Gibs & Material

[TomB]

What is a good material for machine Gibs? The choices I see are corrasion resistant steel, some sort of plated steel, or oil filled bronze.
Intuitively I seem to favor the bronze material as it would give very good sliding properties and it would be plenty straight and flat. However to make the gibs I will have to chamfer the two long sides so the cross section is a trapezoid. That is likely going to be a hand grind then file operation as none of the machines in my shop are working. I'm not sure the oil filled bronze will cut well. Any relevant shared experience will be appreciated.

Thanks Tom

[pete]

Cast iron is another traditional gib material Tom. It's also got those self lubricating qualities. Engineering wise you want a softer material than the way surface. Higher tech which is likely well outside what your wanting, but steel or any metal could be used with a proper designed for the job plastic such as turcite bonded to the gibs sliding surface. There's a few other brands designed to do the same job. All of them are fairly expensive per square inch. Almost all material is going to warp while having metal removed, keeping or making your new gib flat after machining is the tough part.

Good design always has the cheapest part (gib) wear out first. Unfortunately all design is a series of compromises and the softer gib still isn't the perfect solution. That softer surface can pick up and have harder material get embedded in it. That's when way surfaces start to get scored since the gib is then acting like a lap. Keeping a machine clean and well lubed as well as protecting those surfaces from getting hard chips or abrasive material on them will always do the most for extending the life span of those all important way surfaces.

[armscor 1]

Watch Keith Rucker on youtube making a cross slide Gib for his Monarch Lathe, very informative.
Cast iron would be my choice.

[choprboy]

Cast Iron. Stefan Gotteswinter recently did a video on machining gibs:
https://www.youtube.com/watch?v=BTeoIT-l68s

[SteveM]

Don't use oil-filled bronze (aka Oilite). It's sintered metal and can't handle high loads and shock.

Don't use stainless, as many grades suck as a sliding material. The only thing worse might be aluminum.

Nelson's "So you want to build a live steam engine" book had a chart of material-to-material sliding properties and bronze and cast iron were good with just about anything.

Steve

[TomB]

Thanks for the references to youtube. (1) they convinced me that I need to make cast iron gibs. I had been thinking I needed to find stock in bars of sheets that was the thickness needed for the gib; it never occurred to me that I could band saw, then clean it up on mill and grinder. (2) I am so impressed with the quality of work shown and the condition of the shop and the tools. However I'm not sure my band saw can cut straight enough to rough out gibs. Right now everything I own has a layer of surface rusty, maybe someday I will look at a machine tool and see a silver rust free surface.


Although I can see why they used cast iron and how they did it my tool are still being restored after flooding. 7 years ago my shop in NY flooded, 3 feet deep. It was clean water and 12 inch floods had happened in the past. Like always I got things dried out then started all the motors so as to run them until they dried internally. Same sequence I had done in the past. At the time I had my 3-in-1 apart trying to straighten its gibs. Then I ended up moving to VT and while doing so I packed up tools put them in an unheated garage. I had bought a house that seemed to have a back basement suitable for a shop but when I went to fill it, everything would not fit. I bought a tent and put extra stuff in it hoping to get things cleared up over the winter. But during that winter my wife developed more and more dementia. I ended up being a full time caregiver and none of the tools in the tent got moved inside. Now I'm back trying to restore my shop. I've found:
1) one gib to the 3-in-1 is lost
2) the table lead screw was installed as a hack by the factory
3) none of my motors seem to work. I had hoped to use horz mill to cut parts but I'll have to buy a new motor before it turns again.
4) neither motor on the 3-in-1 works. Not sure why as neither was below water level.
5) Surface grinder is in tent and slightly rusted. I bought it used at Cabin Fever and when I got it home discovered it was missing a gib. Since that tool seems to be needed to make quality gibs I'm not sure how to proceed.
6) My swinging arm bandsaw in in the tent, It was covered in enough oil that it has not rusted, but I never remember it cutting straight enough to match the quality shown in the youtube videos.

I'm a bit overwhelmed, but I try to remind myself the machine shop is just a hobby. Do one thing at a time.
Thanks again for the information.

Tom

[pete]

I can relate to that overwhelmed feeling Tom. Do you have a surface plate or can you buy a heavy sheet of plate glass? Glass won't be surface plate flat, but should be ok to test and get you a flat enough gib to work. About the best method I can think of is rough out, file or do whatever you have to for a gib that will work for the surface grinder. At least you have a surface grinder and that should make the job a whole lot easier.Then use it to make a decent permanent one. Boot strap your way up. It sounds like all the gibs you need are just the straight variety. Those still need a taper cut on the top and bottom to match the machines dovetail angle and the gibs width, but there still a whole lot easier to make and fit than the tapered type.

Before milling machines were invented files and good hand / eye coordination skills were the first mills. As long as a gib is flat enough to not rock on a flat surface it will be good enough to work until you can make better with the SG.

[TomB]

... Do you have a surface plate... Those still need a taper cut on the top and bottom to match the machines dovetail angle and the gibs width, but there still a whole lot easier to make and fit than the tapered type.

Before milling machines were invented files and good hand / eye coordination skills were the first mills. As long as a gib is flat enough to not rock on a flat surface it will be good enough to work until you can make better with the SG.

I have several surface plates.(granite 24x36", steel 28x18" granite 18x12" & granite 6 x6"). I was sort of thinking about approaching things as you describe. If I first bought a new 3/4 hp 110v motor for the horz mill I could use it to cut off a piece of cast iron about .5 x1x36" long. Then with a 4" grinder and files I could true it to the correct thickness. Finally I could cut to make the trapezoid cross section using the horz mill with the gib-to-be screwed onto a piece of angle iron.

Thanks for the suggestions and encouragement. Tom

[jscarmozza]

Tom, attached is a photo of salvaged gibs that I have no real use for, if you want any, just pay for shipping.
John

[TomB]

Thanks. I sent you a PM.

[jscarmozza]

Tom, I didn't receive your message, do you want to try again? John