave them proud of the bottom by 0.020", refit the jaw, and pull down with the small adjusting screw till there is 3 to 4 thou gap between the jaw and the rails, when you tighten something in the vice it will pull it down on to the parallels, no need for hammering down, the only thing I have against it is it is very soft material

[@HaxbyShed]

Oh righty Peter, I will think about that suggestion. I need to come back to the vice anyway to machine the tramming keys to fit my half inch T-slots. Oh and fix the wonky pivot on that handle. Cheers

[@SeanBZA]

To extend the bar you can make a slightly larger diameter end that is a press fit for the bar, so that you get a thicker bar each end. More rigid, and even if the rod is flexing so long as it does not touch that is your cutting force.

[@HaxbyShed]

Yes Sean I agree the bar does not need to be so thin before the cutter, and maybe to some extent after so long as there is room for the swarf cuttings to get out. Cheers

[@Throughthebulkhead]

You could put the bar between Centre’s and then after the cut you could pull the bar out after the cut and reinsert it after running the carriage back. Delrin bushings to pilot the cutter would help. If you had a narrower cutter you could then widen the cut with the compound sitting parallel. ( you would have to correctly index the bar going back in between centre’s. Large acme threads are done by widening the cut with a narrow cutting tool. These could also be applied to the boring bar to reduce deflection from the cutting forces

[@HaxbyShed]

Hi throughthebulkhead, yes I agree with all of those suggestions thank you. Now I've had a go at it I'm sure I could make the method work, next time. Cheers

[@camillosteuss]

We literally have the same pair of callipers... Same design, same crack in the screen, it`s just that mine don`t work anymore for some reason... Tried fiddling with them, but to no avail... Still have them - I`ve been considering grinding them into a sort of an adjustable parallel... Or grinding attachments for them for threads on the inside of the jaws and grinding the jaws again parallel on the outside for micrometer reference... Cheaper and more versatile than a thread mic set of 5, when i can use this and my regular mic set to span the ranges... Other attachments could also be made for grooves and similar hard to measure nonsense geometries... I on the other hand expected this to work, the line boring i mean... Why not, it`s the same principle, just in reverse from the ordinary toolholder approach... I generally like this approach to boring bar making, tho mine are for ordinary setups... And yes, any boring bar that is less than 14mm dia is a nightmare... No room for a rear setscrew to drive the nib forward... Tho, regarding hardening, i`m not sure, mine are stainless steel rods and they have not failed yet... And they aren`t hardened, nor can they be hardened - being inox... Now some inox can be hardened, i know, but these rods aren`t... The only thing that can fail due to lack of hardening is the threads really in the cross screw hole because those see some proper cranking and often during use... Either way, there is no better tool to make if you have the tendency to break small taps and drills... Also work great with a pcb carbide drill set - just grind the drill sections off and make a carbide nib with a flat for the screw... Savage performance can be had with those... Some really fine carbide is used for those drills and it comes in 10 packs for cheap... And the broken taps are there anyway, so why not use them... Both pcb drills and broken taps also act as amazing locating pins - being precisely ground and hard af... Not great as high load bearing pins at that size, but precise location for setups, oh yeah... Best regards! Steuss -edit/ps- Nah, that was a crackhead up in the branches, i know what a bird looks like, this was 100% a crackhead right there, squatting in the branches, waiting to take a steaming shit on the whoever passes right under, i mean, that thing that looks like a beak is actually a crack pipe, no doubt about it... :p

[@HaxbyShed]

Hi Stuess, the crack in the callipers screen came from my lathe clutch lever (the callipers got caught under the lever). I'm not sure the bar really needed to be hardened - I just followed the suggestion from a viewer. In fact next time I would just use high grade steel without hardening, to avoid distortion. I need to make more use of broken drills and broken taps as cutting tools, but I don't break many 😁 Cheers

[@camillosteuss]

@@HaxbyShed I don`t break all that many either, but i picked up a 10kg pack of broken taps on the scrapyard, so with that, i`m set for good... And i still will break many more myself through the years, so there`s that also.. Sure, just going with a good piece in the first place is a great option... Hardening is really more of a full blown triple course meal... Machining oversize, hardening and grinding thereafter... And that is much more of dedicated job that kinda requires a design not intended for a single time use tool, not with all the effort involved... Best regards!

[@paulrayner4514]

I think your proof of concept worked. re cutter depth just use a mic with a gauge block to increase the cut. that's what I do with my cylinders.

[@HaxbyShed]

Thank you Paul.

[@yelims20]

cut three flats with a shoulder on the bar, then you can remove and replace the bar in the chuck without losing your place. set up a v block and indicator on the surface plate, that will allow you to adjust your cutter.

[@HaxbyShed]

Yelims, I think that's the best idea. I can see that working well. I need to look out for a cheap heat treatment oven so I can harden and temper the whole length of the bar and that would stiffen it appreciably. Cheers

[@swanvalleymachineshop]

Good one Paul . I wonder how it would go with a support bush on the bar as it goes through the bore . Cheers 👍

[@HaxbyShed]

Hi Max, thinking about that, any bush would still need to allow the chips to escape. That would be ok if the bush was leading the cutter (bush goes in first) but by the last turn the bush might be out and the bar free to bend. But now my brain ticks over and an idea might be to have a bar the same diameter as the hole in the nut (so the bar can't deflect) but have a slot along the length of the bar in line with the cutter so it forms a scrap channel. I think that would work. Permits a thicker bar and the bar is supported by the nut during the operation. ta-daah 🎺🎺😁 !

[@MatthewTinker-au-pont-blanc]

Interesting! I've thought about this technique for an up and coming project, I have to cut an internal 2" square, 2TPI thread 10" long nut for a leg vice! I can make a 35mm diameter, 300mm ish stick out boring bar, which should work, but I might need to try your method to overcome chatter and cut a decent thread in a home made Al Bronze casting! Cheers, Matthew

[@HaxbyShed]

Hi Matthew, you have got me thinking now about 2tpi, 2 start. I wonder if ........... ?? Cheers

[@MatthewTinker-au-pont-blanc]

@@HaxbyShedSingle start 2TP, 2" square thread ! It's 30 cm long. Two options either your boring law technique which is not easy to mount the work on the carriage, or, mount a very narrow parting profile tool on an internal boring barin ithe carriage using the top slide at right angles to increase the wdith of cut and the cross slide to increase the depth of cut. I've made made the split form and the sand cores to cast an Al bonze nut blank. Al bronze is an unknown quantity, I've been casting Al and Zamac for 20 years, but so for no copper alloys ! Lot's to think about! Cheers !.......

[@StuartsShed]

Looks like a very promising approach. Yes needs refinement - but the approach looks good.

[@HaxbyShed]

Hi Stuart, a couple of ideas from viewers would improve it: 1) put a triangle or hex and collar on the chuck end so I could take the bar out and set the cut carefully on a surface plate in V Blocks, 2) increase the size of the bar to the size of the hole in the nut but make a scrap channel along the length of the bar in line with the cutter so the chips could get out. With these too changes I'm 99% sure I could make it work. Cheers

[@aidannolan6656]

Loosing small parts 😮..! Reminds me… I must give the shed floor a good sweep. A while ago I was fixing my daughter’s laptop PC on the dining table and dropped a tiny screw - I heard a single ‘clack’ but no other sound, so I was convinced it hadn’t gone far. I ended up taking a photo of the inside of the laptop and went over every millimetre of the picture looking for this damn screw… I eventually found it stuck to one of the magnetic speaker cones. Now… where’s that broom…?

[@HaxbyShed]

Oh yeh Aidan, that sounds about right. My method is not to take my eyes off the falling part until it stops rolling. If I lose 'eyeball lock' on the escaping part I'm doomed to spend ages on my hands and knees hunting in all the wrong places. Cheers

[@lawrencewillard6370]

Going to be trying to make LH acme thread crossfeed brass nut. Interested to see what you do. Mine is only about 40 mm long, so easier, hopefully. Thanks for this.

[@HaxbyShed]

Hi Lawrence, hopefully yours will be a sensible TPI for the size of screw. All this kicked off because I had to make a tap to cut 5TPI ACME on a 5/8 diameter screw for my Herbert surface grinder saddle. 5TPI is a course thread for 5/8 - that would more normally be 8TPI and much easier to do on the lathe with a threading bar coming in from one end. The 'tapping hole' for 5TPI was only 11.5mm and even that was generous. According to the book it would be more like 10.5mm. Cheers.

[@colincreedtattoomachines]

If looking for examples of "how" you might set & adjust the cutter depth, have a look at how Kurtis from CEE (Cutting Edge Engineering) in Australia is adjusting his cutters when doing the "line boring". Granted everything he does is on a far larger scale but you're looking for viable examples & inspiration on "how" it might be done.

[@HaxbyShed]

Hi Colin I'll do that. I know the channel. Thanks for the tip. Cheers

[@andrewdalgarno5322]

I might have started with a larger hole (a couple inches), larger diameter line bar (1" +), etc to make it easier to prove the concept before trying such a small internal thread. But well done Paul! Line boring on the lathe, I have done. Line threading? Line bore threading? (What are we calling this technique?) is not something I have done. But now I'm interested in trying! Andrew

[@HaxbyShed]

Hi Andrew, I started with 11.5mm hole because that was the 'tapping hole' I used for 5/8 5tpi ACME when I made/used the tap. I think if I started with a larger hold people with just say use a simple threading bar with an insert - "why are you making it so hard for yourself?" You can say stuff like "pretend this hole is only 11.5mm" but people maybe don't hear that especially if they are skipping through the vid. Cheers

[@mapp0v0]

Good day to you

[@HaxbyShed]

... And good day to you too Matthew.

[@kingy550]

I wonder if adding the travelling steady into the setup would help reduce the threading bar deflection? Excellent experiment though.

[@HaxbyShed]

Hi Richard, I wondered about a travelling steady too. There might be some milage in that idea. Cheers

[@reamer1363]

Could this be done in a four jaw between centers with a fixed stop in the chuck for bar to come against so no linear movement and using the chuck as your adjustment and a dti as your control. I guess start with your tool preset and slightly longer bar to allow for clearances.???? Nice video thanks.

[@HaxbyShed]

Hi Mr Reamer, yes I think somehow the bar has to come out to set the cut, then it's just a case of finding the right index method to get it back but keeping the thread registration. It's possible, I'm sure. Cheers

[@skysurferuk]

Interesting. Also that's a Starling.

[@HaxbyShed]

Hi yes I thought maybe Starling or Thrush. It must be about the only tree around here without a Pidgeon in residence .... Cheers

[@SW-qr8qe]

The bar needs tension to stiffen it. Could it have a thread and pass through the tail stock, being supported by a thrust bearing behind ? It’s a bit much and would reverse the normal thrust on the chuck. Idea improvements welcome.

[@HaxbyShed]

Hi SW, yes maybe the bar could be under tension. A viewer suggested tungsten carbide bar, much stiffer, but I do not know if it would be workable. Next time I would use a bar the same size as the hole in the nut but cut a scrap channel along the bar to extract the swarf. That way the nut would support the bar during the process and stop the flexing. Cheers

[@chrisstephens6673]

Now that you have that out of your system, conclusion possible but at this size impractical(?), have you thought about making a boring bar ftom tungsten carbide. For a given diameter it is 3 times stiffer than steel, of any hardness, and excellent for boring bars. I made a boring bar for cutting trapezoidal threads using 10mm TC bar with a hardened steel tool holder loctited to the end, it worked admirably. I was cutting a 20 by 3 backlash adjustable nut but could have made the end smaller if needed. TC bar is quite cheap on ebay these days in 4 inch lengths. Just a quick calculation (very late st night) shows a 10mm TC bar is as stiff as a 17mm dia steel one.

[@HaxbyShed]

Hi Chris, I did not know about the stiffness of tungsten carbide. Thanks for the tip. Cheers

[@mikegregory460]

run the cutter out then loosen the fixing screw and pull the cutter out completely then wind back to start and insert the cutter again with a bit more cut using the back screw

[@HaxbyShed]

Thanks Mike. 👍

[@peterfitzpatrick7032]

Instead of constantly backing the "insert" off when returning the carriage, loosen the clamp screw and remove the insert, then re-install it on the "other side"... 🤔

[@HaxbyShed]

Hi Peter, after more thought I favour making an index on the bar (e.g. a hex on the chuck end) and maybe removing the bar between cuts. Then I could set the next cut with a gauge on the surface plate perhaps. Cheers

[@markmckenna1353]

could you put the cutter in a blind hole and shim it out the required depth of cut increment?

[@HaxbyShed]

Possibly so Mark. Thanks 👍

[@dennisbjones]

The bird was sure that you were there too.

[@HaxbyShed]

Hi Dennis, the bird was so still so yes perhaps. I wondered where all the birds went at night. Cheers

[@dennisbjones]

@@HaxbyShed yeah, I think it was passing bricks as you were talking near it 😭

[@engineering_noob1260]

assuming your chuck allows it, why not just run the lathe in reverse to retrieve the bit? this would make the bar shorter As Preso says below - there are tools for line boring that can measure the height of the bit - Curtis uses them to advance the cut

[@benjo233223]

The tool needs to be removed because of the backlash in the gear train, the cutting tool would not line up with the thread it just cut and more than likely break.

[@HaxbyShed]

Hi yes backlash in the gear train is the problem - the cutter does not follow the same path in reverse. Cheers

[@jaybailey3518]

You would have to use your dial indicator to advance the cutter in very small increments, possibly .001" per pass, with many spring passes after.....buy a tap !

[@HaxbyShed]

Hi Jay, I agree it is very difficult to set the cut whilst the bar is in the lathe. I made a tap actually and it took me forever, it was a lot of work, and somebody said the boring bar method would be quicker (hence the experiment). I think I could make the boring bar method work with some changes. Cheers

[@bin_chicken80]

Nice work. Great to see a different approach. No meth heads found 😂

[@HaxbyShed]

Defo no meth heads, though that bird did look like it was up to no good if you ask me. 🙄

[@carlwilson1772]

I wonder if a traveling steady would have helped.

[@HaxbyShed]

Hi Carl a travelling steady might have helped. If I was doing this again I would make the bar the same diameter as the hole in the nut but make a cut-away along the length of the bar in line with the cutting bit as a scrap channel (so the chips come out along the bar line a trepanning tool scrap channel). That way the nut itself would support the bar to stop it bending. Cheers

[@timogross8191]

650 Pounds for a vise! You would need a forklift 🙂Or at least some sort of jib crane? 21:07 how do those small parts allways know were to roll to end up under some furniture or machine? A lot of food for thoughts another project for "the list".

[@HaxbyShed]

Hi Timo, yes it does sound strange to have pounds money and pounds weight, but think about it we also have degrees temperature and degrees angle - I did not even notice that until somebody pointed it out to me a few days ago. There were two little cutters in the pot and as they fell off the table my eyes tracked one but lost the other. My brain can only track one target at a time ....... multitasking not possible. Cheers

[@terrygreen5225]

Should have contacted Tracy Tools and see if they had a tap ,just a thought

[@HaxbyShed]

Hi Terry, I bought some drills from Tracy Tools recently. I know them. Cheers.

[@Rustinox]

For an upcoming project, I Need to cut a 1mm pitch theaed in a 9mm hole. I don't know how to do that but this could be an idea.

[@HaxbyShed]

Hi Michael, now I know what the project is. You probably know you can get taps for 10mm x 1.0mm super fine thread maybe Eur 12 to 15 max. But who wants a tap if you can develop and demonstrate a new skill? 🤣 Cheers

[@shootgp]

As small as that cutter is, making a whole set shouldn't take that long. Rough cut with 55° or 60° before moving to the acme form. Progressively longer/deeper cutters would allow for controlled cut depths without the need to fiddle with an indicator or micrometer. The 55°-60° rough cutters at that size would only take a minute or two on the grinder....

[@HaxbyShed]

Hi Shootgp, yes when I have finished the renovation on my surface grinder making a set of cutters will be a lot easier. Making thread cutters by free-grinding on a bench grinder takes forever with a high chance of messing up. That's why I was very reluctant to butcher that 5tpi ACME cutter, which I spent a couple of hours grinding up to get it right. Cheers

[@erlinghagendesign]

couldn't you just make 3 or 4 cutter inserts in target lengths and just make their backs flush to the rod with each step of cutting ( all on the left side )? it will keep the whole rod length shorter and don't need to try to fiddle with the set screw on the right side

[@HaxbyShed]

Hi, I think that's a good idea but viewers have pointed me towards these between-centres boring bars which have a tool setting fixture and that looks like a good idea also www.hemingwaykits.com/HK1020 Cheers

[@erlinghagendesign]

@@HaxbyShed maybe a misunderstanding: I didn't mean to avoid the centre boring bar. Just to make several cutters and just change the cutter with a simple method of adjusting, instead of trying to adjust 1 cutter, which is very difficult in such a tight space.

[@HaxbyShed]

@@erlinghagendesign ah yes I see. 👍 Thanks.

[@user-gl5kj1fm5x]

Hedgehog Cam?

[@HaxbyShed]

Yes there is potential. Move over David Attenborough. 😁

[@TalRohan]

these seem to be very cramped tolerances youre working with..and that camera system is very nifty I don't think anything is getting across your garden unnoticed with the heat sensitive cam...not even a meth head

[@HaxbyShed]

Hi Tal it's a common problem to cut a deep thread through a small hole. I think I could make the boring bar idea work ok with a bit more development. The thermal cam gives a completely different view of the world, and hidden things become visible. Cheers