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Discussion Starter #1
I bought this DeWalt 7 ¼” Blade for plastic and it melted the plastic instead of cutting it on my 10”TS. It is a brand new blade never used.

I thought it would be an easy cut, but it started moving all over the place of my line and I was unprepared for it. I guess I’m going to have to mount it on a piece of plywood before cutting it again.:huh: I cleaned off most of the plastic but I was thinking of freezing it to get the rest off.

Is it the RPM or what? I’m hoping the plywood will keep the plastic from accumulating on the blade.

 

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Sawdust Creator
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Stupid question....was it mounted the right way??? From the direction of the build up it almost looks like it could have been backwards?? Don't ask how I know but that doesn't work real well.
 

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Discussion Starter #4 (Edited)
Stupid question....was it mounted the right way??? From the direction of the build up it almost looks like it could have been backwards?? Don't ask how I know but that doesn't work real well.
It was going in the correct direction and there was equal amount of plastic on each side of the blade.

As far as the feed rate i was pushing it slow because it was throwing a lot of plastic at me and then I started to lose control of it when it started drifting away from the fence. I couldn't stop and had to push it all the way through. This was one of those times when I wished I had a large safety switch that could be pushed with my knee because I could not let go.

Maybe I need the blade up higher? It was only about a 1/4" above the plastic. Well maybe more like 1/2 to 3/4"
 

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Sawdust Creator
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I think two things happened....

1. Your slow feed rate allowed too much heat to build up.

2 as it drifted off the fence the work side loaded the blade...again building heat quickly.

The teeth should be slightly thicker than the blade body allowing the material to pass by the blade without contacting it. If it wasn't cutting a perfect straight line....and it wasn't if it was drifting off the fence....then the material likely rubbed the body of the blade.

I don't think the plywood will help any as much as a quick straight clean cut will.
 

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Discussion Starter #7
I think two things happened....

1. Your slow feed rate allowed too much heat to build up.

2 as it drifted off the fence the work side loaded the blade...again building heat quickly.

The teeth should be slightly thicker than the blade body allowing the material to pass by the blade without contacting it. If it wasn't cutting a perfect straight line....and it wasn't if it was drifting off the fence....then the material likely rubbed the body of the blade.

I don't think the plywood will help any as much as a quick straight clean cut will.
Well I guess I was cutting for the second time while you were replying and I used a piece of plywood under it. This time I was successful and the plywood did help. It was really weird because the sawdust from the plywood was absorbed into the plastic and left a string that looked more like yarn.

My face shield broke just before the second cut and I had to use regular safety glasses. I have plastic in my nose, mouth, ears and hair. God I hate the smell of melted plastic.

Below is the aftermath of Cutting Plastic on table saw: LOL



What "plastic" were you cutting?








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It was 1/4" thick clear plastic sheet. I'm not sure but it might be acrylic.
 

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Discussion Starter #9
That is the wrong blade for cutting acrylics. It's designed for "plastic laminates", like Formica. It's a steel blade and has too many teeth.






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Wow, I didn't know that. I have an old 7 1/4" Carbide Blade. Do you think that will work?

I still have two more cuts with the table saw to make a 2”x6” notch and I can’t make a mistake because it can’t have any slop. I’m not sure how I’m going to make the final 2” cut and I’m a little nervous after the first cut. I guess I can fix the piece on the saw and crank the blade up for the finish cut.
 

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Old School
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I don't use 7¼" blades on the TS, but if you do try a 40T carbide tipped blade and run it high. I would raise it all the way up. You may still get some melting, but it won't be anything like what happened.

Some "acrylics" cut better than others. Most of the box store stuff is extruded material. Cast acrylic cuts much better.






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Discussion Starter #12
I’m using the 7 ¼ because I just happen to have them and I don’t want to ruin my good 10” blades. I bought the 7 ¼” plastic blade 10 yrs ago for another project, but never used it until now.

Well I don't want to buy a blade so I guess I'll try my old carbide blade.
 

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I turn a general purpose blade backwards when I cut plastic and thin aluminum....
I've never cut acrylic this way, so don't know if it would work...

Sent to y'all offen' a iPad thing......
 

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Discussion Starter #14
I turn a general purpose blade backwards when I cut plastic and thin aluminum........
I have a little story about that and hope no one minds. I once built a 50’x150’ prefab steel shop for a ranch and when I was building the forms for the foundation it was ¼” out of square. I decided that it wasn’t enough to square it up and continued on. We starting assembling the building as soon as the concrete dried and the walls went right up with everything bolting up perfectly including the roof support columns and trusses.

Then when I started screwing down the steel roof panels I noticed a saw tooth pattern developing along the front and back because of that stupid ¼”. :eek: The back had gutters to cover up my mistake, but the front OMG you could see it from a 1/2 mile away against the skyline.

Oh man I was panicking and called an architect friend for help. He told me about turning the saw blade around and cutting ¼” off along the whole front of the building. Well I strung a chalk line and did exactly what he told me. Man I was happy because it saved my butt and after that I never ever allowed even a 64th out of square.:thumbsup:


Anyway back to this topic, I put on the carbide blade in the correct direction and it was a little scary, but it made all the difference in the world. I just had to go slow.

 

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Discussion Starter #15
This video from Tap Plastics says Router is best cutter

I wish I would have known about this video from Tap Plastics because it appears that a Router is the best cutter

 

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Old Methane Gas Cloud
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IMHO, the 7-1/4" blade has the teeth moving too slow. Plastic, especially acrylic, likes to be cut with very high speed cutters.

BTW - I usually cut a piece of plastic window glazing with the table saw in three passes. First I score about 3/64" deep on each side and then raise the blade to about 1-1/2".

Also a plywood push stick on the top of the plastic helps a lot.
 
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Discussion Starter #17
Now that I've already have melted acyclic on my new saw blade, how do I clean it up like new again?
 
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