Thread: Diamond shaped insert tools

Rather frustratingly I was just at the "I'll give it just one more turn" of the tapping stage, when one of my "amazing value" Indian taps snapped off.

I'd say a deserved result! Sub continental shopping Come on Pete..

Actually the rest have been remarkably good Bob, especially considering the pittance they cost, nobody was more surprised than me. This was actually a 1/4" and some of the smaller taps stood up to much higher torque that this one. I only bought them with the intention of using them to clean up threads but you know how it is. Normally taps and cutters are things I never skimp on. Never mind. Won't take long to whip up a new one as the mill is still set up for slotting.

Pete

Bob the holder is as per the link earlier, and the inserts are Lamina DCMT 11T304 NN. I didn't buy a whole packet until I saw how they performed, so have the one in the holder plus two spares.

http://www.lamina-tech.ch/img/catalog/503.pdf

BTW re the sub-continent quality, I was just drilling some pilot holes in thick steel plate and snapped a Sutton drill so there you go; looks like we can all have "one of those days"

Pete

I will admit to being in agreeance there Pete. I had been using an M8 Sutton die on some manly 4140. It was a split die and when I nipped it up a touch to slightly reduce the thread diameter, it did nothing. It would not cut a whisker off the previously cut thread.

I went to Alltools, a nearby tool seller, and tried to buy a new Goliath die. I was told they were buy in items and would cost twice that of the Sutton. Bought a new Sutton die to finish the job, the adjuster for the mill table. Came home and purchased a English Totem die from a seller in Denmark. Multiculturalism.

Oh gawd don't mention M8 to me. I'm having one of those days today. I drilled the tapping hole for the M8 I planned to use for a job. No particular reason to use M8, just seemed a good size. I then went to grab the tap ... scratch scratch scratch, no tap! No idea why it's not there. Too late to go smaller, not really enough room to go bigger. Fortunately I had a cheap M8 in a metric set I bought years ago. It cut terribly and I was cringing the whole time just waiting for that familiar "crack" and let's make it TWO broken taps and a drill bit it one day. I don't think I've ever backed off a tap so many times in my life, it took forever

Originally Posted by Anorak Bob

I have a problem achieving a nice finish on 4140, unless it's a heavy cut, say 2-3mm.

BT

With 4140 I can get a better finish than with you normal mild steel, you seem to be able to run it slower than mild to get a better finish, your inserts might be a grade not suited for it or something.

OF,

Any chance of letting me know what make, grade and shape insert you use?

The inserts I have been using are Kennametal KC5025 CCGT.

BT

OF,

The photo attached is indicative of the finish I have been getting. This is 1045. This would have been a light cut. You will notice how it looks " torn ".

BT

Bob have you tried higher speeds? Also try rotating or a new insert for a fresh edge.

Pete,

That was turned pre the 2600rpm pulley setup. It would have been 700 rpm.

Have you tried your inserts on something toughish? How about a high tensile bolt if you haven't got a piece of chrome moly laying around.

BT

What was the surface speed at 700 rpm Bob? That sounds way too slow to me but I may have the size perspective wrong in the photo.

No I haven't had a chance to try it on anything tough as yet. I've been pretty busy today just making up a jig for my QCTP to take my Proxxon drill. I need to powdercoat it when I get back later today, then maybe I can try the insert on other materials.

Pete

Hi Bob,

Have a look at this thread I think that covers some of the issues.

http://www.woodworkforums.com/f65/fi...us-doc-131110/

The quick summary, is that, for light cuts, I got better finish by reducing the nose radius of the insert. (opposite to what I would have initially thought) Took a few goes on the diamond wheel to figure out what worked.

What you are seeing on annealed 1045 looks similar to what I was seeing on mild.

Regards
Ray

Maybe about 230sfm, Pete. The body of the slotter crankshaft pictured is about 32mm in diameter.

Do you have your own powder coating facilities? Tell more.

Originally Posted by Anorak Bob

Maybe about 230sfm, Pete. The body of the slotter crankshaft pictured is about 32mm in diameter.

Do you have your own powder coating facilities? Tell more.

Bob, racing out for a ride (not raining here in Sydney for once ... hey come to think of it, when I was over there the other day it was p%%ing down), so will give you all the details when I get back. But yes, powder coating is terrific, just need to build a bigger oven.

Here are a couple of pics I could quickly find of powder coated parts

Originally Posted by RayG

Hi Bob,

Have a look at this thread I think that covers some of the issues.

http://www.woodworkforums.com/f65/fi...us-doc-131110/

The quick summary, is that, for light cuts, I got better finish by reducing the nose radius of the insert. (opposite to what I would have initially thought) Took a few goes on the diamond wheel to figure out what worked.

What you are seeing on annealed 1045 looks similar to what I was seeing on mild.

Regards
Ray

I need to move back onto the lathe for a bit more experimentation, Ray. Inserts are to me, a minefield. There has to be a better way than having to resort to a file and wet and dry to clean up a mess.

BT