Official Luthiers Forum!

Anyone who's worked with both of these materials care to comment on their machining properties?

I/ve been working with acrylic, and it melts if you look at it. I used weldon thin solvent (boy is THAT nasty) to laminate some. Then I laminated it again, but with superglue. After machining, I intodued the finished dremel base to mr propane torch to gloss up the sanded areas. The weldon buble out the lamination. The superglued lamination took the heat well.

After glueing, bandsawing, filing, machine and hand sanding, drilling, and flaming, I'm tired or it. Maybe a little sick too. Anyone work with something more friendly (No Friendly Plastic jokes here...) of the clear variety?

BTW I did some brass machining lately and I love working with that where it's appropriate!

Terry, Lexan is your friend. Bonds with CA (or weldon if you are into such things), machines without melting and most importantly is doesn't chip and crack like Acrylic can. Lexan is actually what they use for bullet proof glass. It's expensive but you can look for polycarbonate which is what Lexan is without the name brand. It's still expensive but worth it.

What Paul said...except it would be a mistake to assume that all polycarbonates are like Lexan. They're not. Lexan is "a" polycarbonate, but there are many different polycarbonates out there. Still, they machine better than acrylics which are more prone to chipping out.

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"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

For jig and fixture work, I like Garolite from McMaster-Carr.   It's a linen/phenolic and it's tough as hell.   I'll use acrylic for jigs I want to see through, but Garolite for working templets for the pin router or table routers.   Great stuff and smells awful when you machine it...the worst!

My understanding is that Plexiglass is a brand name - where does it fall
in the spectrum of acrylic/polycarbonate/other? I ask because it's
available in convenient sizes from the local big box stores and seems
relatively inexpensive..

You can often get Lexan scraps cheap from a plastics or window shop.
Acrylic is NOT your friend. It cracks when drilled, chips &/or melts when sawn & breaks very easily unless you round the edges carefully.
Lexan is very cool stuff. It is soft enough to work with a hand plane, doesn't dull the knives on your jointer & CA sticks it together with little loss of original strength.
I was sold on the stuff years ago when I saw a display in the local plastics shop.
In a 10" square frame there were two pieces of 3/16" Lexan MR4000 about 3/4" apart. Smack in the middle was a .308 slug which penetrated the first sheet & was completely stopped by the second.
I'm not a fan of Phenolic because it stinks when you machine it & the dust is (i've been told) quite toxic. Otherwise it is a terrific material.

P.S. Plexiglas is an acrylic & Lexan is polycarbonate.Daniel M38816.7243402778

Lexan is a General Electric product manufactured in        Mt Vernon Indiana. I recently did some electrical work in the Lexan plant. It's great stuff, made from some of the most dangerous chemicals that you can imagine. They are making the stuff as fast as they can, and upgrading the plant for higher production. Interesting though....Even with all the nasty chemicals, I never felt like I was in danger. The quality control, and safety program are some of the best that I have seen in any chemical plant.

Al

An interesting story...GE was working on developing a material for something, and a chemist mixed up a batch of some stuff which had some promise. As he mixed the batch, a bunch of it stuck to a stir stick and formed a big glob on the end. The material was a faliure for what they were doing, but the glob on the end of the stick became a hammer that they used in the lab for different things. Eventually they figured out that the "hammer" plastic had some great qualities, so they went back to their notes and recreated the "failed" material, and Lexan was born.

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"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

I heard the same story at the GE plant.

Al

[QUOTE=Pwoolson] Terry, Lexan is your friend. [/QUOTE]

Most of the time I would agree with that statement. Here is a pic of double layer Lexan stuck together with CA. It was cut on a tablesaw and as you can see, it is very clean and would make great jig material. Of course, Lexan can also be your friend if you're being shot at. The bullet holes in the pic come from a 7.62 and 5.56 round I shot from 25 feet away. As you can see, it easily went through double layer lexan. The shot of the very right was from a low-calibre handgun, and if you look close, you can see the slug imbedded in the lexan. With a rifle shot, the bullet gets slowed down just enough to shatter and maim or stay impacted versus going through clean. Of course this really isn't an issue unless somebody is trying to shoot up all your guitar jigs. I hate it when that happens.   





Cheers!

John

Well, it looks like I'll pay another trip to the place that gave me acrylic, and get some Lexan. Seems like I had some kicking round somewhere....

I need to get a McMaster catalog. Yeah, I know they're online. I like the paper catologs much better for window shopping.

Thanks for the tip Rick, I'm aware of phenolic. Used to be able to get it more readily than these days it seems. Woodcraft used to carry it, not sure now. It is pricey, but for certain items requiring durability and longevity, a good way to go, like aluminum.

Cool, another friend for me!

John thanks for the great idea, working in NYC I have found my bullet-proof shop apron cumbersome to say the least. I believe Lexan is my solution!
Evan

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http://www.NewYorkGuitarRepair.com

[QUOTE=John Elshaw] Of course this really isn't an issue unless somebody is trying to shoot up all your guitar jigs. [/QUOTE]

With an AK, no less.   

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Brock Poling
Columbus, Ohio
http://www.polingguitars.com

Something to consider when making jigs: Lexan is more flexible than acrylic. That can be an issue when long spans are needed or heavy items are attached. It will sag more readily.

Just to add a bit to this --

I picked up some lexan from the scraps bin at a local plastics/sign shop, enough to make four or so body templates out of. I went back there a few months later and got some more to use for a fret-slotting template in my Stew-Mac fret slotting jig. (I needed a template for a 640mm scale, which Stewmac doesn't offer) Total for both trips was less than $20.

I find that it machines and sands well, with no melting.

Best,

Michael

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Live to Play, Play to Live

+1 on the Garolyte from McMaster although I use the XX flavor which is resin & paper. It doesn't stink much when machined and is rigid and dead flat out of the box. Regal and a couple of other local plastics wholesalers stock the cloth or linen based phenolic. There's a slight tolerance on thickness with all I've tried. YMMV

Some stained glass studios use Lexan, and may be a source for scrap.

CrowDuck

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Chris Nielsen
Soquel, CA.

Only downside with Lexan vs. Acrylic is Lexan scratches much easier -- not sure if that matters in your application.

The key to machining acrylic is to use cutting oil(a little)and to climb cut at low RPM's. It works well then.
Cuts come out ready for polishing, otherwise it melts and sticks to everything.

As for Lexan V. Polycarbonate, I have alway heard they were the same. I've never heard of any spec calling for Lexan specifically, and I used to work in some of the most demanding of plastic tooling and molding fields.

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Billy Dean Thomas
Covina, CA

"Multi famam, conscientiam, pauci verentur."
(Many fear their reputation, few their conscience)

would it be possible to sandwich a piece of acrylic in between two pieces of lexan? It seems the acrylic would stiffen up the Lexan and the lexan layers would prevent the acrylic from chipping. I'm just thinking out loud here. I did try to use Plexiglass to make a template. It was a horrible failure.

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Joe Breault
Merrimack, NH
Perpetual novice

Lexan sure seems like the way to go. So who is the most reasonably priced suppliers? I checked around and some suppliers want you to buy a huge sheets at likewise prices. So where do you guys get yours?

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Dave Bland

remember...

"If it doesn't play in tune...it's just pretty wood"

My local woodcraft has small pieces (12x12) for use in making router bases. But it costs about $18. I think the scrap bin is the place to search.
I once found a piece of UHMW in a scrap bin that was 35" x 47". Someone screwed up and cut it wrong so it was scrap. They sold the whole thing to me for $50. (that would probably have been a $300 piece of material if it were an inch bigger both ways)

Okay, this is probably a long shot, but it might be worth a try. Just out of curiosity, I visited my local Habitat for Humanity "ReStore" a while back, and in a beat-up shopping cart that someone had just dropped off were several pieces of 1/4" Lexan cut-offs, approx. 7" X 20", with the protective paper still on them. They sold them to me for $.50 apiece! Not large enough for body templates, but plenty useful for jigs.

If you haven't checked out a ReStore yet it might be worth a trip. All their stuff is donated by businesses and contractors, and you never know what you'll find. On the same trip as above, I got a 24" X 48" piece of laminate material, blemish-free, for $2.50; and they had a lot more of that.

Carlton,

Great idea!!
Reminds me that my local 'dump' has areas for 'recycleable' items, paint, building materials, etc., and I think the stuff's free for the taking.
Thanks,

CrowDuck

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Chris Nielsen
Soquel, CA.