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View Full Version : Mill/Drill head out of alignment.



gundog
11-03-2004, 08:57 PM
I decided to check my mill /drill head to see how it lines up with the table. I have posted some pictures they are not clear so here are the results. The arc I swung measured 7" front to back .030" difference. Side to side .035" difference. It is no wonder I have been having problems getting holes to line up and everything I mill has a tapper. Is this the best way to check this and were can I find some shims to fix it? I did not have a collet the right size so I used my drill chuck I can turn a shaft down to fit one of my collets if I need to.
Mike

IMG]http://img.photobucket.com/albums/v292/millnut/DSC02069.jpg[/IMG]

http://img.photobucket.com/albums/v292/millnut/DSC02070.jpg

hollister
11-03-2004, 09:12 PM
that is seriously out of tram , usually you can make adjustments at the head but I don't know much about these smaller mills .can you post pics of the head area? I think even a mill/drill should adjust left to right but the forward/back out of tram might mean a bent column.nice doggy!

gundog
11-03-2004, 09:24 PM
Hollister this is the head. This machine was dropped at on time but nothing was broken it is possible something got bent.
Thanks Mike

http://img.photobucket.com/albums/v292/millnut/DSC01802.jpg

The column is bolted down to the base with four bolts. I planned on shimming the bolts to tilt it back and square it up.
Mike

[This message has been edited by gundog (edited 11-03-2004).]

hollister
11-03-2004, 10:42 PM
I have never worked on anything like this . A rough and ready fix, if the vice jaws are removable would be to make soft jaws , install them , and mill a step in them so at least you are holding square to your head. It is not a compleat fix but just a start.perhaps feeler gauge stock for the shim. Another board "the home machinest" has a section especialy for 3 in 1's and I think this problem would be a common thing on that sort of machine so you might try them.I just noticed your name,my "nice doggy " coment was for the dog in your pic not you http://bbs.homeshopmachinist.net//wink.gif

Yankee1
11-03-2004, 11:29 PM
Hi Mike
On my small micro mill I cut shims from Pepsi cans About .004" and used them and they worked perfect. I shimmed under the column base just like you are going to do.
It does not take much to make a big difference. I just received my new Mini mill
from Grizzly today, installed a power x-feed
and will start mking chips tomorrow.
Chuck

gglines
11-03-2004, 11:52 PM
Mike:

Typically, these mills are shimmed where the bolts fasten the column to the base. You can buy ready made shims in .001 increments from the industrial suppliers, buy shim stock, or use what is handy like aluminum cans.

If you cut the shims in a U shape, you don't have to remove the bolt, just loosen it and slide the shim around the bolt.

George

Paul Alciatore
11-04-2004, 12:23 AM
I used my Grizzly for a year and a half and wondered why things weren't quite right. It looks a lot like yours so what I did should work for you also.

I did a tram with the largest circle that would fit on the table (8 or 9 inches) and found about 0.070" difference, mostly side to side. Was it made that way? Damage in shippment? Chinese tolerances? Who knows?

I had to scrape a bunch of caulking off the joint between the machine base and the column base, but it was easier than I expected. I had a coworker assist in case of surprises - a 300 or 400 pound head could wreck your entire day if it fell on you. But it was easy. I loosened the four bolts about 1 1/2 to 2 turns but still secured by many threads and rocked the head and column to the side to allow cleaning up the joint. Then I used shims from the assortment I bought to level the lathe and in about three or four tries, it was within 0.001". You have to tighten the bolts to test every shim combination.

When I did the final tightening, I used a torque wrench to get them even and then cheated a bit to try and tweak the adjustment the final half thou or so. Not sure that worked but I had to try and the lack of any further change assured me that I had cleaned all the trash out of the joint.

Overall, the job was easy. It took a few hours because it was the first time and I was super cautious. Don't be afraid to do it.

Much better results now. I had to shave the rear jaw of my favorite vise again - I did it wrong the first time due to the misadjustment of the column. Probably should check the tram again from time to time.

Paul A.

[This message has been edited by Paul Alciatore (edited 11-03-2004).]

Rich Carlstedt
11-04-2004, 01:51 AM
Shim the base, to get it 'Plumb'
BUT, an easier way is to drill and tap set screw holes right next ( about 1/2" away) to the hold down screws.
Then you can "Jack up" the base against the screws while plumbing the column and not have to mess with shims
After reaching the desired point, feed some two part epoxy (or grout)in between the base and column finish the job, and to prvent "ringing"

darryl
11-04-2004, 02:17 AM
First off, check the stand. The base of the mill will be warping the surface of the stand that it's bolted to, and transferring the warp to the feet. Rear feet should be adjusted to make the mill table level side to side, then the front feet adjusted to level it front to back, while at the same time carrying the same amount of weight. This likely won't be easy to determine, but can be done by tilting the stand backwards, then dragging a cardboard shim under both front feet as the stand is slowly tilted back onto the front feet. Each should get the same amount of increasing friction while this is happening. Obviously, control here is important, you'll need some help, and don't drink beer before the test, only after http://bbs.homeshopmachinist.net//smile.gif. Anyway, once the table is level and you're happy that the feet aren't applying twist through the stand to the mill table, then do your sweep test again, but check it at more than one height of the head on the column. Any setup to hold the indicator should be ok, as you're only interested in relative differences between the measuring tip and the table. If the differences you already noted are the same at different heights of the head on the column, then the column isn't bent or warped. I should add here that your procedure to tighten the head to the column should be consistant. I think you have two bolts that clamp it, is this the case? Tighten both alternately to the desired torque- this way you'll get a repeatable fitting of the head to the column.
By this time, you will have noted if there were any other reasons for the errors you measured. Now you can go ahead and loosen the column mount bolts to clean out the 'paint and grit' shims if they are there. Take note of any real shims that may have been put in. Since your alignment is a long way out, remove any shims, and after cleaning the mating surfaces between column and base, rebolt and test again. You'll only need to use one height setting of the head from this point on.
Now there's a bit of math involved. If you can take two measurements at a distance apart the same as the distance between the mounting bolts, then your difference in reading directly becomes the shim thickness required. If your front to back distance between mounting bolts is about 3-1/2 inches, then set up your indicator to read at two points on the table that far apart. The side to side distance between bolts will be about 7-1/2 inches, so set up the indicator for that distance between reading points for left to right. Now you have all the info you need to shim each corner just right, or at least get down to a very small error. This procecure should save you considerable time as you should only have to rebolt and measure a few times at most.
If there's any other thing to be aware of before beginning the adjustments, that would be to make sure the spindle lock is left tight, or retightened the same, during the measurements. This amount of tightening the spindle lock should be the same you would use when actually milling, and the spindle shouldn't be extended more than about half it's full travel for the measurements.
This has been another long post, but I should also add that the feet on the base should be in the same position on the floor when you're done as they were right after the levelling and weight test adjustments. Mark the position with a felt pen.

[This message has been edited by darryl (edited 11-04-2004).]

gundog
11-15-2004, 12:43 AM
Thanks for all the help guys I finally had time to go work in the shop today. I made shims out of pepsi cans like Yankee1 sugested. I have it within .001" in a 7" arc. I could get closer but I need some different thickness shims.
Thanks Mike

Paul Alciatore
11-15-2004, 01:41 AM
Believe it or not, I have used ordinary aluminum foil for fine shims. It is readily available and easy to cut to shape. Multiple layers are needed for most purposes.

Paul A.