Building up gibs?

Someone posted that last week in RCM. There are strips (out of PTFE) available with a calibrated thickness that stick on one side. The brand was ... wait ... here it is:

| Turcite B, Garlock Multifil or Rulon something-or-other. They're teflon | filled composites that are epoxied to sliding surfaces.

|

| The stuff is expensive, but I have quite a lot of misc pieces. Will | trade for brushes, if you're interested.

The discussion started here: Message-ID:

HTH, Nick

Attaching a strip of shim to the existing gib will probably work, but only after a fashion, and a poor one at that. Even assuming that your gib is evenly worn along its length (very unlikely), the problem I found when I tried attaching shim to the worn gibs of my Elliot mill, was to produce an effective adhesive substrate of constant thickness. A few thou out here or there and I was as badly off as when I started! I spent hours experimenting with brass and stainless shimstock, superglue, epoxies and rollers before playtime was abandoned and I called in the professionals!

Unless you can get your gib built up with Turcite, or one of the other PTFE-based materials, and reground, your time would probably be better spent producing new gibs, not too difficult, especially if you have access to a surface grinder.

Suitable cast iron strip is readily available and College Engineering Supplies

will cut to size.

HTH --

Chris Edwards (in deepest Dorset) "....there *must* be an easier way!"

Not long after getting my mill many years ago and being dissatisfied with the play on the long axis of the table I stripped the gib down to see what was what. It was, like yours, at the end of its adjustment and no easy way to solve it. Needing to use it again fairly soon I regret to say I folded up some newspaper and stuffed it behind the gib. It's been like that quite happily ever since. I did use a quality broadsheet though. Financial Times I think it was :)

If I ever get the bumper sized box of roundtuits I need I might have a go at fixing it properly one day. There's always something more pressing to attend to though.

-- Dave Baker Puma Race Engines

Camp USA engineer minces about for high performance specialist (4,4,7)

technique?

(4,4,7)

Strip of thin paxolin insulation behind the gib and not glued is said to work quite well

AWEM

That's OK if you happen to have some thin Paxolin about the place. Perhaps I should try a couple of cut & folded pages from the MEW plans issue

Cheers Tim

Dutton Dry-Dock Traditional & Modern canal craft repairs Vintage diesel engine service

Nah - way too expensive!

Regards, Tony

Tim Hi,

Once in position the shim will not move far as Dave's newspaper shows. In the past I have used brass shim stock which I cut to match the gib strip including the adjustment slot (about twice as long as cutout to stop shim crumpling when adjusting gib) and bent at >90 degrees a small location strip (2-3mm wide) along the top edge (just clips over the top edge of the gib (between non sliding contact face and casting) as there is normally enough clearance between gib strip top and the moving slide). I just clamped the shim between the gib strip and a length of steel and folded the location edge over with a length of wood and a hide face. This was belt and braces really just to stop any possibility of the shim sliding down and out of the open dovetail. I used about 10 thou shim if I remember correctly and it worked fine for several years until we shut the workshop down and I moved on.

I've also seen Paxolin used with great success as Andrew suggests. This offers the advantage of being very slightly resilient so that the slide can be adjusted at the worn area and the slide will tighten but not jam at the non worn area, within reason of course. It will not compress enough to overcome heavy wear but will allow for a few tenths.

By using thicker shimming at the non-wearing face it allows you to take a lick with the surface grinder to remove any uneven wear on the sliding contact face of the gib strip. Got to be worth a try before making a whole new gib strip. Tim, I have to declare that these "repairs" were both on milling machines but I don't see any great difference to your setup although I don't know the DSG at all. Us "youngsters" were never allowed to use those top class machines and had to make do with the Harrisons and Colchesters, I think you had to be there at least 20 years before being considered for such trust when someone died! Those were the days, they keep telling me.

Best regards

Keith

I have wondered if a few small countersunk flathead brass screws or rivets might hold a brass shim satisfactorily. I have seen loose brass gib shims that seemed not to create any problems.

Don Young

I tried contacting the UK Busak & Shamban a while ago - I thought this material would be good for changing the shear used for guidance on an ML7, or shimming the saddle up after bed grinding.

But I got no answer to my email - maybe one of the Cynical Traders would have more luck with the chance of a bigger order ?

-adrian

Sign of the times I guess. I have had some dealings with them for prototpye high temp oil seals when I worked on engine development. But then we were spending 500 quid per seal on 10off quantities!

Some of the machine tool re builders will certainly have the stuff.

Wayne...

Tim,

I have a qty of 0.8mm thick tufnol clone sheeting. If that is not too thick for your gibs and you want a piece, let me know the size you need and your snail address. No beer vouchers needed! My proper email addy is bobdotminchinatntlworlddotcom. regards

Bob

Bob

Many thanks

email sent

Cheers Tim

Dutton Dry-Dock Traditional & Modern canal craft repairs Vintage diesel engine service