Acrylic fabrication questions? I can help!
- Thread starter JohnL
- Start date
not really, Plex G is generally referred to as Mex-Plex as it's always been made in Mexico.
Plex G should run ~20% more.
it's not just consistency. The material is prone to inclusions in the material, pitting, and any other imperfection that get's caught during quality controls. There are *zero* quality controls on this material. It's decent stuff, but it really is a "you pays your money, you takes your chances" material
Personally, I might use it for the top and bottom, but I wouldn't use it for any display panels. I simply can't sell that to a customer. You might not mind so much for a personal tank, but if you see any imperfections, they might grind on you over time and for the extra coupla hundred for the G material... well, your choice
Water jets suck for edge-work on acrylic, leave bad edges for gluing. CNC routers *can* be good, you will want to use a large diameter cutter though IMO.. at least 1" diameter, preferably 1.5" if you can. Most folks want to use 1/4" cutters on CNCs and they will simply flex too much on 1" material.
If you have a decent router table, CNCs are a waste of time for these sorts of things IME, but opinions vary. They are nice for the tops though, credit given there
It is a *very* rare case when I see CNC edges that are anywhere near as good as they are when done by an experienced fabricator on a good router table for this type of work. Going back decades in memory, I can count these occasions on one hand.James
what brand? the yellowing is due to cadmium in the material. Most, if not all US brands removed cadmium back in the '80s and early '90s, but I can't speak for imports, different rules..
James
Thanks for the sage advice James
Looks like I will be using Plex G and building a quality router table. Imperfections would gnaw at me and I can't see losing that much material to a large bit.
Rough cutting with a 1/4" cnc and then edge prep with a 1.5" dia x 1.25"L bit on router table would be ok though?
The yellowing acrylic was chinese import scrap given to me by a fabrication shop, they don't use the stuff and were just experimenting. For their purposes they have been happy with the PMACS, though they are not building aquariums and everything gets frosted.
Scott
Looks like I will be using Plex G and building a quality router table. Imperfections would gnaw at me and I can't see losing that much material to a large bit.
Rough cutting with a 1/4" cnc and then edge prep with a 1.5" dia x 1.25"L bit on router table would be ok though?
The yellowing acrylic was chinese import scrap given to me by a fabrication shop, they don't use the stuff and were just experimenting. For their purposes they have been happy with the PMACS, though they are not building aquariums and everything gets frosted.
Scott
neurosis05
New member
Ok so I have all my sides glued together and the seams look great. Now I have to bond the perimeter and base to the sides. But on some corners, the edges of pieces aren't flush. Some of the pieces are just a hair longer than others. Just enough to catch your fingernail on it. Can I just sand one side down so they're flush? If yes, how long should I wait after gluing? I noticed this before I started, and tried to sand them all to the same length, but I guess not quite enough.
When I build a vessel, I leave the front and back 1/4'' longer on both ends, ( 1/2'' ) overall.
That allows me enough material to get a nice fillet on both sides of the seam.
After the sides, front and back are welded, to the (again, oversized bottom) I then use a router with a flush trimming bit to flush all edges.
Where the bottom and sides create an odd spot for the router I have to go over it twice. No big deal.
I wait 24 hrs before I rout the edges flush.
James will have a better time line.
That allows me enough material to get a nice fillet on both sides of the seam.
After the sides, front and back are welded, to the (again, oversized bottom) I then use a router with a flush trimming bit to flush all edges.
Where the bottom and sides create an odd spot for the router I have to go over it twice. No big deal.
I wait 24 hrs before I rout the edges flush.
James will have a better time line.
neurosis05
New member
Unfortunately I don't own a router. And I'm only talking about 1/64" if that. A very small overlap. wouldn't it be easier to sand it down? I would use a sander or a sanding block to insure I don't get an angled edge.
Floyd R Turbo
Either busy or sleeping
I think there is some confusion regarding what edge you are talking about. I think peppie think that it it the edge along the joint where one panel sticks out over the other. Typically the front/back panel is a little longer so when you bond it, you leave a lip along the joint that you flush trim off. However, neurosis05, I don't think this is the joint you are talking about.
Correct me if I am wrong but I think you are referring to the corners of the pieces not lining up at the joint, where the top and bottom panels will be bonded - correct? So it sounds like you tried to make the "height" dimension of the front/back/sides all the same, but it wasn't quite perfect, so when you set the joint and lined up the panels so they were flush with each other along one joint (the bottom, for instance) the top side didn't quite line up?
If this is the case, then yes, you can just scrape the excess material off of the panel that is a hair longer with a razor blade, or by sanding, or both. This might take some time however and sanding may cause rounded edges so you have to be careful. razor blades work best IMO, but takes time even if it's only 1/64". Takes practice too. Then when you get ready to set the panel for that edge that you just sanded/scraped, that's when you'll see if you rounded edges, left a high spot, etc. You may find yourself getting the panel in position then deciding that you need to scrape a little more off one spot. You may experience this multiple times. I've been there. I've scraped, prepped, and positioned a tank for setting a seam half a dozen times before I felt it was right. 1/64" may not seem like much but it can make it a pain. This is where a good router table makes all the difference.
Take your time and do it right.
Also, if you have a choice, make the joint that does not need any additional sanding/scraping the bottom joint, as this joint needs to be the strongest because it is under the most pressure. At least that is what makes sense to me - I could be wrong. I would think that any imperfection in the 'squareness' of that panel w/r to the stand it is sitting on would make for a stress point where you don't want it.
Correct me if I am wrong but I think you are referring to the corners of the pieces not lining up at the joint, where the top and bottom panels will be bonded - correct? So it sounds like you tried to make the "height" dimension of the front/back/sides all the same, but it wasn't quite perfect, so when you set the joint and lined up the panels so they were flush with each other along one joint (the bottom, for instance) the top side didn't quite line up?
If this is the case, then yes, you can just scrape the excess material off of the panel that is a hair longer with a razor blade, or by sanding, or both. This might take some time however and sanding may cause rounded edges so you have to be careful. razor blades work best IMO, but takes time even if it's only 1/64". Takes practice too. Then when you get ready to set the panel for that edge that you just sanded/scraped, that's when you'll see if you rounded edges, left a high spot, etc. You may find yourself getting the panel in position then deciding that you need to scrape a little more off one spot. You may experience this multiple times. I've been there. I've scraped, prepped, and positioned a tank for setting a seam half a dozen times before I felt it was right. 1/64" may not seem like much but it can make it a pain. This is where a good router table makes all the difference.
Take your time and do it right.
Also, if you have a choice, make the joint that does not need any additional sanding/scraping the bottom joint, as this joint needs to be the strongest because it is under the most pressure. At least that is what makes sense to me - I could be wrong. I would think that any imperfection in the 'squareness' of that panel w/r to the stand it is sitting on would make for a stress point where you don't want it.
neurosis05
New member
Yes Floyd you are correct , the corner edges are the ones that are off. The base is flush except for one corner so that's good. I didn't even think of using a razor. I'll be sure to be very patient. Should I still wait 24hrs?
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So need a little help and some professional opinions on a tank I just bought. The tank is 86"x30"dx37.5" tall, it is built with 3/4" acrylic accept each end of the tank it looks like they used a prefabbed overflow piece for each end. The overflow piece is narrower than the 3/4" acrylic and it looks like they used small triangular pieces in each of the inside corners. I was looking at one of the seems and on the outer edge there is one section near the top that looks like it was cut short or separated slightly. I took a couple of videos that hopefully will illustrate the seam to let you know if I should brace it further or if anyone has any recommendations. They are links to a dropbox link where I uploaded the video files.
https://www.dropbox.com/s/tjmjspf8fbe2f2v/20121014_172014.mp4
https://www.dropbox.com/s/8hut8ze7l7oghjk/20121014_172124.mp4
https://www.dropbox.com/s/tjmjspf8fbe2f2v/20121014_172014.mp4
https://www.dropbox.com/s/8hut8ze7l7oghjk/20121014_172124.mp4
Honestly, I'd walk away from it. Hate saying that, but..
it's underbuilt and the joints are already failing. The tank should be built from 1" minimum and those ends are brutal.. someone's home-built tank?
You can try to reinforce it but you'll likely have issues with it regardless and simply not a tank I'd feel safe about long-term.
Wish I could say something better..
James
Yeah, was afraid you were going to say that, what is the value of the tank as it is do you think and if it didn't have these problems? I was told it was a tank done by glasscages and it had been up and running with no issues. Guess that's what I get for being trusting and buying based on pictures. Maybe that's my queue to get out of the hobby entirely instead of upgrading to a larger tank.
as is, maybe a coupla hundred. If it was done correctly - perhaps $1000-1500 or a li'l more depending on who built it. There's a hundred bux simply in recycle value of the acrylic (regrinding it)
and it may have been, I can't argue that. It's just one that *I* wouldn't feel safe about.
IMO, don't get too down about it.. we all do this from time to time. In the larger scheme of things in this hobby - no biggie
don't worry about it, move forward FWIW I don't like even thinking about the money hmmm "wasted" in a couple of my other hobbies... eek
James
Yeah, I might recoup half the money I spent on it if I'm lucky, it came with another 180g acrylic to use as a sump that appears to be in good shape except where they cut out a couple sections of the eurobracing for hang on filters and a light fixture. After losing that kind of money just makes me sick (and feel stupid for being so trusting). Not sure I have it in me to scrounge up the money for another tank of this size.
I have researched Acrylic Tank Building until I was blue in the face. This is by far The Best information you will find Anywhere on how to, and how not to build an acrylic tank.
It is all here in this thread. You will need some time to read it, and yes you should read ALL of it. But it is all here.
Check your yellow pages. You need Pexiglas -G, or Polycast. To build a vessel.
Nizz
New member
As I do agree that this thread is full of info. Just seeing if everybody uses the Garf site to get there tank builds info and general size of the acrylic since they provide it. I will be starting to build a 40 breeder and that site told me to get 3/8" acrylic. I don't plan to make the tank rimless. Just wanted to make sure if that thickness is enough before I start hunting for my acrylic manufacture.
