Replace compond with block would you ?

[verbotenwhisky]

If chatter and grabbing while parting off is the reason for wanting more rigidity, be sure to try a good carbide parting tool, and run it hard enough to break a chip. Sounds backwards for a small flexy lathe, but it worked for me. HSS parting tools needed to be run at slow RPM, and fed in agonizingly slow, and it would still catch and shatter the blade sometimes. I changed to GTN-3 inserts, something like 10x the RPMs and a fairly fast feed, and I parted off some 3.5" 1018 as my first test. It still chattered a bit, which is scary at that higher RPM, so I fiddled with it, lowered the RPM a bit and increased the feed until it was breaking chips, and the chatter magically (?) went away. Parted thru that steel in a small fraction of the time it would have taken with HSS, and with less noise and drama. Honestly with my old HSS parting method I would have started the cut then finished it on the bandsaw. Surface finish in the parting cut was pretty nice too! This is with the factory-installed compound. Which I use a lot, and would miss if it were gone.

I've heard the quality of the carbide is important, so I ordered real Iscar inserts and put them in an Aloris holder (71-125-1BSL GTN-3, in an AXA 71). I'll leave it to others to decide if that was really necessary or whether cheap Chinese knockoffs could do the job well enough for the $$ savings. Note there are also smaller/wimpier holders for GTN style inserts — the ones I got are the big skookum ones. Very happy with the results, it's night-and-day better than with HSS
.
My lathe is a 1982 Enco 12", weighs about 600 lb and sits on a wooden benchtop, so this is not a very rigid lathe. Better than a mini-lathe, but still in the hobby range.

I have an Iscar cut off tool also and highly recommend it. Another issue I found is making certain the tool is perpendicular to the axis of rotation, if it is a little off it'll scream...

 

[savarin]

Stuck a solid plinth on my 9x20 with an AXA QCTP, never had a problem with it. It stays on the lathe till I need to turn a taper.
Threading goes in at 90', never caused a problem, even 39x4 mm, parting is excellent, I could see the tool visibly flex with the compound.
Chatter is only a problem with very hard steels so far.
Heres mine

Plinth For Qctp On 9 X 20 Lathe

In my never ceasing search for more rigidity in my lathe I decided to make a plinth for the qctp. In its normal configuration I can often see the complete top slide assembly flex slightly. (I think I punish my lathe a bit) After seeing Bill G's plinth I felt it was time to go. I forgot to take...

www.hobby-machinist.com

 

[XPFTP]

local blacksmith . goin to ask him if he has a 3 by cold roll . see what i can destroy lol ..

 

[hanermo2]

As bulgie said.
Increase rpm and thus sfm to insane levels, and carbide will work really well, and leave beatiful finishes.

I did a 3 mm deep cut on tool steel, at 900 rpm or so, on a very big 100 mm cube.
By mistake.
Scary, but worked really well, with great finish.
Black and blue chips ..

The carbide wont mind, interrupted cut, and I use a heavy 10" 4-jaw on the 12x lathe.
Faster rpm is better, and faster feed is ok (powered feed, servos).

Took the compound off maybe 8 years ago.

 

[dabear3428]

just did it!

MX-600A 9"x24" mini lathe

well i bit the bullet and bought a MX-600A (1100w brushless 8.7X23.6 with a F/R H/M/L gearbox and a 1.5" spindle bore, shipps with a steady rest, a follow rest and a dead center) off of e-bay, after getting it and turning some steel (does a decent job IMO). I got this expecting a box of lathe...

www.hobby-machinist.com