Plastiglas

[Guest]

Hello,
I have not been scroll sawing for very long and trying different woods and plastics. I am making the 12 Days of Christmas in transparent acrylic plastic and the edges are coming out pretty sharp to the touch. I have been using a fine crocus cloth and it does pretty well, but was wondering what is best? I am using FD-SR #3 / 7 rev. teeth. Is there a better blade # to use? Thank for any suggestions.
Dena F

[BobD (Archive)]

Re: Plastiglas

Dena,
Acrylic is tough because as your blade heats up (normal friction from cutting) the acrylic can actually melt back together. I don't know what speed you're cutting at, but I reccomend a slow speed.

Another option to de-bur the acrylic is to use some sort of fine rotary cutting tool (like a dremel tool) Use a very fine cutting burr (not a diamond or stone wheel) and a light touch. That way you have a cut rounded edge rather than a sanded one.

Hope this helps!

Bob Duncan
Editor, Scroll Saw Workshop

[3_M]

Re: Plastiglas

Hei Dena,

Sorry Bob but I have to disagree with you about cutting plastic or acrylic. You should not use a blade with reverse teeth. The best one is the Polar # 3 or 5. The teeth are off-set a little, which helps to keep the kerf clean. Use 2' clear package tape over the pattern, it eliminates that the sides melt back together and you don't have to do any sanding. Sanding might even discolor the acrylic. I don't know what a fine crocus cloth is.
The speed can be from 1/2 t0 3/4.

Mike M

[BobD (Archive)]

Re: Plastiglas

Mike,
You have a lot more experience than I do!!! No need to apologize! I'm still figuring out about the different scroll saw blades and their kerf. I was commenting more on how to fix the problem after it happens...your solution prevents it from even happening!!

Bob

[will8989]

Re: Plastiglas

Well here's a third opinion. I am cutting a dragon 12' circle windchime out of nairoc (or whatever that plastic corian is called) and am using Mike's #7 Reverse blade and having no problems at all. I have a variable speed and have slowed it down to around 600rpm and it works very well for me. I am about 3/4 finished and am only on my 2nd blade. Just take this one slow, slow, slow.

[randy48]

Re: Plastiglas

OK here's how to cut plexi without it being able to melt back together - put the blade in backwards. It makes a wider and cleaner cut in the plastic, it won't weld itself back together, and cleans up nice and smooth with a plain old file.

[Guest]

Re: Plastiglas

BoB,
Thanks for your reply, I really don't think I'm having a melt together problem. I do have a Dremel Tool and it probably would work just fine on the outside edges, but the inside cuts I would not be able to use. My cuts are smooth, just sharp. Forgive me, but I'm going to address all reply here, rather than one by one.
Mike,
I probably will make an order for the Polar# 3 & 5 blade soon as you have suggested. I did use the clear packing tape, the plastic had a brown protective paper already on, so I glued the pattern on and added the clear on top of that. It was slow going, my little MicroLux scroll saw has 600 - 2700 SPM and speed was at about half. My blower had trouble keeping my line clear of the build up. I have done four ornaments in the plastic, they came out real nice with the blade I'm using, just sharpe edges. A fine crocus cloth is a sand paper (600 or 800) not sure which. I tried 1500 sand paper but found it left scratches on scraps tested.
Will8989,
Good luck with your Dragon, I had to change blades after the second ornament.
Randy48
If you turn the blade around to the flat side how does it cut the plastic? Sorry, I don't understand.
Thank you all for your replies and suggestion. I have been reading the board for a while. Its a very nice place to come too. Thanks to all
Dena F.

[3_M]

Re: Plastiglas

Hi Randy,

That is the best kept secret about cutting plexi.  I don't understand how it works however.  Putting the blade in backwards?  No teeth? How do you get a wider kerf with the blade backwards?  The blade is only so wide.
I'm sorry but I think your post must be too early, about 4 months maybe? John, do you know what I was asking?

Mike

PS, Dena, please email me.

[jttheclockman]

Re: Plastiglas

I am with the others on this one I have never heard of putting a scrollsaw blade in backwards. You can't cut anything without teeth can you????????? You maybe thinking of turning a tablesaw blade backwards and cutting plexiglass, in that case that works but with carbide teeth. As far as the edges being sharp there is no way around that. It is the nature of the beast. To eliminate the edges on the top and bottom the best way is to sandwich the plexiglass between two pieces of scraps such as 1/8' plywood or scrap paneling. Outside edges can be sanded but to do all interior cuts would be too time consuming. Try the sandwich thing you will like it. Mike is right on again about the right blade for cutting plexiglass and slowing the speed down. The packing tape is also a good trick for any cutting.

[Sparkplug]

Re: Plastiglas

3_M Mike,
It took a few minutes to catch on about the 4 months early. You must have meant April Fools day about the backward scrollsaw blade ? ? ?
: :P
Sparky

[randy48]

Re: Plastiglas

The edges of the blade do the cutting. I learned this trick while in the army trying to cut plexi with a jig saw. I was making an inside cut and it welded itself back together as I cut. So I cut it again with the same problem. On the third try, I happened to pull the saw back towards me and the cut opened right up, so I recut again only backwards, the piece dropped right out. So just to try it, I turned the blade around and cut the scrap piece using the back of the blade, it made a near perfect cut.

The next several cuts I made were done with the blade backwards, I just used acouple swipes with a flat file to clean up.

This is something you'll have to try yourself to believe it! I've used this technique on plexi from 1/8 - 3/4 inch with excellent results.

[3_M]

Re: Plastiglas

Hi Randy,

I just tried it on my scroll saw with a # 5 blades.  IT DOES NOT WORK.  It heats up very bad and the kerf melted right back together.

Now about what you have been doing.  You are talking about a jig saw.  That is a complete different tool as a scroll saw.  Jig saw blades don't even come close to a scroll saw blade.  Jig saw blades are much thicker, they can not be used to make ornaments, the inside cuts are too small for a jig saw blade.

Randy, do you have a scroll saw?  If yes, could you try it on your scroll saw and let us know who it worked for you.

Mike M

[Sparkplug]

Re: Plastiglas

3_M Mike,
Whether it is a jig saw or a scrollsaw the blade has teeth on the front and is flat on the back. I also cannot for the life of me imagine how using the back of the blade would work . It would be lucky to cut styrofoam or paper on the back of the blade so I am not even going to try a backward bade on anything.
Sparky

[randy48]

Re: Plastiglas

I've cut 1/8 inch on my scrollsaw using dremel blades from Walmart with no problem - blade backwards! In my last post I explained how I came about this discovery in the first place.

I've got a microwave cart and a wall shelf to build this weekend, if I can make good time, I'll setup my scroll saw and take some pictures and possibly a short video (my camera does like 20 or 30 second videos) and see if I can't make it easier for ya'll to understand.

Also yes, I do know a jigsaw and scroll saw are two different tools, I've used both and one hell of a lot more over the last 40 plus years!

[jttheclockman]

Re: Plastiglas

OK RANDY

I am going to be the first to sayI AM SORRY TO DOUBT YOU!!!!!!!!!!!!!!I tried your method and it does work. I tried cutting pleiglass mirror with a #7 blade and it did a fine job cutting but I had to push rather hard and if I used a smaller blade I feel it might break. You learn something everyday. I should have been more open to this idea because as an electrician we use mason's string line to cut PVC pipe. Now will I use this method to cut plastic I would have to say no because when you use the right blade and speed of saw there is no problem. But it would make a good bar bet. Thanks for the tip. I have to say that is one I never heard of except with a tablesaw blade and miter saw. :-[ :-[ :-[