Tool holders for T2 (I think) quick change toolpost

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Originally Posted by Jonathan

The toolplate does look like a good way of doing it, but more awkward to set up and not as many tools. Also limits travel I suppose. Great for small jobs like in the video though. It's a similar concept to what I did with the milling machine here:


I will still want to use the lathe manually when it's converted to CNC.

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

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

Agree the toolplate would only suit small parts and be time consuming to set.

Phil
Attachment 3975

The trick is to make a toolplate for each job.

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Originally Posted by M250cnc

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

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

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Originally Posted by M250cnc

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

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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.

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Originally Posted by i2i

The trick is to make a toolplate for each job.

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

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Originally Posted by Jonathan

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

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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. :wink:

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

Phil

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Originally Posted by M250cnc

FYI a toolpost grinder would be used to grind round stock,...

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Of course, but you can use it for surface grinding. Dress the wheel using the cross slide then fix the work to the faceplate. Also could be used to grind the faceplate.

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Originally Posted by Jonathan

Of course, but you can use it for surface grinding. Dress the wheel using the cross slide then fix the work to the faceplate. Also could be used to grind the faceplate.

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But can you hold the piece to be ground on a magnetic chuck with only light magnetic force so as not to distort the piece to be ground. Then clamp to an angle plate to get it square.

Can you take a CUT of 0.000005" yes that's not a mistake, on the lathe with a toolpost grinder, can you get a part of 6" x 18" flat with a tolerance of 0.0001"

If you can then yes you can do surface grinding on the lathe. :rolleyes:

Phil

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Originally Posted by M250cnc

But can you hold the piece to be ground on a magnetic chuck with only light magnetic force so as not to distort the piece to be ground. Then clamp to an angle plate to get it square.

Can you take a CUT of 0.000005" yes that's not a mistake, on the lathe with a toolpost grinder, can you get a part of 6" x 18" flat with a tolerance of 0.0001"

If you can then yes you can do surface grinding on the lathe. :rolleyes:

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I'm not saying it will be as good as a lathe, of course not. If it was you wouldn't have a surface grinder!

You can take pretty small cuts though. The dials on my lathe are graduated to 0.001", you're cutting a 200th of that so put the top slide at an angle of arcsin(1/200)=0.29° (ok that's tricky to set) to the face. Clearly in practice that method has limitations - if you want to take a reasonable amount off then you're going to run out of travel and have to keep setting it.

There was a surface grinder at school, rarely used but useful when it was. One thing they did with it was to turn the old blades from the power hacksaw into parting tools for the wood lathe.

[QUOTE=M250cnc;21885]Well you could take longer to make the toolplate than to do the job



obviously this is when he goes to cnc.:tongue:

I will at least make a rear parting tool holder since I use the parting tool on almost every part.

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Originally Posted by i2i

obviously this is when he goes to cnc.:tongue:

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Are YOU doing it this way on your CNC lathe ?

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Originally Posted by Jonathan

I will at least make a rear parting tool holder since I use the parting tool on almost every part.

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Good idea, are you gonna grind it. :heehee:

Currently Mach3 cannot use a rear tool. :sad:

You have to get round it by using G51 X-2 then using G50 at the end of the tool to clear it.

Phil