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Thread: DIY RDF "2.0", The Beast

  1. #21
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    I enjoy the journey. Some people pass the time watching TV or cat videos - I build stuff. If the end result is something useful and cheaper than could have been bought, that's icing on the cake. I save money, have fun building things, and learn new skills. I could have bought one, then been at the mercy of the manufacturer for support, if they're even around when needed.
    Last edited by kimini; 02-13-2017 at 12:43 PM.
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  2. #22
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    And presto, one basic - and giant - drum. Some of the ribs aren't exactly straight but big deal. 1/2" end rings still need to be added plus making the screen clamp, but it's basically there. Now the design of the enclosure can proceed.

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    Last edited by kimini; 02-14-2017 at 11:50 AM.
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  3. #23
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    Hat off
    Cant wait to see it running

  4. #24
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    Quote Originally Posted by kimini View Post
    And presto, one basic - and giant - drum. Some of the ribs aren't exactly straight but big deal. 1/2" end rings still need to be added plus making the screen clamp, but it's basically there. Now the design of the enclosure can proceed.

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    do you think you may have twisting of the drum due to rotational torque. from you picture it looks like the ribs are very thin and flexible. if i understand correctly you are going to weld them in place but will that be enough to stop twisting.


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  5. #25
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    Some twisting torque is expected since the ribs effectively form "paddles" in the water when submerged. Since the drum will be wrapped with a large sheet of expanded stainless however, it will act as a rigid collar to resist any twisting. If for some reason there's still an issue, stainless safety wire (from the car project world) will be used as stabilizing guy wires inside the drum.
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  6. #26
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    Next is fabricating the drum ends and since they support the full weight of the drum, they'll be 1/2" thick. As wasteful as the fabrication will be, the rings will be single-piece; it's too risky making them from segments (without the precision of CNC) and expect them to end up accurately round. The cut-out centers will be used for interior gusseting. Since SeaBoard is available in different colors we whimsically decided on something more closely matching what passes for soil here.

    Though I haven't done the math, the finished assembly will weigh around 150-200 lbs. The plan is to move the basic unit into place then install the drum and lid separately.

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    Last edited by kimini; 02-16-2017 at 03:45 PM.
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  7. #27
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    I am really impressed by the attention to detail and fabrication skills involved in this project. Thank you for sharing the process with the forum.

    I am also in SoCal -- San Diego County to be precise. Let me know if you need to recruit extra muscle when it comes time to move this thing....

  8. #28
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    Thanks! We're in the north county of San Diego. We were in the San Diego Koi Club a long time back, dropped out, and are now back in it, attending when we can. I'll have to address one of the meetings, asking if there's a Paultergeist present.
    Last edited by kimini; 02-16-2017 at 06:56 PM.
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    Quote Originally Posted by kimini View Post
    Next is fabricating the drum ends and since they support the full weight of the drum, they'll be 1/2" thick. As wasteful as the fabrication will be, the rings will be single-piece; it's too risky making them from segments (without the precision of CNC) and expect them to end up accurately round. The cut-out centers will be used for interior gusseting. Since SeaBoard is available in different colors we whimsically decided on something more closely matching what passes for soil here.

    Though I haven't done the math, the finished assembly will weigh around 150-200 lbs. The plan is to move the basic unit into place then install the drum and lid separately.


    Oh Noooooooo.... You bought the Seelye Welder That is the first "professional" welder I bought as well. It works okay but you have to be VERY careful with the heating element and make sure the welder is not dropped and is allowed a nice cool down before turning off the air. Also be very careful with the stainless heat shield (I like to call it the OUCH YOU MOTHER .....ER SHIELD) because you will burn yourself many times and it really hurts. The heating element inside the welder is very fragile as well and the resistance wire will break on you without warning. This will cause little shorts inside the heating element and the hot air will vary in temp as the wires get shorted and then open back up. If you notice your welds are burning one second and not producing enough squeezout the next moment you can blame it on the heating element. Leister Pen S is my favorite welder so far and the way they route the air over the heat shield you do not have to worry about burning yourself, unless you remain in contact with it for long periods of time. If there is ANY chance that you can return the Seelye and buy a Leister I would highly recommend you do that. You may spend a little more money this way but you will not regret it.

    Good work on the RDF design though. It really is amazing what a craftsman can do with standard woodworking tools.
    Zac Penn
    904-288-6199
    Zac@DeepwaterKoi.com


  10. #30
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    Are you going to build a custom controller or do you have an "off the shelf" option?

  11. #31
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    Quote Originally Posted by Zac Penn View Post
    Oh Noooooooo.... You bought the Seelye Welder .
    Story of my life... research something to death, make a choice, make a purchase, and only then do people come out of the woodwork, "What you should have done was..."

    It was bought used yet practically new for way less than the new price, so it's here and will be used. Doing a lot of metal work, I know all about avoiding burns. It has an automatic low-airflow cutoff to protect the heating element but I never count on it. I just ordered a spare heating element, so there's that.
    Last edited by kimini; 02-17-2017 at 01:06 PM.
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  12. #32
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    Quote Originally Posted by tbullard View Post
    Are you going to build a custom controller or do you have an "off the shelf" option?
    I already built one for RDF v1.0 so it'll get transferred over to this one when the time comes. There are a couple pictures of it in the other RDF thread: http://www.koiphen.com/forums/showth...Diy-rdf/page16 in Post #318. It uses a really cool 12V 10-amp timer module that was only about $20. I'll redraw the schematic more neatly and post it in this thread when I get around to it.
    Last edited by kimini; 02-17-2017 at 01:13 PM.
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  13. #33
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    That is a huge drum! Did you do any rough calculations to determine the size of the drum and how much flow it can handle? Great workmanship by the way.

  14. #34
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    The entire design is based around a standard 4'x8' sheet of expanded metal which is used as a drum-surround, so it was known from the start that the drum diameter would be 96" / pi, or 30.56". As far as predicting the flow, there are too many squishy variables so it would just be guesses. The unit I'm running now uses a plastic 55-gallon drum with a bunch of 3" holes in it and 65-micron polyester filter cloth, cycling about every 30 minutes but I don't know the flow rate. With the far greater surface area of the new setup, I may try 40-micron filter cloth and see how it goes. The flow will be whatever it is; I'm assuming from its sheer size that we won't ever have to worry about overloading it.
    Last edited by kimini; 02-17-2017 at 03:39 PM.
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  15. #35
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    Added the drum ends:
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    Next, choosing the best seal for the drum. Ended up going with the one at right but keeping the others around just in case:
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    And attached. Bolts double as insurance that the seal adhesive doesn't break free and also attaches the end ring to the drum. The reason to add the seal at this early stage is to get an honest idea of the overall length of the drum assembly. The outer filter housing has to compress the seal but only just so:
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    Trial screen fit-up; it still needs a bit of trimming and a hinge added half way around to make filter element replacement easier with the drum in-place. The trick is figuring out how much clearance is needed to replace it without having to pull the drum out:Name:  IMG_20170218_165701.jpg
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    Last edited by kimini; 02-19-2017 at 11:22 AM.
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    Kimini,
    Your filter is coming along nicely. I do want to interject a little bit from experience, and you can do with it what you will...
    Using silicone, foam rubber, epdm, etc... as the seal of the RDF creates some complications. The rubber will require lubrication to get it rotating smoothly against the plastic. This lubrication will eventually wash away/dry up as the seal rotates and squeegees the lubricant away from the rubber. Then you have rubber on plastic, and even at low RPM's the friction buildup is more than you would expect. The seal will start to leave some rubber on the plastic similar to a burnout strip at the racetrack. Then you have rubber on rubber and the friction gets even greater. This extra friction will try to rip the rubber off of the drum at the adhesive (which doesn't adhere well to HDPE) and then tear it at the mechanical fasteners.
    You may want to look into LDPE as a seal material because it has a far less coefficient of friction and it is very pliable. I am pretty sure that is what is used on the Profidrum as a seal.

    I do not envy you when it comes time to weld all those support rids on the drum. That is going to take forever!!!!!! Make sure you have some good tunes playing while you tackle that portion of the project.
    Zac Penn
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  17. #37
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    Quote Originally Posted by Zac Penn View Post
    Kimini,
    Your filter is coming along nicely. I do want to interject a little bit from experience, and you can do with it what you will...
    Using silicone, foam rubber, epdm, etc... as the seal of the RDF creates some complications. The rubber will require lubrication to get it rotating smoothly against the plastic. This lubrication will eventually wash away/dry up as the seal rotates and squeegees the lubricant away from the rubber. Then you have rubber on plastic, and even at low RPM's the friction buildup is more than you would expect. The seal will start to leave some rubber on the plastic similar to a burnout strip at the racetrack. Then you have rubber on rubber and the friction gets even greater. This extra friction will try to rip the rubber off of the drum at the adhesive (which doesn't adhere well to HDPE) and then tear it at the mechanical fasteners.
    You may want to look into LDPE as a seal material because it has a far less coefficient of friction and it is very pliable. I am pretty sure that is what is used on the Profidrum as a seal.

    I do not envy you when it comes time to weld all those support rids on the drum. That is going to take forever!!!!!! Make sure you have some good tunes playing while you tackle that portion of the project.
    Yeah I wondered how EDPM would hold up to sliding friction. I thought (hoped?) that the combination of water as a lubricant and the seal being lightly-loaded would let it live. I'll investigate using foamed LDPE as a gasket.

    About welding the support ribs, they're a press-fit into the rib supports - I had to use a mallet to seat them then tacked them in position. Additionally, the screen also keeps them in place so they're captive with no need for welding.

    I figure the design went wrong long ago, as Zoki51 has been very quiet, no doubt being polite instead of listing out all my design flaws!
    Last edited by kimini; 02-20-2017 at 12:42 PM.
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  18. #38
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    I have done some experiments myself with Epdm foam rubber just like your design. I agree with Zac. Too much friction. In the end, I changed the design to a flat sheet of silicone rubber about 1 inch wide that rides on the inside lip of the drum. I have seen many of the professional units use this type of design. What I see is that if the strip is wide enough, the waste will glide over it and get stuck on the screen even if the seal is not perfect. Also, if you change your design, don't forget to seal those bolt holes...ask me how I know

  19. #39
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    Quote Originally Posted by kimini View Post
    Yeah I wondered how EDPM would hold up to sliding friction. I thought (hoped?) that the combination of water as a lubricant and the seal being lightly-loaded would let it live. I'll investigate using foamed LDPE as a gasket.

    About welding the support ribs, they're a press-fit into the rib supports - I had to use a mallet to seat them then tacked them in position. Additionally, the screen also keeps them in place so they're captive with no need for welding.

    I figure the design went wrong long ago, as Zoki51 has been very quiet, no doubt being polite instead of listing out all my design flaws!
    Hi, Kurt!
    I have been here from the beginning watching intently and you are doing a good job. Everyone has their own preferences in designing things and it is not my place to criticize anyone. Main thing is that youíre going to get it working in the end, how you get there is not important. Keep up the good work! Iíll be watching from the bleachers and cheer from time to time.
    Zoran

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  20. #40
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    Change of plans on the gasket, it's coming off and will be replaced with something a lot more like what Zoki51 used and what's working fine on my current unit. I was already planning to have a box sticking out the end to handle the inlet pipes so it's easy enough to add a circular hole that matches the drum inlet and adding the gasket there.

    Anyhow, the gear was added to the end of the drum and the hinge welded to the screen. The push to get the drum done is to determine the final width and diameter requirements so the outer assembly can be sized. I found out the hard way how heavy a sheet of 0.50"-thick HDPE is so the plan is to come up with the housing dimensions and let the plastics shop cut it. At $2 a cut it's worth it because it kills three birds with one stone: makes the pieces luggable, cuts them to size, and makes them fit flat in the truck. A full size sheet of SeaBoard is 54" wide so it doesn't lay flat in the truck bed, meaning it warps the longer it sits there. The plastics shop uses a HUGE CNC-controlled circular saw for straight cuts that can handle 10x20' sheets, supposedly accurate to 0.010".

    Don't worry about the comments bothering me. I learned when building the car that what doesn't do me in makes me stronger. I know there's a million ways of doing things, varying in degree of expense, ease, simplicity, weight, elegance, functionality, reliability, and probably a dozen other parameters. During the car build, if someone was getting a bit testy, saying "let me see how you did it on your your car" usually quieted things down. (I also learned to add "eligible" people to my ignore list and the out-of-sight-out-of-mind really does work).

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    Last edited by kimini; 02-20-2017 at 10:10 PM.
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