Anyone plane UHMW polyethylene? Gotchas to watch for before I start?

[Justin Meyer]

I'm making runners/ spacers for window sashes. I'm using 3/4" x 3/8" miter slot stock which is the closest I can get from McMaster-Carr, but it's just a touch too think...I'd like to plane it down about 3/32" to ~.300". Would this stock be too thin and flexible, maybe get picked up by the segmented head? I'd appreciate any thoughts....

[Peter Rawlings]

I've machined UHMW lot of ways but don't think I ever planed a piece. It tends to be "stringy-er" than HDPE which I have succesfully planed with a Byrd head and milled flat on conventional blade jointer. At that thickness it may want to move around before and after pressure rollers in planer, but I doubt it'd break. More likely it would snipe so I'd have some excess I could cut off ends to correct length and take light passes.

Have you got a piece to experiment with? I've taken 1/2" HDPE to 1/4" successfully with planer.

[Dan Friedrichs]

I've had similar problems and reservations about running it through a power planer. FWIW, a sharp block plane works great.

[Frederick Skelly]

I too use a hand plane.

[Mark Hockenberg]

I've routed and edge sanded it. Like Peter, I found it to be really stringy.

For planing how about this - Leave it long to deal with snipe / Glue it to a stable piece of lumber - Maybe in a wide dado / Then run through the planer

[Rod Sheridan]

I'm making runners/ spacers for window sashes. I'm using 3/4" x 3/8" miter slot stock which is the closest I can get from McMaster-Carr, but it's just a touch too think...I'd like to plane it down about 3/32" to ~.300". Would this stock be too thin and flexible, maybe get picked up by the segmented head? I'd appreciate any thoughts....

I tried it once, it was pretty funny.

After that I used a hand plane.............Regards, Rod.

[John K Jordan]

I'm making runners/ spacers for window sashes. I'm using 3/4" x 3/8" miter slot stock which is the closest I can get from McMaster-Carr, but it's just a touch too think...I'd like to plane it down about 3/32" to ~.300". Would this stock be too thin and flexible, maybe get picked up by the segmented head? I'd appreciate any thoughts....

Never tried planing but have cut and trimmed on tablesaw and bandsaw.

[Lisa Starr]

Power planing it is next to impossible. I've often milled it on "Bridgeport" with an end mill.

[Jack Frederick]

I cut some on my SS a while back and while it cut ok the shavings wadded up in the throat of the dust collection port right at the blade. I was fortunate to change the blade right after this, otherwise I would not have been aware of the problem until it became a bigger issue.
I have planed it successfully. Long, thin pieces are pretty whippy. Think spaghetti...the cooked kind. Try to make a sled to support it along its length. Otherwise it will roll on you and you end up with inconsistent dimensions.

[Timothy Thorpe Allen]

Rip it down to on a tablesaw? (on edge -- need a good pushstick and featherboard set up)

[Mark Bolton]

Never had a problem but a spray can of static guard is your friend. A light spray on the planer bed and kick on the DC and mist a bit up in around the cutter head and let it run down the DC a bit especially if you have any PVC in your DC run.

[Justin Meyer]

Wow, thanks everyone! Sorry for my delay in getting back, back-to-school night wore me out.

Consensus appears to be that smaller pieces can be a bit finicky, particularly without preparation. (Thank you for the static guard idea, Mark.)

I thought of the hand-plane route, but I may have 10-20 feet to do and holding such flexible and thin material may be a task in and of itself, at least with my limited work space. Hence my wondering if it could be done without risk to my planer. I'll hand plane the prototype and if it is satisfactory I'll try the long pieces on my planer sled with double sided tape. (Thank you for the heads up on that, Jack.)

[Justin Meyer]

I've routed and edge sanded it. Like Peter, I found it to be really stringy.

I'm really surprised one can effectively sand UHMW PE, I rather assumed it would clog up the abrasive in very short order.


For planing how about this - Leave it long to deal with snipe / Glue it to a stable piece of lumber - Maybe in a wide dado / Then run through the planer

Going to give this a try on my planer sled if the prototype works as intended!

[Mark Bolton]

Thank you for the static guard idea

It works wonders for anything static-y. PVC trim, Azek and the like, if your tooling breaks a chip (a planer does it by default) it lets it fly up the DC and not clog. Strings are only going to be an issue with an operation that makes long chips or chips that stick together. Anything plastic I keep a half dozen cants of static guard around and it seems to knock down the nightmare feeling like your working inside a snow-globe. Solid surface helps alot too.

[John TenEyck]

I have planed dozens of UHMW plastic from Mcmaster Carr making my horiontal router mortisers. Straight knife planer. Typically 5/8" thick. Never had a problem. FWIW, you can sand it through a drum sander, too.

John

[Mark Hockenberg]

[QUOTE=Justin Meyer;2952757]I'm really surprised one can effectively sand UHMW PE, I rather assumed it would clog up the abrasive in very short order.

How right you are! I made a mess of the paper on my disk sander.

[Curt Harms]

I've routed and edge sanded it. Like Peter, I found it to be really stringy.

For planing how about this - Leave it long to deal with snipe / Glue it to a stable piece of lumber - Maybe in a wide dado / Then run through the planer

I've never done it but if I were to try, the snug fit dado seems like what I'd try. Maybe piece of ply with 1/4" thick strips forming the dado glued to the base piece.

[Justin Meyer]

So, hand planing UHMW PE worked, but was a bit tricky. I had to take almost 0.020" shavings to reliably get a "bite" on the material. Clamped the material from the back so it was in tension, and it still tried to wander a little. Blade was sharp, so my technique is off (one edge about 0.020" thicker than the other after 5 passes), but the result more than acceptable.

418470

I notched the pieces on the table saw, sprayed the blade and cabinet interior with Static Guard, which worked great!

418471

Only needed to plane one strip of PE, if I have to do more I'll definitely try the planer...probably with a sled or at least a piece of melamine over the tables.

[Frederick Skelly]

Thanks for following-up with us Justin. I always appreciate hearing how the advice here works out.
Fred

[Bill Dufour]

I do not know why people insist on gluing sacrificial wood strips longer at each end to reduce snipe. Just shove the loose boards in along with the good wood but start them a few inches before the good wood. Of course gluing does reduce the handling time at the planer but the extra time for glueup and edge jointing the sacrificial wood seems like more work to me..If you are really planning 20 foot pieces, remember you only need the sacrificial piece at each end nothing needed in the middle of the cut.
Bill D

[Jack Frederick]

I'm in the process of rebuilding my last wooden structure on the property to fire harden it and will be using some Azek corner boards for the trim over the hard siding. I will have to do some work on the Sawstop. I was really surprised how the UHMW shavings wadded up on the saws lower blade guard. I will run to the store this am for some static guard and try it.
Timing is everything. while writing this I got a call from PG&E. They are turning the power off in about an hour. The last three have been 2-2.5 days. No rush I guess. The Generac should be here this week. Ah, the joy!

[Mark Bolton]

I do not know why people insist on gluing sacrificial wood strips longer at each end to reduce snipe. Just shove the loose boards in along with the good wood but start them a few inches before the good wood. Of course gluing does reduce the handling time at the planer but the extra time for glueup and edge jointing the sacrificial wood seems like more work to me..If you are really planning 20 foot pieces, remember you only need the sacrificial piece at each end nothing needed in the middle of the cut.
Bill D

That works until the loose boards skew, slip, feed at a slightly different rate than the others. This is especially true if you dont have segmented feed rolls. Its why most planers without segmented feed rolls state never to feed multiple boards at the same time/ganged even though most all of us do it. But the few slightly thinner boards in the stack, or an errant chip(s) get between a board and a non-segmented feed roll and other parts will stop feeding/slip/skew or fly back if your planer doesnt have anti-kickback pawls. Beyond that it can become a juggling act if things dont feed perfectly.

I never bother with either and just leave parts long. A planer is a roughing tool not a finishing tool. You just have to plan for a few inches of possible waste.

[Brian Holcombe]

Same experience as Mark.

Accurate jointing greatly reduces and can eliminate snipe. If a board is flat against the bed it doesn’t flop up into the cutter and snipe.

[Mark Bolton]

Same experience as Mark.

Accurate jointing greatly reduces and can eliminate snipe. If a board is flat against the bed it doesn’t flop up into the cutter and snipe.

Ive beat this drum for years to no avail but in my experience most all chased snipe, other than someone just learning/starting out letting the board drop on in and out feed, is actually caused by mechanical slop/flexure in the planer head itself. I have tried this even with planers up to like a 15" 4 post import with thick stock. You can lift up on the end of the material enough to literally have the outfeed end of the machine off the table/floor, and if there is slop in the head (the planer head walks/racks up on to, and off of, the part) you will get snipe. No amount of in-feed or outfeed support will make it go a way. Of course if its a support issue thats easy, but often times even with way more support than necessary it will still be there. Its mechanical slop in the assembly even when engagning post locks.

I had a friend with a 15" 4 post planer that would snipe and one time he was planing 6/4 material and he lifted the outfeed end enough to see the edge of the planer up-weight off the floor as it was coming out and there was still snipe. Locking the post locks helps, but it was still measurable.

If every inch of the material is absolutely needed/valuable, adding sacrificial material to the part or a hand plane would be a better option in my opinion.