Specific carbide insert holder question

[Reddinr]

I've done quite a bit of research needed to choose some improved inserts and holders for my lathe. I have a specific question about the holder.

I have a 4HP 16" lathe. I turn anything from stainless to plastic. The tool post is a quick change CXA size. Most of the tool holders are 5/8" deep where the tool or insert holder goes. I plan to start with 3/8" IC 80 Deg. inserts for now. Prior to this, I've been using a cheap set of carbide and HSS.

Does it make any real difference choosing 5/8" vs 3/4" insert holders? With 3/4", 1/8" of the insert holder overhangs the tool holder and there would be that much more lever-arm hanging from the QCTP. But, the 3/4" might be more rigid? My gut is saying 5/8" is the right answer but my head is swimming from the tens of thousands of choices there seem to be with inserts.

What is your experience? Are there other advantages or disadvantages for a larger shank insert holder?

 

[Shotgun]

The larger shank is more expensive, and unless you're using long stick-outs I don't see much need for the increase in rigidity. Especially if you're using a 3/8" insert.

 

[davidpbest]

My experience on 14" lathes suggests that the compound itself is the least rigid aspect of a QCTP setup - not the shank size of the toolholder.

 

[Reddinr]

Thanks. You may have noticed that I have been shopping for a year and a half now. I forgot I had already asked the cross-section question. But, for a hobby, it is a big investment and I've been going in circles for a while. I think I'm finally getting close to pulling the trigger though.

 

[Reddinr]

BTW, David. I did buy your book. Very very good read and resource. It is jam packed with practical information.

 

[davidpbest]

BTW, David. I did buy your book. Very very good read and resource. It is jam packed with practical information.

Thanks. I hope it helps you with tool selection. You might also find the attached helpful.

 

[Mitch Alsup]

It is not so much the 14" but the 4 HP that drives my response::

Get tool holders as big as you can find that fit your QCTP--I am using 5/8ths in a 2HP 13" Lathe. I still wish I had more rigidity--and I mostly work 6061T6 aluminum.

Oh, BTW 3/4 is 2× as rigid as 5/8ths.

 

[Nickm512]

Yeah I’m off the use the biggest tooling you’re able too practically camp. I buy most of my tool holders as NOS on fleabay. My lathe is a 1640 with a multifix type tool post setup. All of my holders are 3/4 or larger. I actually find its cheaper to buy the larger ones most of the time because not as many people are looking for the larger ones I guess. More hobby guys have lathes in the 12 to 14 inch range which is too small for 3/4 shank tool holders.

NM


Sent from my iPhone using Tapatalk

 

[Shotgun]

Rigidity (or lack thereof) does stack up. Ways to carriage to cross-slide to compound to tool post to tool holder to tool to insert. A loss at any point is a loss. If you can get the bigger tool for less, you rock!

It may not improve things, because it is fully overshadowed by another junction, but it definitely won't hurt.

 

[Reddinr]

So after much unnecessary delay, second guessing myself etc., I finally have a decent set of holders and inserts for steel and aluminum. Thanks to all for advice and hand-holding for the last year. I think I'm almost set for a long time now.

What I ended up with:
8 new CXA holders from Amazon. They seem to be of excellent quality. "findmall CXA #1 Quick Change 250-301 Tool Post Turning & Facing Holder"

The following I bought from LatheInserts.com. They came quick, good communication and it was mostly a one-stop shop. The quality of the holders appears to be top-notch. I still want to find a straight-in MCLN holder, which they didn't have. The holders are ZCC-CT (Zhuzhou) and "Cobra Carbide" branded. The inserts are private labeled by LatheInserts.com so not sure of the origin.

5/8" LH and RH CCMT holders
CCGT inserts for aluminum

3/4" LH and RH MCLNL / MCLNR holders
CNMG431 and 432 inserts

5/8" LH and RH DCGT holders
DCMT 32.51 CVD coated inserts for steel/stainless
DCGT 32.51 inserts for aluminum