12x36 Lathe: CCMT21.51 or 32.51?

[mksj]

CCMT 0602 is the same as CCMT 21.51, right?

Yes, it is the same. 06 is 1/4", 09 is 3/8", 12 is 1/2" inscribed circle size for CCMT. One is the US ANSI the other is European ISO
These are the ones I use use for my boring head. ISCAR Carbide inserts CCMT 2-1-SM CCMT 060204-SM Grade IC907

 

[stioc]

Hope @Splat doesn't mind me asking a few questions here. I have a 9x20 lathe (AXA holders) and I've been using the TCMTs that came with the $35 3/8" tool holders in a wooden box. They're not horrible but I'm wondering if the CCMT bits are better for a small lathe and why. They seem to be highly recommended and most widely used on youtube.

Also, with the CCMT bits it seems one can only make use out of two sides as opposed to the TCMTs where you can use all three sides of them.

I already recently purchased three new SCLC boring bars and ten CCMT21.51 inserts for them so I think I just need to find three holders i.e. left/right turning and a straight threading holder. Anyone have any recommendations for those?

 

[jwmelvin]

This means I just need to buy a couple of SCLC tool holders so I can use the same inserts as my boring bars.

A holder like SCLCR1212H06 will hold them for turning or facing. A SCKCR1212H06 will hold the inserts to use the obtuse corner but oriented in a way that is tougher for turning. I recently ordered a a left-hand version (SCKCR1212H06) to try as a fly cutter.

Edit: it looks like a SCXCR boring bar holds the inserts to use the obtuse corner for boring through holes.

SCMCN1212H06 holds the inserts with the small angle centered, for chamfering either side.

 

[stioc]

I just found this fantastic article on the insert types:

Sandvik Coromant

www.sandvik.coromant.com

I can take a .05" DOC in alum with my machine fine (with TCMTs) just the vibration is increased compared to .02" DOC. So I'm guessing for smaller machines (less than 12" swing?) the WCMT style is probably a good balance between DOC and finish? Or may be I can get away with the CCMTs for turning.

 

[jwmelvin]

oops, meant SCKCR1212H06 as the left-hand version I ordered for a fly cutter

...and finally found the unused-corner holder for turning: SCBCR1212H06.

All the holders come in a variety of shank size (the "1212" portion above).

 

[jdedmon91]

I’m going to chime in again. My go to insert is a CNMG 432. It’s mounted in a standard negative rake 1” tool holder that is dovetailed and has an adjuster in it just like a BXA block. I’ve never had a minutes trouble with this set up. Also it opens up the possibility of getting deals on surplus name brand and grades of carbide inserts. I have a supply of these inserts that I picked up at reasonable prices. Yes I don’t always have the speed to run them as designed but they have served me well.

I’ve shared this link before, but just in case this video shows how I modify tools meant for larger lathes to fit a home hobby lathe in my shop.

Sent from my iPad using Tapatalk

 

[stioc]

So I looked at the boring bars I got which take CCMT 21.51 inserts and they say SCLR on them. Since they have flats machined on the shank I chucked one up in th AXA 101 and tried to use it for turning. It worked fine for up small DOCs but for .055" DOC I think it was a bit too much of a bite for it as there's some visible damage/gouging on the insert. The TCMT insert didn't seem to have this when I tried a similar .05" DOC pass. So I'm guessing these boring bars are really just for boring (since they seem to tilt downward) or can they be used for facing too?

 

[mikey]

These bars that have a flat that orients the bar with a downward angle (this is called negative axial rake) is not useful for turning. It is meant to provide added relief when boring. Thing is, this doesn't work all that well for boring either, especially if you are trying for a precision bore. Best idea is to get some turning tool holders and put that boring bar away, maybe someplace where you'll forget about it.

 

[stioc]

These bars that have a flat that orients the bar with a downward angle (this is called negative axial rake) is not useful for turning. It is meant to provide added relief when boring. Thing is, this doesn't work all that well for boring either, especially if you are trying for a precision bore. Best idea is to get some turning tool holders and put that boring bar away, maybe someplace where you'll forget about it.

Haha, ok, I'll get some standard turning bars, I didn't know if all SCLRs are the same or if this one was different.
As for boring bars, do you have any recommendations? I hate the brazed carbide tipped bars, they're terrible and just rub. These ones seem to work a little better but if there's a better option I'm all ears.

 

[Liljoebrshooter]

Look for a thread that Mikey did a while back. It is titled " A Boring Primer", I think. Lots of good info on boring a hole.
Joe Hynes