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[Wet Thumb Forum]-Definitely alpha (long)

1K views 6 replies 4 participants last post by  Josh Simonson 
#1 ·
While working toward my DIY canister filter idea I have been experimenting with different materials and techniques. I thought I'd throw out some pictures of different things I've tried. I'd like to get comments on ways to improve what I'm doing or better ways to do the same thing.

I'm working with 4 inch schedule 40 pvc pipe and 3/16" pvc sheet. Right now the pipe I'm using is the basic cellular core stuff used for sewer pipes. The pipe is light and plenty strong, but cut surfaces are rough because the inside of the pipe wall is foam. I think to get a smooth cut I will have to get solid pvc pipe. Solid pvc pipe is used mostly for large water lines, so it's hard to come by in small quantities. I may have to buy 20 feet to get any at all. I'm trying to avoid using standard plumbing fixtures because I don't want the end result to look like a sewer line.

The first pictureshows an assembly that includes most of the details I've worked on. Two sections of pipe are joined together by two door hasps. The joint between the two pieces of pipe is a seal. A filter would be built similarly, but it would be 14" to 17" high and (obviously) it would be closed at both ends.

The second picture shows the two sections separated to show the seal. I cut a deep groove into one section using a 1/8" single-flute router bit and seated a 1/8" cross section Viton O-ring in the groove. The opposite side is cut to fit into the groove. When the hasps are latched down the top part seats against the O-ring. This seems to work in theory but has several problems in practice. First the Viton (aside from being expensive) is probably firmer than it should be. I might use a Buna-N or (if I can find it) silicone o-ring. Second, the cut surface is a little rough. A cut on solid pvc should be smoother, but I don't know if it would be smooth enough. That's why I think it needs a softer and more forgiving o-ring. Last, the door hasps work great, but they are very difficult to adjust. Once the last screw hole is drilled there is no way to loosen or tighten the joint. If the two hasps aren't evenly adjusted the seal doesn't work right. Does anyone know of a different kind of latch that might be used?

The third picture shows an alternative to the first seal. It is just a rabbet cut into each side so the pipe fits together. The seal would need a gasket. So far the only gasket I've tried squeezed out of the joint as soon as it was compressed. Any other ideas?

The fourth picture shows the end of the pipe. The end is made by cutting two disks from 3/16" pvc sheet -- one the same size as the inside of the pipe and one the size of the outside of the pipe -- then fusing the disks together with solvent cement. To make the disks I cut squares from the plastic sheet and drilled a 5/32" hole in the center of each square. The hole fit on a 5/32 inch steel post in a jig that let the piece rotate while I cut it on a router table. The jig was also used to hold both disks in place while they were fused together. The two fused disks made a single 3/8" thick disk with a rabbet around the edge that fit snuggly over the end of the pipe. The disk is fused to the end of the pipe with solvent cement. The hole in the middle of the disk can be plugged with a piece of 5/32" pvc stock The hole can also serve as a pilot for a large hole drilled for a fitting.

The piece shown is my only attempt so far. The seam between the pipe and the end leaks, but could be sealed from the inside.

The last picture shows a way I found to make pieces to thicken the inside of the pipe. This can be used where screws might go through the pipe wall or where I need something to support screens or internal baffles. I cut a 1.5" x 2.5" piece of the pvc strip like the one sitting in front of the pipe then put the plastic strip in a pot of boiling water so that it could heat and soften. Once it was hot I took it out of the boiling water and held it against the inside of the pipe (ouch! hot! hot!) When it was cool I had a plastic strip that fit exactly to the curve of the pipe.

I have still not decided whether I will a) build a submersible pump into a chamber inside the canister b) mount a power filter pump to the top of the canister or c) use an external non-submersible pump. I'm leaning toward a) because I think it might be quieter. Any suggestions?

I did try drilling and threading a hole in the side of the pipe for a 1/4" NPT fitting. It was fairly easy to do and held a brass fitting very well. I would not use brass in the actual filter. I also want to use 3/8" fittings or larger. With the larger hole I might need to thicken the wall to get a strong joint.

Comments and suggestions, please!

Roger Miller
 
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#2 ·
While working toward my DIY canister filter idea I have been experimenting with different materials and techniques. I thought I'd throw out some pictures of different things I've tried. I'd like to get comments on ways to improve what I'm doing or better ways to do the same thing.

I'm working with 4 inch schedule 40 pvc pipe and 3/16" pvc sheet. Right now the pipe I'm using is the basic cellular core stuff used for sewer pipes. The pipe is light and plenty strong, but cut surfaces are rough because the inside of the pipe wall is foam. I think to get a smooth cut I will have to get solid pvc pipe. Solid pvc pipe is used mostly for large water lines, so it's hard to come by in small quantities. I may have to buy 20 feet to get any at all. I'm trying to avoid using standard plumbing fixtures because I don't want the end result to look like a sewer line.

The first pictureshows an assembly that includes most of the details I've worked on. Two sections of pipe are joined together by two door hasps. The joint between the two pieces of pipe is a seal. A filter would be built similarly, but it would be 14" to 17" high and (obviously) it would be closed at both ends.

The second picture shows the two sections separated to show the seal. I cut a deep groove into one section using a 1/8" single-flute router bit and seated a 1/8" cross section Viton O-ring in the groove. The opposite side is cut to fit into the groove. When the hasps are latched down the top part seats against the O-ring. This seems to work in theory but has several problems in practice. First the Viton (aside from being expensive) is probably firmer than it should be. I might use a Buna-N or (if I can find it) silicone o-ring. Second, the cut surface is a little rough. A cut on solid pvc should be smoother, but I don't know if it would be smooth enough. That's why I think it needs a softer and more forgiving o-ring. Last, the door hasps work great, but they are very difficult to adjust. Once the last screw hole is drilled there is no way to loosen or tighten the joint. If the two hasps aren't evenly adjusted the seal doesn't work right. Does anyone know of a different kind of latch that might be used?

The third picture shows an alternative to the first seal. It is just a rabbet cut into each side so the pipe fits together. The seal would need a gasket. So far the only gasket I've tried squeezed out of the joint as soon as it was compressed. Any other ideas?

The fourth picture shows the end of the pipe. The end is made by cutting two disks from 3/16" pvc sheet -- one the same size as the inside of the pipe and one the size of the outside of the pipe -- then fusing the disks together with solvent cement. To make the disks I cut squares from the plastic sheet and drilled a 5/32" hole in the center of each square. The hole fit on a 5/32 inch steel post in a jig that let the piece rotate while I cut it on a router table. The jig was also used to hold both disks in place while they were fused together. The two fused disks made a single 3/8" thick disk with a rabbet around the edge that fit snuggly over the end of the pipe. The disk is fused to the end of the pipe with solvent cement. The hole in the middle of the disk can be plugged with a piece of 5/32" pvc stock The hole can also serve as a pilot for a large hole drilled for a fitting.

The piece shown is my only attempt so far. The seam between the pipe and the end leaks, but could be sealed from the inside.

The last picture shows a way I found to make pieces to thicken the inside of the pipe. This can be used where screws might go through the pipe wall or where I need something to support screens or internal baffles. I cut a 1.5" x 2.5" piece of the pvc strip like the one sitting in front of the pipe then put the plastic strip in a pot of boiling water so that it could heat and soften. Once it was hot I took it out of the boiling water and held it against the inside of the pipe (ouch! hot! hot!) When it was cool I had a plastic strip that fit exactly to the curve of the pipe.

I have still not decided whether I will a) build a submersible pump into a chamber inside the canister b) mount a power filter pump to the top of the canister or c) use an external non-submersible pump. I'm leaning toward a) because I think it might be quieter. Any suggestions?

I did try drilling and threading a hole in the side of the pipe for a 1/4" NPT fitting. It was fairly easy to do and held a brass fitting very well. I would not use brass in the actual filter. I also want to use 3/8" fittings or larger. With the larger hole I might need to thicken the wall to get a strong joint.

Comments and suggestions, please!

Roger Miller
 
#3 ·
Roger....very nice. You are definatly a diy-er. A good one too. I have a few comments but they will be jumbled and in no particular order.

For a built in pump could you use the magnetic kind like are found on HOB filters. Atleast that way you would not have to deal with getting the power from inside the canister outside.

I like your gasket/latch idea but I agree tht your carches are definate crap. A couple alternatives come to mind. First, you could make,or buy, a threaded T bolts that you then tighten down to create the seal. You would need 3-4 around the peimeter, depending on the size of the canister. I would make it so that a block is attached below the seam, I will call that part the canister. The block on the canister could be made of anything that will hold threads but the thread part should be metal for durability sake. You could epoxy threaded inserts into teh blocks, which could be made of plastic or wood, screwed and glued to the canister body. I could make up a pic if you want. I am not always great at explaining things in words
The bolt would have a threaded stud with a shoulder in it leading up above the t- handle at the top of the lid of the filter. The shoulder would bear against another block, with a hole sized so the threaded part will pass through it, attached above the seam tothe "lid". This method would allow you to use as much pressure on the seam as you want.

I like your way of building up the wall for threading into. Seems like it will work well. I would not use brass either and you should probably try to use like materials when threading for durability as well as for ease of sealing the joint.

back to the pump. Could you use my idea from before? You might try a higher quality and higher flow rate than i have. Mine is just sititng by the way until I can get back to it. One thing it taught me is that the infeed tupe must be the same size or larger than the outfeed or the pump runs itself dry. My shut off valve is useless. Atleast where it is.

You know I should pull that out and start playing wiht it again. I ran out of time for a bit and then never got back to it. hmmmmm.

As for sealing where the "lid" meets the "canister" I would try an actual o-ring. You could probably find one the corect size at home depot or such. Maybe you will get lucky and the size you need will be a readily avaliable replacement part for home water filters or something
The seal will only work well and dependably if you squish it between the top and bottom of the seam. Having it fit tightly on the sides of the rabbit won't work as well.

You might also try auto parts stores for gasket material. A liguid gasket material might also work. As far as that goes a bead or silicone would work too. Route a shallow grove in each piece, prefferably with a round bottom, adn apply a thin bead of silicone to the grove. Cover with something that the silicone wont stick to, maybe saran wrap, or maybe wax the surface good?, adn apply LIGHT pressure until it is dry. Full pressure should create a tight seal. Seems like a lot of work though. Maybe if you just used your second joint that is simple a rabbit and streached an o-ring around it, then tightened. The combination of the 2 should not leak.

Well, thats my 2 cents for know. Hope i did not ramble to much
 
#4 ·
Hi Roger,

Nice work you have there. I'm working on a DIY calcium reactor and am using a similar design as you are on this canister. I can see a couple of problems in the design shown in your second picture, mostly to do with servicing. Getting that o-ring out must be a pain and if any junk gets in there it could cause a leak.

I like your second design (third picture) the most and it closely resembles the seal I'm going to be using. Actually I did nothing but copy the seal on my Eheim canister. Here's a sketch of the cross section:



The advantage to this design is that any dirt usually gets pushed away when sliding the two pieces together, wetting the parts helps considerably. It also allows me to be not-so-accurate with the seating of the two pieces and the connectors that hold the two together. With this design, it wouldn't matter if things were a little out of alignment. It was an easy cut to make with the lathe too.

I'm actually making the diameter of the reactor the same as a 2213 canister so I can simply buy the Eheim o-rings to use with it. I hadn't thought about using these connectors, I might have to steal that idea from you


Hope that helps
Giancarlo Podio
 
#5 ·
Giancarlo,

You're right, the O-ring in a deep groove is subject to problems with grit or anything else getting on the ring. I haven't tried getting that o-ring out yet. It won't be easy.

The face seal that I think Dennis was describing might work better than what I have, but I'll have to work on it.

You can probably get about any size and kind of O-ring you want. You don't have to use Eheim parts. I checked the yellow pages here and found a shop that sells nothing but o-rings, seals, connectors and the fittings to use them. I imagine that most urban areas have such places.

I considered the radial kind of seal that you're using but didn't try it because PVC pipes aren't really very round, because the cut I get from my router it not very smooth and because I don't have a very good way of cutting the radial gland. Aside from that, it seems like a great idea
The radial seal has the big advantage that the quality of the seal isn't going to depend on the tension in the hasps.

Roger Miller
 
#6 ·
Roger,

I'm using some black PVC connectors for connecting lengths of pipe together, they are much thicker than PVC tube and also quite round. The lathe obviously makes the cut perfectly round, not sure what kind of contraption you'd need to setup to get the same cut from a router.

Otherwise squashing the o-ring between two flat surfaces is probably the easiest and most common way of doing it. Even commercial units use this method. Most use 4 or more nylon nuts and bolts to hold the two plates together. Plus the top plate can be used to connect all the hoses to and possibly mount the pump on if you choose to go external. It may take a little longer to open the canister up each time but I think it will be less work to make.

Keep us updated on the progress
Giancarlo Podio
 
#7 ·
You can rub the o-ring with some silicone plumbers grease, it will soften the rubber of the o-ring as well as provide a goop like filler around it in case the seal isn't that great.

You could also try making the bottom instead of the top removeable and just use a threaded end cap with lots of teflon tape.

Or, if you can get 4"ID silicone tubing and a pair of 5" diameter hose clamps...
 
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