Acrylic fabrication questions? I can help!

[fredej80]

Thanks Floyd. I did walk away but am just trying to make sure I made the right decision. I can buy it for a song. Even considered cutting it up for some future diy projects. Just hate to cut it up if fixable.

 

[fredej80]

Btw, I would love to hear your reasoning sometime if you have a chance. Trying to learn what I can. Guys on other sites said it's any easy fix, a patch over the crack with some weld on 40 and good to go. Seems too easy to me, so that's why I am asking questions.

 

[Steveb]

Some acrylic questions

I'm thinking I want to remove the two internal overflows on my large tank.

The back panel of the tank is .75" clear that has a piece of .125" black bonded to it.

1 - the overflows look to be solvent welded (weld-on 3 or 4) to the back panel and then on the bottom it appears they may have used something like weld-on 40. The overflows are not attached to the eurobracing at the top. If I cut the panels free what is the best way to remove (sand/grind) the ridge that will be left on the back panel and bottom?

2 - the current overflow has hole(s) through the bottom. The bottom is .5" thick clear acrylic. Can I cut a plug and then sand using weld-on 40? I have some lids that came with the tank that I could get them from.

The tank has been dry for > 1 year and was only filled one time to do leak test. Also I am not opposed to laminating another thin sheet of black to the back panel if needed.

Some pics that hopefully will help show what I am talking about....

 

[Floyd R Turbo]

Did you happen to get this tank from a guy in michigan? I've only seen that grey stuff used one other time. Check to see if it is soft. I'm guessing that is actually silicone. The overflow is likely bonded to the bottom then the silicone seals it because it leaked.

So the back panel lamination, black on the inside? Some manufacturers make the overflows by bending one longer sheet into shape and laminating it to the clear back panel.

Cut & grind however you like. Dremel prob best, then sandpaper by hand

Holes can be plugged with patches of scrap, prob should use same thickness and WO 3. 4, or 16 is fine. 40 not needed. You could even silicone a patch on, the pressure is going to hold it in place- it's not structural.

 

[Steveb]

I got it from fishtanksdirect...

No its not gray and not soft. Just the way the light was hitting it. Its clear.

Its one solid sheet of black laminated on the inside and then the overflows are attached to that.

I was stupid.... I should have ordered it with a coast 2 coast but I had just gotten back into the hobby after a long hiatus. I didn't really know about bean animal and when I was in the hobby previously everything was durso...

 

[Floyd R Turbo]

That's all right, when I got back into FW in 2000 after a 5 year hiatus (before I got salty) I set up my UGF then I went online...

 

[Steveb]

LOL yeah my first SW tank a 29g had a UG filter attached to an eheim canister.

How much smaller should the plugs for the holes be?

i.e. if the hole is say 1" diameter exactly how large should the plug be?

 

[Floyd R Turbo]

3" square patch

 

[Steveb]

Ok so don't plug the hole but cover it then..

 

[Floyd R Turbo]

Yes, that's what I thought you meant. I suppose you could cut a circle of acrylic 1/4" smaller in diameter and then fill it in with WO40 but to me that would only do you any good if you wanted to run a BB and didn't want to see the patch. As long as the tank is setting on 2 sheets of 3/4" plywood and the plug was sanded flat on the bottom, that would probably work but I'm not 100% sure.

 

[Steveb]

Does it make sense to put the plug(s) in and do the sheet over the top?

I don't know if it is really a problem but there are 5 - yes 5 holes in each overflow... for (1x1.5", 2x1" and 2x.75" bulkheads) - I don't plan on doing bare bottom but was concerned about the bottom structurally in that area..

Also I am using this between the tank and the plywood -- is it ok in your opinion?

.25" elephant bark - http://www.rubbercal.com/elephant_bark.html

 

[Floyd R Turbo]

James' recommendation has always been 2x 3/4" plywood on top of a solid frame, and make sure it's perfectly flat and you're fine with just that.

The only other recommendation I've seen him make is 1/4" neoprene. I'm not sure what this elephant bark stuff is, seems like the stuff that you put on the floor of a kid's play room? I suppose that would be OK but I don't know. I think that would place some weird pressure on the "plugs" if you did those.

I would just get a piece of acrylic, same thickness as the bottom, and laminate it over all 5 holes and make sure you have at least 1" of overlap outside those. The thing that will take you the longest is sanding the bottom down smooth after removing the overflow. With that taken into account, WO40 might not be a bad choice after all, as it will fill gaps and account for inconsistencies.

 

[Steveb]

Yeah its rubber mat material you can buy in rolls. I have it between the steel frame of the stand and the travertine floor. It has some give to it to absorb irregularities.

So how do you get the "perfectly" flat with plywood? Some type of self leveling compound or use cabinet grade plywood?

I went ahead a got a 50ml WO42 dispenser and some cartridges & tips. I still have to put those triangle pieces in my sump.

 

[Floyd R Turbo]

If you glue 2 sheets of 3/4" ACS grade plywood together, it's pretty hard for those to not be perfectly flat.

Placing those on top of your stand should actually reveal irregularities in the stand. So then you either plane/sand down the stand, or shim between the plywood and the stand and screw it down and you're good.

 

[Steveb]

I guess I used a lower quality, although it was very flat there were still some surface irregularities (which is why I put the 1/4" elephant bark on top of it). Since I'm going to have to redo it (won't need the cutouts anymore) I will look for ACS.

 

[Steveb]

Hey what grit pads should I get to use for sanding and then polishing the back/bottom? Using 5" random orbital sander.

I figured this for the polishing http://www.amazon.com/gp/product/B000H6JDDM/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A2NWLOWWF5G7JX but figured on 300/600/800 as well?

Should I use 300 or 600 along with a grinder to actually take left over material down to the back wall/bottom?

 

[Floyd R Turbo]

yeah, it's going to take some time. Also you don't want to heat up the material any more than you need to. I guess I've never really done what you are wanting to do. The thing I would be careful of is using anything that might cause a lot of shock/vibration. So don't go using a high-speed grinder like a heavy power tool type or anything. One wrong move and you could crack something out or gouge the material you want to keep. A power sander should be fine I would think. Ideally you want something that could take wet/dry sandpaper but then you're into something that would run off an air compressor, which you can rent by the way.

 

[Steveb]

So probably not a good idea to use something like this to cut the overflows free?

http://www.lowes.com/pd_160067-353-...L=?Ns=p_product_qty_sales_dollar|1&facetInfo=

I was thinking it might be faster/cleaner than trying to use a dremel or rotozip...

 

[Steveb]

What about using a router to trim down the material that is left? set a couple of boards in with double sided tape to hold in place to rest the router base on, and then use spiral cutting bit set just a hair higher than the back.

 

[Floyd R Turbo]

To cut the overflow off, might be OK. I was thinking of the part afterwards where you are left with some material sticking up that you need to grind down flat. If you are using something that might "grab" and throw the power tool sideways, you could end up banging against the wall/bottom and that impact might do some damage.

I've used a sawsall for hacking stuff apart before, it's just not pretty. And I didn't care much about damaging the walls for what I was doing. As you get down to the finer detailed steps, I think it's better to use smaller tools. That's all.