Acrylic Fabrication Q & A

[TherealplexiG]

I misunderstood, I thought he was installing a new tank. I use composite shims for stand leveling and cedar shims for the pins method. I just go to the hardware store and get a package of assorted sizes and sand if needed.

I usually go with a metal frame stand, wrapped in plywood and laminate. The metal frame has adjustable level feets.

No, we use wooden shims to adjust the bottom sheet so that all the wires are tight in the seam about to be welded. Imperfections in the table, or in the thickness of the sheets (cast sheets are usually inconsistent in their thickness). Wooden shims can be used from the hardware store, but they usually need to be sanded on a belt sander to get them to a fine point. Cedar shakes are another good option because you can pick through them and get the ones that are really thin. It usually doesn't take much to ensure that the pins are tight. We're talking the thickness of a few sheets of paper. Using camper foam to support the parts about to be joined can absorb some of the imperfections as well.

Spot on mate! Can i use popsicle sticks? or laminate cut to fine strips : thickness of laminate being 1 mm to 1.5 mm?

 

[TherealplexiG]

I misunderstood, I thought he was installing a new tank. I use composite shims for stand leveling and cedar shims for the pins method. I just go to the hardware store and get a package of assorted sizes and sand if needed.

I usually go with a metal frame stand, wrapped in plywood and laminate. The metal frame has adjustable level feets.

No, we use wooden shims to adjust the bottom sheet so that all the wires are tight in the seam about to be welded. Imperfections in the table, or in the thickness of the sheets (cast sheets are usually inconsistent in their thickness). Wooden shims can be used from the hardware store, but they usually need to be sanded on a belt sander to get them to a fine point. Cedar shakes are another good option because you can pick through them and get the ones that are really thin. It usually doesn't take much to ensure that the pins are tight. We're talking the thickness of a few sheets of paper. Using camper foam to support the parts about to be joined can absorb some of the imperfections as well.

Spot on mate! Can i use popsicle sticks? or laminate cut to fine strips : thickness of laminate being 1 mm to 1.5 mm?

 

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Cedar shakes are roofing material. They come in bundles usually for something like $20, maybe more

 

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Shims need to be very thin, sometimes you only need a tiny thickness to shore up a pin. Normal shims & things like Popsicle sticks typically will not work as they aren't thin enough or not tapered

 

[TherealplexiG]

Cedar shakes are roofing material.

We seldom have roofs in India.

Shims need to be very thin, sometimes you only need a tiny thickness to shore up a pin.

I understand the logic behind it. I'll probably figure out what to use as shims.

BTW i got the plexi sheet waterjetted, the finish came worst than a saw cut. If you want pics of the finish let me know, i'll post here later. Now i guess have to do the router table thingy. Fortunately my router table is up and running only prob is the 25 mm dia bit i ordered would take a month to reach. I have 12 mm dia bit with me. Do you think it would flex while routing and produce uneven surface? The collet of the router is 12 mm.
Plexi is 8mm thk.

I have made jigs for holding the acrylic panels, CNC routed MDF 18mm thick then glued together. Local shops who has CNC routers does not have a vacuum bed, they clamp the material to be routed on MDF. So my MDF was mounted by nails to another termited (They use it untill its messed literally, looks like it has been eaten by termites) MDF. Although pieces which came out were pretty square, i measured with digital vernier and parallel end difference was around 0.5 mm and opp was around 0.8 mm. i filled up the voids with synthetic rubber glue to make the final adjustment to square it up. It's now square like a hare in the county fair. But i guess can't use those CNC's for acrylics.

It has been a hard time getting up all the stuff which does not exist locally, but the process was educating. For instance spring clamps, i ordered a few and they came in giant sizes even though the opening was only 70 mm the size of the grip was too big to be handled with one hand. Then i ran a thought about that end panel move where you loosen the clamp for a fraction of second. Fortunate now i got the smaller ones from a friend travelling back from Germany.

I guess it will be good to go for the tank in couple of days. i'll probably wick on tuesday..Keep ya'll nukas updated.

 

[TaylorPilot]

Popsicle sticks are way too thick. I usually only have to have shims that are the thickness of a few sheets of paper on the skinny end. Typical wooden door/window shims are too thick in their stock form, and if you look at the end the are usually tapered one way or the other. I use them, but I have a bench belt sander and can get them super thin. Even being super thin, I rarely have to stick any more than the very tip under the acrylic. It helps when your surface is flat though. Mdf with camper foam is good, but mdf can begin to droop over time, so mine has 1x4 ribs screws to the bottom that I hand picked then ran through a jointer to make them straight. It has remained straight for 6 months so far and really cut down on the amount of shimming required.

 

[TherealplexiG]

Mdf with camper foam is good, but mdf can begin to droop over time, so mine has 1x4 ribs screws to the bottom that I hand picked then ran through a jointer to make them straight. It has remained straight for 6 months so far and really cut down on the amount of shimming required.

Could you post a pic please?

I will later on however upgrade it to Stainless steel jig, surface grounded all holded up by allen bolts.

I'm proficient with solidworks, however i don't have access to simulation. I've read you do alot of modeling in solidworks. Could you run diagnostics on a tank? probably simulate it in a worst case scenario? And see to it where stress points build up? Would be cool to see those graphs...

 

[TaylorPilot]

Honestly that's a little overkill...the problem is the thickness of the acrylic panels isn't consistent. So you could get one of the laboratory grade granite tables and you'd still have to use foam and shims to account for the difference in thickness. We use Solidworks allot, but we don't do any simulation. Your best bet is to post up the size you want and let the old builders tell you what you need to use

 

[TherealplexiG]

Your best bet is to post up the size you want and let the old builders tell you what you need to use

True!

Was just keen to know where and how the pressure develops by inconstant water movement in the tank. Its like you mod one return pump, few wavemakers or wavebox in a simulation scenario, you put on recommended thickness of acrylic for that particular size and see like where those red zones hit! Coz that would help us with the build to focus on a particular spot. Knw m sayin?

Check out some cool stuff: All you need is some wild imagination.

It would also help determine thickness for steel / wood stands, frames, whatever. Load bearing capacity can be simulated.

Flow simulation:

 

[TherealplexiG]

Difficulty routing strips, say for eg 20" x 1.5 inch strip, how do you route the smaller side ie. 1.5 inch. When I tried it wobbled alot giving a bad pass.

 

[TaylorPilot]

What kind of bit are you using. I cut the sides and braces for the overflows by hand on a router table with a fence. I use a long straight edge that is only probably 1/8" thick so I can see exactly what I am doing. I have routed hundreds and hundreds of them, and while I am cautious, I don't get nervous anymore. Someone will come over and see me start doing it and about have a heart attack. How much are you taking off per swipe? I have noticed that if I take off more than say 1/8" at a time, it sometimes tries to grab as you enter the cut. Anything less than that and you can hardly tell it is cutting. Make sure you aren't using spiral bits for this. The tend to pull the piece into the bit, while straight flutes tend to push them away from the bit (what you want in this situation). You should only use the spiral bits for flush trimming.

 

[Pepcrylic]

Difficulty routing strips, say for eg 20" x 1.5 inch strip, how do you route the smaller side ie. 1.5 inch. When I tried it wobbled alot giving a bad pass.

2 way tape. rout 1 edgae , cut it to width, tape it back on the piece you just cut it off of , and rout again

 

[TherealplexiG]

@TaylorPilot
I'm using a flush trim bit, 2 flute straight bit. Just using the flutes to cut, no concern with the bearing. I did not have problem with bigger square pieces just the small side grabbing into the router bit. I am taking off less then 1/8th at a time. Router is 2 1/4 HP, with 12mm dia collet and 12mm dia router bit. I have ordered a bigger dia on the bits, will take a while to reach me. Probably a month.

2 way tape. rout 1 edgae , cut it to width, tape it back on the piece you just cut it off of , and rout again

Hey peps,
You mean that i should tape the strip on a mdf or something by using double sided tape? Make the first pass and then the other?


New router bit, accidentally it nibbled. Lesson learnt, wear protective gloves.


I tried gluing a scrap piece.
Humidity is 80 percent, temp 27 deg Celsius. mix was DCM 95%, Acid 5 %
Why am i getting blobs squished out? Also tiny miny mo bubbles in there, not a lot by many.

 

[TaylorPilot]

Yea, it shouldn't be that hard. I did probably 20 1"x3" strips tonight and didn't have an issue with any of them. Get a freud diablo bit. I use the 3/4" diameter with a 1/2" shank. They cut like butter and are cheap enough I can just throw them away after they start showing wear. Are you putting the piece in between the bit and the fence? I apply a little bit of back pressure pulling it towards the fence and away from the bit, when I start it into the bit I go a little slower, then move at maybe 1" per second. Does any of that make sense? Here is my first router table. The 1" thick piece of acrylic is my fence. In the second picture just imagine the bit being larger with the piece of acrylic being smaller. LOL

 

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Difficulty routing strips, say for eg 20" x 1.5 inch strip, how do you route the smaller side ie. 1.5 inch. When I tried it wobbled alot giving a bad pass.

If you are referring to finish routing the 1.5" edge of a 20" x 1.5" long piece by using the technique of passing the part between a fence and the bit: No, do not do this. In general, you need a certain width compared to the length in order for that technique to be effective, or else you get what you experienced - the part wobbles. This is highly dangerous to try, so just don't. instead, double-stick-tape another piece of acrylic and use a flush trim bit to get your 1.5" edge where you want it.

New router bit, accidentally it nibbled. Lesson learnt, wear protective gloves.

I will say this loud and clear so there is no mistaking this

ABSOLUTELY DO NOT USE GLOVES AROUND ROTARY POWER TOOLS/EQUIPMENT

Wearing gloves will make any potential injury severely worse. Think Chinese Finger Cuffs. Now imagine your hand in one of those and a blade spinning at 25,000 RPM coming in contact.

My Dad made this mistake when running a bench jointer and finishing an edge. The glove tip got caught in the blade and pulled his hand into the blade. Luckily, it jammed the rotor and stopped it before taking off his finger. He has a scar to remind him of this incident.

No gloves. Not around table saws, circular saws, routers, jointers, band saws, jigsaws, drill presses, hand drills, really any high-speed rotating tools of any kind, and I mean any kind. That is a serious mistake that you will eventually pay for.

The answer is to pay attention and respect the tools.

 

[Turbo's Aquatics Verified Sponsor]

Humidity is 80 percent, temp 27 deg Celsius. mix was DCM 95%, Acid 5 %
Why am i getting blobs squished out? Also tiny miny mo bubbles in there, not a lot by many.

Answered on other forum, but your humidity and temp are too high. Below 74F for sure, and no more than 50% relative humidity, otherwise any solvent drying on a surface will turn it white.

I can't really tell from your pics, they are not in focus, but it looks like the joint turned white too. May not be bubbles

 

[TherealplexiG]

I can't really tell from your pics, they are not in focus, but it looks like the joint turned white too. May not be bubbles

 

[TherealplexiG]

Next gave it a try on plexi sheet, using 0.4 mm pins, when i wicked it didnt flow well into the joints, i had to wick it from both the sides, got some air trapped in, and while i pulled the pins, it didnt flush out. It eventually did mess the whole thing. But i'm never going to give up until i get it straight.
some pics...

 

[TaylorPilot]

If you are referring to finish routing the 1.5" edge of a 20" x 1.5" long piece by using the technique of passing the part between a fence and the bit: No, do not do this. In general, you need a certain width compared to the length in order for that technique to be effective, or else you get what you experienced - the part wobbles. This is highly dangerous to try, so just don't. instead, double-stick-tape another piece of acrylic and use a flush trim bit to get your 1.5" edge where you want it.


I will say this loud and clear so there is no mistaking this

ABSOLUTELY DO NOT USE GLOVES AROUND ROTARY POWER TOOLS/EQUIPMENT

Wearing gloves will make any potential injury severely worse. Think Chinese Finger Cuffs. Now imagine your hand in one of those and a blade spinning at 25,000 RPM coming in contact.

My Dad made this mistake when running a bench jointer and finishing an edge. The glove tip got caught in the blade and pulled his hand into the blade. Luckily, it jammed the rotor and stopped it before taking off his finger. He has a scar to remind him of this incident.

No gloves. Not around table saws, circular saws, routers, jointers, band saws, jigsaws, drill presses, hand drills, really any high-speed rotating tools of any kind, and I mean any kind. That is a serious mistake that you will eventually pay for.

The answer is to pay attention and respect the tools.

I didn't notice the part about it being 20" long. The longest I do regularly is about 7-8"

 

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And while we're talking about safety, take off all jewelry and pull back your hair if it's long. I do a lot of woodworking as well and always put my hair in a pony and remove my rings, necklaces and bracelets. hearing and eye protection too - always! wood is bad in your eyes but acrylic is worse.