Tool holders for T2 (I think) quick change toolpost

[Jonathan]

This is what i made for drilling, ground all over and i have different size bushes made for different size drills etc

Looks good, you have a surface grinder then? Or are you using a toolpost grinder in the lathe to do it?

I had to make one particular holder be perfectly ground as the slots can be surprisingly a long way off.

I've just been and tested the holder I have with a Mitutoyo 0.0001" DTI. It seems pretty close to me, but then it clearly depends on what you consider close! I took several readings and averaged them...

Measuring on the lower surface, where the tool sits parallel to the bed the width is 18mm and I get a maximum variation of 5.2 thou at the back of the holder, 4.4 in the middle and 4.0 thou nearest the tip (0.132, 0.112,0.102mm respectively). That's going to affect the side rake of the tool by about 0.4 degrees. It's lowest nearest the chuck.

Now measuring on the lower surface parallel to the cross slide over the 98mm length of the holder, so affecting the tool rake angle. I get 6 thou nearest the tailstock (in the corner of the holder), 5.5 thou in the middle and 7.2 thou nearest the chuck (0.152,0.140,0.183mm respectively). That's going to subtract about 0.09° from the back rake angle.

The next thing I measured was the tool centre height repeatability. I zeroed the dial at the front of the holder, near where the tool tip should be. Taking out the holder and replacing it without rotating the toolpost itself I get less than 0.1 thou (0.0025mm), variation (can barely measure it). If I take the holder out, rotate the toolpost around a bit and replace I get a fraction over 0.1 thou (reading between the lines on the dial!). If I take the holder out and put it in a different position in the toolpost I get +-2.5thou (0.064mm) variation in centre height. I think that's pretty good - better than 0.01mm.

If I push and pull hard on the toolpost I can get the centre height to deflect by about 2 thou.

The last thing to measure is how repeatable the holder is moving parallel to the cross slide, i.e. directly affecting the diameter.

Edit: Measured that now and I get 0.3 thou variation, maybe 0.4 ... hard to tell, under 0.01mm.

[M250cnc]

The trick is to make a toolplate for each job.

Well you could take longer to make the toolplate than to do the job.

Looks good, you have a surface grinder then? Or are you using a toolpost grinder in the lathe to do it?

Thanks, yes i have a Jones & Shipman 540 surface grinder, FYI a toolpost grinder would be used to grind round stock, but i have a cylindrical grinder to do that.

Any grinding on a lathe is to be done under caution that grinding dust gets everywhere if your not careful, with serious consequences.

Phil

[i2i]

The trick is to make a toolplate for each job.