Acrylic Fabrication Q & A

[Matthias7]

Acrylic is 3/8 and the bit I believe 1/2 inch. Very close picture

 

[cromag27]

hard to say if you'll have issues with that finish. i personally like mine more smooth. for 3/8" i use a 1/4" plastic-specific bit and 3 passes (half the diameter of the bit).

 

[Matthias7]

Can you provide a link to the bit you use? Thx

 

[cromag27]

this is just one of the few i use:

https://www.amanatool.com/51404-k-s...x-3-4-x-1-4-inch-shank-up-cut-router-bit.html

 

[Matthias7]

Awesome ty

 

[imustbenuts]

Edges prepped with my router. Do they look good enough?

I see a wave in the cut. Was this cut made against the fence pushing into the bit? If so, I think they showed in the thread to set up a negative cut. The straight edge is moved away from the bit the distance needed. The cut is made opposite the fence/straight edge. I like to use the spiral upcut bit as well. It is a little smoother cut. When i get close to the final cut I only shave it and run it through a couple times to make sure all the panels are the same size.

 

[cromag27]

My bad, thought this was cut with a cnc. Disregard what I said about passes.

 

[Matthias7]

I see a wave in the cut. Was this cut made against the fence pushing into the bit? If so, I think they showed in the thread to set up a negative cut. The straight edge is moved away from the bit the distance needed. The cut is made opposite the fence/straight edge. I like to use the spiral upcut bit as well. It is a little smoother cut. When i get close to the final cut I only shave it and run it through a couple times to make sure all the panels are the same size.

I did not think about doing a negative cut I should have would have made they setup much easier. What specific advantage does this provide to cut?

 

[Turbo's Aquatics]

For a router table, I use this for all edge prep
https://www.lowes.com/pd/Bosch-3-4-in-Carbide-Tipped-Straight-Bit/1081969

I like to use the spiral upcut bit as well. It is a little smoother cut.

I recall being told to avoid spiral bits for edge prep. One reason is that they tend to pull the material into the bit, so it's a bit trickier to get a final finish without a bump/dip. They really should only be used for flush trimming or pattern cutting. Not to mention, that's a really $$ bit to use for edge prep, JMO

If so, I think they showed in the thread to set up a negative cut.

I can't say I've heard specifically of this term actually...but you describe it correctly, you are passing the material between the fence and router bit

I did not think about doing a negative cut I should have would have made they setup much easier. What specific advantage does this provide to cut?

Definitely do a negative cut. The specific advantage is related to perfect squaring and paralleling. When you do a negative cut, you know that the two opposite edges (fence and bit) are going to be parallel. so you only need to square up one corner, and then you can make the other 3 square by negative cuts.

Being as perfectly square as possible is critical for the end panels. Having 2 perfectly parallel edges is critical for the front/back panels.

 

[rbarr110]

Edges prepped with my router. Do they look good enough?

I would still give it a light scraping before trying to weld it.

 

[Elder1945]

I use spiral bits on acrylic .




If you are using a router table your best bang for your buck is the cutter @Floyd R Turbo recommended. It gives a perfect edge.

 

[Turbo's Aquatics]

For CNC, yes. For hand passes on a router table, straight cutter.

 

[Tobbe]

i might missed it as its a long tread and old and slow head
i have used acetone to weld acrylic then i made skimmer stands, frag racks etc as cement used in states in more or less impossible to get here
is it any problem to use acetone? as i got it to fuse rock solid
thanks for great tread and info

 

[Turbo's Aquatics]

I seem to recall that MEK is one of the things you can use to weld acrylic in a pinch, but I'd have to do some digging.

Are you saying that you can't get high-grade Methylene Chloride in Sweden? MC is used as an industrial solvent in many cleaning products, I think you would have a very difficult time banning that from being publicly available.

Maybe the Weld-on / Sci-Grip commercial products, those are even being targeted here as well, but MC I can get that from a chemical supply company any day. You want to get the highest purity you can, that might be your stumbling block. If you can also get a small amount of Glacial Acetic Acid (Glacial = pure) then that's all you really need (5% AA to 95% MC, good to go)

 

[Matthias7]

Perfect I will the material through one more time using a negative cut. I appreciate the advise

 

[Tobbe]

I seem to recall that MEK is one of the things you can use to weld acrylic in a pinch, but I'd have to do some digging.

Are you saying that you can't get high-grade Methylene Chloride in Sweden? MC is used as an industrial solvent in many cleaning products, I think you would have a very difficult time banning that from being publicly available.

Maybe the Weld-on / Sci-Grip commercial products, those are even being targeted here as well, but MC I can get that from a chemical supply company any day. You want to get the highest purity you can, that might be your stumbling block. If you can also get a small amount of Glacial Acetic Acid (Glacial = pure) then that's all you really need (5% AA to 95% MC, good to go)

Thanks i will call around again to sort it, but is it problematic to use acetone as the stuff i made have hold and looks to get a solid weld i used a syringe and injected in the seam any advise to stop using this?
many thanks for your time and knowledge

 

[imustbenuts]

For CNC, yes. For hand passes on a router table, straight cutter.

The problem I ran into with a straight edge bit was chip out. I didn’t seem to have any issues with the spiral bit when I used it.

 

[Elder1945]

The problem I ran into with a straight edge bit was chip out. I didn’t seem to have any issues with the spiral bit when I used it.

When we trim acrylic we use 1 flute spiral endmill.. These are a pain and overpriced at bigbox hardware stores. The flush cut bits work just fine just need to be sharp and find the right feed speed.

 

[Turbo's Aquatics]

The problem I ran into with a straight edge bit was chip out. I didn’t seem to have any issues with the spiral bit when I used it.

Can you explain? I've never really had an issue with chipping. The last few passes should be paper thin

 

[Elder1945]

Still unnecessary for almost every aquarium, since you don't need to use 2-part when solvent will do up to 2" thick just fine, and when you're that big, you're not annealing usually because of the sheer size of the build (which would require one of those ovens like ATM uses)

My point is that for the average hobbyist or even the average to above average tank build, annealing is really not needed.

I'm not sure why 2-part is used so extensively in the EU or Far East, do they just not have access to Methylene Chloride?

Slowly reading through thread , We use 2-part as it takes less time to train someone how to use it. When you get into the hundreds of items it is not practical to train everyone. I have a manager mix and check seams she can check over quite a few items before they dry. Make adjustments or save items. We have a failure rate in the 1-2% that gets trashed before finishing. This would include excessive bubbles, Improper jig placement, Dropping (yes people drop stuff all the time it is quite annoying).

We also find the finishing work takes less time when using 2 part. We use metalized tape to protect the acrylic (the tape use use for duct work). When this is placed properly there is almost no bleed so less polishing/finishing on items made.

As for the Annealing.. You are right ATM does not do this.... This was quite apparent in peters tank.. .. No one anneals in this hobby that I know of. I have only seen this working with submarine domes and some work that NASA wanted done.