UHMW Questions

[Stephen Edwards]

I have a few questions about UHMW for those who are familiar with it, please.

1. Is it rigid or is it flexible?

2. Is it suitable for jig platforms?

3. Can it be easily machined on woodworking machines without damaging TS blades, jointer knives, etc?

Any other input or advice based on your personal experience would be appreciated. Thanks.

[Doug Shepard]

It's rather on the soft side and flexible. Distorts (bulges) fairly easily if screws through it are too tight. No problem planing/jointing. I've used a block plane without any problems. It cuts sort of like hard cheese. Haven't found anything that will glue it but some of the specialty plastic glues would probably work.
I wouldn't recommend it for jig platforms. It's just not rigid enough. If you're after something with a smooth sliding surface I'd try some of the phenolic ply. Woodcraft sells it in I think 2'x4' pieces but it's a bit on the pricey side. Good ply underneath the phenolic layers though.

[Stephen Edwards]

Thanks, Doug. Do you know of any sources for buying cutoffs of solid sheet phenolic?

[Doug Shepard]

I haven't had much luck finding a better (cheaper) source for the phenolic ply. One other option is just to use baltic birch ply and pick up a roll or two of the UHMW tape and put a couple strips under the BB ply if you just want smoother sliding.

[Danny Burns]

1. Is it rigid or is it flexible?

Fairly rigid.
Yes it will bulge when a screw is driven into it, ie. in a mitre slot to ensure a snug fit, but you would be hard pressed to bend the thicker pieces.




2. Is it suitable for jig platforms?

Ideal in the use of jigs, but I'm not too sure I would use it as a platform!

http://www.leevalley.com/wood/page.aspx?c=2&p=32044&cat=1,43455,43831&ap=1




3. Can it be easily machined on woodworking machines without damaging TS blades, jointer knives, etc?

Very easy to machine. Treat it just like wood. Not hard on the tools at all.

http://www.leevalley.com/wood/page.aspx?c=2&p=32045&cat=1,43455,43831&ap=1

http://www.leevalley.com/wood/page.aspx?c=2&p=43210&cat=1,43455,43831&ap=1

[Cliff Rohrabacher]

Ultra High Molecular Weight (UHMW) - - - what?
All sorts of things come in UHMW specifications.
UHMW mineral oil is Petroleum Jelly.

There are a variety of polymers that come in UHMW grade. Polyethylene is one of many.

[pat warner]

Modulus of most plastics (<5/8") is so low that substrates will bend under modest loads. 1 or 2 250-500 pound toggles (rather light duty) will pretzel
3/8" laminate/phenolics, polyethylenes, polycarbs & acrylics. 3/8" aluminum (http://patwarner.com/images/drilling1.jpg)will stand 5 to 10x the force with very little deflection.
You need slip? Then screw a little UHMW polyethylene to it (aluminum).
May take all day to prepare a substrate, but it will last all your life.

[glenn bradley]

Your responses seem to be conflicting and I think we could put a better focus on the responses if you could tell us what you are trying to do. Based on the info at hand;

1. Is it rigid or is it flexible?

Quite flexible till you get to thicknesses approaching 3/4" as Pat stated above. I have a 3/8" plate of it and it flexes easily under fingertip pressure.

2. Is it suitable for jig platforms?

Not in my experience. BB ply (1/2" or 3/4" depending on span) works well. If you need friction reduction, as with a sled, shellac the surface, sand to 400 or 0000 wool it and paste wax it. I have large sleds with surfaces prepared this way that move quite easily across full surface contact areas.

3. Can it be easily machined on woodworking machines without damaging TS blades, jointer knives, etc?

It machines quite well on the table saw or router table, drill press, etc. The bandsaw makes quite a mess. Adhered to something else to act as a friction reducer it is great. As a stand alone stable platform . . . not so much. I use UHMW solids and tapes on several jigs and fixtures and after years of use it remains unchanged to the naked eye. Very handy stuff if used appropriately.

I generally just pick it up at the shows or on sale wherever it happens to turn up. Peachtree, Woodcraft, Lee Valley, Rockler and all those folks carry it. If you're put off by the price, you can take comfort in the fact that if you use the right form/shope for the right purpose, it will probably outlive you ;-)

It might also be worth noting that HDPE and UHMW are different, although similar in look and feel, HDPE does not have the very long chains of ethylene monomers (or so I read), will not endure as much impact or survive in a repeated wear-use application like a miter slot runner as well as UHMW.

[Lee Schierer]

Good info so far regarding UHMW polyethylene. I can be formed to some degree. Heat it to about 150F and bend it on a form. Hold it until it cools and it retain much of the shape. It does not melt like most plastics and will start to burn before it becomes a liquid.

Most plastic supply houses can get it in a variety of shapes and sizes. Not a cheap date ever.

[Bob Wingard]

One point I've noticed lacking here relative to suitability for jigs .. .. UHMW is extremely sensitive to heat and it's thermal expansion coefficient. I've made zero clearance inserts out of it, and one day they'll just drop in and the next I have to pound them in. This is one of the reasons it is so difficult to glue it to anything. I've used hundreds of sheets of this stuff in industry, and have brought home loads of cutoffs/scraps over the years. Most of it went into the trash eventually as it does tend to crystallize, then fracture with exposure to sunlight.

[Dan Forman]

Thanks, Doug. Do you know of any sources for buying cutoffs of solid sheet phenolic?

Look in the yellow pages under "plastic", there might be a source where you live that works with what you are looking for and would sell you what you need. Some of the plastics are quite expensive, so they might now be giving away the cutoffs, but would sell at a reasonable price.

Dan

[Matt Ranum]

Bob brings up some good points. It moves a lot with temperature, an 8' sheet will gain 1/2" in length out in the hot sun. Our local distributor where I get mine from recommends using a drill 2 sizes over for holes. There is some that are UV stable. From our local supplier its color coded for the most part. Green, and black(recycled) are fine in sunlight but white is not stable in direct sunlight.

[Stephen Edwards]

Thanks for the replies and info. I'm just curious about it, and other plastics, for use in the shop. I've read several people comment on using it (UHMW) for miter slot runners on sleds, using it for facing machine fences, etc.

I bought some today to experiment with. So, I guess I'll get some experience and an education, by trial and error, in regards to how useful it is and what things it's suitable for. Your suggestions and advice will also come in handy.

As for what kind of UHMW.....whatever the stuff is that you see advertised in the woodworking supply houses. Somehow, I don't think that that material is petroleum jelly. I'm almost certain that the petroleum jelly wouldn't machine very well. One would think that it would also have major sag as a jig platform.

I purchased:

1 piece Black Marble UHMW 1" X 10" x 48"

1 piece natural HDPE 1 3/4" x 17" x 18"

1 piece Polypropylene 3/4" x 10.5" x 48" - Natural SR

I suppose the "black marble" is the recycled stuff that someone mentioned. I don't what the "SR" means on the Polypropylene. Does anyone know?

I want to replace the melamine coated MDF pieces on my Rockler aluminum router table fence. Of the three materials above, which one, if either, would you recommend for that? Why, or why not?

Thanks again for your suggestions and advice. I appreciate it.

[Noah Katz]

I've been using it for tool and accessory racks.

I like the look, it cuts easily, and it doesn't need to be finished.

However, I always seem to end up with whiskered edges which don't look good and hold dirt.

Sanding doesn't work, and I tried a deburring tool with little success; it takes the whisker off but messes up the edge.

Any suggestions?

[Alan Schwabacher]

A finely set block plane will give you a clean small chamfer on an edge.

It's difficult using just words to say how hard something is, and that's reflected in the variety of answers above. UHMW polyethylene is reasonably hard and it wears very well, but it's not the best thing to use if you need something to be stiff. Aluminum, as mentioned, is excellent for that. Where UWMW-PE shines is in making things slippery without wearing much.

But if it cuts like cheese, even hard cheese, I think you have a different material. Cutting boards that resist knife marks are made of HDPE. UHMW-PE is considerably harder to cut with a knife than that. It cuts easily with a saw, and both will plane well if the plane is set fine enough.

[Gene DiNardo]

Noah,
Card scraper works great.
Gene

[Matt Ranum]

While not woodworking related....I built a new blade for my snowplow last year. It was basically an open framework design built out of square tubing and I put 1/4" UHMW Re-Pro(recycled) on the moldboard face and made a flap out of it on top and I was amazed at how much easier it was pushing snow. In fact the new blade was wider and taller than the old one and still was easier on the truck.

[Karl Brogger]

Does anyone know where to get really big sheats? Along the lines of 4' wide, and 18' long? Or what kind of supplier I should look into for them?

I'm kicking around getting a new trailer for doing installs and would like to cover the whole floor in the stuff. While a slippery floor may be semi dangerous for pedestrians, it would absolutely rock for loading and unloading cabinets. Plus easy to clean. My though was to recess screws to hold it down the center, and just have a piece of angle aluminum along the sides to hold it down, so it could float along the edges and expand/contract with out much buckling.

[Matt Ranum]

Does anyone know where to get really big sheats? Along the lines of 4' wide, and 18' long? Or what kind of supplier I should look into for them?

I'm kicking around getting a new trailer for doing installs and would like to cover the whole floor in the stuff. While a slippery floor may be semi dangerous for pedestrians, it would absolutely rock for loading and unloading cabinets. Plus easy to clean. My though was to recess screws to hold it down the center, and just have a piece of angle aluminum along the sides to hold it down, so it could float along the edges and expand/contract with out much buckling.


I see your in Minnesota and it would be a bit of a drive here but this is who I get my stuff from. http://www.badgerplastics.com/

They line dump truck boxes with the stuff too so they should be able to do what you are wanting. They have a 800 number, give em a call.

[Doug Shepard]

Does anyone know where to get really big sheats? Along the lines of 4' wide, and 18' long? Or what kind of supplier I should look into for them?

I'm kicking around getting a new trailer for doing installs and would like to cover the whole floor in the stuff. While a slippery floor may be semi dangerous for pedestrians, it would absolutely rock for loading and unloading cabinets. Plus easy to clean. My though was to recess screws to hold it down the center, and just have a piece of angle aluminum along the sides to hold it down, so it could float along the edges and expand/contract with out much buckling.

My brother did that with big sheets of 1/8" thick UHMW though I'm not sure where he got it. He put it on the floor of his large snowmobile trailer (fits 4 machines). It did help with being able to push them around some inside but after a while it got fairly scarred up and the slippery aspect sort of disappeared so I'm not sure it was worth the cost. Sliding cabinets in/out might not subject it to as severe wear though, but I thought I'd relay his results.

[Noah Katz]

Thanks, Gene, I'll try one out.

Any recommendations?

[Fred Campbell]

UHMW [plastic, I assume it's PolyEthylene (PE), not some other substance] is mentioned in many places. Some people have said that cutting boards are made of it and suggest buying it at big stores like W-M. Other people say that cutting boards are HD not UHMW PE. I have several pieces of white plastic in my shop and I don't know what they are made of. Does anyone know how to identify UHMW PE and differentiate it from other forms of PE?

[Tom Esh]

Generally too flexible for platforms - much more so than MDF even. However it makes for a fantastic sliding surface or face when backed by something else.

Machines real easily. Won't damage blades, but if you get it too hot it'll start to melt and gum up cutting edges making them act dull. Keep your feed rates up and it shouldn't be a problem.

One thing it does not do is sand well. Ends up fuzzy. I clean up corners & bevels with a little modelers plane. I keep meaning to toss a piece in the freezer overnight and see how it sands then.

[glenn bradley]

UHMW [plastic, I assume it's PolyEthylene (PE), not some other substance] is mentioned in many places. Some people have said that cutting boards are made of it and suggest buying it at big stores like W-M. Other people say that cutting boards are HD not UHMW PE. I have several pieces of white plastic in my shop and I don't know what they are made of. Does anyone know how to identify UHMW PE and differentiate it from other forms of PE?

UHMW resists wear substantially better than HDPE. HDPE is tougher initially but fails sooner. That sounded bad, what I mean is that HDPE is more brittle but more stable. Hmmm, still not too good a description . . .

HDPE uses long chains of ethylene monomers. UHMW uses REALLY long chains of ethylene monomers. Here's some science to throw at it but, most of it escapes me: http://www.boedeker.com/mtable.htm