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Favorite negative insert clamping system


Aug 19, 2018
I'm looking to get a new set of tool holders for negative W-shaped inserts (i.e., WNMG), and am uncertain which clamping system I want - there's a large variety of systems to hold inserts down into the pocket available and the manufacturers (and from what I can see, extant forum threads) don't seem to say anything about why I'd want one rather than another.

I count at least (3) options. In Kennametal and ISCAR's terminology:
W style - "Traditional" pin and top-clamp
D style - Top clamps that have a nub that grabs the hole and pulls back (as they clamp down)
P style - "lever lock" setups that drag the insert down and back from be through-hole

(For reference, ISCAR has a nice graphic which seems to cover all the options I've seen yet (page 6 of their non-rotating inch catalog))

Now, I like the idea of the D-style setup over the W style - one less screw to turn (or strip the hex out of by using the wrong type of driver) - but I wonder what I'm giving up in holding ability.

I also think the P-style setup is pretty spiffy, but it seems like a design intended for tight spaces or chip control, trading off a lot of security in the process...

What do you guys think? Some fourth or fifth option that I missed?

Context: medium-sized MRO shop; we see some roughing and a lot of interrupted cutting in stainless weld overlay. It's a bonus if the toolholders are resistant to abuse by the (training-resistant) guys who we let run the lathes.


Feb 7, 2007
Aberdeen, UK
D style is by far the best, as evidenced by the fact that every tooling vendor has jumped on that bandwagon wholesale since sandvik first brought it out about 15 years ago. It's extremely secure.