Parting tool recommendation

[DiogenesIIParticipant @diogenesii]

[Sonic EscapeParticipant @sonicescape38234]

Posted by DiogenesII on 05/08/2023 12:21:39:

The center section was cut with a hacksaw?

[DiogenesIIParticipant @diogenesii]

..yes, I ran out of 'reach' – there is nearly as much blade sticking out as there is left in the tool holder..

I can't remember what the cut depth was but well over 30mm using a 19mm 'high' blade. The stock is 100mm diameter.

Just wanted to show that these tools are capable of giving good service under less than ideal conditions.

[KWILParticipant @kwil]

3.5 inch PB parted all the way

[samuel heywoodParticipant @samuelheywood23031]

Hi Sonic.

Something like the 1st picture would be your best bet IMO. I've two different ones which both seem ok for the job.

You don't say for which lathe.

The one Arc Euro Trade sells i find works best in the mini lathe as the blade is a little thinner than others i've seen~ which is kinder on the mini lathes limited power & rigidity.

Regarding parting off on mini lathe, a few tips.

1 ~ never have blade sticking out more than is necessary for the job in hand.~I broke my first blade recently on 10mm silver steel,because i was too lazy to wind it back in after a bigger job .

That made me jump! Blade shattered, good job i had my safety specs on.

2~ make sure the blade is dead square to the work.

3~ plenty of lube if parting off steel.

4~ slow steady cross slide feed & i find around 250-300 rpm works best for me.

5~ lock off everything you can (except the cross slide obviously)

 

Edited By samuel heywood on 05/08/2023 20:24:41

[DMBParticipant @dmb]

Agree with Samuel Haywood, speed for mild steel 200 – 300rpm or roughly half normal turning speed. I have parted off MS dry just to experiment but normally use cutting oil. If tool protrudes say 15mm, you should be able to get a total depth of cut of 12mm or so, or around 1in. dia. I recently offered the side of the cutter up against the stationary chuck and interposed a small section HSS tool between the chuck face and the side of the parting tool as the latter was recessed due to its wedge clamp just for alignment before clamping the toolpost.  Worked OK. Parting toolholder that I'm referring to is the only one that I now use, being in my opinion, the best available – that sold by RDG Tools. Just a very satisfied user. I now always only use 3/32" wide HSS blade which doesn't bend like thinner ones. What's the point in using ultra thin blades? Save metal wastage? Tool bends and creates a concave surface on one side and a convex on on the other, both requiring facing and therefore wasting metal.

If parting very large diameters, try 3 goes at it, side by side, so you have a step each side of the centre cut thus helping swarf clearance. This is shown in L H Sparey's book, "The Amateurs Lathe" page 131. I've not tried it as anything 25mm or more goes into my bandsaw then a facing op.

John

Edited By DMB on 05/08/2023 21:54:26

[Grindstone CowboyParticipant @grindstonecowboy]

Do the T-shape parting blades fit OK in the holders designed for the tapered type, or is a bit of judicious modification required?

Rob

[bernard towersParticipant @bernardtowers37738]

The T type blade I have has the same dims tops and bottom edge as the standard tapered eclipse type and fit in my holder fine if that’s any help.

[DiogenesIIParticipant @diogenesii]

Does anyone regularly use a T / chipbreaker type in stainless?

[Michael GilliganParticipant @michaelgilligan61133]

Posted by samuel heywood on 05/08/2023 20:23:53:

.

[…]

You don't say for which lathe.

[…]

.

There are probably some good clues in Sonic’s concurrent thread: **LINK**

https://www.model-engineer.co.uk/forums/postings.asp?th=187551&p=1

MichaelG.

[Sonic EscapeParticipant @sonicescape38234]

Posted by Michael Gilligan on 06/08/2023 08:56:16:

Posted by samuel heywood on 05/08/2023 20:23:53:

.

[…]

You don't say for which lathe.

[…]

.

There are probably some good clues in Sonic’s concurrent thread: **LINK**

https://www.model-engineer.co.uk/forums/postings.asp?th=187551&p=1

MichaelG.

My lathe is a medium size industrial machine. 750mm between centers, 140mm chuck, 800kg

[Sonic EscapeParticipant @sonicescape38234]

3 months ago I used a brazed parting tool on stainless steel. It worked fine. Even considering that the workpiece was not supported with a live center. But it is about 5mm wide so it is wasting material. Also later I was not able to duplicate the operation. On the same type of material.

Edited By Sonic Escape on 06/08/2023 20:06:23

[Grindstone CowboyParticipant @grindstonecowboy]

Posted by bernard towers on 06/08/2023 00:19:22:

The T type blade I have has the same dims tops and bottom edge as the standard tapered eclipse type and fit in my holder fine if that’s any help.

Thanks Bernard, I'll pick one up at the show in October and give it a try.

Rob

[Mike HurleyParticipant @mikehurley60381]

Just received my new blade from ARC Euro * with a GTN2 insert ; was planning to (when ever I get round to it ) make a rear toolpost for it so hopefully avoiding all the parting-off horrors I've experienced over the years. Believe me I've tried every bit of advice from you good folk on the forum over the years and still could never get a decent job / often getting jams etc with HSS blades.

Just tried the new toy on the ordinary 4 way, made sure everything was locked tight as practical, lowest gear so about 80 – 100 rpm and working on a 2in dia MS bar.

Joy! With consistent manual feed (fairly heavy) went in like the proverbial knife through butter. Brilliant!

Don't now feel a rear toolpost will be necessary for the standard type of materials I use anyway.

Regards Mike

* Other suppliers stock similar models

[Author]

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