Acrylic fabrication questions? I can help!

[sinisterreef]

2. 15-30 seconds. Mainly this depends on the solvent, Weld on #3 evaps faster, #4 longer. I use straight MC with 5% AA and I go 15 seconds minimum. You want enough soak time to "bite" into each side. I've gone longer than 30s but then you have to be sure to add a little weight right away to get the squish out and fillet

4. No, and not advised either. Clamping will push out the solvent and can leave a dry joint. You can and in most cases should add weight, but weight that is evenly distributed. Like for a 30g size build for instance I will set 3 or 4 12 packs of pop on top (on each corner). Or I'll put a couple 2x4s across the top and set a few 10lb weights on the 2x4s

I'm assuming the evenly distributed weight is when you're welding the top back and bottom. But what about when you're doing the sides to the front panel, and they stick straight up in the air?

You use a lot more weight than what I would have thought.

 

[Floyd R Turbo]

I generally don't put weight on the sides when bonding to the front panel (first bond in the assembly process) mainly because it's difficult, and the tendency to cause the panel to tip is too high. Instead I am extra careful to make sure that the joint is perfectly flush with shims before adding the pins, and then when I place my 90 degree bracket in the inside corner, I place a small weight on that (5lb) so that when I pull the pins, the joint doesn't walk on me. After I pull the pins and the joint has started to set up (30-45s in, which is about the amount of time I spend making sure the ends of the joint are flush) I remove that weight, loosen the clamps for a fraction of a second while placing light pressure on the top edge of the vertical panel, then add the weight back on top of the 90 degree bracket.

The reason for removing the weight before loosening the clamps is that I want the vertical panel to settle without the horizontal panel being pushed down at all (even the slightest)

The weight added is actually somewhat insignificant compared to the weight of the assembly for larger builds, but that little extra helps I've found.

Here's an example of my system of weights. It's super high tech

 

[Floyd R Turbo]

This one in particular above had a corner that did not have very good alignment and I had to plane off quite a bit in order to get the 2 panels flush, hence the extra shims and the 25lb of weight on that one corner.

Here's an example of the weights on the corner brackets

 

[AZRippster]

I have an acrylic question that's not so much fabrication, but material selection. I have 2 Hamilton 48" Dual 400W Cebu Sun MH fixtures that have glass sheets for the splash guard/lens. They sit end to end over an 8' tank. They get dusty fairly often on the inside (I'm using a filter over the intake fans). It's a real pain in the rear to take these down every time to slide the glass sheets out to clean them on the inside. I would like to piano hing acrylic sheets to the back edge of each fixture and then use thumb screws on the front edges allowing me to "drop" the lens down for cleaning and lamp maintenance. What I'm unsure about is what or if there is a high temperature acrylic sheet available for such an application. I believe the Plexiglas (Altuglas) HT121 would work, but I can't seem to find a retailer for it I can order from. Any suggestions on material and source would be greatly appreciated.

Thanks

 

[Floyd R Turbo]

No idea...MH lights get really hot, I think you're out of luck on this one unless you know for sure that the lights won't melt the plastic and/or start it on fire. I would just stick to glass myself.

 

[AZRippster]

I spoke to Hamilton about this and they used to offer their fixtures with acrylic lenses, but started having trouble sourcing the acrylic they once used. I was just hoping someone may know a brand/part # of an acrylic that would be acceptable.

 

[karimwassef]

Acrylic will also discolor and crack under prolonged uv unless you get a UV capable grade.

 

[H20ENG]

Could you use epoxy or silicone to attach the hinges to the glass? Or a metal channel the glass can sit in? I assume you'd like to use acrylic since it's easily drilled to accommodate the hinges?
I tried to go down the "acrylic under MH lights" years ago and never found a good way to reliably prevent overheating.
You could try an industrial supplier like mcmaster.com. they have or can get just about any material.
Good luck, and please link back if you get it solved.

 

[AZRippster]

I have made inquiries with a couple of major manufacturers regarding the issue. It's looking like Polycarbonate sheet will be the way, if possible, to go. It won't be any clearer than glass like cast acrylic is, but it will be just as clear as glass with UV resistance. I'm mostly just concerned right now with the heat. Hopefully they will get back to me soon. If it ends up going Poly, it will likely be product lines from Lexan, Makrolon, or PALRAM. Plexiglas also has a product called Altuglas HT121 that may work.

 

[hobbzz]

I'm making a feeding station out of some scrap acrylic and don't want to cut small 1/4" pieces on my table saw. Can I use a trim router to cut 1/4" acrylic? This is the stuff I'd be cutting http://www.estreetplastics.com/Black_Plexiglass_Acrylic_Sheet_p/b012500612.htm

Thanks

 

[AZRippster]

All I can say is, "That's a bit too spooky for me". I use a plywood push jig when ripping on a table saw to keep my finger away. Not sure about the 1/4" cuts with a router. I value my fingers too much to risk something that narrow. Others may have a solution for you.

 

[hobbzz]

With the router I could clamp the piece down and make a jig for the router to follow. Fingers wouldn't be near it. I'm just not sure if a trim router has the oomph to do it lol.

 

[woodnaquanut]

I'm making a feeding station out of some scrap acrylic and don't want to cut small 1/4" pieces on my table saw. Can I use a trim router to cut 1/4" acrylic? This is the stuff I'd be cutting http://www.estreetplastics.com/Black_Plexiglass_Acrylic_Sheet_p/b012500612.htm

Thanks

Rough it out on the TS. You do have zero clearance blade insert, push sticks, etc. for use with your saw, don't you?

Use the trim router to clean up the mill marks from the saw. Here you want to take off a very small amount of material.

 

[hobbzz]

No, table saw is a cheapo my father in law gave me, nothing special. I could easily make a push stick though. Just haven't needed one yet. Thanks for the help guys.

 

[itz frank]

I apologize for the question. This thread is super long and I did wonder through it a little bit.

I have an overflow that is built in that doesn't have toothed design at the top. It's simply flat. I would like to create an overflow cover that works as a flat top with three sides that connect down to the overflow to operate as a strainer and prevent junk from ending up in my overflow.

Can you point me in the right direction? I've done a google search on materials to use but most posts come up rather old and name off acrylic brands that I can not find anymore. If my post is too lazy, please ignore it.

 

[Acrylics]

Frank,
You've got options.. You could basically wrap gutter-guard around the inside of the overflow if you wanted or build the cover as you mentioned - it's just more work. I would use any extruded material for it, don't worry about brand too much for this. It's not under any sort of strain and all extruded acrylics are cheaper and glue up easily

HTH,
James

 

[itz frank]

Gutter gard, eh? I may just go that route for now. A quick home depot search shows quite a few options. Will any plastic work or is there something I should avoid?

 

[Acrylics]

Gutter gard, eh? I may just go that route for now. A quick home depot search shows quite a few options. Will any plastic work or is there something I should avoid?

You can't glue to most plastics at all, so that's the basic reason we stick with acrylic, but yeah - if you're just making a cover to sit on top, you can use use a number of plastics for the overflow cover.
If you're referring to the plastic used in the gutter guard, no plastics I know of to avoid.. just your standard disclaimer of don't use anything with any anti-mildew/microbial agents but I don't know of any gutter guard type products that use these things.

HTH,
James

 

[Westcoastindia]

Hey James,
Hows you homie?
We dont have a single video on the internet of fellas making acrylic tank with weldon 40!
The show Tanked! did show some seldom moments where in they glued few seams, but it wasn't brief.
Could you put a detailed video or something? for others to understand more precisely.
I don't have means to create or shoot a video, maybe you could do that part.

 

[easttexas]

I've also wondered the same thing. I've used WO 40 several times for "tip and pour" and had very good results, but I'm considering going even bigger (built my current 180, and it came out better than most store bought using the pin method found in this thread) What I'd like to know is how they keep it all from squishing out, or make the joints nice and even seeing as how you seem to use spacers of some sort (I think) I know that they sand and buff the excess, but there is almost nothing out there on how to use the WO 40. Thinking 3/4 and thicker plexi joints is all you'd really use it for.