table wear + movement

Discussion on all milling machines vertical & horizontal, including but not limited to Bridgeports, Hardinge, South Bend, Clausing, Van Norman, including imports.

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liveaboard
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Re: table wear + movement

Post by liveaboard »

Harold, are you calling my milling machine a PIG???

Maybe it is for you aerospace guys, but out here in tractor country it's as good as it gets.

Thanks for the dose of reality, I look forward to getting into it and finding out what I can do, and what I can't.
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NP317
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Re: table wear + movement

Post by NP317 »

But it's a NICE pig! ... :lol:
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Re: table wear + movement

Post by John Evans »

With lipstick it becomes !!!! Miss Piggy !! LOL
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Re: table wear + movement

Post by Harold_V »

liveaboard wrote: Wed Jun 16, 2021 11:29 am Harold, are you calling my milling machine a PIG???
Chuckle!

Nope! But if you make the mistake of a partial rebuild, I may be so inclined. (I can now see why you may have thought I was attacking your machine. I was not. I was attacking the concept of addressing only one part of an issue, which does little more than change the nature of the problem, rarely resulting in a solution.)
Maybe it is for you aerospace guys, but out here in tractor country it's as good as it gets.
And that was my point. You are highly unlikely to find yourself in the position of needing high precision. For your needs, that mill should serve you exceedingly well. That would be especially true if you add a DRO, as that would override the wear of the screws, which the machine is sure to have experienced. (Take note of the fact that I rarely promote DRO's)
Thanks for the dose of reality, I look forward to getting into it and finding out what I can do, and what I can't.
I'm not sure you needed any wakeup call, as you had a good and valid question, which deserved a reasonable answer. I strongly suspect that, assuming you can keep the machine running, it's going to address your needs quite nicely. Well done!

H
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RONALD
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Re: table wear + movement

Post by RONALD »

I did exactly what Harold suggests when I got hold of a B&S #2 from the 1950's.

Paid $500 for the mill, it had been used in a high school machine shop, which meant it had not been used every day of the year, only intermittently.

Still worrying about the wear, I decided to buy a DRO, I choose Heidenhain.

Harold no doubt would say "that is like buying a silk purse for a sow", because they are the top of the line in DRO's; it's only $$$$ and it took care of any worry I had about positioning on that mill.

The DRO can be seen in my rebuild at: https://www.youtube.com/watch?v=C-sfBZWdyPA
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liveaboard
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Re: table wear + movement

Post by liveaboard »

I never finished this tale...
To get the ways tight on the vertical slide, I had to push the wedge about 1/2" past it's design maximum. To do that, I made a little fitting to go under the adjustment screw, and another to hold it at the bottom.
Ruhla 250-710 vertical slide adjustment adaptor.jpg
Ruhla 250-710 vertical slide adjustment adaptor bottom.jpg
it does stick just slightly at the top and at the bottom of it's movement.

I did the same thing for the top slide, it wasn't as bad though.

But the main left/right slides that should have the most wear were easily tightened within the normal range; so I assume someone has reworked or rebuilt that part.

Next; the vise.
There seems to be a problem but I hadn't gotten to figuring it out yet. Yesterday I noticed the fixed jaw wasn't well fixed. It turns out someone cut into it and destroyed the fixing screw hole.
damaged vise.jpg
I tried to drill it out but there's something very, very hard in there. I was making achingly slow progress with a carbide drill (the parent metal is only mildly hard). The other screw hole has a helicoil in it.
vise damage detail.jpg
Even worse is the damage to the machined surfaces. As you can see, chips must have gotten in between the vise body and the hard jaw, and then caused this damage when the vise was tightened, many times.
I'll try drilling again tomorrow if it's not too hot in the workshop.

Also, the table doesn't sit quite right on the mounting apron;
gap under table.jpg
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Re: table wear + movement

Post by Wolfgang »

The saddle on my knee mill has a similar tapered gib on the Y-axis. This stuck out so far at the inboard end so as to impede the Y-axis travel, and caused similar problems such as yours on the adjustment end.

I contemplated a repair for this problem when an easy solution occurred, probably while trying to fall asleep.

After removing the gib I cleaned the back side with acetone and stuck a layer of aluminum duct/muffler tape onto the gib. Trimming the excess was a breeze with a sharp knife, followed by rolling a dowel pin over the tape to ensure good contact everywhere.

Replacing the gib and adjusting it showed that 1 tape thickness was the perfect fit, with no gib stick-out at the back and the adjusting screw in mid position.

Worth a try for the little effort it takes to implement.

If more or less than the tape thickness is required (I don't remember its thickness) then perhaps shim stock attached with a layer of spray adhesive may be worth considering.

An aside: Aluminum foil is rolled remarkably parallel in thickness.
Russ Hanscom
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Re: table wear + movement

Post by Russ Hanscom »

very creative
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Re: table wear + movement

Post by Harold_V »

Russ Hanscom wrote: Wed Jul 14, 2021 3:45 pm very creative
Yes, it is, and it's more than adequate for the purpose at hand. Certainly a lot easier than trying to make a new gib.

Well done!

H
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Bill Shields
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Re: table wear + movement

Post by Bill Shields »

i have done similar with very thin ss shim stock.

super-glued it to the back of the gib
Too many things going on to bother listing them.
John Evans
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Re: table wear + movement

Post by John Evans »

On a Bridgeport at least when shimming the gibs you need to match up the oiling holes so oil will get to the actual sliding surface. I have shimmed several experienced BPs ! LOL
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Re: table wear + movement

Post by Wolfgang »

Ha! And here I thought (obviously mistakenly) that I had an original idea!
Who was it that said: "There is nothing new under the sun"???
I'm glad that you fellers chimed in to verify the validity and usefulness of the shimming idea.
I recall a solution to the discussed problem described in Model Engineer Magazine oh so many years ago. The author of said article cut off the excess length of the gib at the thin end, and machined a new piece for the adjustment end, silver soldering both in place. Followed by scraping for good fit-up...
My first thought was: There just has to be a better (easier, cheaper, faster) way of solving that headache... Ofttimes it does not pay to rush into a (first or second) solution that comes to mind.
For a machine that's worked hard, especially if the shim required is thicker, say .025" and up, I'd use hard brass sheet/strip or steel shim. And attach it with small flat head screws. As mentioned above: Don't forget the lube holes if present!
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