Free: Plywood and plexiglass

[smallboat]

Just to muddy the waters - Plexiglas is cast acrylic sheet.
Many people will use the term Plexiglas as a generic for acrylic even though there are acrylics that are extruded rather than cast. d there are cast acrylic sheets that are not branded as Plexiglas.
I’m not certain if it makes any difference in machining, but imagine it could.
I’ve never had any issues with plex.

 

[ChemE75]

Just to muddy the waters - Plexiglas is cast acrylic sheet.
Many people will use the term Plexiglas as a generic for acrylic even though there are acrylics that are extruded rather than cast. d there are cast acrylic sheets that are not branded as Plexiglas.
I’m not certain if it makes any difference in machining, but imagine it could.
I’ve never had any issues with plex.

Yup, different forming methods. But it’s not exactly analogous to the distinction between, for example, forged iron vs cast iron which does affect the crystalline properties. Polymethylmethacrylate is the same amorphous plastic in both methods. I believe the plexiglass method is designed to obtain the best clarity for windows and the like. As best as I know, there is no impact on machinability.

 

[HITCH-]

I have been in the plastic industry for 18 years now. Here are fabrication guides for acrylic and polycarbonate that might be useful for folks.

https://plaskolite.com/docs/default-source/fab/fab004_opx_extruded.pdf

https://plaskolite.com/docs/default-source/fab/fab015_tuf_en.pdf

 

[patlaw]

I have been in the plastic industry for 18 years now. Here are fabrication guides for acrylic and polycarbonate that might be useful for folks.

https://plaskolite.com/docs/default-source/fab/fab004_opx_extruded.pdf

https://plaskolite.com/docs/default-source/fab/fab015_tuf_en.pdf

Is he cutting acrylic or polycarbonate? I asked because I tried cutting Lexan on my table saw exactly the way he did, and I had shards of the stuff flying everywhere.

 

[Wilsoncb]

I have been in the plastic industry for 18 years now. Here are fabrication guides for acrylic and polycarbonate that might be useful for folks.

https://plaskolite.com/docs/default-source/fab/fab004_opx_extruded.pdf

https://plaskolite.com/docs/default-source/fab/fab015_tuf_en.pdf

Did I read that right? For the polycarbonate, it says 5000-6000 ft/min. That’s 83-100 ft/second.

 

[Mike Davis]

Did I read that right? For the polycarbonate, it says 5000-6000 ft/min. That’s 83-100 ft/second.

Around 2000 rpm for a 10 inch blade.

Most table saws run 5000 rpm.

Looking at the link … it says around 6000 rpm.

 

[Wilsoncb]

Around 2000 rpm for a 10 inch blade.

Most table saws run 5000 rpm.

Looking at the link … it says around 6000 rpm.

The acrylic document says “rpm”. The polycarbonate one says “ft/min”. Type-o?

 

[HITCH-]

Is he cutting acrylic or polycarbonate? I asked because I tried cutting Lexan on my table saw exactly the way he did, and I had shards of the stuff flying everywhere.

That's acrylic. The main thing to successfully cutting either on is to hold the workpiece in a fashion that reduces chatter. I use my plywood blade in the circular saw or tablesaw.
If you look at the can he is using it says "acrylic" on it. It is a sovent weld similar to how you fuse PVC pipe.

 

[patlaw]

That's acrylic. The main thing to successfully cutting either on is to hold the workpiece in a fashion that reduces chatter. I use my plywood blade in the circular saw or tablesaw.
If you look at the can he is using it says "acrylic" on it. It is a solvent weld similar to how you fuse PVC pipe.

Understand and agree. I saw "acrylic" on the can. The problem is, I asked him which one it was, and he said polycarbonate. I think he's misremembering.

 

[HITCH-]

The acrylic document says “rpm”. The polycarbonate one says “ft/min”. Type-o?
View attachment 234002

Yes, it is a typo.
They are both 5,000-6,000 FTM

 

[Wilsoncb]

Yes, it is a typo.
They are both 5,000-6,000 FTM

Ok, so I still don’t get it, I must be missing something. How material can be fed that fast. As I explained above that’s 83-100 ft/second. I think I typically feed material through my table saw at about 1/2 ft/second.

 

[Mike Davis]

Ok, so I still don’t get it, I must be missing something. How material can be fed that fast. As I explained above that’s 83-100 ft/second. I think I typically feed material through my table saw at about 1/2 ft/second.

No, that is the surface feet per second of the rotating blade, the speed of the teeth moving through the plastic.

 

[Wilsoncb]

No, that is the surface feet per second of the rotating blade, the speed of the teeth moving through the plastic.

OK, that makes sense, perhaps they need to express it as blade speed at the tooth (versus what I was thinking…feed rate). These spec writers really need to consult with me so they can compensate for my simple mind.

Anyway, it means you would need to use about a 6” blade on a table saw that has a motor speed of 3450 rpm to get 5,000-6,000 FTM.
10” blade = 9027 fpm @ 3450 rpm
7 1/4” blade = 6544 @ 3450 rpm
6” blade = 5416 fpm @ 3450 rpm

 

[ChemE75]

OK, that makes sense, perhaps they need to express it as blade speed at the tooth (versus what I was thinking…feed rate). These spec writers really need to consult with me so they can compensate for my simple mind.

Anyway, it means you would need to use about a 6” blade on a table saw that has a motor speed of 3450 rpm to get 5,000-6,000 FTM.
10” blade = 9027 fpm @ 3450 rpm
7 1/4” blade = 6544 @ 3450 rpm
6” blade = 5416 fpm @ 3450 rpm

Don’t forget that feed rate is mentioned, at least for need to speed up or slow down - didn’t notice if the feed rate they recommend is mentioned anywhere, but number of teeth are mentioned as well as the recommended tooth style. I’m planning on converting covered patio to sun room, mostly will use commercial windows, but for a few narrow sections between posts and house walls, I plan to make window panels using plexiglass so I’m appreciating the insights. Although I’ll risk using an existing blade, hard to spend the $ on a blade just for 3 small panels.

 

[Wilsoncb]

Don’t forget that feed rate is mentioned, at least for need to speed up or slow down - didn’t notice if the feed rate they recommend is mentioned anywhere, but number of teeth are mentioned as well as the recommended tooth style. I’m planning on converting covered patio to sun room, mostly will use commercial windows, but for a few narrow sections between posts and house walls, I plan to make window panels using plexiglass so I’m appreciating the insights. Although I’ll risk using an existing blade, hard to spend the $ on a blade just for 3 small panels.

Yeah, maybe it's just my inner Sheldon (Big Bang Theory) but this spec is just lacking clarity (and/or acuracy). For example for 8-10" blade is suggest "6-8 teeth/inch (per cm)" as if a cm and an inch were equal. Either way 6 teeth per inch on a 10 is blade is 188 teeth or 478 teeth with 6 per cm. Concerning feed rate, the only thing is says is speed up if you have melting and slow down is you have chipping. I guess, my take away for cutting on a table saw is use the smallest, highest tooth count blade you have and do some test cuts. Otherwise, use a band saw, I know from my sign making days in the '80 a high tooth count or metal cutting blade works...or check out this web site.

ACRYLITE® - Equipment Materials and Suppliers

There are several saw blades on the market that can effectively cut ACRYLITE® extruded (FF) sheet. Sharp teeth are essential for achieving good results. Carbide tipped saw blades are recommended for superior cuts and longer life of the cutting edge. It is also important to dedicate saw blades...

www.acrylite.co

 

[ChemE75]

Yeah, maybe it's just my inner Sheldon (Big Bang Theory) but this spec is just lacking clarity (and/or acuracy). For example for 8-10" blade is suggest "6-8 teeth/inch (per cm)" as if a cm and an inch were equal. Either way 6 teeth per inch on a 10 is blade is 188 teeth or 478 teeth with 6 per cm. Concerning feed rate, the only thing is says is speed up if you have melting and slow down is you have chipping. I guess, my take away for cutting on a table saw is use the smallest, highest tooth count blade you have and do some test cuts. Otherwise, use a band saw, I know from my sign making days in the '80 a high tooth count or metal cutting blade works...or check out this web site.

ACRYLITE® - Equipment Materials and Suppliers

There are several saw blades on the market that can effectively cut ACRYLITE® extruded (FF) sheet. Sharp teeth are essential for achieving good results. Carbide tipped saw blades are recommended for superior cuts and longer life of the cutting edge. It is also important to dedicate saw blades...

www.acrylite.co

Ya, the specs seem like an after thought, figuring they should put out some guidance for hobbyists, small shops, etc. Wish I paid attention when I did cut some since it went really well and I know I’d never have risked using any of my high end blades. So it must have been just my basic combo utility blade or a 6-7”. For what I’m looking at later this year, basically a one time usage, I’ll test the spare circ saw blade since it still new unused.