Thread: Fixing up some faults with my machine

Hi Bob

Thanks for the opportunity to meet with you yesterday. It's good to be able to share knowledge and experiences with like minded people.

How do you intend to square / align the spindle mounts once you cut them?

If the mounts are mounted to a plate that is then attached to Z bearings, how can you be sure if every thing is aligned?

Craig

Originally Posted by Smirkin

How do you intend to square / align the spindle mounts once you cut them?

If the mounts are mounted to a plate that is then attached to Z bearings, how can you be sure if every thing is aligned?

Craig

Hi craig, nice to see you come out of the closet. Whoops, I didn't realise that that can have other meanings too.

Get those pictures of your machine up and let others see what you have done.

The mounts thenselves should be square as they were cut with the CNC machine.
The mounts need to be square to the table and also to the cross member. Most of this can be ascertained with a roofing square. If I can get square to the table results with this from the front of the mounting and also the side of the mounting then I think that we can say that the mount is square.

Quite apart from this, we also can use our ears to listen for the noisy cuts and see if there is any change in the cutter sounds.

This is a common issue with most machines, and commercial machines normally have some means to adjust alignment. The process for drills, mills, and CNC routers is called Tramming, and involves using a an L shaped part and a dial guage. The L shaped part is created to be an accurate fit in the spindle collet, and the short end is mounted in the collet, and the dial guage is mounted at the end of the long part. The z axis is then inched down until the dial guage is in contact with the table and the guage is zeroed. It is then manually rotated through a complete revolution of the spindle while the dial gauage variations are noted. When the spindle is perfectly perpendicular to the table there will be no variation in the guage indication, if there is a variation, then the variation represents the degree of error present.

Consider the spindle as the centre of a clock face with 12 oclock pointing to X= 0. Then the difference in reading at 12 oclock and 6 oclock represents the spindle inclination in the x direction, while the difference in readings between the 3 oclock and 9 oclock positions represents the inclination in the y direction.

This of course assumes that the table as flat, as it is in Bob's case because it has been machined flat.

Gents, thank you. Being so very new at this CNC thing, this type of information is perfect.

My new word for the day, Tramming! Malb, would I be correct in saying that the 'L' shaped part would not even have to be perfectly square, just a perfect fit to the spindle collet?

Bob, I had to come out some time!

Hi Guys
Here is a link to a video demonstrating using a tramming head in a mill, applies equally to our routers.
Tramming a milling machine - square a spindle on J head bridgeport mill - Pro Tram - Edge Technology - YouTube
Cheers
David

Originally Posted by Smirkin

Malb, would I be correct in saying that the 'L' shaped part would not even have to be perfectly square, just a perfect fit to the spindle collet?

Yes, basic requirements are a good fit in the collet, and rigid enough to not flex and destroy the indicator reading. The wider the arc it swings the better, but this is limited by table size and clearance from frames etc.