Gallery, Projects and General > How do I??
Gib Strip for a Capco Surface Grinder
philf:
I recently bought a bargain Capco surface grinder aptly described as a project.
There were many bits missing or not quite right but most could easily be made (and mostly have been).
The one part I'm having difficulty with is the gib strip for the main slide which was missing.
It's 640mm long, 9.5mm thick with 55 degree angles.
If I start with 1" x 3/8" cold rolled mild steel it'll no doubt ending up like a banana when I machine 1 of the 55 degree angles.
I thought of taking off a very small amount on one side and then the other to try to balance things out but this will take forever. My angled vice has only 4" jaws so any machining will be have to be in 5 or 6 steps.
Hot rolled steel might distort less but will require the sliding face machining and I'm limited to 300mm travel so again I can't do it in one go.
Anyone got any bright ideas?
Cheers.
Phil.
PekkaNF:
Gib can be banana when it is that slender. But the cross section must stay constant. My friend just ordered spare for one milling machine and spent two weekends scraping it.
Can you use the grinder table (bolt it onto milling machine table) and use that as a jig to mill the gib? If you clock the "jig" or table straight you can move the gib, clamp it against the dovetail and mill the top with endmill with reasonable accuracy.
I wonder if I can explain it right: You size the stock to right flatness, then you have a square bit. Then you clamp this square stock into the dovetail using roll pin or whatever means necessary. Now you are offereing it to the end mill at correct angle, because it is in the dovetail in situ. You mill the top straight (it will be proud of the dovetail, because you have unwanted corner at the bottom), then you shim bottom at the dovetail, put this gib strip atop of the shim, clamp, and mill this other side. I may need to resor drawing (suck at it).
I would not use any type of tilting vice on this long/slender piece. You will be fighting a lit to get the setup repeatable.
Pekka
Pete.:
Just buy the 3/8 cold rolled strip, mill the angles, scrape the working face for oil pockets and fit it. I did this on a lathe recently and it worked out fine.
philf:
Thanks Pekka and Pete,
I'll go down the cold rolled steel route. If it fails it won't have cost much.
Bolting the grinder table to the mill isn't easy as the grinder table is bigger so, unless I drill holes in the grinder table, I cant' get to any T-slots to hold it down.
I have a smaller table off another machine with 55 degree dovetails - I may try to clamp the gib to that.
Whatever - it'll have to wait a few days as my wife and I are off on our bikes for a few days - hope it cools down a bit!
Cheers.
Phil.
Pete.:
If it's not a tapered gib then it must be screw and locknut. There's no reason at all why you couldn't make it in two halves.
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