stoneaxe
Stainless
- Joined
- Mar 2, 2010
- Location
- pacific northwest
The old VN 12 has a out of center spindle taper.
.0006" TIR, measured on the taper. This translates to about .002", two inches from the spindle nose.
If you are not familiar with the VN12, the taper is a short 15 degree (30 degree included) land about 3/8" wide.
I am a complete novice to grinding operations. To hire this done is way more than the machine is worth.
Hence-
Plan is to incline the head to 15 degrees, check exact taper parallel with the table, clamp up a die grinder and use the table Y axis to feed the grinder in.
The taper also has a slight bellmouth to it, as bluing on all the toolholders shows the same band midway up the taper. This bell mouth is so small a .0001" DI will not pick it up- but the blueing does.
I have the die grinder clamped up parallel with the table, the stone is dressed parallel to the table, and I was going to left -right center the grinder in the bore, so the taper is correct.
The plan is to blue the taper, and run the stone in stationary, till it just scratches the blue- due to the bellmouth, this should also serve to check exact parallel, as the bluing should scratch halfway up the taper.
Then to set up the grinder a few thousandths low, and bring it up by .0002" at a time, till I get a full grind on the rotating spindle.
Is a 1/4" diameter stone going to work OK to take off .001? The stone is Pferd, 60 grit, style A24. Plan is to run it at whatever speed the die grinder runs smoothest, up to 30K. I was not planning on any coolant as the stock removal is so slight. Also have a few Grier 1/2" diameter stones, maybe 60 or 80 grit, not sure. Which should I use?
I am confident I can hold the geometry, and move the table up by .0002 increments, (this has been checked using a .0001 DI and a long bar through the elevation handle) but I don't know anything about grinding, removal amounts, grits, finish, etc.
Advice? Reassurance? Instructions to report to the asylum?
Thanks, stoneaxe.
.0006" TIR, measured on the taper. This translates to about .002", two inches from the spindle nose.
If you are not familiar with the VN12, the taper is a short 15 degree (30 degree included) land about 3/8" wide.
I am a complete novice to grinding operations. To hire this done is way more than the machine is worth.
Hence-
Plan is to incline the head to 15 degrees, check exact taper parallel with the table, clamp up a die grinder and use the table Y axis to feed the grinder in.
The taper also has a slight bellmouth to it, as bluing on all the toolholders shows the same band midway up the taper. This bell mouth is so small a .0001" DI will not pick it up- but the blueing does.
I have the die grinder clamped up parallel with the table, the stone is dressed parallel to the table, and I was going to left -right center the grinder in the bore, so the taper is correct.
The plan is to blue the taper, and run the stone in stationary, till it just scratches the blue- due to the bellmouth, this should also serve to check exact parallel, as the bluing should scratch halfway up the taper.
Then to set up the grinder a few thousandths low, and bring it up by .0002" at a time, till I get a full grind on the rotating spindle.
Is a 1/4" diameter stone going to work OK to take off .001? The stone is Pferd, 60 grit, style A24. Plan is to run it at whatever speed the die grinder runs smoothest, up to 30K. I was not planning on any coolant as the stock removal is so slight. Also have a few Grier 1/2" diameter stones, maybe 60 or 80 grit, not sure. Which should I use?
I am confident I can hold the geometry, and move the table up by .0002 increments, (this has been checked using a .0001 DI and a long bar through the elevation handle) but I don't know anything about grinding, removal amounts, grits, finish, etc.
Advice? Reassurance? Instructions to report to the asylum?
Thanks, stoneaxe.