[mrcodewiz]

I am just now re-assembling my G0704 after tearing it completely down for cleaning. I kept trying to install the Y axis but every time I ran the saddle toward the front of the machine, it would bind up. I finally inspected it with a flashlight and I found that the way the gib was made was allowing it to actually slide around the head of the rear gib screw.

Here is the rear of the Y saddle with the gib installed and no gib screw:



Here is a closeup of the gib screw hole. It actually looks like it should work - the gib is within the perimeter of the cutout anyway:



There are a couple problems, though.

1) The hole that is tapped for the gib screw is not perfectly centered.
2) The head of the gib screw is a very, very loose fit in the hole in the saddle. Probably because of #1. The hole is about .67" and the screw head is less than .61"

Here is a picture of the gib - you can see where the screw head rode up the side of the gib when I ran the saddle forward.



I considered making a new screw with a larger head but I opted not to for a couple reasons. I didn't have a metric die and I figured I would run into the same problem since the tapped hole isn't centered. I would have to reduce the head size in order for it to thread in. The only other thing I could think of was to make a spacer to fit over the screw that is just slightly smaller than the cutout in the saddle. I made the spacer .665" and drilled the hole a little oversized so it could float on the gib screw a litte:



Here is a closeup of the gib screw with spacer installed in the saddle. This pictures makes it obvious how off center the threaded hole is within the cutout. Maybe it would be ok if it had been offcenter toward the gib but it just so happens that is offcenter toward the outside. It seems to work but obviously I haven't really used the machine yet.



Does anyone see a problem with doing it like this? I really don't want to go through the headache of having to call up Grizzly and try to do some sort or replacement.



Kevin

[photomankc]

Seems like it should work to me. Is it aluminum? Is there any danger of corrosion from the various metals being in contact? I think the gibs are stainless. I've made some AL parts that are in contact with bare cast iron and I have wondering that myself. Or do you need something like coolent/water to get in there too to get the reaction?

[mrcodewiz]

Hmmm... It was just some steel I had laying around. Probably 12L14. I was going to use aluminum but I was afraid the gib would dig into it.

[photomankc]

I see. Looked like AL in the photo. I see no reason why it wouldn't work fine. As long as it can push the gib down in there and hold it that's all the screws are there to do anyway.

[mrcodewiz]

Yeah, it does. I think that is just my terrible camera. I looked over the X axis gib screws and they don't have the same problem so hopefully this works out OK.

[knudsen]

Seems like it should work to me. Is it aluminum? Is there any danger of corrosion from the various metals being in contact? I think the gibs are stainless. I've made some AL parts that are in contact with bare cast iron and I have wondering that myself. Or do you need something like coolent/water to get in there too to get the reaction?

In a practical sense, yes, you need an electrolyte to get dissimilar metal corrosion (or any form of corrosion). The oil will act the opposite of an electrolyte, and further prevent the dissimilar metal corrosion. You may notice the oil turns black quickly, and that would be aluminum oxide, but in very small amounts.

Intergranular corrosion is the same thing, except it occurs within an alloy. It does happen, but it's pretty slow and seemingly rare. In certain exotic metals, like the older "aircraft aluminum" from the 50's and 60's, it was a problem, and aircraft would develop a lump, and you could punch a screwdriver handle right through it.

Corrosion occurs when there is an anode (metal A), cathode (metal B) and electrolyte (the crap they spray all over Indiana roads all winter).

I studied this many years ago in the early 80's, in a land far, far away, and that's all I remember. :rainfro: Well, I also remember the corrosion on the old, old A-4 Skyhawks was working on. :rainfro: