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Working with Phenolic Plastic?

claycookiemonster

Well Known Member
I've got to say that those white plastic (phenolic) parts are WAY tougher than I first imagined. Today we spent time trying to sand a few thousandth off the blocks that hold the baggage door closed on an -8, and it was not easy. We got it done, but now I'm thinking. If you seriously had to shave or modify those phenolic bits, how would you do it?
 
You mean UHMW (ultra high molecular weight) plastic? It is designed to be hard to scuff and naturally slippery, and it is used a lot in the food industry. Phenolic is something completely different, which is resin impregnated cloth and is more for electrical resistance.

Did you try a disk sander?
 
How to shape uhmw

UHMW is ultra high molecular weight POLYETHYLENE plastic. It is used as rubbing wear resistant surface in mining conveyor chutes and bottling lines for example. It is designed to be slippery,resist abrasion, be easily cleaned. It will cut in band saw, table saw, milling machine and lathe. The plastic nature and slippery abrasion resistance makes dimensional response indefinite compared to Delrin or metal. Sharp cutters are a your friend.
 
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From the way back machine

IIRC, Phenolic was created during (for?) the Apollo program. They wanted a lightweight insulator/board material that met fire class, etc. I believe it was (at least originally) laminated paper than used a phenol formaldehyde based resin; hence its name. That was the tribal knowledge of the day at Kennedy Space Center a few decades ago, probably still today.

There's your useless knowledge for the day.
 
IIRC, Phenolic was created during (for?) the Apollo program. They wanted a lightweight insulator/board material that met fire class, etc. I believe it was (at least originally) laminated paper than used a phenol formaldehyde based resin; hence its name. That was the tribal knowledge of the day at Kennedy Space Center a few decades ago, probably still today.

There's your useless knowledge for the day.

Got to go further back for phenolic plastics (bakelight). It sands super easy, but an old piece is often full of asbestos.
 
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UHMW plastics can't really be "sanded", they have to be "machined". They're specifically used to avoid damage due to abrasion, which is what sanding is. They need to cut, so you need something with a significant 'tooth" to cut the material. CNC cutter, Drill bit, rasp, blade. It can be whittled quite nicely by someone with a good pocketknife and a steady hand.
 
Got to go further back for phenolic plastics (bakelight). It sands super easy, but an old piece is often full of asbestos.

Guess I shouldn't be surprised. NASA folks have long perpetuated that and similar stories e.g. Velcro was a Space Program invention which spun-off into civilian application. Not true. The later programs truly have spun-off some great innovation though. Anyway, thanks.
 
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Sorry to have used the wrong word, I'm not sure where "Phenolic" came from in my brain. Yes, that slippery and really tough stuff used for Baggage door latch parts and flap hinge bits.

I have been able to cut it with saws as you've said, but once installed, it's REALLY hard to modify with either a sanding disk or a Dremel. So, I guess this is appreciation for the material, but also a lesson learned to do all your fitting in advance and not assume you can easily alter in once in place.
 
I can't remember ever doing it myself...and so this is just thinking out loud brainstorming
but I wonder if a sharp edge scraping blade (wood working) would shave off a very thin layer
 
It can be sanded and I have done so, though bits and blades work better for anything beyond very light removal. Sanding is more aggressive than most give it credit for. Hardened steel that can't be touched with milling bits, drill bits, saws or files, is formed with grinding wheels which are made with the same materials as alum oxide sandpaper. Very little on this planet that cannot be surfaced with grinding wheels, though tough to duplicate 3000 RPM with your hand.

Larry
 
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Make friends with a local woodworker or machinist - should be no problem for somebody with even a basic router table or milling machine. Or, consider this your entry point into at least one new hobby. :)
 
IIRC, Phenolic was created during (for?) the Apollo program. They wanted a lightweight insulator/board material that met fire class, etc. I believe it was (at least originally) laminated paper than used a phenol formaldehyde based resin; hence its name. That was the tribal knowledge of the day at Kennedy Space Center a few decades ago, probably still today.


I don't think so. They may have used it, but didn't invent it. I've seen phenolic pulleys and phenolic wear blocks in plenty of pre-WW2 aircraft.
 
I don't think so. They may have used it, but didn't invent it. I've seen phenolic pulleys and phenolic wear blocks in plenty of pre-WW2 aircraft.
Yep. Already called out on it. Said it was tribal knowledge. Anyway, still my bad.

I am surprised to here it called plastic but if Fiberglass is thermosetting then the logic follows, just wasn't in my mindset.
 
Here's an example of Phenolic. Dynon-supplied shunts use a plastic base. I had one melt in my Rocket, and one fracture in my new build. In both cases, I rebuilt them using 1/4" Phenolic, which is a very rigid and heat tolerant insulator.

IMG_2638.jpg

Vern
 
I used an end-mill to take my UHMW flap actuator blocks down a few thousandths. Worked like a charm.

Check around your circle of builder friends. Chances are someone's got a bench top mill with the know-how to do it.

52461340868_338ac59413_c.jpg
 
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