Gallery, Projects and General => How do I?? => Topic started by: AdeV on March 17, 2018, 11:48:21 AM

Title: Parting off on a Warco WM280V
Post by: AdeV on March 17, 2018, 11:48:21 AM
One of the guys I share my shed with has the lathe bug now (nothing to do with me, probably!  :lol:), so he's bought himself a shiny new Warco WM280V lathe.

One of the issues he's having with it is trying to part off something - the chatter is indescribable! Now... when I'm parting off, I generally have the lathe at 680rpm (i.e. flat out) and use a 3mm wide parting tool (Mircona with carbide inserts). So long as my carbide is good, and so long as the part is held firmly enough, and so long as I stick oil into the cut, this generally proceeds without any real issues. If I'm cutting quite a lot of metal off, I'll usually stop it before it's cut all the way through & finish with a hacksaw, that's only to stop the cut-off material from sagging inwards & jamming the tool (guess how I know THAT happens!)...

Trying the same thing on my mate's lathe, and it starts vibrating so hard I'm worried it'll bring the building down!

Is this just a rigidity thing, or is there something else at work here?

At the moment he's using the standard tool post (QCTP to come), and HSS parting off blades.

Which actually leads me to another question: His parting off blades (as supplied) have a slightly triangular top face, so the top of the cutting edge isn't flat. Apparently this reduces tool load & chatter, but to my  mind it means there's no top rake, and it's harder to get a truly sharp edge (now you need two razor sharp edges)... anyone got any experience of this? FWIW, the amount of chatter & vibration seemed to be about the same no matter what the tool form was. The only way we could get close to making it work was to slow the lathe right down, at which point it became very easy to stall.
Title: Re: Parting off on a Warco WM280V
Post by: Joules on March 17, 2018, 12:01:43 PM
Can you clock the tool holder whilst swinging on the top slide, see how much itís moving about.  Any chance of trying an insert parting tool, they are pretty good and cheap from the likes of Banggood of all places.

Not a fan of that parting tool profile, I have just ground them with top rake and been happier using the tool.
Title: Re: Parting off on a Warco WM280V
Post by: awemawson on March 17, 2018, 01:03:50 PM
Sounds like top slide or cross slide gibs not being adjusted - can you feel any slop?

Definitely rigidity and mass needed in large quantities for parting off. Can he try a rear mounted toolpost with an inverted parting off blade? This often cures such ailments.

Title: Re: Parting off on a Warco WM280V
Post by: AdeV on March 17, 2018, 02:02:59 PM
Thanks for the suggestions so far - I'm not there today (bad back), but if we're both around tomorrow, I'll check. It's possible the gibs haven't been adjusted since he installed it.
Title: Re: Parting off on a Warco WM280V
Post by: John Rudd on March 17, 2018, 02:32:11 PM
I have a clone similar to the 280 from SPG..I use hss blades and/or carbide tipped like the BG one( excpet mine came from JB and uses the 3mm inserts). I have no issue at all powered parting brass/aluminium/steel of various grades (EN1 or 8 ) and am using a qctp.....

As Andrew and Joules, I'd look at where there's slop.....

Ooerrr.... My bad, my machine is similar to the 290.... A bit bigger than the 280... :Doh: :Doh:
Title: Re: Parting off on a Warco WM280V
Post by: appletree on March 24, 2018, 03:50:19 PM
Parting off is one of those areas where witches have input, when its good its good and when its not its not, its all about attention to detail. that said it still does not work.
Recently I had some repetitive work, left some work parting on power cross feed whilst I went and brewed a cuppa LOL.

Mad or what? Phil 
Title: Re: Parting off on a Warco WM280V
Post by: AdeV on March 24, 2018, 03:54:01 PM
 :lol: If I left a parting operation under power & made a brew, it would taste of FEAR!

In fairness, my old Edgwick is generally pretty good about parting off - so long as I use a decent amount of cutting oil, and don't part off heavy lumps (unless supported), it generally goes straight through no bother. I mostly use Mircona insert tooling.

I have, in the past, smashed a few inserts when, in the dying seconds, the part that's being cut off has sagged, trapped the tool and caused mayhem (well, usually a broken insert & often a damaged tool holder). So, anyone who's been trying to buy Mircona MT-3 tips, or RH parting off toolholders on eBay, er, sorry. I probably bought it...  :wave: