paul
Member
Posts: 8
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Post by paul on Dec 17, 2007 22:33:26 GMT
Finally managed to get a parting off operation to go right. Sharpened HSS tool a gnats doo-dah above centre, a little oil and gritted teeth did the trick! www.artefact-rescue.co.uk/video/parting.aviI love it when that steel comes off in a long ribbon  |
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Post by Shawki Shlemon on Dec 18, 2007 9:47:05 GMT
Well done , it is a good Christmas Present .  |
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Post by circlip on Dec 18, 2007 10:19:28 GMT
It's sooo satisfying when you do this BUT don't get complacent, it takes a lot of regrinding if a BANG happens. Have you tried it with Stainless yet? Loverly SHINY ribbon.
Ian
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paul
Member
Posts: 8
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Post by paul on Dec 18, 2007 22:35:53 GMT
It's sooo satisfying when you do this BUT don't get complacent, it takes a lot of regrinding if a BANG happens. Have you tried it with Stainless yet? Loverly SHINY ribbon. Ian Ian, almost everything I've tried to part off so far using a HSS tool has gone belly up i.e. major dig-in, usually later rather than sooner (which to me suggests incorrect tool height?) so I'm not complacent - I EXPECT it to go wrong!! But I've got everything locked down tight as poss/minimum overhang/sharp tool/carefully set height/adequate lubrication and managed three good partings. I've used a blade type tool but it doesn't fit well with my mini-lathe so I'm sticking with HSS. although most 'authorities' suggest a low speed Tel told me to give it a little oomph and it seems to work. |
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Post by baggo on Dec 18, 2007 23:55:07 GMT
Hi Paul,
I tend to agree with Tel - you can be over cautious and run the lathe too slow. You then have to really force the tool to cut and that's when it digs in. Run it faster and feed in slowly.
I used to avoid parting off like the plague but don't have any real problems now. Over the last few days I've been parting off 1½" steel bar etc in the ML7 with just a plain HSS blade (in the ordinary tool post) and cutting fluid.
John
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Post by circlip on Dec 19, 2007 12:34:11 GMT
Yep, speeds and feeds every time. When you see it done on "MENS" lathes in industry and then try it on our toy lathes the 12" parting tool comes out (hacksaw) until you feel REALLY brave and keep the tool CUTTING, not RUBBING. It also takes practice to maintain a continuous cross feed. Not all of us have got the industrial standard of power cross feed.
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Post by circlip on Dec 19, 2007 13:54:59 GMT
It's IMPOSSIBLE for the tool to dig in on that set up, it backs off if you try to overload it.
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Post by GeorgeRay on Dec 19, 2007 20:00:48 GMT
On my old 55 year old ML7 parting off was something that could only be attempted with a rear tool post. On my new big bore 7 I can part off 1" diameter with a HSS blade on the front tool post at the lowest open speed with no trouble at all. I can only quote 1" because that's the largest that I have actually tried. The whole feel of parting off is totally different with the new lathe compared with the old, it feels like the proverbial knife through butter rather than struggling against the immovable object. I can only surmise that there was some slack in the old girl which is hardly surprising after that length of time.  |
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Post by circlip on Dec 20, 2007 6:52:30 GMT
I wonder how many secondhand machinery dealers would let you try a "PARTING" cut on a lathe offered? Certainly shows up Headstock bearings,slide integrity and feedscrew backlash.
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russell
Statesman
Chain driven
Posts: 762
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Post by russell on Jan 17, 2008 21:37:16 GMT
I always had problems parting off on my old Atlas lathe. Recently I cut a slit in the feedscrew nut with a screw to tighten it to remove (most of) the backlash. No problems since.
Russell.
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Post by teakfreak on Jan 23, 2008 12:06:24 GMT
I could never part anything off in my ML&, but then I bought one of the Quick-cut replaceable tools from Greenwood and have never looked back - expensive but a godsend!
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ianmac
Part of the e-furniture
Posts: 308
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Post by ianmac on May 29, 2008 6:49:09 GMT
"I always had problems parting off on my old Atlas lathe. Recently I cut a slit in the feedscrew nut with a screw to tighten it to remove (most of) the backlash. No problems since.
Russell. "
I have done the same. I fitted a washer behind the feed wheel which has removed the backlash all together. I suspect the angle of the Blade is wrong. What angle should i grind a parting off tool to.
Ian
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Post by ravensworth2674 on May 30, 2008 7:07:44 GMT
Ian,
I noted comments about drilling and parting off- almost together here.
Again, you refered to an old mangle- sorry, an Atlas lathe.
A great deal has been written about both topics and might I suggest that you get hold of a copy of GH Thomas's Model Engineers Workshop Manual- published by Tee?
If you want to do the whole hog, get the Workshop Techniques book as well.
I confess to having both Myford lathes for which much of the information was based on but it is fairly easy to 'modify' much of what is contained for your machine. In his long discussion on Parting Off, he applies his advice to lathes which are long past the first flush of youth- like mine and yours-----( and me.)
I also have his books which is also shows an abnormal amount of use.
Get the books, get the aspirins out and a wet towel- and never look back
Cheers
Norm
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