Replies

1. 
   dougmeyer | Dec 20, 2007 08:28pm | #1

   I have cut this type of stuff a few times and I have about a 25% trash it average, so I say go very slow and hope for the best but I would not try this if you can not afford to mess it up.  And I think something smaller like a Dremal or some such is a much better idea (smaller/faster bit).

   Doug

2. 
   forestgirl | Dec 20, 2007 08:35pm | #2

   I would look up "plastics" in the Yellow Pages and try to find someone who could guide you on this.  Acrylic fails in nasty ways, and it doesn't sound like you can afford to make a mistake here.  I know there are drill bits for plastic, but obviously they're too small for this purpose.

   Where is 'PlasticsJoe"? -- he used to be a member here. Darn.

   forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 
   
3. 
   jump | Dec 20, 2007 11:02pm | #3

   I have cut a lot of holes in acrylic plastic. I have used both hole saws and router/template. The hole saw makes a rough hole edge and usually requires a drill press. The hole edge can be sanded to make it more attractive. A router and template does a nice job and gives a smooth edge.  Sometimes I will use a hole saw to make the templace for the router.

1. 
   forestgirl | Dec 21, 2007 03:16am | #4

   I sometimes work with acrylic, and would love to know what specific bit you use to accomplish this.  Is it a spiral of some sort?forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

1. 
   Routerman | Dec 21, 2007 04:31am | #5

   A couple of choices.

    

   Routs acres of AC

1. 
   forestgirl | Dec 21, 2007 09:02am | #8

   Thanks, Pat.  The spiral bit is self-evident.  Are the other two simple straight bits, or is there some characteristic I'm not seeing in the picture?forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

1. 
   Routerman | Dec 21, 2007 05:48pm | #9

   The carbide faced bits have boring points. They need no pilot hole to get through the material; they'll bore their way through.

    

   Routers

2. 
   forestgirl | Dec 22, 2007 06:23am | #12

   Thanks, Pat.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

2. 
   DonfromUtah | Dec 21, 2007 05:21am | #6

   I recently made a large extension table for my wife's favorite sewing machine (she has several). I used a spiral bit to create round corners and the cutout that fits around the base of the machine. The table was made of 3/8" cast acrylic - my plastics supplier recommended cast acrylic because it machines much better than extruded acrylic. This table machined quite nicely.

1. 
   forestgirl | Dec 21, 2007 09:00am | #7

   "my plastics supplier recommended cast acrylic because it machines much better than extruded acrylic."  Thank you for that detail -- a distinction I was unaware of.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

3. 
   jump | Dec 21, 2007 06:14pm | #11

   I use straight bits, because that is what I have. Spirals may work better but I have never found them necessary. I have never used acrylic thicker than 1/2"; spiral may do a better job in thicker material.

   I have used both cast and extruded and have not found a large difference. I have machined both and they both work.  When I have made a Y with acrylic pipe, for example a 3" pipe intersecting a 4" pipe at an angle, using 1/4" wall thickness rather than 1/8" helped reduce shattering more than using cast. If you needed to do very precise machining, cast has an advantage.

4. 
   KeithNewton | Dec 21, 2007 06:09pm | #10

   I have done lots of this, I ran a production plastic shop for a year back in the early nineties.
   A template with a guide bushing and a standard 1/2" straight should do this fine. I would cut in the CCW direction to avoid chipping in the final edge.

   I have not had good results going with smaller bits as Doug suggested, because they have a harder time ejecting the chips, which them melt and weld to the bit, and cut edge. In fact cutting too slow with any bit can cause heat which may cause crazing as well as the above problem. Cutting too fast though is more likely to chip out, so just make sure that you have a sharp bit, and move the router along at a steady rate giving the bit a chance to make chips instead of fluid.

   Larger bits actually cut plastic fine, but most larger bits start getting more hook, or sharpness angle than is needed for this.

5. 
   jump | Dec 24, 2007 07:06pm | #13

   Forestgirl, I have both a VS router and a single speed router. I use either one. As KeithNewton mentioned above, higher speed causes less melting. The melting problem is greatest with a hole saw, which is one of the reasons the edge is so rough.

1. 
   KiddervilleAcres | Dec 28, 2007 09:47pm | #14

   I am making a TS blade guard out of ¼" acrylic and am wondering what is the best glue for glueing the sides to the top.  Also want to provide for DC so thanks for the advice on cutting.  Ideally I'd like to afix a short tube for the DC attachment.

   Any recommendations for the above?

   Regards,

   Bob @ Kidderville Acres

    

   A Woodworkers mind should be the sharpest tool in the shop!

   Edited 12/28/2007 1:47 pm ET by KiddervilleAcres

1. 
   dgreen | Dec 28, 2007 10:24pm | #15

   Would pictures and dimensions of Biesmeiers overhead guard help you any?------------------------------------

   It would indeed be a tragedy if the history of the human race proved to be nothing more than the story of an ape playing with a box of matches on a petrol dump. ~David Ormsby Gore

1. 
   KiddervilleAcres | Dec 28, 2007 10:30pm | #16

   Sure.  I haven't settled on a final design yet.  Got the ¼" acrylic for zip at the local hardware.  The guy was wearing a Santa Claus suit!?

   I'm planning on an overhead setup (homemade).

   Regards,Bob @ Kidderville Acres

    

   A Woodworkers mind should be the sharpest tool in the shop!

2. 
   KeithNewton | Dec 28, 2007 11:20pm | #17

   Methylene chloride is the solvent type that you use a syringe to squirt into the joints while they are held together. It melts the two surfaces, and weld them together. You need a really good clean cut for it to work at its best. Have you ever done this? I am sure that if you google it, you will find good instructions. If not, just ask for more specific details.

1. 
   KiddervilleAcres | Dec 28, 2007 11:28pm | #18

   Keith,

   I have never done this B4.  I did find several sites with procedures for doing same, I think Plaskolite?  I plan on cutting the pieces with an 80 pt TS blade, then smoothing with sandpaper on glass B4 gluing.

   As for the hole for DC I'm still wrestling with that part.  Sounds like router is the way to go but I still need some sort of recepticle for the hose.  Not sure if I can somehow weld a plastic connector from a DC adapter?

   It might just be cheaper/better to purchase just the guard part and adapt it to a homemade arm..............

   Regards,

    Bob @ Kidderville Acres

    

   A Woodworkers mind should be the sharpest tool in the shop!

1. 
   KeithNewton | Dec 29, 2007 12:07am | #19

   I wouldn't sand. The 80 pt. blade may be good enough by itself it is sharp enough, and you feed the right speed. If you need better than that, you can set your table router up like a jointer with the fence lower on the infeed side, to get a perfect cut. You should be able to find acrylic pipe which will glue to the other sheet material, then rout the middle out with a bearing flush bit.A good trick for getting a clean cut is to use a 5/8" bearing on a 1/2" bit for a rough cut, then change to the 1/2" bearing for a finish trim cut. One of the trickiest parts is to hold the parts together just right while you tip the syringe in just so, to get into the high corner, then drag the tip along so that it fills the space evenly from one end to the other, then get the needle away without spilling some where you don't want it.
   Practice on some scrap before helps, but it is not rocket science, just a bunch of little tricks.

2. 
   KiddervilleAcres | Dec 29, 2007 04:33pm | #20

   Keith,

   I have found that acrylic can shatter so I have since decided that I will use Lexan II as it's a polycarbonate.  Sorry for the confusion.

   I will engage an assistant to hold the pieces or clamp them.  Thanks for the tips.  As for cutting the straight pieces, I have a TK 80 tooth blade for a circular that is made for cuttin plywood and am wondering if that blade might work better.

   Regards,

   Bob @ Kidderville Acres

    

   A Woodworkers mind should be the sharpest tool in the shop!

   Edited 12/29/2007 8:35 am ET by KiddervilleAcres