Thanks, though sharp-eyed viewers will note the wetness around the foot of the RDF, indicating that there are still leaks. I'm telling myself that the tiny holes will slowly plug themselves up. Yes, that's it.
Thanks, though sharp-eyed viewers will note the wetness around the foot of the RDF, indicating that there are still leaks. I'm telling myself that the tiny holes will slowly plug themselves up. Yes, that's it.
Author of Midlana, Build this High Performance Mid-engine Sports Car. http://midlana.com/stuff/book
You sure it's not from the spray bar?
Yes that's it... No, it's coming from underneath.
Author of Midlana, Build this High Performance Mid-engine Sports Car. http://midlana.com/stuff/book
Shucks! Well, good luck on the repairs.
It's not enough to worry about as long as it doesn't get worse.
Author of Midlana, Build this High Performance Mid-engine Sports Car. http://midlana.com/stuff/book
While plumbing the RDF inlets I looked under the enclosure and was shocked how bowed the bottom panels are due to the weight of the water. Frankly, I'm impressed the welds are dealing with it and should have seen this coming since there's about 1000 lbs of water the bottom panels are supporting. Probably the most straightforward solution is a bolt-on strut that runs across with a couple supports. Short term I can shove some blocks under it, though the risk is that it works well enough that I forget about it.
Last edited by kimini; 04-19-2017 at 06:09 PM.
Author of Midlana, Build this High Performance Mid-engine Sports Car. http://midlana.com/stuff/book
So I decided to deal with the bowed lower tank panels - the fear was that the distended panels could burst their welds and lead to a serious pond situation. Since the tank is elevated, fabricated "support bras" could be positioned under the floor panels yet not require drilling into them. Using the "go big or go home" method, 3" angle stainless was used since with about 1000 lbs of water, smaller material would bend.
Speaking of that, the remaining side panel (the one without a stiffening rib) has slowly warped to about 1" in the center, so that'll need help as well.
Last edited by kimini; 04-24-2017 at 10:21 AM.
Author of Midlana, Build this High Performance Mid-engine Sports Car. http://midlana.com/stuff/book
why not just set the rfd on a concrete block base
Three may keep a secret, if two of them are dead. - Benjamin Franklin.
you cant fix stupid no matter how hard you try.
The four feet are on concrete blocks. The bottom of the enclosure has two panels angled in towards each other and is raised slightly so that the tank can be fully drained if necessary. In hindsight, I agree a flat bottom would be easier, but would then require setting the finished unit on a flat and stable surface.
Last edited by kimini; 04-26-2017 at 09:48 AM.
Author of Midlana, Build this High Performance Mid-engine Sports Car. http://midlana.com/stuff/book
Two-week update:
With the filter up and running, time's being spent installing the liner in the new pond adjacent to the old one. That was done last Sunday, and on Monday I added about a foot of water so I could "manage" the wrinkles - the water saved me a lot of grief later...
Came home Tuesday and immediately checked on the pond, noticing that the existing pond level was about 6" low... uh oh, where'd it go? First, a bit of an explanation is necessary: The RDF uses a float switch to trigger a cleaning cycle. Because I'm changing the yard all around, the RDF is currently being fed by the old pond and pump, so water's being pushed to it and it gravity-flows through a moving-bed filter back to the old pond. Because the RDF is being pump-fed, that necessitates having the float switch on the inlet side where all the dirty water is, where it's vulnerable than if it were located on the clean outlet side of the drum. Well, in two weeks of use, enough algae and gunk built up on the switch that it froze it in the I-don't-need-any-cleaning-thank-you position. Sigh...
So being pump-fed and not cycling, the RDF overflowed, which isn't a huge deal. What is a big deal is that the water flowed down along the new pond's pipes, down under the new liner. So when I came home and saw the mess, I also noticed that the liner in the new pond looked a little "bloated", and that's when the light bulb went on in my head with an "Oh, ****." If it wasn't for the water already in the liner, it would have been completely floated, but with at least some downward pressure, it more or less remained in place but definitely felt "squishy" due to the water and mud below it. I used a sump pump to pull out as much water under the liner, then figured the best thing to do was to fill the new pond further to increase the hydrostatic pressure, pushing the new liner down and forcing the remaining water out from under the liner. So with that fiasco solved, the evening was done, with just in time to take this picture of our backyard mayhem. Though it looks touched-up, the pic is straight out of a Google 6P phone - pretty amazing what these weenie cameras can do when everything's just right.
PS: What appears to be a small pile of dirt in the background is actually a huge pile (one of three...), which will be pushed into the old pond once the fish are transferred to the new one. That area will then become a proper vegetable garden, watered by wonderfully rich pond water. For those who are wondering, the landscaping blocks are new to the market (Home Depot) and are enormous 6"x12"x18" 54-lb units. They should be called "birth-control blocks" because after moving a bunch of them, you don't feel like doing anything else!
Last edited by kimini; 04-28-2017 at 10:21 PM.
Author of Midlana, Build this High Performance Mid-engine Sports Car. http://midlana.com/stuff/book
The chain broke on the RDF. I knew plastic chain was a risk but thought that its 45-lb rating would be okay - apparently not. A side plate failed, causing the remaining side piece to twist the chain link right apart. Stainless chain has been ordered though its capacity is only 60-lbs. I'd have expected it to be far stronger but it is what it is.
Separately I'm going to look into why it's taking 45-lb+ to spin the drum. Being on four rollers seemingly should have kept it below that and it may be the start-up jolt that's the issue.
Author of Midlana, Build this High Performance Mid-engine Sports Car. http://midlana.com/stuff/book
Why are you using such light chain? Maybe you explained this earlier. Misumi USA has some great calculators on their product pages that have been a big help for me.
https://us.misumi-ec.com/pdf/fa/2010/p3503.pdf
Light chain, as in power-handling ability? During development, 45 lbs was more than enough to rotate the drum. Plastic chain was chosen because it would always be wet and because it's cheaper than stainless chain. Well, it failed, so now it'll be stainless, rating at 60-lbs. Going higher than that means going to a different gear tooth pattern. Calculating startup tension is far from trivial because it's: a ribbed drum with some degree of rotational resistance, partially-submerged some amount, with an unknown amount of debris in a random distribution, driven by a DC gearmotor. Couldn't plug these variables into a table!
Last edited by kimini; 05-01-2017 at 12:38 PM.
Author of Midlana, Build this High Performance Mid-engine Sports Car. http://midlana.com/stuff/book
560 lbs
Zoran
There is no delight in owning anything unshared
"We believe .....that the person who says that "nothing comes for free"
knows absolutely nothing about the power and strength of human kindness"
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Zoran, I saw that but without an explanation of what "corrosion resistant" means didn't convince me that it would hold up in water. Is this what you used? McMaster being what they are, the stainless one's already on the way, but if you used the above chain then I'll order that next time - while hoping there is no next time.
Hope all is well with you Zoran, good to see you here.
Last edited by kimini; 05-01-2017 at 06:46 PM.
Author of Midlana, Build this High Performance Mid-engine Sports Car. http://midlana.com/stuff/book
Hi Kurt.
Thank you, everything is good here, just trying to take up bushcrafting! My retirement is coming in 99 days. Hope all is well with you too.
I actually used an acetyl stainless 40 lb chain but if McMaster says it is corrosion resistant I would trust them.
When the term corrosion resistant is used it means that the material can withstand a chemical reaction and will not oxidize, therefore a less chance for rust to occur. But hopefully you won’t have to use anything other than what you have purchased.
Looking forward to your next update and great job on the RDF!
Zoran
There is no delight in owning anything unshared
"We believe .....that the person who says that "nothing comes for free"
knows absolutely nothing about the power and strength of human kindness"
< My album
This RDF is beating me up - the root problem being that I underestimated the force needed to turn a submerged drum and as a result, the chain, sprocket, and motor mount aren't happy and the chain pops apart, breaks, or derails. Chain tension caused the motor mount to distort, causing the drive sprocket to not only get out of alignment, but also decreases chain tension - both of which cause increased derailments. Also, I used a Nylon sprocket - never mind why - and it can't deal with the torque, which means the sprocket wants to slip.
It's all fixable (chain, stainless sprocket, and a proper tensioner are already on order) but because I'm transitioning from an old to a new pond, there's all sorts of kludged-together stuff that just has to last "a few weeks." While trying to get the main work done I find I'm having to babysit half a dozen other things. Seems like I go out to work on the pond for an hour but spend 40 minutes of that fixing something instead of building.
The rest of the RDF is holding up fine, though the gearmotor is likely becoming an issue. At 8 ft-lbs it's sufficient to turn the drum but has developed a fair amount of radial shaft play. I suspect it's not suited for the side load imposed by the chain and that a "real" gearmotor is going to be required.
Doing it over again I'd more seriously consider driving the drum directly with a suitable slow speed gearmotor. This would avoid all the drama with chains, sprockets, alignment, and tension, but does involve couplers, water-tight seals, and possibly a redesign of the controller.
Last edited by kimini; 05-04-2017 at 05:52 PM.
Author of Midlana, Build this High Performance Mid-engine Sports Car. http://midlana.com/stuff/book