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View Full Version : How to adjust tilt on a custom mill machine



DrStein99
08-22-2007, 12:35 PM
I built a cnc milling machine, which is aluminum duty and am upgrading slowly to handle steel. My max work area is 12" x 16". Mostly I use the machine for artistic sculptures, fixtures, and also to built parts for its own upgrades and other machines.

I was wondering if anyone had any advice or links to information regarding adjusting (or making an adjustible fixture) to mount the spindle head. I know if I make a round compound platform, I can adjust the swivel of the head, from left to right, and precisely clamp it dead perpendicular in that direction.

But I am lost on how to make a fixture to adjust the TILT of the head, which would be FRONT-TO-BACK. I do not want to just shim the mounts, that seems weak. So I was looking for some advice, or links to people who have built machines or worked around machines that have a decent system for adjusting the tilt of a spindle head, to make it perfectly true perpendicular to the table, vise, or work piece.

NickH
08-22-2007, 01:10 PM
A photo would help, it depends how you have constructed the mill what options might be open to you,
Regards,
Nick

Peter N
08-22-2007, 01:50 PM
Have a look at this recent thread:

http://bbs.homeshopmachinist.net/showthread.php?t=25148

Perhaps you can e-mail or pm the OP to see how he did it.

Peter

DrStein99
08-22-2007, 04:04 PM
I don't have any yet. Basically, the "Y" axis is bolted to a table of aluminum. The "X" and "Z" are bolted together and mounted to a right-angle frame. The spindle is a mini-mill r-8. None of the plates are precision ground or surface milled.

There is no existing adjustment to tram the spindle head, and I kinda got away with shimming. I am designing a rotary compound mount same to the one I see on the siege x3 mill to handle side-to-side tramming. But I am stumped on what to make for a fine tune tram on the spindle from front to back, with precision, NOT using shims, that is solid and holds rigid against vibration.

Ryobiguy
08-22-2007, 11:37 PM
I bet there's a name for this thing I'm thinking of, but imagine a thick adjustable parallel, made of two triangles stacked on top of each other when viewed from the side. Slide the top triangle right, and it shortens the height of it, move the top one left, and it raises the height of it. Mill a slot left and right through the middle of them so you can send a bolt through both of them to limit the slide and thus how low it can go. Perpendicular to this (up and down,) mill some more slots for the spindle bolts to go through. Now you have a (rather thick) adjustable shim.

I remember thinking about this type of device for leveling under the lathe feet, so maybe that's where this type of simple machine is used.

DrStein99
08-23-2007, 10:08 AM
Oh wow, that thread pretty much explains it all. Thats about the type of adjustment and support I was looking for.

Though, I'm not completely sure the distance of that head away from the column is completely rigid, for as slim as that is.

lazlo
08-23-2007, 01:45 PM
I would be careful about rigidity too -- the "nod" heads, even on a full-sized turret mill (i.e., a Bridgeport) reduce rigidity, because the ram (or the vertical column, in your case) is connecting to essentially a U-joint, instead of a solid ram ending in a ball joint (for the left-right tilt).

The left-right tilt is a pretty good compromise, IMHO -- it doesn't reduce rigidity, but still gives you one axis of tilt.

If I need to tilt in the Y-axis (toward the column), I use a tilting angle table.

DrStein99
08-23-2007, 02:15 PM
Well thats a better idea. If I can find a 6" or 8" hemisphere balljoint clamp, would do the trick.

Mcgyver
08-23-2007, 03:16 PM
if you're doing sculpture, I suppose you might be looking for 5 maybe even six axis stuff, but have you priced the software :D

on my xlo which is i think slightly beefier than a bridgeport, it has the knuckle on the ram allowing tilting in both directions. after ten years of owning it, want to know when those two axes get used? when re tramming the head after some heavy milling :) in other words, the (someday) increase in utility is not worth the sacrifice in rigidity.

have you considered putting the fourth axis on the work, ie rotary table or try platform like the full sized cnc mills use? might be more rigid. or even custom design a head the work mounts to that rotates and tilts.

DrStein99
08-23-2007, 04:41 PM
I don't use 4,5 or 6 axis to make sculptures, they are basic 2.5 d cam cuts out of flats. So having an articulated arm really means nothing to me.

I am trying to make a rigid / solid clamp for my spindle head, and allow some fine-tune level of adjustment without using shims. Its true; once its bolted in place I don't expect to change it. But I do tend to upgrade or modify the machine every 6-9 months. So shimming and recalibration is a real drag.

DrStein99
08-23-2007, 08:59 PM
Ok I think I found the prefect fixture. Steel construction, milling duty.

http://www.grizzly.com/products/G5758

Paul Alciatore
08-24-2007, 01:47 AM
Actually, I think that shiming the mount at the mounting bolts, instead of being weak, is probably the strongest, solidest way of adjusting the tilt of the head. And it is the least likely to be changed by external forces.