DIY tangential tool | Diamond Tool Holder and plans in video description

[homebrewed]

I also use a norman style QCTP. In addition to the typical square or rectangular holders I have made them with an angle on one side.

View attachment 405482

Could do something similar for a tangential tool holder.

View attachment 405483

Yes, the usual approach is to employ a compound angle to get the job done. But your rendering doesn't look quite right to me -- the cutter's angle component ponting to the right is OK, but shouldn't the other angle be reversed, so the cutter points toward the viewer?

The whole idea of my proposed alternative was to avoid a compound angle, relying on a rotation of the tool holder to provide clearance and provide a kinda-sorta compound angle. I think the scheme would work OK in some cases but it wouldn't be good for an all-around cutter. But that's not a total loss -- after all, a boring bar isn't all that great for an all-around cutter either.....

 

[mickri]

I looked at your drawing and duplicated the angled slot on the end of an angled tool holder. Here is a top view. Don't know if that helps.

 

[homebrewed]

Your top rendering looks OK. If the angles are correct, the top face of the cutter would obscure its body.

 

[mickri]

What do the angles need to be? I will correct the drawing and include the tool bit.

 

[homebrewed]

What do the angles need to be? I will correct the drawing and include the tool bit.

Typical angles for the tool holder are 12 degrees forward (toward the headstock) and 12 degrees back (away from the operator). This permits both facing and turning, IF no part of the holder is forward of the cutter tip. This includes the fixing system used to attach the bit to the holder.

The tool bit is sharpened at 20 degrees, so it presents a top relief angle of 8 degrees to the work when it's installed in the holder.

 

[mickri]

Did another sketch. This time instead of drawing a dedicated tool holder to fit on the post I drew a holder that would fit in one of my existing tool holders. It is 1" H x 5/8" W x 3" long. The bottom is angled 12* tilting the holder towards the headstock and the slot for the tool bit is angled 12* tilting inward. That should give the required compound angle with two simple milling operations. I like to use 3/8 tool bits and have the tool bit stick out a bit from the holder. The slot is 5/16 deep by 3/8 wide. I haven't checked the height of the tool bit to see where it would be in relation to centerline on my lathe. Will probably have to make some changes to dial that in.

 

[mickri]

Did another sketch. The one in my previous post was too high to work on my lathe. This one is made from 1/2" square by 3" long steel bar. The portion that fits in the tool holder is angle 12* top and bottom for a better fit in the tool holder. The slot for the tool bit is angled 12*. I also angled the side by the tool bit for better clearance when facing. Don't know if that is needed and I will make some test cuts before I do that. Don't know when I will get to this. I am still in the middle of remodeling my new place. My garage shop is a mess with barely enough room to walk through it.

 

[homebrewed]

The required cutter height made a big difference in my version of the tool holder -- The cutter tip is only .620" above the compound. The only way it would work was to arrange things so the cutter hangs down below the side of the compound. Like this:

 

[mickri]

There is 1.1875" from the top of the compound to centerline on my lathe. I may have to make a dedicated tool holder.