Acrylic Fabrication Q & A

Discussion in 'Do It Yourself (DIY)' started by Floyd R Turbo, Dec 7, 2015.

  1. Floyd R Turbo

    Floyd R Turbo Super Duper Member R2R Supporter Gold Sponsor Toys For Kids 2016 Article Contributor Partner Member 2018

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    The primary brace is on the longest dimension. The purpose of the brace is to prevent bowing. The brace absorbs some of the pressure that is placed on the vertical panel and transfers it throughout the brace. The stress point is going to be where the brace meets the side vertical panel, because there is A) no structural component to take it anywhere else and B) no brace on the top edge of the side panel, so these are additive forces

    It's not a major stress as the tank is not very tall, but it's a stress nonetheless.

    Adding the side panel top brace (like in the sketch) will help, as will the center brace. If you want peace of mind, do the 4 piece brace and then add 3 front-to-back braces and you should be very well set.

    Also I just noticed that you are using 3/8" so I would definitely do a little over-building if you're not going with a 1-piece euro for that thickness of wall.
     

  2. Floyd R Turbo

    Floyd R Turbo Super Duper Member R2R Supporter Gold Sponsor Toys For Kids 2016 Article Contributor Partner Member 2018

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    The other thing you could do is reconfigure your tank dims so that you could use a full euro. Is there a reason you want it 70" long?
     
  3. Matthias7

    Matthias7 Well-Known Member

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    The dimensions fit the room wanted to maximize space as best I could. The acrylic is cut already so no way to reconfigure the only way to go one peice now would be to buy another sheet, which I could do but would prefer not too
     
  4. rbarr110

    rbarr110 Member

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    Hoping to get a little input. I am intending on building my own acrylic sump (30"x16"x16" +/-). I have my own CNC machine so cutting will be a breeze. However, after pricing acrylic, I am thinking of using 1/4” extruded rather than 1/4” or 3/8” cast. For 3/8” the plastic shop only has cast.

    A 4’x8’ sheet of ¼” extruded is about $180, and for ¼” cast I was quoted $370, didn’t even bother to ask about 3/8” cast as it will easily be over $400.

    I am designing the sump similar to the Trigger Ruby 30, here are some screen shots of the model. I am leaning towards the ¼” extruded acrylic for obvious cost differences. I am considering routing channels for the acrylic to be placed in and then use capillary solvent welding. I also intend on using silicone at all the joints. Any thoughts or opinions on the plans so far? Model isn't complete yet.
    Sump 1.JPG Sump 2.JPG
     
  5. Floyd R Turbo

    Floyd R Turbo Super Duper Member R2R Supporter Gold Sponsor Toys For Kids 2016 Article Contributor Partner Member 2018

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    Holy @#$@ on that pricing. Maybe I just haven't purchased acrylic in a while, but I think you're getting hosed here.

    Last I checked, 1/4" clear Plexiglas-G 48x96 was $130, 3/8" clear PMACS (which is the generic version of Plex-G) was $180, and 1/2" PMACS was $275 - and those are all cast prices.

    Unless they're quoting you Polycast, yeah I'd go somewhere else.

    Sabic Polymershapes (might just be Polymershapes now because "Sabic" is the parent company which is a Saudi company)
    Laird Plastics
    Port Plastics
    Regal Plastics

    Start there.

    I would not do this. I get the idea, but it's just not going to turn out how you think. Just plan for the ends and baffles to be exact (cut the parts to their finished/final dims) and then add 1/4" or so to the length of the front/back panels (this is overage for flush trimming afterwards) and 1/4" to both length and width of the bottom and euro (again, overage for flush trimming) and use the pins method. It's not overly difficult, and results in a much better bond.

    You can use extruded for the whole thing, but if it were me I would use 3/8" for the walls and baffle and 1/4" for the top/bottom. But for that layout, you can get it all out of one sheet so it's likely more cost efficient to get one sheet of 3/8" and make it all from that.
     
  6. rbarr110

    rbarr110 Member

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    So the quotes are from Tap Plastics, there is one less than a mile from where I work. Here is what I was told, the manufacturer is "Chemcast".
    1/4" Extruded
    50"x98" $175
    60"x96" $195
    72"x96" $243

    1/4" Cast
    72"x96" $355
    51"x125" $329

    3/8" Cast
    50"x96" $360
    60"x96" $408

    Going to check with Onlinemetals.com as they sell acrylic as well and they also have a warehouse a few miles from where I work.
     
    Last edited: Nov 3, 2017
  7. Floyd R Turbo

    Floyd R Turbo Super Duper Member R2R Supporter Gold Sponsor Toys For Kids 2016 Article Contributor Partner Member 2018

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    Chemcast historically has been blacklisted by many tank manufacturers. They had a really bad history of tanks falling apart (literally) 6-12 months after being filled. I would only use Plexiglas (arkema) brand, or their generic version PMACS (pronounced "p-max")

    Acrylite used to be #2 but they have fallen out as well, review comments by @mixer911 (Synergy Reef) and others on that (they had a batch that wouldn't solvent weld).

    That's honestly highway robbery to charge those prices for Chemcast.

    Laird: 650 S Industrial Way, Seattle, WA 98108
    Port: 1228 Andover Park E, Tukwila, WA 98188
    Polymershapes: 18292 Andover Park W, Seattle, WA 98188
     
  8. Floyd R Turbo

    Floyd R Turbo Super Duper Member R2R Supporter Gold Sponsor Toys For Kids 2016 Article Contributor Partner Member 2018

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  9. cromag27

    cromag27 anemone whisperer & acrylic/wood expert R2R Supporter Gold Sponsor Article Contributor

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    i find that extruded cuts like garbage on my cnc machines.

    but yeah, i don't like the slot idea. and silicone won't bond well to acrylic, therefore might not help at all.
     
  10. S-t-r-e-t-c-h

    S-t-r-e-t-c-h Well-Known Member R2R Supporter

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    Anyone have any advice on trimming and finishing the edges on cast acrylic tubes? I'm thinking 6" - 8" cylinders for skimmer & ca reactor bodies that will be seeing some pressure.
     
  11. imustbenuts

    imustbenuts Well-Known Member

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    I’ve only cut and prepped 4” but I used a table saw with a stop on a cross cut sled. Then layed 400 grit paper on a flat surface and leveled the cut. It seemed to weld up strong.
     
    Floyd R Turbo and S-t-r-e-t-c-h like this.
  12. rbarr110

    rbarr110 Member

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    Thanks for the help there. I contacted polymer shapes and they quoted me
    1/4" 4'x8' $136
    3/8" 4'x8' $248

    I have inquired about 3/4" but have not heard back yet. However, I ended up buying some upgrades for my CNC, and the tank/sump work will have to wait for a little more cash to build back up.
     
  13. Floyd R Turbo

    Floyd R Turbo Super Duper Member R2R Supporter Gold Sponsor Toys For Kids 2016 Article Contributor Partner Member 2018

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    Better. Was this for Plexiglas-G or was that for Arkema PMACS? Sometimes you have to train your rep to get you the correct pricing. I write down the actual item numbers so I don't have to re-train every time but I'd have to dig those out (and they changed them not too long ago).

    The PMACS is usually 30% cheaper, so that $248 for 3/8, you might be able to go down to $200
     
  14. rbarr110

    rbarr110 Member

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    So I inquired about 3/4" (0.708") and is $446 a sheet. They also confirmed pricing was for PMACS. I was considering making a 90-120 gallon tank with 3/4" and move to 3/8" for sump, but may just continue to watch for used 90-120 gallon tanks as prices for used have been a around the $400 or less mark.

    Just put $1300 into CNC upgrades, so the waiting game for used tanks will be fine, but still probably going to build a sump from 3/8" after CNC upgrade installation is complete.
     
  15. Matthias7

    Matthias7 Well-Known Member

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    Edges prepped with my router. Do they look good enough? 4D83FD36-844B-4B9B-91E0-7F2CAD554041.jpeg
     
  16. cromag27

    cromag27 anemone whisperer & acrylic/wood expert R2R Supporter Gold Sponsor Article Contributor

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    What bit, feed rate and rpm did you use?
     
  17. Matthias7

    Matthias7 Well-Known Member

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    25k rpm straight flush trim bit (carbide)
     
  18. cromag27

    cromag27 anemone whisperer & acrylic/wood expert R2R Supporter Gold Sponsor Article Contributor

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    How many passes and feed rate? Looks a little rough and was the acrylic old? I see some ridges and piting.
     
  19. Matthias7

    Matthias7 Well-Known Member

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    2 passes per cut new acrylic. Feels very smooth to touch way smoother then the saw cut it he previoulsy. No idea on feed rate
     
  20. cromag27

    cromag27 anemone whisperer & acrylic/wood expert R2R Supporter Gold Sponsor Article Contributor

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    Hmmmmm....do you know what size bit it was? And how thick is the acrylic?
     
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