How accurately are you tramming your mini mills?

I noticed that the first piece I milled on my new Sieg didn't come out straight. A little investigation found that there was a 0.3mm height difference between the left and right sides of the table.

I found there were no shims under the column so it looks like these machines come out the factory with no attempt made to tram them. The thinest M8 shims I could find are 0.05mm, and with those I could get to within 0.07mm on the x length of the table, and 0.03mm on the y length.

I've read that tin foil can be used to shim in 0.01mm graduations, but is there a limit to what can be achieved on these machines? How far have you gone with your tramming and whats realistic?

Look up Shimming techniques. Dr_GMJN is doing his now. Plenty for you to look through.

Steve.

Shimming. 

Edited By Steviegtr on 19/12/2020 20:55:57

Have a look at the other thread "shimming techniques" that is running at the moment.

Bit of old feeler gauge got my two Sieg mills ( X3 and SX2.7)to less than 0.01mm over a 140mm dia circle.

I just rotated the head to be perpendicular to the table on my SX3 and it seems fine. Perhaps I got a good one.

Or you might be totally confused by all the unicorn chasing going on in that thread. Best follow Jason's advice and use a bit of feeler gauge or a piece of flat shim stock available on eBay etc in sizes down to .001" aka ,025mm.

I wouldn't use aluminium foil because it is very ductile and could squeeze out of the gap somewhat over time and repeated stress cycles under cutting load. But others use it and seem to be happy. So take your pick.

As to how close? You could probably live with .025mm variation for most hobby purposes. But its nice to get closer to .01mm etc if you can, without spending the rest of your life chasing it.

Edited By Hopper on 19/12/2020 23:38:13

Philip, Does your mill have a fixed or rotating head ?

I used to have a Seig SX3 with a roatatable head and found that the location pin that locked the head was not accurate (OK for general operations) but normally used an indicator on a 250mm arm to tram and clamp the head. (the longer the tramming radius, the more accurate the setup)

If you have a fixed head, then you have to shim the column.

Paul

Edited By Paul Lousick on 20/12/2020 01:40:14

Mine has a fixed head.

I have the SX2P shimmed with pieces of feeler gauge it has changed a tad since I trammed it, currently it is 0.025 mm in Y from front to rear of table and 0.04 mm in X across 175mm.

I,m happy with that for what I do, most of the parts I make are well inside of those dimensions.

Edited By Ron Laden on 20/12/2020 07:08:58

The thickness of aluminium cooking foil varies from make to make, I have never measured it, but the Asda stuff I have at the moment feels much thicker than Bacofoil.