Acrylic Fabrication Q & A

[cromag27]

I hate hate hate cutting PC. The only thing I use it for is the lids on my rear boxes. It always seems to chatter and really tries to lift if I don't use really shallow DOC. I am using an uncoated Spetool (cheap) 1/4" O-Flute at 18k and 145 IMP. I have used the coated Amana bits, but never seemed to see much of a difference in cut. I see you cut some pretty intricate stuff and I am blown away that you can hold it down. I made a custom fixture with cover gasket to get max sq-in and am holding almost 14" of vacuum, and I still have to baby it...I can rip through acrylic at those same settings. Any recommendations on different tooling or S&F.

you need a cnc with an extremely rigid gantry, so you’re looking at the big commercial units.

i use the coated amana bits and replace very often. cut depth is half the diameter of the bit per pass, and you have to experiment with the feed rate and rpms.

i use a 3/4” mdf spoilboard and double sided carpet tape to hold the material.

https://amzn.to/3OLk60L

 

[braydenmm]

Hello, I have been studying this thread with plans to build a very large display tank. 8'x4'x3' (LxWxH) with 1" thick acrylic. With the top brace being an almost full sheet of acrylic with cut outs. I plan to do a few practice builds before I attempt this to prepare. I know the sheets are going to weigh a ton so it won't be easy. Would such a large build be possible with the methods in this thread? Any advice?

 

[Lowell Lemon]

Hello, I have been studying this thread with plans to build a very large display tank. 8'x4'x3' (LxWxH) with 1" thick acrylic. With the top brace being an almost full sheet of acrylic with cut outs. I plan to do a few practice builds before I attempt this to prepare. I know the sheets are going to weigh a ton so it won't be easy. Would such a large build be possible with the methods in this thread? Any advice?

There is a technique for large acrylic sheet. I unfortunately forgot some of it over the years and just got a new lesson recently. You will need guitar string, foam tape for canopies on pickups, solvent mixed to the recipe in this thread. Edge prep with router and acrylic bit. Someone to cut your parts with a CNC or a precision ground straight edge. Table large enough for construction. Polishing kit, and other items. By the time you add it all up you might just contact James at Envision Acrylics. He has acrylic in stock for this build and not many sources left for acrylic sheet this size. I can give you more specifics if you want to PM me.

 

[Turbo's Aquatics]

Echoing LL here, you can solvent weld 1" all day long using the techniques in this thread. The trick is going to be getting straight square parallel edges on your long panels and perfectly square end panels. That and manipulating hundreds of pounds of acrylic

 

[cromag27]

or you can use wo 40/42 but good luck with that if you’re not experienced.

 

[gsd78]

I hope this is an appropriate question for this forum, as I wasn't sure where else to put it. I recently purchased a custom built acrylic aquarium (builder to remain un-named) that is 93" x 20" x 18". After receiving the tank and inspecting it I noticed that the front panel seemed to be bowed out quite a bit along the top front edge. For reference, the tank has a full top panel with 4 large cutouts in it. When I measure it front to back across the top panel it is 1/2" wider in the center than at the ends. I contacted the builder and he says this is normal and there is no way to avoid the bending and to pull the panel back in to be perfectly vertical during assembly. He also says it has zero impact on the integrity of the tank. While I understand some minor variation is expected I think 1/2" is extreme and it is very noticeable to the eye when looking at the tank. I think the front panel could have been pulled back in with clamps (and maybe a straight edge) to be much closer to vertical rather and just glued in place wherever it ended up and router trimmed flush after gluing.

Do any of you acrylic fabrication experts think I'm being overly picky? Is the 1/2" bow acceptable and normal? Should I have any concerns from a structural integrity standpoint? I'd appreciate any input.

 

[braydenmm]

There is a technique for large acrylic sheet. I unfortunately forgot some of it over the years and just got a new lesson recently. You will need guitar string, foam tape for canopies on pickups, solvent mixed to the recipe in this thread. Edge prep with router and acrylic bit. Someone to cut your parts with a CNC or a precision ground straight edge. Table large enough for construction. Polishing kit, and other items. By the time you add it all up you might just contact James at Envision Acrylics. He has acrylic in stock for this build and not many sources left for acrylic sheet this size. I can give you more specifics if you want to PM me.

Thank you both for the replies. I had a local acrylic supplier that said they could cut them, I assume their cuts would be precise enough but I will ask them . I Plan to set up a large workspace in the basement for the project and take my time on the build moving things and will have help. I am going to do a lot more research and some smaller practice projects. My brother will be helping me and if all goes well we will build him a tank after of similar scale

 

[cromag27]

Thank you both for the replies. I had a local acrylic supplier that said they could cut them, I assume their cuts would be precise enough but I will ask them . I Plan to set up a large workspace in the basement for the project and take my time on the build moving things and will have help. I am going to do a lot more research and some smaller practice projects. My brother will be helping me and if all goes well we will build him a tank after of similar scale

depends on what machinery they’re using to cut it. saw? cnc router?

 

[Turbo's Aquatics]

Thank you both for the replies. I had a local acrylic supplier that said they could cut them, I assume their cuts would be precise enough but I will ask them . I Plan to set up a large workspace in the basement for the project and take my time on the build moving things and will have help. I am going to do a lot more research and some smaller practice projects. My brother will be helping me and if all goes well we will build him a tank after of similar scale

If they don't cut acrylic for aquarium fabricators, I'd triple check that...most suppliers just use a panel saw, which IMO would not be good enough. CNC saw, maybe. CNC router, better - but they better change the bit to a new one, use the right feed rate, good chip clearance, if they have to make multiple cuts they should do a final pass (or two) for the full profile cut with a fraction of a millimeter bite, make sure the parts don't move, etc etc...

 

[Turbo's Aquatics]

I contacted the builder and he says this is normal and there is no way to avoid the bending and to pull the panel back in to be perfectly vertical during assembly.

yeah that's total bs. Just to make sure I understand what you're saying, the front-to-back measurement across the top (and bottom) of the tank is 1/2" more in the middle of the tank versus the ends?

The assembly process is bond the ends to the front, then flip and bond to the back. Now you have the 4 vertical panels assembled. then you place the euro flat and place the assembly on it and bond. When you set this up, it should be obvious if the panel has a bow to it in the center, and you would just add a clamp or some blocking of some kind to remove the bow. Even better would have been to sight the bow and place it on the inside, then push the bow out to straight with spread clamps on the inside (that way your "push blocking" is not in the way of the pins or solvent running).

Then when you flip the tank to bond on the bottom, the bow will be less prevalent (but probably still there) and minimal blocking or spread clamping should be needed.

 

[gsd78]

yeah that's total bs. Just to make sure I understand what you're saying, the front-to-back measurement across the top (and bottom) of the tank is 1/2" more in the middle of the tank versus the ends?

The assembly process is bond the ends to the front, then flip and bond to the back. Now you have the 4 vertical panels assembled. then you place the euro flat and place the assembly on it and bond. When you set this up, it should be obvious if the panel has a bow to it in the center, and you would just add a clamp or some blocking of some kind to remove the bow. Even better would have been to sight the bow and place it on the inside, then push the bow out to straight with spread clamps on the inside (that way your "push blocking" is not in the way of the pins or solvent running).

Then when you flip the tank to bond on the bottom, the bow will be less prevalent (but probably still there) and minimal blocking or spread clamping should be needed.

Thanks for the reply. Yes, the front-to-back measurement is 1/2" more in the middle of the tank versus both ends when measuring on the top surface of the tank and 1/4" more in the middle versus the ends when measuring on the bottom surface.

The builders exact words were: "There is no way to keep the vertical panels absolutely straight when putting the top on." My response was that I understand some small variance is possible, but there's no way 1/2" is acceptable.

I did put an 8ft level across the tank and the majority of the bow is in the front panel. The back panel is not 100% flat, but I think its within acceptable range.

My follow up question to you would be do you think its merely a cosmetic issue or also a structural integrity issue?

 

[cromag27]

Thanks for the reply. Yes, the front-to-back measurement is 1/2" more in the middle of the tank versus both ends when measuring on the top surface of the tank and 1/4" more in the middle versus the ends when measuring on the bottom surface.

The builders exact words were: "There is no way to keep the vertical panels absolutely straight when putting the top on." My response was that I understand some small variance is possible, but there's no way 1/2" is acceptable.

I did put an 8ft level across the tank and the majority of the bow is in the front panel. The back panel is not 100% flat, but I think its within acceptable range.

My follow up question to you would be do you think its merely a cosmetic issue or also a structural integrity issue?

refund

 

[gsd78]

refund

Builder is refusing return/refund saying that there is nothing wrong with the tank. I'm trying to figure out next steps to resolve the issue.

 

[Turbo's Aquatics]

Theoretically, let's say you had a stand made for the tank that had trim around the bottom to cover up the bottom panel/wall joint and extended up a bit. If that was made based on the LxW dims it would not have fit. This guy, sheesh

 

[Lowell Lemon]

I hope this is an appropriate question for this forum, as I wasn't sure where else to put it. I recently purchased a custom built acrylic aquarium (builder to remain un-named) that is 93" x 20" x 18". After receiving the tank and inspecting it I noticed that the front panel seemed to be bowed out quite a bit along the top front edge. For reference, the tank has a full top panel with 4 large cutouts in it. When I measure it front to back across the top panel it is 1/2" wider in the center than at the ends. I contacted the builder and he says this is normal and there is no way to avoid the bending and to pull the panel back in to be perfectly vertical during assembly. He also says it has zero impact on the integrity of the tank. While I understand some minor variation is expected I think 1/2" is extreme and it is very noticeable to the eye when looking at the tank. I think the front panel could have been pulled back in with clamps (and maybe a straight edge) to be much closer to vertical rather and just glued in place wherever it ended up and router trimmed flush after gluing.

Do any of you acrylic fabrication experts think I'm being overly picky? Is the 1/2" bow acceptable and normal? Should I have any concerns from a structural integrity standpoint? I'd appreciate any input.

That is why we used forms for assembly to maintain proper spacing. I know we all have some different views on this. Just my two cents.

 

[gsd78]

That is why we used forms for assembly to maintain proper spacing. I know we all have some different views on this. Just my two cents.

Theoretically, let's say you had a stand made for the tank that had trim around the bottom to cover up the bottom panel/wall joint and extended up a bit. If that was made based on the LxW dims it would not have fit. This guy, sheesh

That's exactly how I was planning to make the stand and how I've made stands for my other custom built acrylic tanks. Taking measurements to design the stand is how I discovered the issue.

The builder is definitely capable of building a quality tank. His years in business and all the other very positive reviews I read show that. I did a bunch of research before going with them. In the case of my tank though he missed the mark, He is now blaming me for having buyers remorse, partly due to the fact that I initially left him a positive review before I noticed the dimensional issues. Its a shame too, because the seam work on the tank is beautiful.

 

[cromag27]

That is why we used forms for assembly to maintain proper spacing. I know we all have some different views on this. Just my two cents.

this. lots of jigs and other things to keep alignment/spacing/whatever.

this “fabricator” was not ensuring the panels were straight and just welded them how they were. very bad.

 

[Turbo's Aquatics]

My follow up question to you would be do you think its merely a cosmetic issue or also a structural integrity issue?

If the seam work is good, it might be OK. Some of this has to do with overall fabrication technique.

Follow me here

Let's say the panels are prepped with nice flat square edges and the vertical walls are assembled square and true. That's kind of a given, as long as your end panels are perfectly square. Now you have your center point of your bottom edge of the front panel bowed out 1/4". If the top is also 1/4", then that top and bottom seam from end to end is "similar". But if you kick out the top edge of the front panel another 1/4", you inherently add a very slight angle to that edge. Take it to the extreme and hold the bottom panel in place and pull the top panel a few inches forward - now it's no longer planar.

If you did not further edge prep prior to adding the top/bottom, this might be a future issue. But, acrylic is very forgiving.

Now, if you took the additional step of sanding/scraping the entire top and bottom edge assembly to make those both fully planar prior to bonding the top/bottom off, you would remove this slight angle and you'd have a flush bond joint

In either case, you have a non-90 angle along the top edge.

93 x 20 x 18, assuming that's LWH, 18" tall, yes?

What thickness material? Is it the same for walls and top/bottom?

 

[cromag27]

If the seam work is good, it might be OK. Some of this has to do with overall fabrication technique.

Follow me here

Let's say the panels are prepped with nice flat square edges and the vertical walls are assembled square and true. That's kind of a given, as long as your end panels are perfectly square. Now you have your center point of your bottom edge of the front panel bowed out 1/4". If the top is also 1/4", then that top and bottom seam from end to end is "similar". But if you kick out the top edge of the front panel another 1/4", you inherently add a very slight angle to that edge. Take it to the extreme and hold the bottom panel in place and pull the top panel a few inches forward - now it's no longer planar.

If you did not further edge prep prior to adding the top/bottom, this might be a future issue. But, acrylic is very forgiving.

Now, if you took the additional step of sanding/scraping the entire top and bottom edge assembly to make those both fully planar prior to bonding the top/bottom off, you would remove this slight angle and you'd have a flush bond joint

In either case, you have a non-90 angle along the top edge.

93 x 20 x 18, assuming that's LWH, 18" tall, yes?

What thickness material? Is it the same for walls and top/bottom?

but what happens when the tank is filled and the acrylic naturally bows even more?

 

[gsd78]

but what happens when the tank is filled and the acrylic naturally bows even more?

That's my main concern and I have voiced this to the builder. To answer your questions. yes, the tank is 93" long x 20" wide (front to back) x 18" tall. It has 3/4" material for the four sides and 1/2" for top and bottom.