6mm Keyway in Shaft -- limitation with X-axis stroke

Hi Guys,
I need advice with one of our parts. Attached 2# drawings.

One of the actual Shaft(6x25-Plain) and another one tilted arrangement.

I need to cut (in single setup) 2# keyways in a shaft which measures 418mm in length. Straightness of both these keyways is very crucial. Now, my actual X-axis stroke of the machine is 400mm.

I'll be holding this in a V-block. I am thinking to "tilt" the V-block to appropriate angle within stroke limits so that I can cut these both keyways in single setup. Refer Image-Tilted6x25.

I need ideas to:
1. Find the exact Y-axis centre of the shaft.
2. Determine Angle of tilt.

I am open to accomplish this in 2 setups; provided there is foolproof method to get both these keyways aligned within 0.03 mm w.r.t shaft centreline.

P.S. Currently I am not equipped with any probing; so using probes is out of question here.

what about bolting 2 bits of scrap to the bed then machine the V's into them at an angle, drop the part into freshley machened V's and then you know exatley where it is.

seimens controls have a setting where you can rotate the work offset by a set amount, so when you jog or run the handwheel in one axis it will move at the set angle. its very handy for clocking stuff like this!

"seimens controls have a setting where you can rotate the work offset by a set amount, so when you jog or run the handwheel in one axis it will move at the set angle. its very handy for clocking stuff like this!".......

That's pretty damn cool !!

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Vishrut said:

Hi Guys,
I need advice with one of our parts. Attached 2# drawings.

One of the actual Shaft(6x25-Plain) and another one tilted arrangement.

I need to cut (in single setup) 2# keyways in a shaft which measures 418mm in length. Straightness of both these keyways is very crucial. Now, my actual X-axis stroke of the machine is 400mm.

I'll be holding this in a V-block. I am thinking to "tilt" the V-block to appropriate angle within stroke limits so that I can cut these both keyways in single setup. Refer Image-Tilted6x25.

I need ideas to:
1. Find the exact Y-axis centre of the shaft.
2. Determine Angle of tilt.

I am open to accomplish this in 2 setups; provided there is foolproof method to get both these keyways aligned within 0.03 mm w.r.t shaft centreline.

P.S. Currently I am not equipped with any probing; so using probes is out of question here.

Click to expand...

Do you have a sine plate? Build up the angle on the sine plate, lay it on it's side, clamp the shaft to it then indicate in the bottom of the plate along X axis and then clamp it down.

Clamp a vee block to the middle of the shaft. Set the vee block on a 1-2-3 block or some other precision surface on the table and clamp the end in a vise. Mill your keyway.
Flip end for end and repeat.

Or talk to the customer. Chances are there is no angular relationship required between those two keyways.
It's just easier to draw that way.

I agree with lumley32 with milling a fixture to establish the angle. The tolerance issue depends on the accuracy of the stock. I would establish two offsets. One on each end of the stock. Your oal tollerances will determine the location of the end away from your stop on each part. Picking up the offsets is as easy as picking up 3 points using the end of the stock and 2 points on the cl of the 17mm dia with a indicator in the spindle. Making a 8.5mm dia circle basically. If you trust your stop you only need to check the offset opposite of the stop to establish the 2nd end to compensate for length variation. As far as indicating the angle a simple mdi move using a tangent calculation . I hope this makes sense. Good luck!!!

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lumley32 said:

what about bolting 2 bits of scrap to the bed then machine the V's into them at an angle, drop the part into freshley machened V's and then you know exatley where it is.

seimens controls have a setting where you can rotate the work offset by a set amount, so when you jog or run the handwheel in one axis it will move at the set angle. its very handy for clocking stuff like this!

Click to expand...

I found that by accident recently.
My eyes like'd to'a bugged out when I cranked the handwheel after that!


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Think Snow Eh!
Ox

I like the "qualify your own V" approach as said above.

With that said, there's one idea that you might not be able to get away with on your machine. You can see if you can extend the travels of your machine past their pre-set limits.

BE VERY CAREFUL IF YOU CONSIDER THIS. We have 1000mm (39.4") machines that we were able to extend to about 41.5" in x (1054mm) by adjusting the soft overtravel limits and moving the overtravel dogs on the machine.

our 1300mm machine (51.2") now has 55.6" of travel in x. (this one doesn't have x way cover nor enclosure, so we were able to move it more.)

Whenever I need to get that extra .1" out of a machine, I watch the axis loads to prevent crushing a way cover or running a ballnut into a support, etc. You gotta be extra careful and leave a little bit of extra, just in case.

Your ability to do that will be very dependent on the machine and to be honest, you might not get any more out of it. but if I was only 3/4" short of doing it in x, I would at least investigate whether it was possible or not.

If I was going to do this in one setup (ie set at an angle on the table), I would just machine the fixture into a couple of blocks of aluminum so I didn't need to do any math. Fast and easy.

If I was going to do this in two setups, I would just put the shaft into an old school 5C Collet Block. Machine one side (leave the collet block in place) and then flip to the other side and use the 5C block to time the two keyway slots. Depending on the quantity, I would lean towards the second option. I could get this up and running in less than 10 minutes.