Cardibe inserts

I purchased some 16mm carbide inserts the hole in the centre is smaller than my current ones I can not get the retaining screw through the hole. I thought they would all be a standard size.

Oops they are VCMT

They are of a standard size, but there are many standards...

Hi Dave,

I found this site helped me understand the arcane numbering. Now I look again it does look like the standards do not specify hole diameter which sounds right screwy.

Maybe someone here with more experience can shed some light on this?

Adrian

Hi Dave,

Are you absolutely sure they haven't sent you VNMG tips by mistake? They're the same shape but are designed to clamp with a pin on a cam operated by a grub screw; the hole is smaller on this tip type. The normal ones I use are VBMT which are often used for fine finishing.

Bear

You could forget the hole and use holder with a bridge clamp, as I have done on my home made tool. The tip is 16 mm with no chip breaker, it's the type I use on the 50 mm face mill.

Ian S C

I might be being a bit radical here but you could always send them back for a refund or exchange?

Edited By Hollowpoint on 07/06/2019 11:48:19

Hi Dave,

Some of the inserts I have has a small hole in the centre, they are intended for holders with a short pin on the underside of the bridge clamp (see Ian's post), the pin prevents the insert from moving when taking heavy cuts (well, so I was told when I bought the inserts). May be yours can be used in a similar holder.

Thor

You might be lucky enlarging the hole with a diamond file out of one of those cheap sets of needle files.

As already mentioned, are you sure the inserts are the same as what you have already got? VCMT have only 2 edges at a 7 degree angle and VNMG have square ends and 4 edges.

I double checked and with the help of google determined that they are actually VNMG not VCMT as I thought.

My mistake I ordered the wrong inserts. As I have quite a few of them I decided to buy a suitable tool holder and use them.

Thanks for the feedback.

The tool holders are easy enough to make, although the one in the photo was fairly heavy going as is is a bit of a car half shaft/rear axle, the bridge piece is just a bit of steel from the junk box, the erosion on it was from some heavy work on some 316 stainless(I was warned there would be miles of sharp swarfe). The bolt is 10 32 unf 5/8" .

Ian S C

I have bought lots of the cheap Chinese toolholders for carbide inserts on ebay, they are almost as good as the big named brands. 

 The second letter "c" indicates a positive tip angle of 7 degrees, and the insert is held level in the toolholder and the "n" means neutral with no relief (square end) with the insert dipping down 7 degrees in the toolholder to provide cutting relief. When you get the other holder the difference will be obvious.

Edited By old mart on 09/06/2019 19:11:11