Tips on drilling and cutting plexiglass for CP

[y2k600f4]

I am currently trying to complete my CP and have come to the step where I need to cut and drill out 1/8" plexiglass for my control panel overlay. I need to cut the outline of the CP (not square) along with all the button holes, joystick holes and trackball hole. I am thinking this is going to take some time !! Any suggestions and tips would greatly be appreciated. I planned on scoring the outline with an exacto knife than snapping the general shape. Rounding the edges and corners with a dremel. For the holes I was going to either drill or use a hole saw (both smaller than the holes) and finish each hole by hand with a dremel. If that is the way to go, I am not sure what bit to use to "grind" the plexiglass so I don't get any chips. Thanks !

[lanman31337]

I cut my marquee with a jigsaw - i used a metal blade, it's 24 tpi.  as long as you keep the speeds down you'll have no problems chipping.  I used my dremel to cut out my cpo - it's a funky looking bit with long flutes - worked like a champ.

[Teknique]

I have lexan as my CP top so its much less fragile, but I drilled out my button holes with a large drill bit (very slowly to avoid cracking the lexan) The drill bit had to be just large enough to fit the ballbearing guide of a laminate cutting bit through the hole.  I then used my router with laminate bit  to make perfect circles for trackball, spinner , buttons, etc. by using the predrilled holes of the cp as my guides.     I also used the laminate cutting bit to trim the edges of the lexan around the cp.  Before trimming the edges, secure the overlay by putting in 6 or so buttons through the plexi and wood so the plexi does not move on you.


Tek    

[ChadTower]

Scroll saw will work well if you have one.

[unclet]

I cut plexiglass for my control panel top.  I used a scroll saw blade (made for cutting through plastics) to cut the outline of my control panel top.   I used a standard 1-1/8" wood bit to cut out the holes (make sure the holes are cut 90 degrees so the actual pushbuttons will fit into them straight).   I went real slow and it worked real well.

I was worried about cracking as well, so I sandwiched my plexiglass between two 3/4" MDF pieces of wood before cutting.   Basically, I made my control panel top out of 3/4" MDF and cut/drilled everything out of it.     To set up for cutting my plexiglass, I placed spare 3/4" MDF board on my workbench (ie: bottom piece), then placed the plexiglass on that and taped the plexiglass down which a lot of blue painter's tape all the way around to make sure it would not move at all.  I then placed my 3/4" MDF control panel top (which already had all the holes, etc... cut in it) on top.   I then clamped both MDF (bottom and top) together (with the plexi in the middle).   I made sure to clamp to the left and right side of where I was going to cut/drill so there was always a nice firm "sandwich" created.    Finally I used my top control panel MDF panel as a guide to cutting out the holes and trackball space, etc...    It was nice since the button holes already drilled out of the top MDF piece guided the drill bit correctly into the plexiglass.  Basically, it made sure the drill bit was cutting into the plexi at a 90 degree angle.  The bottom piece of MDF was basically scrap and was thrown away when i was done.

The more you speed up, the more chance of cracking.   I would try to get spare piece of plexiglass to practice on.  Once you do it, you will understand what needs to happen in order to cut nicely.

I believe the idea with cutting plexiglass (or lexan) is that you really do not want to "cut" right through the plastic as if it were wood (ie: do not push your scroll saw blade through the plastic with a lot of force).  Instead you want the moving blade (or drill bit) to heat up the plastic befoer trying to apply more pressure to make it cut through.   For example, cutting a 1-1/8" hole for a button you would not just place your drill bit at the desired location and start pressing down and drilling right through the plastic, but rather you would allow the little point of the drill bit to spin in place a bit, thus heating up the plastic .  You would then push down until more of the drill bit goes through the plastic and then wait for more of the plastic to heat up a bit and then continuing pushing down, etc, etc .... until you are all the way through.

** Plexiglass and lexan usually come with a thin protective film applied to it to keep it from getting scratched when it is stored with a bunch of other pieces.   I would "highly recommend" you keep this protective film on the plexiglass until you are done cutting everything.    It obviously will protect your plexiglass when your cutting but it also seems to reduce (a bit) the amount of cracking which might occur (if any). 


So to recap:

1) Practice on some scrap first (if possible).
2) keep protective film on plexiglass
3) sandwich plexiglass between your true control panel top and some scrap to use as a guide
4) Cut/drill slowly so plexiglass melts as it cuts

[brock.sampson]

I did mine very similar to Teknique.  I used plexi for my cp.  I actually had the pleasure of doing my plexi twice.  I chewed the plexi and the trackball mounting plate when I was cutting the first one with a laminate cutoff bit.  I couldn't set the height correctly for the bearing to hit the mounting plate and the blade to hit the plexi.  For round two I got a 3" hole saw and a template bit and cut my trackball hole first.  I lined that hole up with the mounting plate on the cp and clamped down the plexi.  I used a forstner bit to drill a pilot hole to get the laminate cutoff bit and finish the rest of the button and joystick holes.  I got my second piece of plexi big enough so when I was done with the holes I could go all the way around with the laminate bit and get a perfect edge.  My advice is take your time when drilling and routing you will save yourself more time in the long run.  

[More Cowbell]

I have also used the sandwich technique where I put the plexi between two pieces of MDF and cut through all the layers. It keeps the plexi nice and tightly packed so it is less likely to crack. Worked for me.

[ahofle]

4) Cut/drill slowly so plexiglass melts as it cuts

To expand on this, I've found that keeping the drill on the highest speed and using MINIMAL pressure is what prevents the cracking.  If you press down really hard (or put the drill on a slow setting) before the plexi starts to melt it will crack.  So crank the drill speed and gently put pressure on the piece until you start to see it melt, then use a little more pressure to drill through the plexi.

[Jouster]

I started using the cutting tool and a straight edge to break it...but quickly switched to using my router.

One tip though...melting plexi/Lexan isn't as cold as you'd first think...don't wear sandles!

Jouster

[y2k600f4]

Thanks for all the tips eveyone ! After work I will be attempting to give it a try !

[More Cowbell]

One tip though...melting plexi/Lexan isn't as cold as you'd first think...don't wear sandles!

Great tip. Also wear goggles. I got nailed in the eyeball with some molten plexi once. When I closed my eye quickly, the plastic hardened and seald my eye shut! It hurt like hell and I thought I was going to have to go to the emergency room but I peeled it off of my eyelids (losing a few eyelashes) and ended up with some minor redness and itching for a few days. Could have been much worse. Debbie Downer signing off.... 

[unclet]

More Cowbell
Sorry to hear that happened, although next time it does, make sure to snap a picture so we can use it as an example of what to try to prevent   

[shorthair]

Safety gear is really the first stuff one should invest in.

[Zeno]

So it looks like the general concensus is NOT to try and cut 26"W marquee or CP with a pelxi cutting knife and snap it?

[Zakk]

I have cracked probably 10 or more pieces of control panel plexi.  The only way I have found to eliminate cracking is to use a router.  The ludicrous-speed of the bit goes through it like butter, and doesn't give it a chance to catch and crack.

[y2k600f4]

hmmmmm....which I read your post Zakk before I cut my CP plexi. I sucessfully drilled out all 19 button holes and 2 joystick holes (still need to do trackball, once I know the dimension of the hole). Cut using the jigsaw method, slow speed, fine blade. Worked good until i got to the end and the blade snagged.....and resulted in about 1" crack in the corner. Guess I will live w/ it for now 

[Zakk]

If you check out my project pages, you will see that almost ALL of them ended up just like yours.  Problem is, when the panel is almost done, there is very little structural integrity left, so it's easy to snap crackle and pop it.  The router was the only thing that seems to eliminate the problem. 

[crsdawg]

zakk is right on...use a flush trim bit for the edges and a panel pilot bit for the holes (the latter has a drill bit built in that will punch through the material, makes doing the button holes a one step process).

the cps come out perfect every time. just make sure to wipe away all the acrylic chips after each hole, otherwise you will most likely scratch the plex (they get sandwiched under the router and can cut through the protective plastic film on the plex/lexan/whatever your using).

[cadis12]

One tip though...melting plexi/Lexan isn't as cold as you'd first think...don't wear sandles!

Great tip. Also wear goggles. I got nailed in the eyeball with some molten plexi once. When I closed my eye quickly, the plastic hardened and seald my eye shut! It hurt like hell and I thought I was going to have to go to the emergency room but I peeled it off of my eyelids (losing a few eyelashes) and ended up with some minor redness and itching for a few days. Could have been much worse. Debbie Downer signing off.... 

When I started cutting my control panel for the first time I started with a router and it was going so well that I didn't want to stop.  I had goggles in the basement but didn't want to stop to go get them.  So I kept going with my eyes squited.  Stuff was flying all in my face.  Wasn't a big deal.  Felt like I had a few particles in my eyes but it was cool at the time.  Then later that night I went to bed and when I would shut my eye lids and keep them closed it felt like sandpaper!!  I couldn't sleep all night cause I couldn't shut my eyes!!  I learned my lesson and I hope others read this thread and take the time to put gear on. 

[cadis12]

Oh, and the flush trim bit is my new best friend! 

 

[Zeno]

Okay... I just cut out my pelexi CP cover while at work on Fiday (don't tell the boss man).

It looks perfect.  Here is what I did...

First I traced my cp on the plexi and used a band saw to cut out the overall size.  Easy, now for the holes...

1. Get a template of your CP with all holes cut out, including the 1 1/8 holes and carriage bolt holes.
2. Put down a piece of scrap wood that you don't mind drilling into.
3. Lay the uncut plexi on top of the scrap wood (don't remove the film cover).
4. Place the cut template over the pelxi.
5. trace the template out on the plexi film. This includes ALL holes.
6. Remove the template and look at your soon to be CP with holes drawn on the plexi film.
7. Find the center of all 1 1/8 holes by using a compass.  Draw a dot in the center.
8. Use a 1 1/8 spade bit in REVERSE and cut through about 1/3 to 1/2 of the plexi.  Repeat for each 1 1/8 hole.  DO NOT GO THROUGH THE PLEXI!
9. Flip the plexi over and repeat step 8 for all holes.  This time, you can go through and pop out the holes.
10. For the carridge bolts, go ahead and slowly use a standard bit in reverse and follow rules in step 8.

Your money.  This was my first attempt and it worked out great.

[y2k600f4]

Finished my first CP plexi. Lots of good tips here and I know what NOT to do and what to try for round 2. In the meantime I will utilize my $10 piece of plexi that unfortuneately has a small crack and a few chips on one edge. Other than that the 19 button holes, 2 joystick holes and 1 TB hole worked out well for my first run. I used various techniques including a holesaw/sandwitch method, jigsaw, router and even a dremel. Experience is the best teacher. Next time I will NOT use the jigsaw but rather a router.