[cowanrg]

I'm moving along in my conversion of my PM30. I installed the oiler, but when I put the saddle back on, I'm noticing that the gib on the Y axis is a bit too fat.

It's hard to explain, but the strip doesn't push all the way in without getting wedged between the saddle and the base. The back adjustment screw can be screwed all the way down, but the strip isn't hitting it yet, it's still sticking out about 1/4" - 1/2" in front. If I slide the saddle back and forth, you can see the strip sliding in between the two adjustment screws, and it will bind in one direction (effectively wedging itself in), and be loose and free the other way. If it was just a tad thinner all around, it wouldn't wedge itself in there, and the adjustment screws would do their job and I've have one smooth sliding saddle :-)

I'm getting a granite surface plate tomorrow, does it make sense to sand it down a bit on the back side?

[pippin88]

If it fit before you have to wonder why there is a problem now. Is it in the right way?

[cowanrg]

sorry, I should have clarified. I've never used the mill, I unpacked it and went right to work on the conversion. The Y axis was always a bit stiff, but I assumed it was just because it wasn't properly oiled/adjusted yet. Once I tore everything apart, cleaned it up, and got it oiled, I found that the strip was a bit too tight.

[Fastest1]

Are you sure you didnt swap the Y and X axis strips?

[cowanrg]

yep, I'm sure I didn't mix them up. The X strip is about 4 inches longer. It's pretty easy to tell them apart...

to sum up...

it's the right strip, it's in the correct orientation, and yes, it's actually a gib strip.

It's just ever so slightly too thick.

[arizonavideo]

Most of the time the tapper is wrong. Might check it first so you can change that at the same time.

Blue it up.

[AiR_GuNNeR]

If you machine down the gib to get rid of the thick end, you will still be left with an improper taper. Here is a technique that will fix that.
I did a rebuild of a CNC mill a while back. I ended up scraping everything in, which of course made the gibs too thin. I handle that by cutting some stainless steel shim stock to the correct width, and long enough to bend over the ends. I squished a small ball of epoxy, (I used the knead-able type because it's like a putty consistency), every inch onto the gib an put the shim stock over it. I slowly pushed the gib into place. It really takes quite a bit of force, but slow and steady will get the gib into place. The epoxy will slowly flow and take up the correct amount of space to establish the proper taper. Once the epoxy hardened, I pulled the shim stock off and filled in the places where the epoxy didn't flow. Search on my thread for pictures.

[cowanrg]

I will check the taper when I get home. From my preliminary findings (before I started this thread), I found (unscientifically) that the contact/taper seems fine, it's just overall too fat. There's no "thick end" really. It slides in fine, but just needs to slide in another 1/2" so the rear adjustment screw makes contact. My guess is that if it was maybe 1mm thinner all around, it would be the right thickness all around, and would not bind (and the adjustment screws would work as intended).

Does that make a bit more sense?

I'll check it in the next day or so to see how the taper is. It slides smooth as butter (one one direction), but when you push it the other way, the strip wedges itself in place (since there's not a stop for it, it just slides further in the channel), and it binds up. However, I can still move it, but barely.

[arizonavideo]

The lock pins stick sometimes too.

[cowanrg]

I assume the lock pins are the little brass pins that push against the gib strip for locking it down... Those were removed when I did the oiler setup. They're not in the way.

I seriously spend a good couple of hours checking out all possibilities. This is my third conversion so I'm a bit familiar with the mechanics of how everything works.

There's no debris in the way, nothing else obstructing it, the movement is smooth, it's just a bit tighter than it should be, for now being fully adjusted into the channel yet.

[cowanrg]

I took the saddle off the mill this morning and flipped it upside down. I put the gib strip in the dovetail (the correct way), took out the adjustment screws, centered the strip, and measured the distance from the edge of the strip to the opposing dovetail. This should give me an idea if the taper is correct, and if it's significantly thicker on one end. It doesn't seem to be. At most, it's off by 0.1mm. I measured all along the strip, from the front to the back, and it's generally pretty consistent. of course it varies, but not by a whole lot. And it's not necessarily thicker on the end that binds (the back). It looks to be a pretty even fit.

I get my granite surface plate tomorrow so I can see how flat it really is, maybe it's bowing out somewhere. I can also blue it up and check for flatness that way. Initially when I took the saddle off, I left the adjustment screws in their previous position, which was where the front was best adjusted. When I flipped it over, I noticed that there was maybe only 1/8" between the gib and the rear adjustment screw. So, it's pretty close to being right, it's just a tad too tight.