MicroMark Jumbo cut-off tool

[patmat2350]

I have a teeny 5/16" deep cut-off blade in a wee little holder on my 7x10... needed something a bit bigger for many jobs, picked up the JUMBO cut-off tool from MicroMark. .. a whole 1/2" deep.

Should I return it?

Looks funky to me... the holder clamps up squarely in my 3/8" tool holder, but the blade sits at a weird angle... could work, is it supposed to be like this?

One side is about perfectly vertical (no clearance), the other side leans way over. And it has a peaked (convex not concave) upper surface, which presents as 1/2 flat, 1/2 leaning over.

And the holder seems hard, don't really want to anneal it to machine an angle on the tab...

 

[patmat2350]

Oh, and with that angle on the bottom and matching groove in the holder, the blade isn't reversible, should I want to grind each end differently...

 

[mikey]

I've never seen anything quite like that! A novel approach, I have to admit. Aside from the weird way the blade is held, I have to wonder if a blade ground like that will even cut. Have you tried it yet?

Personally, I would send it back and make my own from a block of aluminum to fit in my QCTP. I would also use a P-type blade that has the typical 5 degrees of bilateral side clearance and grind a 7 degree front relief angle on it.

 

[Tozguy]

Good pics, makes it clear what the problem is.
I have been using one of those blade holders for a while now. The lower edge of the blade needs to be shimmed away from the holder so that the blade sits perfectly vertical and have even relief angles on both sides. A thin gauge of copper wire would work as a shim because it can be flattened easily to the right thickness. Leave the shim in place.

I would only plan on using one end of the blade. It is easy to remove the holder from the tool post to resharpen when needed.

PS There seems to be a lot of overhang in your picture. Try to have only as much blade sticking out that you need to get to through the work.

 

[patmat2350]

Shim- great idea, thx.
Grinding- would be handy to have a 0° rake on one end and positive on the other... guess I can buy a 2nd blade...
Overhang- as received, haven't touched anything yet while I figure out if I want to keep it.

 

[Tozguy]

If you want two different grinds on the blade then using both ends makes sense. Careful though one sharp end will be pointing at you.
The way the holder is designed it is easy to flip the blade end for end and also easy to adjust how much the blade sticks out of the holder.

 

[chips&more]

The top of that parting blade with the multi angles is very normal, I have seen that many times. You must grind the top to your liking, this is normal. Just grind the business end. Do not grind all alone the top because then the holder may not hold the blade correctly or at all. As for how the holder is positioning the parting blade. The blade should have equal angles to vertical on both sides when mounted. But, I guess any position of the blade that allows zero to normal side clearance will work. I have a holder somewhere in my piles with that same holding angle like yours and I have used it and it works…Good Luck, Dave.