Thread: Try and repair or learn to live with it?

I wouldn't worry about the bend in the gib just yet. But then I'm not sure yet what the issue is.
To back up a little. The checking you did in post 4. You checked for movement on the left side with the table to the right and movement on the right side with the table to the left. Did you check for movement on the right side with the table to the right and left left.
I'm wondering if its really a wear issue.
You haven't adjusted the gib with the right hand lock not fully undone? or a burr from the locks on the back of the gib?(assuming the gib is at the front)

Originally Posted by Stustoys

I wouldn't worry about the bend in the gib just yet. But then I'm not sure yet what the issue is.
To back up a little. The checking you did in post 4. You checked for movement on the left side with the table to the right and movement on the right side with the table to the left. Did you check for movement on the right side with the table to the right and left left.
I'm wondering if its really a wear issue.
You haven't adjusted the gib with the right hand lock not fully undone? or a burr from the locks on the back of the gib?(assuming the gib is at the front)

Good point. Let me take a few more measurements so we get a good baseline for what I’m trying to solve.

Gib is at the front too and has a couple of divots from the locks. Do I need to address those or will they be ok in test phase?

Divots are fine, just as long as there are no raised area around it.

Originally Posted by Stustoys

Divots are fine, just as long as there are no raised area around it.

I will stone them quickly to make sure before they go back in for measurements.

Hi Guys,

I took the front mounted gibb out of my mill some time ago to have a look at it. It too is cast iron and was bowed towards the table, maybe 5 to 8 thou. It looked as if it had been very roughly milled, I gently rubbed a file over it just to take off the high spots. I used plenty of oil when I put it back in. It made a fair difference, the table moves more easily now.

No divots in it at all just the notch at one end where the screw adjuster was. There are some marks where the table lock screws bear on it. I did replace those M6 screws with stainless hex socket ones, I domed the ends on the grinder so they turn without that stick slip feeling. It doesn't take much to lock the table at all, maybe half a turn.

HTH.

BaronJ, mine is the same, actually I would say it’s likely rougher. The machining marks are clearly still visible and I can’t imagine are helping with the smoothness of the table sliding:

Back of the gib:





Front is better but still with some odd marks and a couple of gouges that look like it was finished with an angle grinder





The marks where the locks go have clearly raised a burr, so I stoned them flat. I have since replaced the locks with Alu in between the gib and steel bolt to stop marring in the future.

Redid the measurements. Decided to dial back the backlash adjuster on the X Axis screw so I didn’t have that interfering with the feel/readings.

I tested either end of the table with the table in the far left, central and far right positions. I aligned the table with the lower casting to get a similar reading each end.



With the gib screwed in the table was tight to move on the screw, so I backed it off so it was easier to move. It created movement in the table still though, so I really need to address the condition and straightness of the gib as I’m sure it’s stopping me from being able to screw it in enough to remove the slop.

Table to the far left.
Right side: 0.03mm
Left side: 0.09mm

Table in centre.
Right side: 0.09m
Left side: 0.25mm

Table to far right.
Right side: 0.09mm
Left side: 0.16mm

Hi Neevo, Guys,

Those figures you’ve measured are not that much different to the ones on mine ! In fact looking at your pictures I would say that apart from table length your mill table isn't that much different.

I did notice that you have some divots that my gibb strip doesn't. I wonder if that is because I never used the clamp screws before replacing them. I did try putting some tiny plastic discs in the holes but they fell through, so I removed them and just rounded off the ends of the screws.

I wonder if when they made the gibbs, they didn't just saw off slices of cast iron plate, because that is how rough mine was. I gave it a rub with a file but deliberately didn't try to get it smooth on the premise that it would retain oil in there. The actual dovetail was quite good without any rough patches. I give it a squirt of oil every now and then though.

Originally Posted by neevo

With the gib screwed in the table was tight to move on the screw, so I backed it off so it was easier to move. It created movement in the table still though, so I really need to address the condition and straightness of the gib as I’m sure it’s stopping me from being able to screw it in enough to remove the slop.

Table to the far left.
Right side: 0.03mm
Left side: 0.09mm

Table in centre.
Right side: 0.09m
Left side: 0.25mm

Table to far right.
Right side: 0.09mm
Left side: 0.16mm

Well thats half the problem gone Its also close to the pattern of wear I would expect.

You can likely remove the bend in the gib with the pressure of your thumb*.......sure its not perfect but I doubt its effecting your numbers a great deal.

Judging by the pictures the gib doesn't seem to have much wear.
It would see more wear than the dovetail.. right?
So I'm still not sure its a wear issue.
I'd take the gib locks out, just to be sure.
With the table to the left pulled towards you, can you get a feeler gauge behind the gib on the right hand side?
It will be hard to see in there with the table on but if something is holding the gib forward on the right it could be part of the issue.
If you can find and remove a 0.06mm ding/bump/hump holding the gib out of place on the right hand side, your numbers should be closer to
0.0mm
0.0mm

0.03mm
0.16mm

0.03mm
0.07mm
If my third attempt at the numbers is the correct one

Seems to be something strange at the far end of the gib. but I cant tell which end it is.

*I mean pressing it flat against a flat surface, not talking about trying to straighten it.

Thanks everyone. Agree it seems I’ve taken a bit of the issue out with the smoothing of the back of the gib. Are those divots ok or should I look to braze some silicone bronze in them to file them flat?

I will try a feeler in the gib next. It does look like something is inconsistent on that side. This time when measuring I noticed more spring in the dial indicator than I did before which I assume is related to the bend in the gib?

I have ordered a surface plate, so once I have that in hand I will test the gib and try and get that dialled in.

Hi Neevo, Guys,

Those divots will try and push the gibb around when you tighten the table lock. I'm not sure what would the best thing to do there. Certainly it would be better if they were not there.

Originally Posted by BaronJ

Hi Neevo, Guys,

Those divots will try and push the gibb around when you tighten the table lock. I'm not sure what would the best thing to do there. Certainly it would be better if they were not there.

That was exactly my thinking too. Given I have a bent and poor quality gib to begin with, I’ll TIG braze them up and fix the movement after.

Would it be correct to say that your gib is only adjustable one way or is there a screw at each end?
I would think that if you adjust the gib then those little spot faces would not line up with the table locking screws, if that's the case then they are serving no purpose and could be removed.

Originally Posted by pipeclay

Would it be correct to say that your gib is only adjustable one way or is there a screw at each end?
I would think that if you adjust the gib then those little spot faces would not line up with the table locking screws, if that's the case then they are serving no purpose and could be removed.

Correct. Gib screw is one end only. I think they’re damaged from someone cranking on the axis locks like a gorilla. I’ll braze them up and grind them back.

Hi Neevo, Guys,

You might also find that the gibb changes shape when you tig those divots.

I would check that there isn't an adjusting screw or threaded hole for one at the other end. Mine has ! But it had dropped out and was in the tray. It nearly got binned when the magnetic wand picked it up.