Acrylic fabrication questions? I can help!

[ronn1234]

I just got back from picking the sheet up. I think it was just stuck where he tried to peel it cause when I tried it seemed easy. I bought this to make a sump what is the best wo# to use on 1/2' "I did not buy the wo#3 after i saw it online for $6. This will be my first one ever and your thread inspired me to do this what kind of saw blade/router bit should I buy keep in mind this is a one time project.

[RokleM]

If this is a one time project and/or you have no need for the hardware, I would recommend seeing if anyone local has tools you can work with. The tools and parts alone could cost in excess of $300, offsetting any money you may have saved in buying a pre-built for a one time deal. If you have a use for the tools however....

[Slakker]

I'm looking into perhaps building a 24x24x12 (somewhere in the neighborhood of 25g) acrylic tank over the summer while I've got a break from college, and am not sure where to start.
I've done a bit of reading, and it seems like 1/4" acrylic is going to be the best bet, and Weldon #4 to cement it. I plan on trying to pick up some scrap acrylic for real cheap to get some practice in before giving the full tank a go. (I don't plan on bending anything, either, which should make it easier.)

First question is this: What do I do to prepare an acrylic edge for cementing? After cutting should I be sanding the edge or anything like that? Is it more ideal to have a rough or smooth surface for gluing?

[ronn1234]

well I was purchasing a table saw any way and i have a router i was talking bit and blade wise is there a cheeper alternative to a 150 dollar blade and a 30 dollar router bit?

[ronn1234]

i had a question about prep as well after you cut lets assume you made a good cut do you polish the ends before or after you join them? I have a propane torch I'm gona practice polishing on scrap with that was just curious at what point do you do it

[Acrylics]

Some folks just glue a sawcut edge. While this works, not the best method for edge prep. I'd advise routing the edge or at least running the piece through a jointer to prep the edge. If these are not in the cards, maybe pay a local fabricator a coupla bux to cut/prep the edges for you. For a small tank, shouldn't take the guy longer than 15-20 minutes to do this so should not cost too much if you have a reasonable guy around. A decent woodworker should have these tools around as well. Edges should be very smooth for gluing, sanding can work but most times - folks end up rounding the edges which isn't good either, edges should be flat, straight, and smooth.
You don't need a $150 blade, a laminate cutting blade will suffice. Router bits are really one of those things that "you get what you pay for", good bits cost good money, and good bits do a better job, generally speaking. I wish all mu router bits only cost $30 each, if you do get into this as a hobby - be prepared to spend $60-80 for a good router bit. Worth every penny too
Take a look at http://www.reefcentral.com/forums/sh...hreadid=390652 it shows a good method for prepping the edges using a router table. Also maybe do a search for "acrylic" & "edge prep" here on RC for this. IMO, some of the threads here on RC are the best available on the net, without question.
Do not polish the edges prior to gluing, this is just asking for a crazing problem. If you are looking to flame polish the edges, do so *only* after all work is done, trimmed, and the tank is fully cured for several days - else you may fry the joints. Propane is a dirty gas and without a supplemental oxygen tank - doesn't burn that hot so may take a bit of practice. FWIW I'd advise sanding & buffing over flame polishing as the propensity to craze is much higher but using the flame is kinda the industry norm.

Practice on good material; since you will be gluing good material on your tank, practice with what you are actually going to use. There is a vast difference between good material and cheap, garbage material. Practicing with the cheap stuff will not properly prepare you for using good material - different world IMO.

HTH,
James

[kenny77]

is there any page were i can automatically find out wich acrylic thickness to use? some were reliable?

[Acrylics]

Originally posted by kenny77
is there any page were i can automatically find out wich acrylic thickness to use? some were reliable?

No, 'cuz it's not that easy. Thickness will depend on too many factors: Span (length), height, deflection tolerance, flange (eurobrace) width, crossbracing (number & width of each), and so on. Many of these variables are interrelated as well so this compounds the issue.
There have been a coupla sites which claim to tell you what thickness to use, but IMO they are not accurate and/or are very limited in scope. Even Cyro's thickness calculator is very flawed though it's about the best there is. www.cyro.com

James

[kenny77]

ok thank. this is my situation. soon I need to star building 18 tank for my LFS that will open ending 2007.

9 of this tank will be tank will be 30" x 12" x 12".
6 tank of 30" x 10" x 10" with a divition in the middle to make 2 tank out of one. for smaller fishes
3 tank will be 30" x 10" x 10" also. But instead of dividing it in 2. will have 3 divition to make 4 tank out of that same tank. this will be use for small invert.


this tank will be made out of 4' x 8' 1/4" acrylic. 33 tank will be more than enought I think.

will this tank need an eurobrace or will the divition do the job. the firt one will have a center brace of 2"

what you think?

[Acrylics]

IMO they should all get 2" eurobrace

James

[cashman95]

James,

I recently bought some 1/4" tube from MRC and a flange kit as well. My question is: How should I go about gluing the tube to the base and top. The base has a routed out grove that fits the 1/4" tube perfectly, and the flanged top is just flat. I only have #3 and #16 weld on, and even though I have read where you didnt prefer these #'s can you give me some tips that might help my application. I really dont want to have to go and buy anymore weld on or for that matter spend much more money on this calcium reactor project. For what I will have in this setup I could have easliy bought a used one for that....let alone if I have to spen anymore money I could have bought a new one for 220.00

Please help me get this right the first time!!!!

Brian

[cashman95]

James I just have one more question. I am planning on using two bulkhead to pipe into and out of the top flange. The reason I am ging to use bulkheads is for an easy "for sure" seal. My question is: Can I somehow get away without having to use bulkheads and just glue a pvc pipe adapter to the acrylic flange, or is that kinda risky?

Thanks Again Brian

[RokleM]

Silly question, but I'm having a hard time finding the answer... What's the name of the bit or device that you can use to create threads in acrylic? For example, I want to screw in a hose adapter instead of using a uniseal.

[RichT]

RokleM, its a Tap - be sure to get the NPT (normal pipe thread) type. Your also gonna need to be careful with your drill bit selection. Most standard bits will grab the acrylic, maybe break it and generally give you a fit. There are twist bits made specifically for plastics but there not real common over 1/2 inch. I've had good success with paddle bits.

[RokleM]

That's it! Thanks

[RichT]

Eric,- I've edited the post to include a little input on drill bits as well.

[slavearm]

I have had really good luck using forstener bits to cut acrylic cleanly. Just go slow.

[RokleM]

Thanks for the info RichT. I've been using forstener for normal holes.

Which leads me to another question...

So... question about the router bits. I've been using some $10 WoodCraft branded bits, which honestly have worked OK for now. I'd like to get a cleaner cut, but not break the bank per say. I don't know how many acrylic projects I'll do in the next year. I know it's not going to be 100, but it won't likely be under 10 either

My most commonly used ones are the 1/2" straight cutter and the 1/2" flush trim. How often are you replacing bits? Are there specific ones you'd recommend? I have a Sears professional 2.25 hp router (yeah I know it's not the best, but it's what I had starting) that accepts 1/4 and 1/2 bits, so I'm pretty open.

[costa13]

When you are building a sump in what order do you glue the sides (Front , right side, ect.) I am trying to figure out in what order should I weld each side together.
Thanks in advance

[slavearm]

Woodcraft sells a $29 spiral cut flush trim bit that rocks! It is only the 1/4 diameter one, but works fine. A step up would be the $59 half inch version of the same bit.

For the straight cuts, I have had really good luck recently with the three flute straight cutter from MLCS.

All the bits mentioned above are carbide so they should last a good long while just cutting acrylic.

PS- I am not really an acrylic expert, but those bits have served me very very well.

Originally posted by RokleM
Thanks for the info RichT. I've been using forstener for normal holes.

Which leads me to another question...

So... question about the router bits. I've been using some $10 WoodCraft branded bits, which honestly have worked OK for now. I'd like to get a cleaner cut, but not break the bank per say. I don't know how many acrylic projects I'll do in the next year. I know it's not going to be 100, but it won't likely be under 10 either

My most commonly used ones are the 1/2" straight cutter and the 1/2" flush trim. How often are you replacing bits? Are there specific ones you'd recommend? I have a Sears professional 2.25 hp router (yeah I know it's not the best, but it's what I had starting) that accepts 1/4 and 1/2 bits, so I'm pretty open.

[RokleM]

Originally posted by slavearm
Woodcraft sells a $29 spiral cut flush trim bit that rocks! It is only the 1/4 diameter one, but works fine. A step up would be the $59 half inch version of the same bit.

For the straight cuts, I have had really good luck recently with the three flute straight cutter from MLCS.

All the bits mentioned above are carbide so they should last a good long while just cutting acrylic.

PS- I am not really an acrylic expert, but those bits have served me very very well.

$29 spiral cut flush trim -- Is it Woodcraft branded or something else? I've looked at the MLCS selection as well, but never ordered there.

[slavearm]

Not really sure if it is woodcraft branded or not. I bought it a little while ago. They had them in a clear acrylic case above the other router bits at my local store.

[RokleM]

Would you check if you can? We've got 4 huge cases of bits at our location.

[H20ENG]

James!!
Only red Xs for your jig pics! Guess you gotta be quick around here!

[slavearm]

James,

I am really having a hell of a time with cutting this 12" OD tube.

Getting/keeping everything square while you spin the tube is... um difficult.

Should I build a cut out box maybe? I dont really have one truely square end either, so I am thinking the cut out box and then maintain the length of the tube against the end of the cut out box closest to me and spinning it.

Maybe I should just buy an extension to my miter saw table and spin it in place there.... maybe.