Shim material

[YYCHM]

How does one lock the compound?

I have been locking the carriage.

Tool tip height set to tail stock center tip height.

Used a square to align tool to work piece.

100 RPM or there abouts, pretty darn slow. The chips looked good and evacuated the slot nicely.

Applied lots of cutting fluid.

 

[Dabbler]

Parting an be done on the lantern tool post. But improvising with it, well, you see the result. I *think* I have a parting tool holder for a rocker, I'd have to check. (It's been very long since I used it).

For all the parting I've done, the most stable was the 4-way, but I've managed to make my AVA part well, after a LOT of tweaking. (4-way is still my go-to on that lathe)

Robert renzetti removed his compound and uses a solid block where the compound used to be - It improved his parting performance a lot, and his lathe is MUCH bigger... just sayin'

 

[trlvn]

...Robert renzetti removed his compound and uses a solid block where the compound used to be - It improved his parting performance a lot, and his lathe is MUCH bigger... just sayin'

For parting steel on my tiny Atlas 6 X 18, I do essentially the same thing (solid tool post). The tool post shown below came with my lathe. It mounts directly to the cross slide (shown); the compound has to be removed to use it.
It may be ratty and ugly but I've successfully parted off 1.25" steel with it!

@YYCHobbyMachinist rigidity is hugely important for parting off. Plus proper tool geometry and getting on centre. But fixing any rigidity problems will pay off for everything you do on the lathe. Have you been getting any chatter during the parting off attempts?

Another avenue you might explore is 'reverse parting'. The cutter is turned upside down and comes at the work from the far side. Lots of people on YouTude swear this is the least-stressful way to do parting. Or run the lathe in reverse and use the tool from the normal side. This won't work with a screw-on chuck (like mine) since it will just unscrew the chuck from the spindle.

Craig

 

[Bofobo]

Parting is a tricky business, I tried many ground hss blanks ir removing huge areas of material (carbide tool sized) for parting but nothing works like a proper parting tool. Mine was BB cheap, I used the floor model lathe to pick the right sized one and glad I did, it is now 1 of 2 tools “permanently” attached to my lantern tool post and is an hss blade. I trained with carbide parting inserts but prefer the very slight forgiveness of the hss and it can be reformed rather than just shatter apart

 

[Dabbler]

One caution about parting in reverse: some of the smaller lathes rely on the flatway below the dovetail on the cross slide for rigidity. When you are parting in reverse it puts pressure on the dovetails instead. On larger lathes, this is insignificant. On small lathes this can be far less rigid.

The primary way to increase stiffness on the little lathes is to substiture a solid riser for the compound rest.

 

[CalgaryPT]

When I was small my uncle owned an old fashioned printshop with Linotype machines etc., in Lethbridge. All the guys there did their own machining to keep their print machines running themselves. One guy had a mini hacksaw blade in a custom attachment that affixed to the tool post. I think it attached behind the workpiece as well somehow, but I can't recall. I do remember they had to face the part afterwards though. I do very little parting off, but the hacksaw attachment sounds creative to me.

 

[Tom Kitta]

When parting on an old lathe that has a lot of give make sure you tighten the screws that hold cross slide. To test lean back and forth on your cross slide and see whatever there is any movement. On my rather large lathe I can only part when I tighten stuff up. If I do not I end up with broken parting tool holder. What happens is that as you part the tool holder with parting tool will at some point get "sucked in" too deep and break if you have loose slide. The results are broken parting tool, damaged work-piece and sometimes even damaged chuck. Plus it is scary.

For another creative use of a shaper you can add hacksaw to it and now you have power hacksaw.

 

[Tom O]

I’ve never liked using the cutoff blades and use a power hacksaw where ever possible.

 

[Bofobo]

I don’t recommend it but my first good parting tool was a hack saw, turn the machine on and start stroking like a violin bow, RPM’s were low and it was my 7X14 lathe so minimal real danger but I parted a good many parts that way.

 

[Johnwa]

I’ve never had problems with the JT taper not holding but have had the MT slip. One of the suggested remedies that would work for both is to put a lathe dog on the chuck and support its tail on the compound.

 

[Tom Kitta]

I did not put the lathe dog on the chuck as I don't have such a huge dog to put in the chuck in (usually massive monster as well) so I put the dog on the much smaller drill. Works great. The actual taper just needs little bit of help so the dog is not doing a lot of work. The tail-stock is not really the right place to use for some heavy drilling - it is just more convenient then say tool post - which is much better suited to heavy drilling.

 

[Johnwa]

Tom, the dog goes on the drill chuck with the set screw in one of the key holes. It probably only needs a 2” dog.
Ive never used a dog but have used a metal rod stuck in one of the key holes. It works but is a bit dodgie.

I did find this for max drill size for MTs
MT3s range from 21/32" to 1 1/4"
MT4s range from 19/32" to 2 5/8"
MT5s range from 1 17/32" to 3 1/2"
MT6s range from 3 1/8" to 4" (MSC doesn't go any larger, either)
there was also a note that for mt2 the max size should be 7/8”.

 

[Tom Kitta]

Good idea with they key hole - I should have dog big enough for that - next time drill chuck slips in the taper I use it. However when drill slips in the chuck itself (because someone for example turned down the shank) the only thing to do is a dog on the drill bit itself.

The max MT range is probably in mild steel or cast with a sharp drill bit plenty of cutting oil and moderate feed - I seen plenty of sub 2" drills have their drive tongue twisted or broken in MT4. I never saw MT3 in 1 1/4 - I do have 1 1/8 so maybe 1 1/4 do exist.

 

[PeterT]

found this vid, shows most of the parting basics

 

[Dabbler]

I really like Winky's solution to parting on a small lathe. His parting tool is described below:

 

[Chicken lights]

Hey look! Santa was early!

Thanks!

 

[Chicken lights]

Just out of curiosity I measured these ones. I had 8 of them made up for the big truck out of stainless awhile ago. I was interested to see how tight the tolerances were with you guys saying parting was so tricky
Four are on the truck so didn’t get measured. The leftover four two were 0.127 and two were at 0.1265. That’s just my cheapo Lee Valley calipers but anyway I’m impressed. I asked for 1/8” wide which is 0.125, that’s crazy how accurate they got them!

 

[YYCHM]

Just out of curiosity I measured these ones. I had 8 of them made up for the big truck out of stainless awhile ago. I was interested to see how tight the tolerances were with you guys saying parting was so tricky
Four are on the truck so didn’t get measured. The leftover four two were 0.127 and two were at 0.1265. That’s just my cheapo Lee Valley calipers but anyway I’m impressed. I asked for 1/8” wide which is 0.125, that’s crazy how accurate they got them!

Setting up to part off to that tolerance is not difficult, it's completing the cut that can give you grief. The larger the lathe the less likely the grief.