What size parting tool for QCTP?

[DanH]

I am a new lathe owner and need some advice on parting tools. I have a QCTP in BXA size and wonder which size parting tool to get. The slot is 11/16" tall and I think 3/8" deep. Do you need to match the height to the slot height? What's a good starting point for thickness? For now, most of the stock will be smaller in diameter 1" to 3" and mostly 1018 steel and aluminum. Oh, I have a 12x36 2hp ENCO lathe.

Dan

[DaveH]

Hi Dan,

You can use a 1/2" shank or 5/8" shank tool. The 5/8" will have the edge on more rigidity, or at least a better vibration damping effect.

Parting off is one of these perennial things that comes up every now and then, and for good reason. It is one of the "hard to master" processes in lathe work. Not because it is difficult, because there are different views and opinions on the subject. All right, all work, but they won't all necessarily work for you (or me).
So it comes down to finding what will work for you - another learning process

My view is to use a carbide insert tool, an insert with a positive rake, (2mm) 0.080" thick.
It must always be sharp, trying to part off with a blunt tool in the home shop using a home shop lathe is a recipe for a breakage.

I think this is all I have to say at the moment, let some others give their opinions and then you can choose which you feel is best for you

DaveH

[Highpower]

(04-06-2012, 01:47 PM)DaveH Wrote: Hi Dan,

.... It must always be sharp, trying to part off with a blunt tool in the home shop using a home shop lathe is a recipe for a breakage.

DaveH

And "breakage" means more than just the blade. If you ever have the work climb up a dull blade you can literally break the lathe as well.

I could be wrong, but I thought I had a 11/16" blade in my BXA holder. I would have to go look to be sure.

You might want to click on this and have a look at the "About Cutoff Blade and Tool Bit Materials" for a general idea of what to use.

[EdK]

Dan,

I think you are referring to the parting tool holder that came with your QCTP. I also have a BXA size QCTP and measuring the slot it looks like it's made for a 5/8" tall blade that can be a bit over 1/8" wide maximum. This Aloris one would work but it's pricey.

http://www.aloris.com/catalog/aloris-sel...-blade.pdf

And then there is the HSS type.

http://www1.mscdirect.com/cgi/NNSRIT2?PM...rchResults

Ken will have some more options for you I'm sure.

Ed

[Hopefuldave]

Hi Dan,

As you have a QCTP, have you considered the parting blade holders sold for it? I have the BXA size, which takes a 1/8 x 5/8 x 4" HSS blade, or for really hard stuff I have an insertable carbide blade in its own holder which in turn goes in the tool slot in a QC holder (like this: http://www.warco.co.uk/parting-off-tools...blade.html - only slightly posher: sideways-T shaped with a tongue to go in the tool slot) - I do fret that having three separate clamping points (QCTP dovetail, QC holder slot, blade location) lessens the rigidity, but no problems so far apart from the inherent brittleness of the carbide inserts - they don't like interrupted parting cuts, for instance!

Dave H. (the other one)

[EdK]

Dave H. (the other one),

That's another good option. I had forgotten about that style. Thanks for posting it.
Here's one stateside.

http://www.mcmaster.com/#3212A09

Ed

[Hopefuldave]

(04-06-2012, 03:25 PM)EdAK Wrote: Dave H. (the other one),

That's another good option. I had forgotten about that style. Thanks for posting it.
Here's one stateside.

http://www.mcmaster.com/#3212A09

Ed

That's pretty much identical to what we get over here - I see the dollar=pound 60% markup's still applicable to stuff in the UK though... If only postage from the US to Europe was as cheap as it is from Europe to the US!

What's with that McMaster site, though? hit "home", navigate to Acme precision threaded rods (of which I need a few), and it says it's suspending access for 52 minutes to protect their information - don't they want to sell anything???

Dave H. (the othe one)

[DaveH]

Dan,

Here is another http://www.glanze.com/indexable-tool-hol...lades.html

Just to show the different types that are available

DaveH

[EdK]

(04-06-2012, 03:57 PM)Hopefuldave Wrote: That's pretty much identical to what we get over here - I see the dollar=pound 60% markup's still applicable to stuff in the UK though... If only postage from the US to Europe was as cheap as it is from Europe to the US!

What's with that McMaster site, though? hit "home", navigate to Acme precision threaded rods (of which I need a few), and it says it's suspending access for 52 minutes to protect their information - don't they want to sell anything???

Dave H. (the othe one)

Hi Dave,

I didn't have any problem with McMaster's web site. Try this link and see what happens.

http://www.mcmaster.com/#about-acme-prec...ds/=gzqkve

Ed

[Bogstandard]

For the larger size of lathe, ones that use the BXA size of toolholder, if you are lucky, you can pick up professional parting off systems off ebay.

I picked this type up for about 25 UK pounds ($35) each. One left, one right handed, and I bought all shapes and widths of tips for 2 pounds each

The advantage with this type, they can also be used for long reach left and right hand turning as well, as you can pick up a full range of different tips for them. I am also starting to pick up other holders as well, that all use the same tips. My latest one is for plunging into the end of a bar, for doing recesses.

This is how I part off with them.

http://www.youtube.com/watch?v=BG4qEw3eMcQ

And this is how the manufacturers show how to use them, and it is well worth watching to the end.

http://www.youtube.com/watch?v=ZUwJXZEyctI

Even though mainly designed for CNC work, they are perfectly happy working under manual operation as well. So don't discount them as not fit for purpose just because they are used mainly on high speed machinery.

My holders have allowed me to turn (no pun intended) a lot of those difficult jobs into easy ones.


John