x-axis gib + shim question

Have done nothing with my mill yet. Purchased the r8 adaptor from GizmoWizard (thanks Paul) so I can use all the stuff I had for my mill drill.

Last weekend, Paul and I dissassmebled the x-axis saddle(?), and found that the gib had a shim glued to it. We measured the shim to be ~0.003.

Has anyone seen this practice being employed?

The shim is bunched up at one end, so the current plan is to replace it with a new one (Pauls suggestion is the shim goes on the stationary side of the gib). I am going to remove the shim and clean up the gib with mineral spirits, if a pic would help, I can do this before cleaning.

What other options do I have for the gib other than this shimming approach?

Thanks,

vinay

What manufacturer and model of mill is this? I don't seem to remember this coming up before.

Chris P

FP1, 1952 vintage.

Vinay;
A shim on the back side of the gib is not unusual. Sometimes when the ways are re-scraped ,or the gib is re-scraped, to get it back into a useable adjustment range a shim is glued or soldered to the back side of the tapered gib. If the shim is replced i would surley test the contact of the front surface with the slide using prusian blue to assure that it is making good and even contact. You might be able to use one of the Moglice products to fix the shim to the gib. I am reffering to the Moglice that is used to "set" things like a headstock to a bed on a lathe. (don't know the exact item name or number).
Do a google search for Moglice.
You might be able to use the setting compound in a dynamic setup..that is coat one side of the shim with the compound, then assemble to the slide and lightly adjust the gib. That way the shim will conform to the location needed to get the gib to make contac with the slide. Would contact Moglice before i did this however and be sure to use some reliese agent on the slide surfaces.

Another option would be to make a new gib that was thicker, to account for the shim thickness. This would generally require the use of the mill, and that might be some trouble if the gib can't be used in temporary mode to make a new part. Making a new gib wuld also require scraping the surface in contact with the slide to get a machine quality sliding surface. (not sure if this is a good first scraping project).

You could also bond a layer of Turcite to the front surface of the gib. This is a tefflon way material that is glued on. It is used on machines to lower friction, and also to take up wear on surfaces that have been ground during a rebuild....again this would most likely require finish scraping to get the contact and geometry sutible for a machine gib on a way surface. Also i think you would need to machine the gib a bit thinner before applying the turcite as it is somewhat thicker than .003".

I think the shim is the easiest and quickest solution. I would explore the Moglice setting compound as a possible bonding and leveling agent.
Cheers Ross

vinay

my mill has something similar done to it. the boys at huskys maintenance dept (where my mill was run originally) added a section to the end of the gib for the adjusting screw to push against. seems to work well enough. this might be a situation where you might want to reassemble things with a new shim and verify how bad the repair "fixes" the problem. on my mill the gib adjusts well enough for most work i've attempted so far. as ross mentions this becomes a bit of a slippery slope if you start to address one areas problems...

i have a question relating to rebuilding the x-axis. judging from the way the table rides on the saddle if you scrap the surfaces back into alignment how do you adjust the leadscrew positioning? seems to me if you start to move the table down and inwards this will bind the leadscrew. is this why most rebuilders are using products like moglice?

nathan

Nathan

The leadscrew axis positionning shouldn't be a problem, since all you have to do is to keep it centered with the carriage flanges.

Just a matter of removing the positionning pins and to re-locate or re-drill the holes with a slightly bigger drill bit.

Much easier than if you had to deal with apron/feedbox/leadscrew support alignment on a lathe...

Nathan:
T is correct. In tool reconditioning it is a comon practice to "float" the bearing supports on the table to regain the proper alignment. This is done by removing the dowells and moving the table to one end of travel. The bolts are loosened on that side end plate to allow the screw to "adjust the location of the end plate, then the bolts are tightened. This is the quick and dirty prociedure. A more original prociedure would be to remove the dowells, and "Tram" the leadscrew to assure the end plate mantains the screw alignment to the axis move. Of course you must check the alignment in both the vertical and horizontal planes. Both ends of the screw should be moved , and it may be necessary to do this several times, as moving the screw mount at one end of the table will affect its relation to the opposite.
For light repairs moving the supports is fine, for a machine that requires the parts to be ground and scraped a large amount, i favor regaining the alignment by use of Turcite or Moglice.
Cheers Ross

thanks for the tips guys. i had suspected there would have to be some manipulating of the bearing supports to allow realignment after scraping. when the time comes i'm thinking i'm going to go with the moglice / turcite method of resurfacing the ways.

i'm having too much fun making chips with the deckel to worry about that now though.

nathan