Tramming the Sieg SX3

Hi,

I'm trying to improve my Sieg SX3 milling machine by tramming it in properly.

(Ref this link: Sieg SX3 )

This would be straight forward on something like a Bridgeport, where you can adjust the front-back and left-right tilt angle of the head. However, the Sieg SX3 just has a square column bolted directly onto the base with four M10 bolts.

There's no way to adjust this except by loosening the bolts, slipping some combination of shims in the gaps and doing the bolts back up again.

This is a very laborious process as you have to calculate four thicknesses of shim stock (one for each bolt), based on your DTI measurements of the errors between front-back, and left-right of the stage.

I have tried doing this and I can get down to about 70um (2.75 thou) of TIR across 300mm of the stage.

This is less than half the error it was delivered with, so it is an improvement at least.

The choice of shim stock thicknesses I have seen for sale seems too limited to get any more accurate, (e.g. a 3 thou shim is too small, and a 4 thou shim is too big.)

Is there a better way of tramming a mill like this?

What is a realistic tramming accuracy to aim for on a machine of this construction?

After all, if this small milling machine flexes by 'X' amount when cutting metal, then there's little point trying to tram it more accurately than 'X'.

Regards,

Nicholas Lee

Edited By Nicholas Lee on 14/02/2017 23:53:42

Not an SX3 but you could use a similar method  (Belzona do a range of epoxies here in the UK that could be used)

Tramming a milling machine with epoxy

Edited By Martin 100 on 15/02/2017 00:05:44

You are over-thinking the job, you can do front to back first, then side-to-side after. It isn't necessary to do it all in one and calculate 4 shims, adding 2 shims for each axis still works and allows you to fine tune each axis. the shims add themselves

If you want adjustment of less than one thou, you could scrape the base to suit, but it's not a beginner's job.

.

1.5 thou + 1.5 thou is 3 thou but 2 thou + 1.5 thou is 3.5 thou.

You can add shims and for really fine tuning then use baking foil.

Aligning the column a slow process with a lot of trial and error. If you cannot get the exact thickness shim to put under the front (or rear) mounting bolts, you can also try adding different thickness shims under both the front and back so that the differenece between them is the correct dimension (if that makes sence). There is no need to tram the column for sideways alignment. This can be done by rotating the head. The indent pin only gives an approximate angular position of the head. OK for rough work but not for an accurate tram. I used to have an SX3 and have upgraded to an RF-45 type mill which also has a bolted on column which had to be aligned.

Paul.

As Nick says you are over thinking it, just get some old feeler gauges and poke them in the gap and see what that does to the readings. Another way to get a fine adjustment is to move the position of the shim material as it is basically just one leg of a right angle triangle, the further away you place it the less effect it will have on the column.

Did my X3 that way and not had to touch it again, must have been about 9yrs ago now.

Have you checked the column to base squareness in both X & Y directions during your column shimming ?

This is what you are adjusting with the shims & what you should be checking with this adjustment. Aim for 0.001" per foot against a known accurate square. Ignore the spindle alignment while doing this. When the column is truly perpendicular to the table top (which should be parallel to the base), then check the spindle alignment . If it is out, adjust at the swivelling head joint, not with the column.

Pretty pointless having a spindle that trams "true" if the column is not perpendicular to the table IMO - raising the head when the column is out of square will move the datum point on the job. Tramming the spindle should be the last thing you do whan you know everything else is within spec.

Nigel B

Is there room to fit pairs of 'push / pull' bolts as used on lens cells, telescope mirrors and other optical components?

To be pedantic, you should only need shims in three places, not four

Neil

I need to do this on my Myford VMB mill and was thinking of using thin lead sheet under the column and hoping that I can tighten up the 4 bolts and rely on the squashability (is that a word? ) of the lead to make the necessary adjustment. I have seen 1mm thick lead sheet on ebay so that might be worth a try.

Doug

Would you not want to accurately set it over by x so it's right when cutting?

Martin

70 um is 1.7 thou surely? Over 300 mm that sounds quite good. +1 for baking foil to trim the shims, which I used also on my VMB. I think lead may continue to creep even after you have squashed it down Doug. I hope you find that the 4th bolt screws into the iron and is not held by paint into a blowhole like mine was!

70 um is 1.7 thou surely?

0.07mm / 25.4 = 0.002756" (rounded) is it not ?

Nigel B

Oops! Sorry, wrong way round, multiplied instead of divided. Too early for me.

Nigel B has hit on the problem that I faced when doing the same to a Sieg X3 (with fixed head).

There are two things to align: the column being perpendicular to the table in both planes, and the spindle being truly parallel with the column. Mine was out on the column by about 0.001" per 1" of vertical travel (ignore which plane for now to keep the discussion simple), and a similar amount on the spindle in both planes  - 0.0009" and 0.0013" per 1".

The problem I found was that if I shimmed the column, using a pair of dial gauges rotating on the table, then the error in the spindle resulted in the column still being non-perpendicular.

I think that what I needed to do was 1) clamp a dial gauge on the spindle outer and clock the column ground ways in X and Y while raising and lowering the spindle (with a locked head to column). Then correct the head mountings so that the spindle was able to raise and lower with no change in clock readings - this seemed a tricky job. Then, 2) conventionally 'tram' the column to the table by shimming under the column, knowing that the rotating spindle was now parallel to the column.

If anyone disagrees, or can even understand what I am trying to say, I will be pleased to hear. I actually set the spindle true to the table by shimming the column, knowing that this left the column non-perpendicular. I simply stuck a label on the side of the machine telling me of the head lift X and Y error! It was only ever a problem if I was taking a zero point from the top of a job (e.g. gearbox casing), and wanting to bore precisely a hole 4" down inside which meant dropping the head on the column. I am now fortunate enough to have big second mill so I never went back to fix the Sieg properly.

Norm

" and ) smiley removal!   Edited By norm norton on 15/02/2017 10:23:26

Edited By norm norton on 15/02/2017 10:24:28

Good heavens, Myford making rubbish after all the fine machining and even finer hand fitting and they didn't get it right before charging a premium price ?

And people call imports even though they are probably all a lot of folk can afford.

However if we are to believe what we read in this current ME one intrepid person couldn't bring himself to purchase a mini lathe because it didn't have a hand wheel at the end of the leadscrew unlike a previous Myford he owned, Although correct me if I'm not wrong but not all Myford's were turned out with a leadscrew handwheel as standard ?

Instead our hero chose to buy an EW lathe and before you all rush off and get one as well they went out of business in 1960.

But it had a leadscrew handwheel, in fact it NEEDED a leadscrew hand wheel as it had no half nuts and every thing had to be wound by hand up and down the bed and because they couldn't get the thread right it went the wrong way. How far we will never know because even though it had a hand wheel it had no graduations.

Puts a mini lathe in a different light now doesn't it. ?

.

Doug,

I've never tried this on a mill, but something we did successfully in the vibration test lab. was to use Loctite 638 as a 'liquid shim' ... You could use your 'squashable' material as a means of adjustment, and when the Loctite cures, it should squash no more.

Note: Epoxy resin, or other materials, may be equally effective.

MichaelG.

I got an early model SX2 Plus from Arc. They stated that one pad in the base is intentionally made the highest so you can tell which one not to shim.

It was easy to identify the high pad. I used brass shim, with a torque wrench for consistency while finding the best sets of shims. I don't recall whether or not I then tweaked the torque.

When I was trying to work out how to tram both column and head without a particularly good reference square, I found this very helpful: **LINK**

The gist is:

1. Get the spindle parallel to the column in both directions by raising and lowering the head with an indicator on a longish bar in the spindle. The spindle should be rotated 180 degrees at top and bottom, and the centre point used to check parallel, eliminating runout. This should be done for both x and y. Easy for X by tilting the head, hard for Y as the head to column connection needs shimming

2. Once done, tram the mill (sweeping on the table) by shimming the column.

3. Declare success.