Table Saw Blade? Cutting Acrylic?

[mattboy]

I'm pretty sure the correct blade; triple chip cut 60-80 teeth, installed and adjusted correctly, will do a much better job than a cheap blade installed backwards. Just because someone doing a DIY acrylic project says "it worked great" does not mean that it's as good as the right tool used correctly. Don't forget, if your cut "looks" okay but the acrylic was heated up in the process, it's not as good. And what looks good to one person might not be acceptable to someone else.

Personally, I never, or almost never, solvent weld seams with joints that have been cut on the table saw. I always finish them with a shave on the router; this way I know that the edge is perfect and has not been heated during the process. For someone else who wants to build something quickly with a minimum expense, maybe the cheap blade is perfectly okay. I have no problem whatsoever with that, but it doesn't mean that it's "as good."

 

[ray22]

the point is i gave an opinion i wasn't even talking about a table saw.I was talking about a 10 inch ryobi hand saw . and that it would help not chip the acrylic . if you want to go out and spend the money for an expensive blade that is fine . i did not like the fact that someone would have to say my opinion was not to be considered . . it worked for me and I'm an sure for many others . most people that get into this hobby have enough money to spend on an expensive saw , however most people that enjoy this hobby also enjoy a challenge and the hands aspect of building your own reef tank . again this is a DIY site . not a go spend the most money and pay a professional to do the work for you. I am sorry if i offended anyone on here and sorry for my childish behavior . I would never wish anyones tank to crash . I have seen many ways on here to do the same diy. again people are simply here to help each other out . that is all i was trying to do . we all did not need to hear if you turn the blade around you will cut your arms off and have to go to the ER. ( a little over board .. ya think?) well have a wonderful evening . by the way the 10yr yld is down slightly today . cheers .

 

[Kenfuzed]

I used to work for a major power tool company in the repair department and would see some amazing things. Related to the saw blade issue, one of my regular customers came in one day who was known for his tattoos and piercings. I commented on his newest unusual earlobe hole between two earrings. Turns out that wasn't done on purpose. He had turned his saw blade backwards to cut some plastic since he didn't have another blade. About half way through the cut one of the carbide tips launched off the blade and passed through his earlobe like a bullet.

Needless to say his picture was proudly displayed on the wall right next to the x-ray of another guy who had shot a 3-1/4" framing nail into his leg after removing the nailer's safety.

While something may work better than originally designed, is it worth it?

 

[BigJPDC]

Ha!!

 

[Vincerama2]

OK, when they say they run the blade backwards, I think they mean to MOUNT the BLADE backwards. The table saw motor and blade will still spin the RIGHT way (ie, the top of the blade spining towards you and thus pushing the work piece INTO the table). This is much different from somehow "RUNNING THE BLADE BACKWARDS" implying that you somehow make the blade rotate the other way. See what I'm saying?

Just unmount the BLADE from the saw arbor, flip it around, then remount it. The motor still runs the same way, but you are cutting the acrylic with the back of each saw tooth.

If you left the saw BLADE the same, but ran the MOTOR backwards, then yes, the piece will fly up and hit you in the face.


As an option to using the table saw, you can buy JIGSAW blades that nicely cut acrylic for $5 at places like Tap Plastic. It will make a decent which you can then clean up with a router. That's how I cut my acrylic (though I now have a tablesaw, which I've not cut acrylic with).

Oops, I see that I'm actually on page one of this thread, maybe someone has posted the same info. If so, sorry!


V

 

[Zigzag Man]

Turning a saw blade backwards make sense to me. It just means that each tooth takes less of a bite, which is analogous to feeding the stock slowly.

Actually, no. It's analogous to 'sanding' your way through the acrylic, because you aren't using the cutting edge of the tooth, but the backside of it... so essentially you're just 'wearing' your way through the acrylic.

Personally, I've always just used whatever blade I had on my saw (currently a Freud carbide 40-tooth blade) and have never had any problems cutting acrylic. The secret is to have the blade height about 1/4" higher than the thickness of the acrylic, and feed it slow.

Should cut without any problem.

Of course there's always a better blade for the job (a triple-chip comes to mind), but I'd much rather use a 'lesser' blade the correct way, and compensate for it by technique, rather than try to use a blade the 'wrong' way, and risk injury.

That's just my opinion, of course... I'm not looking down on anybody that wants to try things their own way, just that it's not advisable, nor would I recommend or condone it.

 

[BtheReef]

I read through this thread several times before posting because it looked like it was quickly deteriorating into a flamefest. Anyway, after reading ray22's last post, i think I see his point on something.

Maybe when responding to questions about DIY projects, we should ask, "What quality are you looking for?"

Basically, any blade will cut acrylic, from the $7 one at Lowe's to the $150 Forrest blades. The distinction is what type of quality the cut is. Can the edge be glued right after cutting, is this item going to hold water, does chipping matter to you, etc. are all variables that will change the answer to ray's original question.

Just reminded me that everyone's acceptable level of quality is different, so each person may use different methods or tools to attain this.

Be creative, and always be safe.

 

[bshumake]

While cutting with the blade backwards is essentially "sanding" you way through you're only using the back edge of the carbide teeth. With multiple cuts the blade will heat up and melt through giving fairly rough cuts. A properly oriented blade uses the most stable plane to cut in and keeps all of the force exerted perpendicular to the strongest parts (and sharpest) of the blade. Basically, proper orientation equals more cut, less heat, and vice-versa. Yeah, sure you can cut through backward but you're only using a fraction of the cutting surface, increasing drag, and heat. Try cutting a piece of wood with a backward blade. It'll burn the wood while it cuts at a very slow pace, and this will burn out the motor in your saw. I'd rather pay $20 to resharpen a blade than $100 for a new saw.
And for the cutting blade recommendation... go with a 80 tooth triple chip carbide. With a plum and level blade this will give a nice smooth cut with no chipping. You will have some saw marks on the edge but this works pretty well using capillary method. However If you want the best cuts finnish on a routing table. Yous reams will come out perfect.

 

[bshumake]

<a href=showthread.php?s=&postid=6901356#post6901356 target=_blank>Originally posted</a> by bshumake
Yous reams will come out perfect.

Be sure to use protection while reaming. :rollface:

 

[bradhinz]

re backward blades

re backward blades

I run an acrylic bathtub manufacturing plant and we cut acrylic all day long with skill saws. We use 80 tooth blades installed in the correct fashion. It is the only real safe way to do that.

Having said that there is one way that backwards cutting works for us. Start the skil saw near the end of the cut (drop in cut) then pull the saw backward towards you and it makes a nice fine cut, no chipping. but then again we don't chip the tubs cutting forward in the normal fashion either. Just my 2 cents:rollface:

 

[Acrylics]

Hmm, am hesitant about jumping into this but will anyway

The reasons for not running a carbide blade backwards are twofold: 1) you are heating the material up alot more and will more than likely melt your way through the acrylic inducing stress into the material which can cause problems later on in fabrication, but more importantly, 2) carbide cutting tips are brazed onto the blade plate, when cutting correctly, the blade plate acts as a safety backer behind the carbide tip, if running the blade backwards - you are pushing the carbide tip away from the plate. If the blade has any bad brazing joints, the tip can fly off and who knows what from there. While the backwards blade cut can be made, it is no where near the cut quality that a correctly used tool will achieve.
I do completely understand the concept of cutting corners at times for purposes of DIY, however if this creates a safety problem, it's not worth doing just to save a few $$ IMHO.

James