Acrylic Fabrication Q & A

[Lowell Lemon]

Still use camper shell foam here. Felt is recommended by some manufacturers of acrylic...never used it myself.

 

[TaylorPilot]

Still use camper shell foam here. Felt is recommended by some manufacturers of acrylic...never used it myself.

I must be using the wrong stuff...There are about 10 options...I have always had good luck with it, but the new stuff is very fragile, doesn't rebound between jobs, and tears if you look at it crosseyed...

 

[TherealplexiG]

I must be using the wrong stuff...There are about 10 options...I have always had good luck with it, but the new stuff is very fragile, doesn't rebound between jobs, and tears if you look at it crosseyed...

Closed cell polyurethane foam

 

[Turbo's Aquatics Verified Sponsor]

What is everyone using for matts today. I have always used camper shell foam to decent results, but I built some new torsion style boxes that will stay completely flat. I put the foam on them like normal and am having a heck of a time with it. Hard to shim under, keep getting bubbles, etc. I think it is too soft, which makes it hard to push shims in.

When I was in full production I was using anti-fatigue matting and it was absolutely the best thing

https://www.northerntool.com/produc...pattern-black-7-11-16ft-l-x-3-13-16ft-w-62117
Cut them ~3/4" to 1" larger in all directions according to your workpiece - this is key. Place them pattern-side down (smooth side up) on a doubled-up 3/4" MDF glued together (so 1.5" thick work surface). The 1" extra allows you to put shims between the mat and the MDF if you have areas that are difficult to get shimmed (avoids chasing shims). Then I used narrow shims that I made out of cedar shake (1/2" wide, end pieces trimmed off, sanded paper thin at the end, then cut straight with razor) every 6" plus or minus, and on the corners at a 45. Shim no matter what, even if you don't think you'll need it. Barely insert at first, then pin and tuck shims as needed to get all firm. I found this method allowed for minimum use of shims to get the pins all tight - it went really fast.

The matting is like cheap neoprene, except it doesn't compress as much (which is good). It also absorbs solvent so if you spill, it doesn't have a tendency to burn the surface under the paper (unless you really spill - so you have to watch excess solvent). Bonus, if you do overdo it, use a paper towel and press on the mat next to the spill and it will soak up a bit. Also you can switch out the shim, as it's the shim that causes the solvent pooling, not the mat (the mat will wick it away and disperse). This is a property that the camper shell foam sucked at (also it compressed a lot and stayed there). This mat never permanently compresses - I had 5 or 6 different sizes for different size sumps and ATOs that I used for years without any damage or need to replace.

Pushing down to get a pin in (or pulling out) is usually a breeze. You can push on the shim under the pin a bit if there's a tricky one. I would put weight on the workpiece during pinning to minimize reliance on shims - about 1/4 or so of the final weight. Then once all pins out, weigh it down. Mat compresses, then lightly tuck in all the shims snug (usually very little). Depending on your table flatness - this method will very easily reveal your bad tables, and bad sections of the tables, you can mark the bad areas and they will show up that way every single time. I had a few tops that were very warped but I could predict that and would use them on smaller builds.

I used to use carpeted tables with carpet pad under, that was OK but the anti-fatigue mat is WAY better.

I also toyed around with placing a 24x48 ceramic tile (I think it was ceramic) on top of the MDF and putting the mat on that (I had stands for the MDF, but those still tended to warp over time) but that was a no-go. I was using old steelcase file cabinets for my stands under the MDF tables. Switched to Menards shelving, worked OK.

My wire for pins was dental wire, can't recall the diameter. Dipped the ends in Plasti-dip (3-4 times each) to make a grip. I had ones that were intentionally bent for inside pins (dental wire is rigid, so it would leave wick lines). Super durable, never really had to replace any, just wiped off after each use.

There still was a use for the camper shell foam. Make long narrow boards with foam on one side, and once you have pins pulled, lay these across the build foam-down and put weights on them. I had 2, 3, 4' boards 6" wide. For weights I had been using various weights from Play It Again Sports but shifted over to duct-tape wrapped bricks from Menards at the end (better, easier to move around, lighter for more variability).

I really had it down pretty well until supplier factories started shutting down and burning down in 2023 and then I got cancer. So there's a bunch of my secrets, you're welcome

 

[TaylorPilot]

When I was in full production I was using anti-fatigue matting and it was absolutely the best thing

https://www.northerntool.com/produc...pattern-black-7-11-16ft-l-x-3-13-16ft-w-62117
Cut them ~3/4" to 1" larger in all directions according to your workpiece - this is key. Place them pattern-side down (smooth side up) on a doubled-up 3/4" MDF glued together (so 1.5" thick work surface). The 1" extra allows you to put shims between the mat and the MDF if you have areas that are difficult to get shimmed (avoids chasing shims). Then I used narrow shims that I made out of cedar shake (1/2" wide, end pieces trimmed off, sanded paper thin at the end, then cut straight with razor) every 6" plus or minus, and on the corners at a 45. Shim no matter what, even if you don't think you'll need it. Barely insert at first, then pin and tuck shims as needed to get all firm. I found this method allowed for minimum use of shims to get the pins all tight - it went really fast.

The matting is like cheap neoprene, except it doesn't compress as much (which is good). It also absorbs solvent so if you spill, it doesn't have a tendency to burn the surface under the paper (unless you really spill - so you have to watch excess solvent). Bonus, if you do overdo it, use a paper towel and press on the mat next to the spill and it will soak up a bit. Also you can switch out the shim, as it's the shim that causes the solvent pooling, not the mat (the mat will wick it away and disperse). This is a property that the camper shell foam sucked at (also it compressed a lot and stayed there). This mat never permanently compresses - I had 5 or 6 different sizes for different size sumps and ATOs that I used for years without any damage or need to replace.

Pushing down to get a pin in (or pulling out) is usually a breeze. You can push on the shim under the pin a bit if there's a tricky one. I would put weight on the workpiece during pinning to minimize reliance on shims - about 1/4 or so of the final weight. Then once all pins out, weigh it down. Mat compresses, then lightly tuck in all the shims snug (usually very little). Depending on your table flatness - this method will very easily reveal your bad tables, and bad sections of the tables, you can mark the bad areas and they will show up that way every single time. I had a few tops that were very warped but I could predict that and would use them on smaller builds.

I used to use carpeted tables with carpet pad under, that was OK but the anti-fatigue mat is WAY better.

I also toyed around with placing a 24x48 ceramic tile (I think it was ceramic) on top of the MDF and putting the mat on that (I had stands for the MDF, but those still tended to warp over time) but that was a no-go. I was using old steelcase file cabinets for my stands under the MDF tables. Switched to Menards shelving, worked OK.

My wire for pins was dental wire, can't recall the diameter. Dipped the ends in Plasti-dip (3-4 times each) to make a grip. I had ones that were intentionally bent for inside pins (dental wire is rigid, so it would leave wick lines). Super durable, never really had to replace any, just wiped off after each use.

There still was a use for the camper shell foam. Make long narrow boards with foam on one side, and once you have pins pulled, lay these across the build foam-down and put weights on them. I had 2, 3, 4' boards 6" wide. For weights I had been using various weights from Play It Again Sports but shifted over to duct-tape wrapped bricks from Menards at the end (better, easier to move around, lighter for more variability).

I really had it down pretty well until supplier factories started shutting down and burning down in 2023 and then I got cancer. So there's a bunch of my secrets, you're welcome

 

[TaylorPilot]

Awesome stuff. I will go to northern tool tomorrow. I got sick of warping mdf, so this week I built some melamine tortion boxes on the CNC...dadoed so they fit together like ikea furniture...36" machined straight edge and can't see a flashlight under them...They are flat, and based on the amount of glue and screws I used, they should stay that way.

I hope you giving away secrets doesn't mean that you are out for good. I still have one of your scrubbers sitting, ready to use if I ever set a tank back up. The design was well thought out and well built. I hope your health is doing better. Cancer is no joke, I wouldn't wish that on my worst enemy.

 

[TherealplexiG]

Awesome stuff. I will go to northern tool tomorrow. I got sick of warping mdf, so this week I built some melamine tortion boxes on the CNC...dadoed so they fit together like ikea furniture...36" machined straight edge and can't see a flashlight under them...They are flat, and based on the amount of glue and screws I used, they should stay that way.

I hope you giving away secrets doesn't mean that you are out for good. I still have one of your scrubbers sitting, ready to use if I ever set a tank back up. The design was well thought out and well built. I hope your health is doing better. Cancer is no joke, I wouldn't wish that on my worst enemy.

So how do you plan to execute these torsion boxes exactly? would you be laying something on top of it other than an eva sheet what bud recommended. I am rusty these days but I think glass would work nicely on top of those torsion box. What do you think?
What cnc's you got these days?

 

[Lowell Lemon]

My production tables were butcher block that I had run through a wide belt sander at a local cabinet shop. We then had laminate applied to handle the solvent spills. Then used the polyurethane foam for camper tops with very little shim placement and guitar wire and 28 Guage steel wire for the majority of our bonding tricks. The guitar wire was for large heavy tanks.

 

[TherealplexiG]

@Lowell Lemon
How are you doing?
Beast of a table, it would have served you well.

 

[Lowell Lemon]

@Lowell Lemon
How are you doing?
Beast of a table, it would have served you well.

Doing all right. How about you? Still building tanks or did you move on to other things?

 

[Lowell Lemon]

This is what I do every day now. Build counters and showers.

 

[TaylorPilot]

So how do you plan to execute these torsion boxes exactly? would you be laying something on top of it other than an eva sheet what bud recommended. I am rusty these days but I think glass would work nicely on top of those torsion box. What do you think?
What cnc's you got these days?

Technically they aren't torsion boxes, because I didn't put a bottom on them. But, I drew them out in fusion using 3/4" melamine. It cut 3/16" deep dados so everything fits together. I run some glue, assemble, then pilot drill and counter sink holes, then runs screws in. the top screws first, so the suck up and make everything straight. Then the sides. It all comes together very tight. The cross beams are 5", so they are very rigid. The plywood table sits about at my hips and the raised table sits at my belly button. I put a machined straight edge on a 3' long one, and i couldn't see any light thru it. This one is 11x23. I made it for assembling the rear boxes on my overflows I make. My plan is to just lay the foam on top of them, basically as Turbo was saying.

As far as the CNC. I built an AVID CNC 4*8. I built my own motion control using a centroid controller and clearpath servos. Now they actually offer that as a package on their website ready to go. I would love to have a big shopsabre, but I need to sell a few more things before I am gonna spend 100k on a router. Mine does have a home made vacuum hold down. Since I only make the same thing all the time, I built some inboard gasket fixtures, and even with only 5-6psi of hold down pressure, I can't move the parts.

 

[Turbo's Aquatics Verified Sponsor]

To be blunt, this seems really excessive when you can just take 2x 3/4" 24x48 pieces of MDF from Menards and lay them on flat concrete, spread wood glue on one and smash them together and place a couple hundred pounds of weight on them. You can even do multiple of these, just stack them up and put the weights on the last one and that generally lasts for years.

Don't overthink.

But I suppose, if you have a specific need (cranking out a product) and you want something customized for that specifically, fire away.

I always end up coming back to the simplest solution, time after time.

 

[TaylorPilot]

To be blunt, this seems really excessive when you can just take 2x 3/4" 24x48 pieces of MDF from Menards and lay them on flat concrete, spread wood glue on one and smash them together and place a couple hundred pounds of weight on them. You can even do multiple of these, just stack them up and put the weights on the last one and that generally lasts for years.

Don't overthink.

But I suppose, if you have a specific need (cranking out a product) and you want something customized for that specifically, fire away.

I always end up coming back to the simplest solution, time after time.

It looks that way, but the first one took an hour to draw out...each additional size took about 4 minutes to resize and generate new cam...then they cut in about 10 minutes each. Maybe 20 minutes to assemble each. I made four different sized ones in a few hours with 1 sheet of melamine.

I went and got that foam today. It looks perfect. I am gonna give it a try tomorrow if I don't get called out on a trip.

 

[TherealplexiG]

Doing all right. How about you? Still building tanks or did you move on to other things?

No tanks at the moment, but I will jump right back to acrylics this year.
I wish we had more people doing kitchen cabinets here, all we have big box stores like ikea and other oem'd Chinese stuff.

 

[TherealplexiG]

Technically they aren't torsion boxes, because I didn't put a bottom on them. But, I drew them out in fusion using 3/4" melamine. It cut 3/16" deep dados so everything fits together. I run some glue, assemble, then pilot drill and counter sink holes, then runs screws in. the top screws first, so the suck up and make everything straight. Then the sides. It all comes together very tight. The cross beams are 5", so they are very rigid. The plywood table sits about at my hips and the raised table sits at my belly button. I put a machined straight edge on a 3' long one, and i couldn't see any light thru it. This one is 11x23. I made it for assembling the rear boxes on my overflows I make. My plan is to just lay the foam on top of them, basically as Turbo was saying.

As far as the CNC. I built an AVID CNC 4*8. I built my own motion control using a centroid controller and clearpath servos. Now they actually offer that as a package on their website ready to go. I would love to have a big shopsabre, but I need to sell a few more things before I am gonna spend 100k on a router. Mine does have a home made vacuum hold down. Since I only make the same thing all the time, I built some inboard gasket fixtures, and even with only 5-6psi of hold down pressure, I can't move the parts.

The box looks solid.
I am in talks with a Chinese manufacturer called quick cnc, a friend of mine owns a machine from them and been running since a decade, price performance ratio is good.
4*8 costs about 12 k USD FOB. Ofcourse imports and other levies ends up costing twice. but still super solid machine.

 

[Lowell Lemon]

I have two Avid CNC's. One 5' x 12' and one 5' x 10' with an Italian spindle for stone, Quartz and porcelain. All standard stepper drives. Vacuum pods for the wet CNC for stone and just double sided outdoor carpet tape for the Solid surface and plastic CNC.

 

[TaylorPilot]

The box looks solid.
I am in talks with a Chinese manufacturer called quick cnc, a friend of mine owns a machine from them and been running since a decade, price performance ratio is good.
4*8 costs about 12 k USD FOB. Ofcourse imports and other levies ends up costing twice. but still super solid machine.

For acrylic, you are limited by the chipload and ultimately speed you can process materials, so they don't put too much of a load on the machine. Wooden panel (plywood) processing for cabinets is where you want a lot of rigidity because you can run those a lot harder and a lot faster. 1000IPM on 3/8" bits at full DOC can be achieved. But you need a rigid machine with strong motion control and often overlooked, a good hold down vacuum. I don't have 3 phase at my house, so I made one of those boxes that mount 4 whole house vacuum pumps on them. It is louder than sin but works for my application. Just from the pictures, that chinese machine looks pretty rigid. The gold standard in America is either Onsrud or Shopsabre. Both border on 100k for a delivered machine with a nice rotary vane vacuum pump. Way out of my price range for this side hustle at the moment.

 

[TherealplexiG]

Yes, you're on point.
Format from felder is every wood workers dream here and very well known, also check out portatec from Germany. They have absolute bananas, especially for plastic routing. Royal exclusiv exclusively uses those..

 

[TaylorPilot]

So I tried the matts today. They worked great. Perfect seams. I really liked the melamine tops as well. Everytime I used MDF I just felt like no matter how well you wiped everything down, there was always dust.

One suggestion my father had, that has worked out great as well, is to use cheap white coffee filters to clean the surfaces before setup. He said they are the best thing ever for cleaning your car windows, and they worked really well on acrylic as well. I have been using microfiber, but those things seem to be dust magnets. The coffee filters left zero lint, they hold up really well and 100 of them are about $2-3.