[bharner]

I know lexan and plexi aren't the same, but I need one of them for a small project (holding a parking pass that I transfer between vehicles, a bicycle, and my backpack) and I'll purchase whichever I can find cheapest.
I'll be using 1/8th or 1/4" thick and just cutting out a small recess to hold the pass.
To make things interesting, and because I don't have a "real" router yet, I'll be using a dremel with a 1/4" straight router bit...
Any retrogradations for the speed to run it at so I don't melt plastic and wreck the bit (granted, it's only $8, but I'm cheap)

Hopefully in a few more weeks I'll have a bit more $$ saved up and I'll make up my mind on a starter router.

 

[TWheels]

Your problem is challenging. The biggest problem you will confront is the plastic melting as you cut. For real routers there are dedicated O-flute router bits but as far as I know they are only straight non-plunging bits. However, the wood-cutting bits can also be used if the right speeds are chosen. You will simply have to try in order to find the best speed of rotation (rpm) and the best speed of feed that allows cutting without melting.
Lexan v. plexi. Lexan has much greater mechanical strength than plexi; NASCAR windshields are lexan, and Formula 1 is considering requiring that their cars have windshields of lexan. On the other hand, plexi has much better chemical resistance.I have not been able to check which is less expensive at this time. There are several online stores that sell each.
Good luck. Keep us posted on your progress.

 

[jschaben]

I know lexan and plexi aren't the same, but I need one of them for a small project (holding a parking pass that I transfer between vehicles, a bicycle, and my backpack) and I'll purchase whichever I can find cheapest.
I'll be using 1/8th or 1/4" thick and just cutting out a small recess to hold the pass.
To make things interesting, and because I don't have a "real" router yet, I'll be using a dremel with a 1/4" straight router bit...
Any retrogradations for the speed to run it at so I don't melt plastic and wreck the bit (granted, it's only $8, but I'm cheap)

Hopefully in a few more weeks I'll have a bit more $$ saved up and I'll make up my mind on a starter router.

Hi Bill, lexan also has a lower melting point but is virtually unbreakable. Not sure how large a piece(s) you need, it is available on eBay in various sizes. Mostly cutoffs from sign making or display mfg businesses. If you have one in your area you may be able to do some dumpster diving for what you need.
I wonder if you are going to get what you expect though. Routing the stuff will remove the surface polish and, unless you have a means or knowledge of how to polish the stuff, it will leave a hazy/milky appearance where it's been routed. Picture is a shot of a zero clearance dado insert I made for my table saw. The hazy areas are where I had to relieve the bottom to provide clearance for the arbor bearing and riving knife bracket. Material was 3/8 Macrolon (lexan with scratch resistant coating).

You may have better luck using two pieces of thinner material glued at the edges.

Just some suggestions

 

[bharner]

Your problem is challenging. The biggest problem you will confront is the plastic melting as you cut. For real routers there are dedicated O-flute router bits but as far as I know they are only straight non-plunging bits. However, the wood-cutting bits can also be used if the right speeds are chosen. You will simply have to try in order to find the best speed of rotation (rpm) and the best speed of feed that allows cutting without melting.
Lexan v. plexi. Lexan has much greater mechanical strength than plexi; NASCAR windshields are lexan, and Formula 1 is considering requiring that their cars have windshields of lexan. On the other hand, plexi has much better chemical resistance.I have not been able to check which is less expensive at this time. There are several online stores that sell each.
Good luck. Keep us posted on your progress.

I checked at my local big box and they have 8X10 sheets of lexan for about $5. I'm going to run down to my local Ace in a bit to see if they have anything and peruse their reconditioned tools for good luck. I've helped my dad bend/mold lexan in the past. He got tired of the sand and salt in the trucks getting wet and freezing so we made some tarp supports out of some rather large pieces of lexan he had laying around. You can do amazing things with lexan and a heat gun (don't use a torch, it scorches easily...)

I wonder if you are going to get what you expect though. Routing the stuff will remove the surface polish and, unless you have a means or knowledge of how to polish the stuff, it will leave a hazy/milky appearance where it's been routed. Picture is a shot of a zero clearance dado insert I made for my table saw. The hazy areas are where I had to relieve the bottom to provide clearance for the arbor bearing and riving knife bracket. Material was 3/8 Macrolon (lexan with scratch resistant coating).

You may have better luck using two pieces of thinner material glued at the edges.

Just some suggestions

I hadn't thought of the polish and haze. I'll have to poke around online or just buy a piece of lexan and see what happens. If I'm out $5 or less, I can happily chalk that up to play and education.

 

[bharner]

I picked up a 9x16x1/4 piece of acrylic at ce for $3 . I'm anxious to see what happens tomorrow. higher melting. point but more brittle...

 

[Thrifty Tool Guy]

You're too hot when bubbles form in the material. I would suggest using the thinnest possible material

 

[Gene Howe]

When I cut either material, I leave the paper on for the cut. I don't know how or why, but the paper seems to dissipate the heat and I get less melting.

 

[LexB]

It's possible to "flame polish" the edges of some types of plastic. You just use a propane torch passed quickly along the edge. Google for more info. I've done it, but it's been years and I don't trust my memory on the subject to give more advice.

 

[Mike Wingate]

I use a lot of Lexan for my routing templates. Why not make a template and rout the actual card holders. You can saw and file the template and leave square corners if you don't rout it. Drill out the waste, scroll/jigsaw to line and file up to size. When you do rout, be prepared for Lexan flakes everywhere.

 

[Ralph Barker]

As I recall, many plastics will "polish" with a light rub of acetone.

 

[jschaben]

As I recall, many plastics will "polish" with a light rub of acetone.

May try that Ralph, to clean up those dado inserts. I thought about trying to flame polish them but chickened out on that deal.

 

[TWheels]

I do know acetone discolors lexan and chloroform can be a very effective glue for both lexan and plexiglass (at least the plexiglass I use in my day job). Thus I a certain chloroform would smooth the edges of cuts. However I have no idea how easy it is for someone not with my day job to obtain chloroform.

 

[jschaben]

I do know acetone discolors lexan and chloroform can be a very effective glue for both lexan and plexiglass (at least the plexiglass I use in my day job). Thus I a certain chloroform would smooth the edges of cuts. However I have no idea how easy it is for someone not with my day job to obtain chloroform.

I guess I won't try acetone.:fie:

 

[bobj3]

Welcome to the RWS forum

 

[LexB]

Here's a thought (disclaimer: I haven't had my morning coffee yet)--why not make the bulk of it from wood, and just use a thin piece of plastic on the face to cover the pass? Or you could use thin plastic for both the front and the back (if the back needs to be visible too), and enclose them in a wood frame? A scrap of nicely figured hardwood would be more attractive than routed plastic.

 

[bharner]

Here's a thought (disclaimer: I haven't had my morning coffee yet)--why not make the bulk of it from wood, and just use a thin piece of plastic on the face to cover the pass?

That's my thought for if I can't get the plastic to work. Working with the acrylic I picked up is kind of a "just because" project...

I did find out that I can route the plastic at about 18,000 without melting the plastic...
That was just a quick test. I accidentally signed myself up to work 75 hours this week since the kids are with the Grandparents so my dreams of spending time in the shop fooling around probably won't happen until Saturday afternoon/evening when I'm hopefully done with it.

 

[TWheels]

That's my thought for if I can't get the plastic to work. Working with the acrylic I picked up is kind of a "just because" project...

I did find out that I can route the plastic at about 18,000 without melting the plastic...
That was just a quick test. I accidentally signed myself up to work 75 hours this week since the kids are with the Grandparents so my dreams of spending time in the shop fooling around probably won't happen until Saturday afternoon/evening when I'm hopefully done with it.

You are working 75 hours this week? Please be sure you are well-rested when you do go into your shop! Routers, even Dremels, Rotozips etc. are dangerous in the hands of someone not alert and thinking clearly. See the fingerprint of my left forefinger for evidence on that point, and I was lucky that it was only the left forefinger surface involved!.

 

[Phil P]

Lexan is GE's version of polycarbonate and it is somewhat softer than acrylics such as Plexiglass, Perspex, Lucite, et. The big plus of polycarbonates over acrylics in certain applications is its' greater impact resistance, which is why it is often chosen for machine guards, etc. Machining is best done with either spiral cutters or O-flutes (see Onsrud Cutter's web site) but the best approach in trms of feeds/speeds is the fastest fed speed you can manage but with a reduced spindle speed (12,000 to 14,000 rpm if you can manage it). this produces a true curl chip rather than just dust and reduces the amount of "churning" (where waste is cut then recut before being expelled from the cutter flute). "Churning" increases the friction causing the waste to heat up and potentially melt-back onto the surface. If at all possible arrange for extraction by a vacuum cleaner (which will also help cool the cutter), use larger diameter cutters if possible (bigger cutters and cutters with larger diameter shanks help dissipate heat) and consider either an air blower or a water spritzer bottle to cool the cut. If you use a spritzer make sure it doesn't go into the router motor and try to use either a 110/120 volt router or arrange to be on a RCD (residual current device) circuit to be on the safe side. Wherever possible retain the plastic/paper coating on the material for as long as possible as it reduces the number of scratches you'll get on the end piece.

Edge polishing of acrylics can be done using a propane torch (work quickly and try not to spread onto the edges), but you do need to peel back the cobver films for this. Not sure it works so well on polycarbonates, though. You can also sand the edges (to get a frosted edge finsih) or wipe with MEK (metyhl eythyl ketone) thinners - but be careful with these as they are a health risk as well as being highly inflamable.

Hope this helps

 

[tmjr]

as LexB stated I would just use a propane torch and dress the edge, all you have to do is run the torch over the cut edge and slightly melt the cut edge. practice on some scrape, the biggest problem from doing this is blistering the peice.

 

[bharner]

What I have learned thus far...
Edge guides are my friend. I freehanded a few tests and got close, but it looked off.
When the acrylic chips come out, they're hot. they then quickly melt to the surface and if you're using a dremel with the basic cutting guide (15k rpm), it will get stuck on the chips. So you'll frequently need to pull it out, brush off the chips, then get going again.
Even at lower RPM if you let it sit still for more than a second or two you'll melt a hole through the acrylic and it will smell horrible in your garage for a long while. Also, your daughter will blame the smell on you and ask you if you're sick because you smell really bad.

So now that I've had my fun I think I'll just route a small cut out in a piece of 1/2" stock, put the pass under that, and secure it to the stock. Maybe not as pretty, but not quite as headache inducing. And I have a lot of 1/2" stock sitting around in various scrap sizes.