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Forestgnome
09-09-2012, 09:23 PM
I'm confused. I have two inserts that are both 3/8" ic, but they have two different hole sizes. One's a TCMT32.52, which fits my holder fine. It's hole size measures 0.171". The other is a threading insert 16ERM, and it's hole size measures 0.153. My holder screw doesn't fit. Do threading inserts have different hole sizes? Something else I'm missing?

PixMan
09-09-2012, 11:13 PM
That's because they are two completely different types of inserts doing two completely different jobs and should be used in two completely different holders.

Other than that, I can't underdstand why they'd be different. :D

Forestgnome
09-10-2012, 09:21 AM
That's because they are two completely different types of inserts doing two completely different jobs and should be used in two completely different holders.

Other than that, I can't underdstand why they'd be different. :D

Wow. They're completely different. That tells me a lot.

rkepler
09-10-2012, 10:02 AM
Wow. They're completely different. That tells me a lot.

The 16ER insert is different because they're usually used with an anvil underneath and a neutral helix toolholder (but some cheap holders have the rake built into the holder and no anvil). Your TCMT usually run on the steel holder, at least I've not noticed an anvil, and it doesn't have helix adjustment built in and likely is set for negative 5 degree rake on the left of the tool, something that you'd not do with a threading tool.

So they're different because they made for 2 completely different applications.

Forestgnome
09-10-2012, 03:15 PM
I see. The helix angle and relief are in the toolholder for threading inserts. Didn't know that.

rkepler
09-10-2012, 03:36 PM
I see. The helix angle and relief are in the toolholder for threading inserts. Didn't know that.

Kind of - the helix angle on the laydown insert (16ER in this case) is adjusted using an angled anvil, the relief in the tool is in the grind of the insert. But now that I've said it someone will point out some manufacturer who doesn't use an anvil with their 16ER holder and instead has a bunch of different holders.

PixMan
09-10-2012, 07:12 PM
On a right hand internal threading bar which uses IR16 (not ER) threading inserts, most bars under 3/4" diameter won't have space enough to employ the various carbide seats. Those smaller bars are fixed at about a 1.5 helix angle.

Almost all external threading holders, even those with 3/8" square shanks, use the interchangeable anvils (seats.) I don't believe I've ever seen one that doesn't have that.

http://img.photobucket.com/albums/v466/kenm10759/Dads%20shop/IMG_1192-r.jpg

The holders have 1.5 machined into the holder. The default shim/anvil is 0. You can get anvils of 0.5, 1.5, 2.5, 3.5 and 4.5 for some really high lead angle threads. Then for using right hand holders and inserts to make left hand (helix) threads, you can get anvils of -0.5, -1.5 and -2.5.

BTW, I'm really sorry about my first reply. I'm not usually flippant like that. Normally I provide far more information than required so that was me having a rushed and/or bad day.

Forestgnome
09-10-2012, 08:14 PM
Thanks for the info PixMan. I was wondering about the anvils and you explained it. The picture helps.