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pntrbl
12-27-2006, 11:18 PM
So my new gibs arrived from Logan today and the 1st thing I notice is there are no locating holes. Am I supposed to drill them? On a 45* angle? And in the right place?

I'm gettin' nervous already ....

Could it be as simple as sending a slightly smaller drill down the hole where the groove pin goes that locates the gib? Seems like the drill would try to take a walk down the 45. The side of the hole would stop it but surely there'd be some loss of metal on the bottom side of the hole.

I'll be calling Logan in the morning but the suspense is killing me.

SP

CCWKen
12-27-2006, 11:29 PM
Don't need holes, just dimples. Install the gib and center it--without the screws. Install the screws tight to mark the the spots, remove the screws and gib then drill dimples. I've used a center punch to mark locations but you need to check the gib as some may be hardened. Center punching may crack a hardened one. If they are hardened, you might have to use a carbide ball end to get the dimple.

pntrbl
12-27-2006, 11:37 PM
Oh! That sounds a lot better. I can probably do that .....

Judging from the mangled condition of the originals I doubt they're hardened. But I'll ask.

Thanx Ken. You da man.

SP

SGW
12-28-2006, 10:37 AM
When I made a gib for my lathe, I used a 1/4" ball end mill to do the depressions. Note that you have to (or ought to be) holding the gib at a 60 degree angle while you're doing the dimpling,, not 45 degrees...I assume.... Check your angle.

shapeaholic
12-28-2006, 11:22 AM
The procedure I have used a couple of times is:
1) insert gib in machine part
2) install a couple of set screws to hold alignment
3) spot through the vacant holes with a taping size drill to mark the location (or if your brave enough drill deep enough to make the dimple)
4) move the set screws and mark the rest of the dimples.

I have used this procedure several times with good success. I usually drill deep enough to make the dimple in the first set-up.

Pete

pntrbl
12-28-2006, 11:23 AM
Hmm. Just like SGW says, don't believe everything you know. The gibs are in fact at a 60* angle.

The gib screws are 90* cone points and I "assumed" that was to lay one side of the cone against the back of a 45* gib. Learn something everyday. In my case it's almost hourly!

So the desired perfect objective here is to have the pinpoint of the gibscrew setting in the center of whatever form of dimple in the back of the gib. Thus the necessity of having the gib angled when dimpling.

Wow. I gotta long way to go.

Thanx guys.

SP

rkepler
12-28-2006, 12:47 PM
I guess that it might not ruin my reputation to mention that when I needed to dimple some flat gibs that I just ran the tap drill into the gib through the tapped hole. The sides of the drill won't cut much if any but you'll end up with a root diameter dimple exactly on the center of the hole. You can widen it afterwards with something closer to the major diameter but the tap size will usually work just fine, even better if you dog point the screws a little bit.

J Tiers
12-28-2006, 02:09 PM
If'n you do that "run the drill in" deal, just make sure that the gib is centered in the gib space (vertically) when you do it.....

You don't want it crammed into the "corner" of the dovetail so that it has all kinds of friction on an unfinished surface.........

Your Old Dog
12-28-2006, 05:58 PM
If you have a Dremel mototool you can get small round stones that will make your dimple after marking them as suggested by some others here.

A.K. Boomer
12-29-2006, 11:15 AM
The only thing I would add is try to use the same diameter marking tool that the tool you will be making the dimple with is (which sould be very close to the same size as your adjusting screws ends are -- otherwize you will get "gib shift" when the handle is moved back and forth) then even though the piece will be at an angle you can touch down with the tool at the same spot and take the guess work out of trying to eyeball it or just plain forget and dimple it only to find that your retaining holes are to high or to low on the gib...

pntrbl
12-29-2006, 09:43 PM
I used the drill thru the threaded hole method and all seems fine. I could feel the corner of the drill catch first and with real easy pressure I could also tell when the drill tip got there. Made a triangular shaped dimple but the pin points from the cones are dead nuts where the drill tip engaged.

Haven't done the cross gib yet. Still waiting on paint to dry ....

You guys are the best. Can't say Thanx enough .....

SP

DaHui
01-01-2007, 03:28 AM
This might be a bit after the fact, but I recently made a replacement gib strip for my machine. I didn't have any idea what I was doing but the new strip seems to work much better than the old one, so at least it's an improvement.

I spotted the holes using layout dye and snugging the screws onto the gib with it in place. After removing the gib again I center punched. To make sure the adjusting screws were perfectly aligned I located the first center punch and then just traversed the X axis without moving the Y.

I managed to hold the part using a bunch of parallels in a vise with some hold down clamps. The other thing I did, which may have been a mistake, was to take my adjusting screws and turn town the pointed tip to a bullet shape. At the time it seemed like this would self center more effectively.

Anyway, scroll down the list on the left at this page to "machining projects": www.the-alchemist.com