Acrylic fabrication questions? I can help!

[Acrylics]

<a href=showthread.php?s=&postid=11402344#post11402344 target=_blank>Originally posted</a> by RyanBrucks
thanks for the info, you've been very helpful for a very long time on this thread I've seen people take up a cause for a short time before, but damn you've been at this awhile.

The hobby/industry has been very kind to me, giving me a career and all, I owe it something and this is the best way I can think of.

I think the main reason I'm getting bubbles in my baffle seams is that I am not putting shims under them. is it even possible to shim baffles, or is there another technique for those? I've just been using pins and letting the weight do things since I'm not sure how to shim or apply the right pressure.

also one of my baffles did not go in 100% perfectly, its actually sticking out about 1mm from the bottom edge on 1 side when it should be flush. The pieces is already glued in, so I guess I will need to find a way to shave it down slightly. I know its not going to be easy, and I might have to use a circular orbit sander (bad, I know, but what else will be able to shave it flush when its already in?) I'm far more worried about that gap messing up the entire bottom seal of the tank than I am about the baffle itself having a perfect seam (I can juse use 16 if the edge is not perfect)

Make the baffles *exactly* the same as the ends and keep a reference corner lined up. What usually causes the problem you are having is something out of square. If you use one corner as a reference on all pieces, they may be a little out of square but at least they'll all be consistent so the tank sits flat which is far more important. You can shim the baffles but shouldn't be all that necessary. (hope this makes sense)

Jay,
There are programs for it but one has to know the sheet sizes first (which are not 48 x 96") Eg., Polycast 4 x 8 x 1/2" sheets are 51 x 100", Cyro GP 4 x 8' sheets are 49.75" and so on, they all vary a little.
Figure it this way:
28 x 18 x 15" tank requires these rough sized pcs:
2 pcs 28 x 15 (front & back)
2 pcs 18 x 15 (ends)
2 pcs 28 x 18 (top & bottom)

Out of a 4 x 8' sheet, cut one ~28" x 48" piece, should be able to get a 28 x 18" pice, and both 28 x 15" pieces. Cut another ~28 x 48" piece and you should be able to get the other 28 x 18" piece and both 18 x 15" pieces with a ~10 x 30" piece left over. So the whole thing will come out of a 5 x 4' sheet, not accounting for baffles.
FWIW, most suxh layout programs set up "nesting" for CNC machinery which is not always applicable to the DIY aspect.

HTH,
James

 

[ReefEnabler]

I did cut all the baffles/ends at the same time, but I think I must have rotated the last piece 180 degrees after removing the protective paper (which had the markings So ya I guess that means my baffles were all cut just slightly off square (half a mm or so, since rotating 180 would double it). I'll definitely be even more careful next time. Maybe I forgot to squeeze down all my clamps again before using the router. I've had a few cuts where the acrylic pieces(s) started to pull a little bit, making a sloped cut from not using enough clamps, or pressing them hard enough.


WRT the order of things.. If you have 3 or more baffles in a row, do you just glue 2 of them onto the front panel, then do the back panel, before putting in the third baffle? or do you just use some kind of super-long nozzle in order to apply solvent between the 1" gaps?

 

[ReefEnabler]

weird, i got an email notification that you replied again, but I dont see it. o well

I used a wooden holding jig very similiar to hold my baffles 1" apart. But when I went to remove the jig it was securely stuck to the acrylic. I was able to get it out by drilling a hole in each end, putting in a woodscrew and pulling on both woodscrews. Guess I assumed wood wouldn't (woodnt react or get stuck. how did you do it like that? After getting the wood out, there was a big gooey stain there. Anybody have tips for cleaning the space between baffles? So far i've been using solvent on a microfiber rag, and using the same wooden block to rub it up and down the space. It removes the nasty, but slowly.

 

[Acrylics]

I personally glue all 3 to one side first, then place spacer blocks between them on the second side to keep them in place.
You'll learn that solvent can flow a pretty long ways from the needle and you'll also learn how to operate the solvent bottle with just 2 fingers so you can fit into these tighter places. I also use several different sizes of wire so the gap narrows toward the end of the joint, thus drawing in the solvent faster. Can also apply the solvent from the other side, if you get my drift

BTW, the wood jigs have an angle cut into them so the solvent won't wick under the particle board. Stock wood won't be affected by the solvent but the resin used to bond particle board *is* affected by solvent, as you now know.

James

 

[jay24k]

lol that sucks. But at least you know not to do that again

 

[H20ENG]

Hi James,
I was wondering what you use to clean your bits and blades after getting streaks of melted pvc and acrylic on them. (I know, you DON'T get streaks with your stock of new, pretty bits and blades )

But, hypothetically, if you had to remove something like that, what would you use? I was thinking of soaking the blades in some MEK or something. Lots of stuff removes wood pitch, but melted plastic is different...
Thanks,
Chris

 

[RokleM]

That's odd. I can't say I've ever had chunks get stuck in the router bits. Are you taking off very large sections at a time? Even when I've done that, I only have a "dust" per say on the bit. I use a solution that feels partially oil based I received from woodcraft to clean/store the bits. I doubt it would work well at removing chunks though.

Here's my big creation finally in place (after playing with a number of acrylic projects). Still a ton of work to do (probe holders, power re-run, pipes/tubes to cover re-route, doors to put on, etc).

Before heh...

 

[RokleM]

Probably worth adding some build pics...

 

[H20ENG]

Nice work! Fun working with thick material after so many smaller jobs. Thin stuff is way harder to work with.

My router bits dont get gummed up really, but my saw blade definitely has streaks of melted plastic (mostly pvc).

 

[Acrylics]

Chris,

When acrylic starts melting onto the plate, it's time to get resharpened
PVC is absolute murder on carbide blades so I have different blades for odd & ends cutting.

I'm not real sure what I'd use to be honest, I'm lazy, when stuff starts melting on 'em - must be dull. But, hypothetically speaking, I'd probably use methylene chloride.

Eric,
Nice work

James

 

[ReefEnabler]

rockle, very inspiring stuff


out of curiosity, can you use thinner material on the bottom of a tank without sacrificing much?

for example, a 36x18x18 tank, could it have 3/8" on the side and 1/4" for top flange and bottom? would it have roughly the same strength as the same tank all 3/8?


Thanks
Ryan

and fwiw I haven't ever seen melted acrylic on my blades, but I DO see a buildup of the paper material on the blade which almost turns into wax. Every once in a while it will cause things to catch. I can scrape it off with my fingernail though. the paper on the top of the piece I am working on often snags my router which is probably the largest cause for nicks in my edges.

 

[Acrylics]

Ryan,
Yes, you can use thinner material on the bottom. I think you'll be fine with w/ 1/4" on top & bottom on that size tank. There are limits to this type of thing though; if the tank could be built from 1/4" and you use 3/8" for the vertical panels, then 1/4" for the top & bottom is fine. But if building a larger tank that requires say 3/4" construction, don't use 1/4" for the top & bottom, may seem like common sense but people do it. For that I'd stay using 3/4" for the top and *maybe* 1/2" on the bottom. Meaning don't go down in thickness for the top from what it could be solidly built from but if you used 1" for the vertical panels - you can use 3/4" for the to since it could be solidly built from 3/4" all around. Similar for the bottom, but you can often go down one thickness for the bottom; ie., if the tank should be made from 1" material, you can usually go down to 3/4" for the bottom. OTOH, there are limits to this as well going the other way in the sense that I've rarely seen (hobbyist size) tanks requiring greater than 1" for the bottom. Hoping this makes sense

James

 

[scouncil]

James, you said I could get a 48x20x20 tank out of one sheet of acrylic, does that include all the baffles to divide the compartments, or can I get 3/8" for the inside baffles (hoping to use 1/2" for the tank itself..... Hate to make 2 trips for the acrylic if we can make just one (but DH always says 3 trips are always required for every project).
Susan

 

[Acrylics]

Hi Susan,

No, doesn't include baffles unless you dont plan on having a top in which case it would include baffles, and then again if you use *just* eurobracing and no crossbrace - then you can get some baffles out of the top cutout. A 3" eurobrace cut out of a single piece will yield a 14 x 42" piece you can use for the baffles (minus kerf space). FWIW I almost never recommend going without a full top. In this sump, if there are baffles in the center - then you really don't need the centerbrace. 3/8" would probably be fine for the baffles.
Cut list:

2 pcs 48.25 x 19.125 (front & back)
2 pcs 19.125 x 19.125 (ends)
2 pcs 48.25 x 20.25 (top and bottom)

Finished size for gluing after machining 1/16" off the gluing edges:

2 pcs 48.25 x 19 (front & back)
2 pcs 19 x 19 (ends)
2 pcs 20.25 x 48.25 (top & bottom)

Should come out of any 99+" sheet with careful cutting and one "drop" measuring ~10 x 19" which could be used as a baffle. Polycast and Cyro Acrylite GP will certainly yield this out of a sheet, can't say about PlexiGlas G with any degree of certainty (I don't buy this material so can't remember the exact sheet size)

And your DH is probably generally correct but do your homework and have a plan and you won't have to

HTH,
James

 

[scouncil]

Full top over the whole thing? I was going to leave it open. Too hot? I have to leave it open over the skimmer part (it's really tall). FWIW (no speaka de txtng)? and Kerf space (the space where the water goes under the middle baffle?

I appreciate the help!! And I don't need a lot of room for the skimmer, right? Just enough to fit it and not crowd it, but have a relatively large return area?

Rokle, why didn't you build 2 and send me one..... it's beautiful!!

 

[ReefEnabler]

hes probably recommending a top piece so you can cut it into a top flange.

http://www.melevsreef.com/acrylics/sumps/diy/flange.html

 

[scouncil]

Oh, I've got it. Extra stability. So I'll still need the flange even if I have the baffles? They wouldn't provide enough stability?

I know the flange would be the best. My current 100 gal is acrylic and the flange is the pain in the butt item that makes it difficult. Of course this will be at ground level.....

 

[dudedudedude]

The thread seems to deal with rectangle tank/sump construction so I might be off topic but, I would like to make an acrylic cone similar to ATB’s skimmers. I have found an online calculator that tells the shape of sheet to cut for a particular size cone. What I was wondering was if this method would be successful. I am going to make a sheet metal cone that has the angle and bottom outside diameter of the desired acrylic cone. McMaster has the softening temperature of their cast acrylic at 80 degrees C. I was thinking that I could cut out the appropriate shape for a cone, heat the cut out cast acrylic piece in boiling water until it reaches 100 degrees C too. Then with water proof thermally insulated gloves take out the softened sheet, join the ends together by hand and then place and press it into the inside of the metal mold so that a cone with a vertical seem is formed. If the seam is not perfect, once cooled I will seal it with some weld on. Will this work?

Thanks,
Sean

 

[Acrylics]

Susan,
The top flange adds structural integrity. I would almost always recommend it and yes - in this case as well. How many 80 gallon tanks do you see out there with no top bracing? What do the baffles do for the sides without baffles attached? The top flange will take pressure off of the joints themselves and I recommend this highly, especially to DIYers whose joints are not always of professional quality, though there are certainly exceptions to this.
Hope you take this in the constructive manner intended

Sean,
80C is definitely wrong for making it pliable. I haven't checked the McMaster site but 80C is a working temperature, not a forming temp. A good forming temp will be more in the neighborhood of 150C or 300F so water will not work, should be done in an oven.
And no, the pliable pieces will not stick together to make a strong bond. You will need to glue the cone together with Weld-on 40 or similar. In order for an inside form to work well though, the acrylic has to be cut *exactly* right with an allowance for shrinkage. (acrylic will shrink when formed)

James

 

[dudedudedude]

Would clear PVC be more feasible? I do not have access to large enough of an oven.