Parting off tool problems ?

[@WilliamChitham]

I had similar symptoms on my Boxford and though I wouldn't say I'm 100% confident parting off now I seldom now resort to the hacksaw. Biggest improvement came from tightening everything - spindle bearings, carriage lock, topslide gibs and most of all compound slide gibs which I lock up solid for a big parting op. I can understand why people replace the compound with a solid block. Cutting fluid makes a big difference as well and I have become quite ambidextrous winding the cut on with my left hand and oiling with my right. Once the cut starts it definitely pays to keep it going at a steady rate. The other thing is using a narrower parting blade. I used to use 1/8" HSS then 3mm carbide but now use 1.5mm HSS or 2mm carbide - less tool pressure = less flex = less chatter.

[@jagboy69]

THIS!!! 👍

[@reamer1363]

I've got an old cud model boxford and can part using a 4mm wide tool and reasonably no chatter, slow and steady with plenty of cutting oil wins the race. I also have an old 3 jaw, a little bit of a bell mouth but I wrap a thin piece of pad paper around my work before I start an this evens out the contract pressure from the jaws on the work especially on any form of black bar stock. Seem to work well for me when turning thinner bar and parting.👍

[@WinkysWorkshop]

Interesting video. I have been exploring problems with cut off for years. That doesn't mean I have all the answers but I have discovered how to successfully cut-off the first time every time on fairly small lathes where rigidity is usually an issue. The first thing I noticed in the video was the enormous overhang on the chuck (distance from the spindle bearing to the work being cut). If the lathe has less than a 2" (50mm) spindle this will likely cause problems. Reducing overhang is often overlooked and always helpful when minimized. The very biggest issue with cutoff on any lathe is the tool grabbing and being pulled deeper into the stock. This is because the "Point Of Flex" (tool post, compound or gibs) is below the centerline of the stock. Things that help are tightening the gips on the compound, centering the tool over the top of the compound, eliminating the compound or eliminating the tool post. I made a very simple direct mount blade holder that worked perfectly but I didn't like the fact that I had to remove the tool post. The other side of the equation is to minimize the load with tool grind, or switching from carbide HSS. HSS will usually be much better. The OTHER OPTION: Change the "Point Of Flex". This was done back in the 1930s (approximate date) by both Armstrong and Williams. They made a tool that was somewhat flexible above the centerline of the stock so that when the tool tried to grab instead of diving into the stock it pulled away. This was for the old lantern style tool post. I made one of these "spring cut-off tools" for a quick change tool post, AXA and BXA. In fact I have made several versions and perfected it. I now cut-off at the calculated speed for HSS at the largest diameter with a feed rate of .002" (.05mm) pre revolution. Sometimes I slow things down just to avoid slinging oil. Cutting a 50mm bar at 200 RPM with auto-feed is never a problem. The only requirements are a good supply of oil. Let me know if you want to know more.

[@tinker7508]

Hi I have similar problems with parting off. I found that tapered parting blades can easily be fitted with the taper uneven either side of the blade effectively removing the clearance angle on one side of the blade (so rubbing occurs). Also thinner blades work better.

[@MartinE63]

Tighten up all gibs, saddle, cross slide, top slide, more preload on headstock bearings, lock the saddle to the bed, new belts, tension the belts. Then look at tool geometry, if persisting with HSS then add side clearance to improve chip evacuation. You should be able to part free cutting mild steel 3/4” dia at 1000rpm

[@ianbertenshaw4350]

I don’t grind the top of the HSS blade - I leave it flat and use the blade horizontally so there is no back rake as I found the positive rake created by grinding the top tends to pull the blade into the work -especially on small machines . All my parting off is done below 200 rpm and I use WD40 as a cutting fluid as I spent a weekend destroying parting tools to find what works best for me and that was WD40 - even on steel ( RP7 won’t work - don’t know why but it just made the jam up worse ). Chatter can be from too much speed , not enough feed ,worn chuck jaws , loose spindle bearings , excessive chuck overhang ( running adapter plates behind the chuck can magnify this ) ,poorly adjusted cross and or compound slide gibs , worn cross slide nut or screw - excessive end float ,too much tool stick out or a combination of any of these . If you take a look at winkys workshop channel he did a few videos trying to sort the same problem out - some good info and ideas on there ! I actually got to the stage where I was considering mounting a battery powered band saw on a sliding rail to my lathe so I didn’t have to part off at all !

[@ianlainchbury]

My 3/32" gives me no issues while parting, even on my little 7x12 Chester DB7. The grind is like a normal tool back rake though...no hook on the end. 180 rpm and lubricant... works well.

[@sonsofmachinery2983]

I had identical results with my Atlas 10F. After a year of chasing vibrations it was finally the spindle bearing preload that was the issue. I had experienced that same sound and faceting that you are experiencing; it was awful. After everything was tightened the lathe parted off beautifully. Good luck. Cheers.

[@jagboy69]

I still didnt see any spectacular parting off operations. The job got done eventually, but it wasnt without hassel everytime.😳 I'd be inclined to measure headstock bearings and take a hard look at the carriage and tool post. All of us are running multi decade old machines and they simply arent tight enough as they were when new. Eliminating the compound altogether helps, but comes with its own limitations.... The saga continues.🥺

[@David-hm9ic]

After the cut is completed at around 14:10 you mention that you're not sure why the tool got below center. Going back to 9:00 take a look at the clearance between the left end of the carbide bit and the circular opening in the holder. At about 9:13 the bit encounters resistance and is pushed deeper into the holder. This happens several times over the next minute and by the end of the pass the bit seems to stabilize in the holder. I think that's where it's getting below center. Was the tool re-centered after changing the bit around 10:25 or did the new bit also get pushed deeper into the holder?

[@TheKnacklersWorkshop]

Hello Alan, Good video... I am starting to record in a notebook what works for my machines, speeds, feeds, material, cutting tool... although books like the engineers black book and machinery handbook give you pointers I think when running older machines it better to know what works in your environment and have the information to replicate it next time. See you next time. Cheers. Paul,,

[@smallcnclathes]

Hi Paul, that is the advantage of making a video, it is all there for you to check what you did last time. I have often used a video as a "how did I do that" reference

[@secondarymachine7521]

I had a similar issue with my first Atlas lathe. After correctly adjusting the spindle bearings (which were a bit loose) the tool worked really great..

[@daveharriman2756]

Very interesting, parting off has never been my favourite task. , it seems to be very crytical the tool height and correct rake, and of course the speed, the smaller the dia, the faster the rpm, I've seen some folks part off from the back, (tool upside down) I'm yet to try this method to see if it cuts better, anyway, enjoying your vids, cheers, Dave

[@raymondsanderson304]

Just watching you use either parting off tool and 1 No cutting fluid means it is grabbing 2 Your tool post is loose and moving during the cut. It actually tilts down toward the lathe bed, this will mean that it is no longer vertical to the side face, the cutting tool is now rubbing and the tip is not square to the job.

[@daveharriman2756]

One more thing I have to know, your handle 'Enot', anything to do with the old factory? when I was an apprentice in the 60's we went on a works trip to the Enot factory in Birmingham, amazing place, not all automated at all, very noisy, loads of Ward capstan lathes, mostly of women operators churning out thousands upon thousands of brass fittings, always remmber that, a great trip out, cheers, Dave

[@enotsengineering]

Hi Dave No I don't have any links to the factory, but like you I visited the factory when I was an apprentice at Austin Rover we had a trip to Enots.

[@petepaine5331]

Of course enots was was Stones

[@bobwilliams7343]

if you are using a tapered parting blade by grinding the tool the way you have the width of the blade at the cutting edge is narrower than the top of the parting blade and so the blade is binding as it moves into the cut

[@hoernst2762]

Hello Alan, nice presentation when parting. I mean a 3mm parting blade is too wide for a lathe of this size and only suitable for industrial machines, so too much pressure is exerted on the workpiece. At 1.5 or 2mm it could look completely different.

[@sidewind131258]

Okay ? I just 2 hours ago parted off in my Boxford AUD mk III wih the same parting off tool, Sounded like a pig the first 2mm but the rest, up to the 25 mm I had in the collet just got off as easy as putting a hot knive thru warm butter. The difference is that I run at full tilt and with a fair amount of pressure

[@Stefan_Boerjesson]

Squaring the part off blade like that gives me problem as well. I square up the blade itself, towards the chuck and the result is great. Adjusting the gib screws in the compund looks like needed if the blade, the toolpost tends to bow......

[@MrKevinlarge]

Well Alan here is my 2 peneth worth I have a Boxford as well and had similar problems I think a quick change toll post has to much over hang for parting off I find a dedicated cut off bolted direct a 100% better and most 3 jaw chucks keep the work piece to far from the spindle I bet if you tryed your 4 jaw you wouldn't get all that chatter just what I've found by trial and error Regards Kevin

[@piclife1178]

For me, the grind on the HSS blade is incorrect. The blade needs the top grind to produce relief below the tip for the full depth of the cut or the sides will start rubbing and the tool jams in the slot. This is because the blades are not actually flat but taper down in thickness towards the bottom to give side relief.

[@clintchapman4319]

Set your parting tool by aligning it with the end of the workpiece instead of the chuck body.

[@CraigLYoung]

Thanks for sharing!

[@johnmcmillan9374]

I found if go in reverse and parting off tool upside down on small lathes works very well with no problems

[@tonypike5785]

You don’t need to grind the top of the cutter, never seen anyone do that. Try a wedge shape cutter, they have side clearance you need.

[@tonypratt1989]

Lubrication is also very important!

[@bobuk5722]

I use a 2.4 mm (0.1 inch) wide insert in a half inch square shank holder carefully set within a few thou of centre. Disconnect lead screw to set top slide gibs with smooth but no detectable play. Lock all other motions. Use continuous lubrication for most cuts. WD40 on aluminium, cutting oil on steel, none on cast iron. The lathe is turning far too slowly, nerves I suspect. Correct cutting speed for material is important here just as anywhere else. Mine is variable and I wind it up as I move in. Never had any trouble. Yup, really, never! Well, apart from when learning! Cheers. BobUK.

[@grahameblankley3813]

AHHHHH Had to stop the video OIL OIL OIL You must keep oil right down at the cutting edge all the time never let it dry out, tool dead on centre not above, make sure it's all locked down solid, with a sharp tool shouldn't need a lot of pressure, when you master it cutting will be smooth chips with a crispy sound listen to your lathe, oil oil oil, hope this rant helps take care, 🇬🇧

[@MF175mp]

I always part dry 😁

[@rayganter8029]

Get rid of the Sharp angle on the parting tool its digging into the metal fine on ali not steel

[@macgolf1194]

No Coolent ...

[@richardlussier2812]

we just can't hear anything of what you are saying.... too bad, could have been interesting....