Acrylic fabrication questions? I can help!

[Floyd R Turbo]

Sounds like a couple of issues. Is the router table a cheap one, like the one you find at Lowe's or Home Depot? Or is it a heavier built one like you would find at a woodworking store?

If so, then it's probably a vibration issue. Those small tables lack the stability. Plus, you're using it as a jointer, meaning you are trying to keep the piece in question level and flat while sliding it and pushing it into the fence that is on either side of the router bit. Push too hard and you move the router table. Push too lightly and the material gets pushed off the bit.

The router should always be run full out, 26000 RPM.

The bigger the bit, the better the edge. The Bosch 1/2" shank 3/4" diameter 2-flute straight cutter ($20 at Lowe's) is my standby edge prep bit.

The thicker the material, the longer bit you want and larger diameter as well, IMO. The Bosch bit I referenced above does tend to bog down a bit with thicker material, but as long as I'm only shaving off a little bit, it's good. I make several "barely touching" passes, probably 1/64" or so for my "final final" edge prep.

hope that helps. let me know if I misunderstood the router table type/setup

 

[dahenley]

when you say you set the fence as a jointer, did you tape a piece of metal (shim) to the opposte side of the fence? because you need the side past the bit to be thicker to take up the difference you just cut off.

a jointer outfeed table is flush with the bit cutting edge while the infeed table is 1/32 or 1/16 lower (or away from the bit)

a picture of your setup might help out

 

[brian cummings]

Floyd R. Turbo- I think it's the bit, and the thickness I was trying to shave off. The table is not sliding anywhere, it's bolted down. It does seem to push the plex away. I am going to get a good bit, possibly an o-flute for plastic by Amana...

Dahenley- yeah, it's setup as a jointer.

So I think with nicer bits, and maybe a 1/32 shim instead of 1/16, that I'll get better results.

Thanks for the quick reply

 

[brian cummings]

Next question, drilling thick plex- I have drilled a lot of thinner plex up to 3/8 using special plex bits, but never anything like what I have now. Need to drill 1" plex for 1/2" bulkheads.... Thinking that a hole saw, unless it's a quality new one, will make a molten mess...

 

[Floyd R Turbo]

I prefer to use a spiral upcut flush trim bit and an MDF hole template. rough-drill a hole smaller than the template, then double-stick-tape the template down, then route out the hole. Makes a nice clean hole. Then knock down the sharp edge with a roundover bit or just a razor blade. Always knock down sharp edges, or else these become stress focus points.

 

[brian cummings]

I prefer to use a spiral upcut flush trim bit and an MDF hole template. rough-drill a hole smaller than the template, then double-stick-tape the template down, then route out the hole. Makes a nice clean hole. Then knock down the sharp edge with a roundover bit or just a razor blade. Always knock down sharp edges, or else these become stress focus points.

Thanks Floyd, I wondered if routering it was the way to go

 

[dahenley]

Floyd R. Turbo- I think it's the bit, and the thickness I was trying to shave off. The table is not sliding anywhere, it's bolted down. It does seem to push the plex away. I am going to get a good bit, possibly an o-flute for plastic by Amana...

Dahenley- yeah, it's setup as a jointer.

So I think with nicer bits, and maybe a 1/32 shim instead of 1/16, that I'll get better results.

Thanks for the quick reply

in my opinion, if you saw cut something to within 1/16 of an inch, you can run 2-1/32 passes to clean up the cuts. because by just taking off the teeth marks, your not bitting into the acrylic so it shouldn't push it away and shouldnt chatter. but its more of a fineness dealing with different sized/thickness acrylics.
wish i could do more. but i think there is just a learning curve that cant be told.... but try the 1/32 cut and let us know how it goes.

 

[brian cummings]

I think it was a crappy bit and trying to take too much off with said crappy bit.

 

[dahenley]

I think it was a crappy bit and trying to take too much off with said crappy bit.

let us know. lots of people ask questions and get things figured out but dont come back and share the outcome of there situation. so if things work out for you. let us know so we can keep it in mind for ourselves and to help others.

 

[brian cummings]

let us know. lots of people ask questions and get things figured out but dont come back and share the outcome of there situation. so if things work out for you. let us know so we can keep it in mind for ourselves and to help others.

Sure. Progress is slow, haven't gotten the new bits yet. Looking at getting a cutter and flush trim bit, looking at amana, whiteside, etc- not sure about all the choices, straight cutter, o flute, spiral, etc. I know to get a 1/2" shank, and at least 1/2" cutter, but beyond that, haven't decided on anything. Maybe some kind of chamfer bit too.

 

[dahenley]

i know chamfer and spiral cutters work great for wood (because of grain)

since plastic/acrylic doesnt have grain or vain or what not, a straight bit works as good as others and is cheaper in price. i asked a question as to what to get earlier and there was some mention to pulling on acrylic but what i said is just my opinion. (and experience)

 

[brian cummings]

Yeah, I have read about pull done by the spiral bits.

 

[Tinkanator2000]

I have an Acrylic 180 (3/8 acrylic I believe, its a Clarity Plus brand) I want to set-up, but it was drilled with 4 closed loop holes in the bottom. I'm not sure if I feel very comfortable with bottom drilled drains in a tank, so I would like to patch over the holes with some squares of acrylic.



My question is, what type of weld-on would be best suited for this project (3,4,16,40)? The patches will be made on the inside of the tank, and oversized by about 1" to cover the hole.





Thanks

 

[Floyd R Turbo]

Anything would work. #16 would be simplest because you can spread it all over then slap the patch on and twist and turn it to get full coverage, put some weight on it, more working time. The pressure will hold the patch in place. you can even use silicone for something like this because of the pressure and non-bowing surface. Then the patch can be removed later if you want for any reason.

 

[2Quills]

Does anyone happen to have any leads for a reputable tank builder or builders in, Texas? Prefferably in the San Antonio or Houston areas?

 

[dahenley]

AGE, but you have to go to through a LFS

 

[ccuk]

hi james
what thickness acrylic would you use on a tank thats 1300mmx1300mmz750mm high euro braced..
with thanks

 

[Phixer]

James, I got my acrylic back from the fab shop today. It's 2.250 Polycast and was machined using a CNC router. The edges came out pretty good but are a little rough with some very small pits. Im able to scrape the edge down about .010 and remove them but this is a lot of work.

Will this matter if I bond the edges with 40/42? Will it fill in these tiny pits to produce an clear seam or should I continue to scrape the edges smooth? Im concerned about it crazing later on.

Thanks

 

[dattack]

I really think it is unacceptable to get a sheet that was cnc cut to have pits. I would tell them to redo it considering it probably cost you a lot.

 

[Floyd R Turbo]

James hasn't been on in a while...I'll ding him