Left to right leveling.

[ynneb]

As some of you may know, I am one of those newbies who has descided to make a big machine as the first project. Oh well, I must keep on with it.

I have made the frame, and its left and right sides are not quite parallel horizontally. I didn't mind this because I knew it could be fixed with milled aluminium strips. My question is, how do I get them milled so it will be completely parallel?

The other thing I am presuming, and am wondering if this is right, is when I get the router up and running I will firstly route the work base (mdf) so as to get it completely parallel with the routers movement. Is this a correct assumption?

[Ken_Shea]

Benny if I am reading you correctly a frame this large would be nearly impossible for the do it your self fabricator to make perfectly flat and square, I would not be all that concerned about it, you can and will need to shim the actual machine rails as necessary.

On your second question, you are correct.

[ynneb]

Yes Ken you read it corrcetly.
When you say I will need to shim the actual machine, does that mean I will need to place packers in order to level every thing up? Is multiple layers of alfoil a good thing to use?

[lsfoils]

Hey Ben,

Soft materials aren't real good shims. Better to use steel on steel if you can. Brass and ali will compress with time and use...

Also, get a hold a good machinist level. NOT a carpenters level. Well, you could use one, but you could introduce a lot of errors, too.

I bought this one: http://www.grizzly.com/products/item...emnumber=H2683

Came with a page about setting it up, which I followed. I spent a whole day setting up my first set of rails. I spent one entire day!

If you can, weld a leveling device to each leg of the stand and try to get the top frame as level as you can. I laid the 2 rails on the frame and I found the highest point and started shimming from there. Its important to keep track of your measurements with a "truth table". This is where you write down all the readings you get from the level as you go (assuming THK rails or the like). The claim is .0005" of accuracy in 10". Or about .0127 mm per 25.4 cms for the level. The idea is to check along the first rail at each bolt position and shim as needed. But keep track of how far off the bubble each bolt is on paper (you may find that it is very hard to get each bolt location exactly level). When you have the first rail adjusted to the point that you can live with, check the truth table. Some find it easiest to graph the table to really get the full visual effect of any deviation.

If your accumulated error is acceptable, go on to the next rail. If not, fix which ever point or points that fall out of your acceptable range. When shimming, I always started by tightening the bolts at the same place (the highest point) and loosened them in the reverse order. You can easily bend the rail by changing the order that you tighten/loosen the bolts. When I had the first rail acceptably level (for me) I laid a Starret straight edge across the 2 rails at the high side of the number 2 rail. It was still lower than the number one rail, but I expected this. I placed shims under the straight edge until the bubble read level and then began the same process on that rail. After shimming and tighting the first bolt I double check to see if it was level and made adjustments.

It is important to continue the truth table and to start the second rail as close to the same height as the adjacent point on the first. Once the shimming is complete and the truth table looks like something you can live with you must decide whether to "bed" your rails. I haven't done this yet. But from what I've heard: remove your rails and carefully set your shims aside so that you can place them in the exact order they were in. Apply a release agent to the bottom of the rails. Mix an epoxy compound (a lot of them out there, I'm going to use JB Weld) and apply it to the proximity on the table where the rails go. Reassemble the rails to the table, along with the shims and carefully tighten the bolts in the same order that was used previously. I imagine that you won't want to get much epoxy on the bolt locations so you don't permanently adhere the bolts to the nuts or threaded holes. If you use a slow curing epoxy you can recheck the level of the rails and have some "cheat" time for corrections. After pulling the rails off as many times as I did and verifying positions, I feel quite confident that unless I trap something between a shim and table or rail that everything should be level within .001" or .002".

If anyone has more information on this, add on or correct. Good luck to you Ben.

[High Seas]

Benny - I suppose you want to get to LEVEL so ya know all the bits are SQUARE?
You can get very very close using Doug's (Isfoils) method. And I'd work towards that goal. And you have a recourse when its all assembeled and running - then mill your working surface with the cnc itself. Sort of let the machne square itself.
The challenge with being out ofsquare - some slight varriation in loads, but wouldn't that be pretty small - unles your REALLY off!
Jim