uhmw Tolerance for mitre slots

[Cory filder]

I plan on making a sled for my bandsaw and using uhmw in the slot. The slot width is an unusual size, so I will have to get it custom cut. what is the typical tolerance that is considered good?
thanks

[Doug Garson]

Don't know but it is pretty easy to file or sand it down it it is too tight, not sure what you can do if it is too small. It's also easy to cut yourself on a table or band saw. I've cut old plastic cutting boards that I assume are UHMW with both my table saw and band saw. I have also used leftover engineered hardwood flooring (basically plywood) for runners.

[Jim Morgan]

For runners that are too narrow, cut vertical slots in the ends & run in (tapered) wood screws to spread the halves apart horizontally.

[glenn bradley]

I agree that buying a standard size blank and cutting it yourself makes sense. I fit mine snug and then card scrape or even hand plane to fit. I have used UHMW for runners with good success on two-runner sleds. I do not know that it would be my choice for a one-runner sled as it is pretty flexible. You could counter this with additional screw points but a strip of straight grained oak would probably work as well. I have commercial aluminum, UHMW and wood runners on various sleds. I can tell no difference in use.

[Lee Schierer]

UHMW polyethylene is easily worked with woodworking tools. You can cut it with a table saw or band saw. A hand plane can be used to make small adjustments. You can run it through a planer or jointer, but the shavings have static cling. You can also buy UHMW adhesive tape in various widths and thicknesses.

I added a strip of 0.004 UHMW tape to the side of my steel miter gauge bar to remove all side to side play. It lasts for many years and is easy to renew when necessary.

[Richard Coers]

Just make it fit, and not rattle, it needs no tolerance on the dimension.

[Mike Cutler]

I plan on making a sled for my bandsaw and using uhmw in the slot. The slot width is an unusual size, so I will have to get it custom cut. what is the typical tolerance that is considered good?
thanks

Tight enough that it doesn't wiggle side to side, and not so tight as that it won't move. It's really just kind of a "feel thing".
Take seriously the advice to add some wood screws to "spread" the material. It may only have to move a few thousandths to be perfect. If I had to pick between a little bit tight, and a little bit loose, I'd pick tight. The miter slot is going to "self machine" the material for you. Whether you want it to, or not.
UHMW is super easy to cut and work with.

[Bruce Wrenn]

No matter how tight you make it, when you add screws to fasten it to sled, it's going to expand. DAMHIK, but I do. For TS sled runners, I use a tobacco harvester wear strip that local farm supply place carries. Come in 3/8" X 1"X ten foot lengths. I rip it slightly oversize, using a shop made jig to support it, run it thru planer to correct size. I like to run a shallow dado on sled where runner is to go. It helps keep it straight. Do the same when using either steel, wood, or aluminum runners

[glenn bradley]

No matter how tight you make it, when you add screws to fasten it to sled, it's going to expand.

I prevent this by using double stick tape between runner and sled base, counter bored holes, and pan head screws. You can still distort the UHMW if you tighten the screws excessively but, you don't need to. I have absolutely experienced what Bruce is talking about though ;-)