Replies

1. 
   forestgirl | Oct 18, 2006 07:40am | #1

   I've cut quite a few sheets for displays I've made.  I use an Olfa plastics cutter ("P-Cutter 800").  Here it is at Amazon, but you can get it at most hardware stores I think.  It's not expensive.  There are saw blades you can use, too, if you want to spend the $$ and take the chance.  I''ve not "gone there" yet -- fingure I'll probably screw it up a couple times before I get it right.

   I clamp a thick aluminum straightedge over the acrylic where I want the cut and make several (several) passes with the Olfa knife.  After about the second cut, the knife stays pretty securely in the groove you're making, and long curls of plastic emerge,  but be careful where your hands are in case the knife slips.

   You'll know when you've gone all the way through, but to check, just wiggle the off-cut a little and see if it feels loose.

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

   
   

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   Edited 10/18/2006 12:46 am by forestgirl

1. 
   Yogi | Oct 18, 2006 09:33am | #3

   Thank you-  I'll get one-

2. 
   RickChristopherson | Oct 18, 2006 09:16am | #2

   You can cut acrylic on a tablesaw using a fine-tooth carbide blade. Triple chip is better, but an ATB will also work. To reduce the chatter, you will need to set the blade height somewhat low (by my standards that is) so that only the teeth are above the sheet surface. Just be careful with a low blade height like this, because the workpiece can lift up at the rear of the blade and kickback severely. This is true regardless whether it is wood or plastic that is this thin and flexible. Make sure you don't allow the piece to drift away from the fence.

   Because the blade is set low, you will generate more heat in the cut and will have some melted plastic ball up around the cut. This just snaps off with your finger.

   If you have one, a variable speed, guided circular saw will cut this without melting and without chatter, but I don't want to turn this into an off-topic thread.

   For cleanup (if necessary) you can feed the edge through the jointer on a shallow pass with excellent results. If you don't have a jointer, you can scrape the edge clean with a cabinet scraper, but I prefer to take the iron out of a plane and use the **side** of the iron as a scraper (jointer is still preferred over manual scraping). Oh I almost forgot, but you can also use a router to clean the edge too. Just set the speed to its lowest setting to avoid melting the cut.

1. 
   Yogi | Oct 18, 2006 09:35am | #4

   Thanks for your thoughts Rick-  Much obliged-  I think I'll try to keep it simple and give the cutter mentioned above a shot for a first attempt-  I'll have your method as a backup-  Thanks again-

1. 
   cadiddlehopper | Oct 18, 2006 02:01pm | #5

   I've cut plastics with several of my carbide table saw blades (36- to 60-tooth). Never had a problem if I fed it very slowly. I would never use my jointer on it! There is a reason for using carbide saw blades. Files & sandpaper will clean up edges for framing. If you are not faint of heart, a quick pass along the edge with a propane torch will really polish it.BTW, leave the paper attached while sawing. Remove it before flame polishing.Cadiddlehopper

1. 
   RickChristopherson | Oct 18, 2006 07:11pm | #8

   Plastic is a very soft material, and it will not damage your jointer knives. A jointer is a standard tool in plastic fabrication shops (I used to be an engineer at a fabrication company).

1. 
   cadiddlehopper | Oct 19, 2006 06:08am | #9

   Then why does melamine do a number on blades?Cadiddlehopper

2. 
   KeithNewton | Oct 19, 2006 06:24am | #10

   The TS does a fine job, and while it is not a good idea to cut too fast, which will cause chipping on the underside, it is also not good to cut too slow. That is what causes melting, besides a dull or dirty blade.After cutting on the TS, you can get a nice clean edge on a router table with the infeed fence set back like a jointer.

3. 
   RickChristopherson | Oct 19, 2006 10:13am | #11

   Quote Candlehopper: Then why does melamine do a number on blades?First off, I don't agree with this assertion, but I won't contest it at this time for the sake of argument. That is a different topic.Melamine is the resin that impregnates the paper of the melamine plywood, it is not the primary material of the product. As a binding agent, it is not the same as acrylic sheet, because acrylic is the primary material being machined, not just a surface finish.Your comparison is drastically flawed because melamine and acrylic are not the same, but you are associating one with the other because you see them both as being plastic-based. Even if melamine was considered a plastic in the same sense as acrylic, which I don't believe it is, that doesn't mean it is the same as acrylic. Not all plastics are the same. Polypropylene is significantly different from acrylic, yet they are both considered plastic.I cannot think of a single plastic, including melamine, that is harder than carbide or high-speed steel, so the myth of melamine or any other plastic dulling your blade does not stand up. A material would have to be either abrasive or nearly as hard as the steel before it will significantly dull your cutters.

   Edited 10/19/2006 3:16 am ET by RickChristopherson

4. 
   Scrit | Oct 19, 2006 01:42pm | #12

   "Quote Candlehopper: Then why does melamine do a number on blades?"

   From experience of CNC machining loads of it I'd say it's generally not the melamine facing which gives the problems, rather the chipboard substrate which can contain recycled metal hardware (screws, staples, buckshot, even shrapnel) as well as hard crystalline accretions from the original trees, not to mention the abrasive nature of the binding materials used in its' production. The exception is possibly some of those "metallised" melamine facings currently popular for urban "high tech" kitchens but which certainly seem to reduce the life of tooling. What I have found with MFC (melamine faced chipboard) as well as MF-MDF is that if your dust extraction isn't up to scratch and your feed rates are too low then you get recutting of the waste which in turn increases friction, the temperature of the cutting tip goes up and you can in extreme instances burn a tip - for brazed tips that means the tip can be thrown, whilst for replaceable tip tooling with thin tips the tip can crack or even fracture completely. These, are, however, not common occurrences, IMHO

   I concur with what you say about cutting acrylic and I'd add that one thing to ensure is that the feed rate is sufficient to reduce the tendency of the swarf to 'melt-back' around the cut

   Scrit

5. 
   cadiddlehopper | Oct 19, 2006 02:00pm | #13

   "the myth of melamine or any other plastic dulling your blade does not stand up."Lest I err, Formica is a melamine plastic. Go cut some with a non-carbide cutter or saw blade. Seen what it does for yourself. I have.Cadiddlehopper

6. 
   KeithNewton | Oct 19, 2006 05:08pm | #14

   Clyde, if you cut particle board with a steel blade, it will dull in a heart-beat also.If they both dull the material at the same rate, however the melamine is only a couple of thousandths on each face, but the core is 750 thousandths, the core is 187 times as thick as the two faces combined. Why would you think it is the face doing the damage? Have you never used industrial PB before?As I stated above, Slowing down the feed rate too far can be as bad or worse than feeding too fast. You are just trading one set of problems for another.

7. 
   RickChristopherson | Oct 19, 2006 05:51pm | #15

   Yes, plastic laminate such as formica is harder than wood, and therefore will dull a blade faster than wood, but it is not the same. You are missing the point of the thread!!! This was about acrylic, and you are associating all plastics with formica, which isn't even a plastic to begin with. Just because people call it plastic laminate does not mean it is plastic. And just because formica and melamine use the same resin doesn't make them the same material either.

8. 
   cadiddlehopper | Oct 19, 2006 07:00pm | #16

   "Plastic is a very soft material, and it will not damage your jointer knives." Your words.Melamine is a thermosetting resin. Isn't that the same thing as a plastic material? Hardness isn't the problem. It is abrasiveness. I don't subject my jointer knives to particle board nor to the glue between the layers of plywood either."You are missing the point of the thread!!!"Please forgive my apparently excessive cranial density. Perhaps that is why I have great difficulty understanding statements like: "Just because people call it plastic laminate does not mean it is plastic." Please tell me what it is if it isn't plastic. Whatever it is, I will not tell anyone to run the risk of ruining his jointer knives on my advice. I sharpen & adjust my own knives, so I know the pain.Cadiddlehopper

9. 
   RickChristopherson | Oct 20, 2006 03:19am | #17

   The original discussion was about acrylic, and acrilic is soft and non-abrasive. For some reason or another you have turned this into a completely unrelated topic and are arguing for the sake of arguing. Nobody was talking about using particleboard or formica. The topic was acrylic, and if you don't know the difference between acrylic and melamine, it is not my job to educate you.

3. 
   JeffHeath | Oct 18, 2006 03:48pm | #6

   My mother is a quilter, and I made a whole bunch (about 25) cutting tables for the women in her guild, using acrylic tops.  I cut them all on the tablesaw, without incident.

   Jeff

4. 
   user-52008 | Oct 18, 2006 06:17pm | #7

   Triple-chip blade on the tablesaw always worked well for me. Make the cut slowly, but keep it moving.