Drypod 2

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Oct 19, 2012
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A coincidence you should post that picture Paul. I was just pondering that very vehicle earlier. I was especially considering the pedal crank and wondering if I could or should incorporate something similar. My head should be as close to central in the canopy as I can foresee at this point. Once I'm essconced in the seat I can set the final height of it above the body. Creating a sliding part equals a body joint which would be almost impossible to seal. I'd also need to create a sliding mechanism which would add weight. The Thermhex is certainly strong enough to carry the weight of itself and canopy and won't flex much even under raising and lowering it. By making the body and canopy essentially one piece I can better seal it. I'll try to incorporate a pair of tailgate rams to pop it open with a simple strap to bring it down and a latch or two to keep it there.

I'm already having a much better feeling that this is the right way to go when compared to the Drypod Mk1. The Mk1 threw up many issues. So long as this is strong enough I currently foresee nothing unmanageable. If it's not strong enough I get a sheet of 18mm and start again. Should anyone be foolish enough to follow me here's my cutting plans. Alter the size of the seat squab and brace to suit your own seat and frame. There's just enough spare to cover most seat types.

 
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Got the seat in. Surprisingly that has taken me a good 5 hours to achieve. I expected less. You can see that the lower mount sits right above the seat bracer and why the seat shelf was so short. All the force is sent into wood mounted vertically, at it's strongest. The upper mount has a 100mm x 100mm spreader plate against the wood. I've also used some aluminium angle and stainless bolts to reinforce the seat to vertical wood joins. This may have been unnecessary but it's made me more confident of it staying together. It was somewhat less than fun getting to the rear of some bolts via the newly bored access holes as that underseat structure makes an enclosed box section. I've sat in it with the front and rear lifted slightly and can report no issues or even creaking. I appreciate that's not the same as any loading it'll get in use but it'll for now. The woodwork looks quite wide when set against the seat but it's very snug in there. Next job will be to get a rear wheel and it's suspension on and by then I may have the materials to start on the front suspension.







 
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Rear wheel part way in:-





I say part way as there's a brace to weld in between the two suspension mounting plates. As the suspension compresses it wants to move the two mountings apart. A brace between the two will go a long way to keeping the wood intact. The shock mount uses the back of the seat mount so hopefully my weight will absorb some of the load. Unfortunately this is where the wooden chassis shows it's weak side in that both mounts are central to the chassis where it's weakest. I may also need to tie the mounts in to the side panels (frankly I expect to need to).
 
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Added the main rear bracing. It doesn't look much but this really makes a massive difference to the load on the wood. Bouncing on the back the suspension seemed quite compliant yesterday. Today it's quite hard. The difference is yesterday the wood was flexing alarmingly and today it's not. I will forgo any further bracing for now though I do have plans to tie the front and rear together with some steel to stop the wood twisting. I'm now expecting that to be all that's needed.



 
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Apr 16, 2017
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Winnipeg, Manitoba
Looking good. Any plans to paint or coat the plywood, especially the parts open to the elements? I know when I built my small off road teardrop style trailer a few years ago I coated the underside with a tar like substance to water proof it. It prevents the plywood from de-laminating.
 
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I'm definitely putting something on the wood. My initial thoughts are some truck bed liner. Tough and waterproof though I'm unsure how well it'd stick to wood. I'm very open to any suggestions as my wood knowledge is pretty minimal.

I started work on the front suspension today. Oh the fun I had when I discovered the 15mm x 1.5mm stainless seamless tube I'd ordered for the pivoting parts turned out to be 15mm x 16swg. My 12mm drill bit is now fit for nothing after reaming into the tube, 16 ends worth, so the flanged bearings will fit. Guess how far I'd got before figuring out the size issue? - no prizes - too easy! Oh the joys of drilling stainless. I only ordered stainless for this as it was cheaper than mild whereas I deliberately chose stainless for the spreader plates as it just offers much more resistance to being deformed than mild for the same weight but drilling those is massively easier than reaming tube.
 
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Got one side of the front suspension fully made and the other side part finished. It's a lever arm acting on a cheapo unit with a 450LB spring with unequal length wishbones.





I've noticed that the chassis is weakest in twist and by some margin so an anti-twist tube will be needed the full length of the underside and Teed off to the front suspension hangers. It doesn't need to be anywhere near the weight of a full steel chassis but the wood on it's own isn't going to be enough. If the rider was lower in the woodwork then the twisting forces would be much less but because the seat is raised my weight has a lever to work with against the wood. Something to bear in mind if anyone considers something similar. The forces would also be much less if I dieted.

Next jobs - finish the other side and then start on the steering gear which will be push and pull levers either side.
 
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A tale of three "£$%^&**" moments today.

1. I put the BB in and realised it's not perfectly true. The least of my issues and will square up with the hammer when it's next removed.

2. I'd measured the front suspension for being installed at the very front edge of the woodwork but then in a flash of inspiration decided to move the wheels back a little to get them to take more weight. I failed to remeasure for the new higher position in relation to the wood so on attaching the wheels the front of the wood barely made it off the ground. Out with my good friend the 9" grinder and some welding later the front wheels are now attached and the suspension is functional. I'm not happy with the uprights and want to give some thought to redesigning them to bring the wheels inwards somewhat. I have a few ideas but need to flash them out.

3. I'd said that the woodwork was susceptible to twist, and it is, but the flex in the front woodwork as I sat in it on it's wheels was alarming. The top of the suspension wants to come inwards to a massive extent and without reinforcement would not last 1 minute. I've added a much more substantial anti-twist bar underneath than I was initially going to and I'll need to add some bracing inside which whilst bracing needs to clear the pedalling action meaning the bracing can't take the ideal route. There's going to be enough bracing to add up to a chassis at this rate! If I discard the suspension and mount the front wheels on a solid axle I'd not have the pressing in at the top and would only need to deal with the twist or if I bring the wheels inward somewhat it takes some leverage away from it wanting to press inwards.





 
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Winnipeg, Manitoba
Would a brace from the top of each shock mount down to the plate your BB is mounted to do any good? It would redirect the twisting force down to the floor
 
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That would be the ideal but it's also where my foot wants to be whilst pedalling. I think I'll brace along the bottom and then put an angled piece near the outside only. I have plenty of width here fortunately so bracing can be used so long as it's near the outer edge. I could have tapered the entire body towards the front but am glad I decided against that now.
I'm fairly certain I can make a much better job of the uprights and bring the wheels in much closer whilst still getting plenty of turning circle. These uprights were from the Drypod Mk1 and I've had better ideas since then. Bringing the wheels in will reduce the leverage on the suspension top mounts. I've found an inclinometer app on the phone very useful whilst sorting wheel mounting out.
 
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Axedale, Victoria, Australia
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Is it only the sides flexing or ...? I was thinking of a gusset plate on the inside face of each side, braced to the floor. You can stiffen the floor if necessary and you should be able to encroach on inside space as far as the shock intrusion without compromising pedaling feet clearance.

That 3 steps forward, 2 steps backward thing again.
 
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The sides come in and the floor bends enormously. The arc of my foot intersects the obvious place for bracing. The bracing is relatively straightforward but will need to be heavier than ideal because I can't take the ideal route as suggested therefore steel will end up in beam rather than compression / tension. The underside T bar should take a lot of that strain too but again it's being used in beam. I beefed it up from what I was intending to use when I was only expecting it to be an anti-twist bar. I'm getting to the point of having to be careful not to weld something in that prevents disassembly. One other brace that will be going in is from just forward of the seat back through the hole to the rear suspension. This absolutely has to be bolted for that very reason.

The new uprights (if they can now be called uprights) will consist of just two tubes. One for the axle to bolt through welded to one for the kingpin to pass through and will go to the side and front of the bit between the rod ends. This will bring the wheels back to a more sensible position nearer the chassis. This will remove a fair chunk of metal for once.

 
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Just acquired a new donor bike so it looks like I'm set for hydraulic brakes, a mid drive motor (and I do mean MID) and the real reason I've got it a Nuvinci N360 hub.





The rear wheel looks like it's seen plenty of rain or been in a canal judging by the spokes, so I'm hoping the hub still functions. It looks like the control shifter is awol so I'll need to acquire one. There's a 36v 250W bafang motor up front and a pair of hydraulic brakes. The current (pun intended) plan is to mount the motor (without it's wheel) under the floor at the back and use a two chain system, One chain from BB to motor and one from motor to N360. Even though it's a front hub motor I believe I can add a freewheel to it and run a central derailleur offering even more shifting range assuming it's a direct drive motor and not geared. If it's a geared motor I can't run it backwards and I'd need to to get a freewheel on there mounted to the disc holes. I know you can get L/H freewheels but they only come in single speed to the best of my knowledge. Nuvinci rate their hubs at just 350W, or 250W on a cargo bike, and my lard probably qualifies as cargo. I have read about one chap putting 1500W through one but I've also read of others breaking them with 750W.
 
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I couldn't get the donor motor to work with the donor controller. Will do some more testing of the wire integrity at another time.

As I said I wasn't happy with the uprights so I've started on a remake. I have one part done with the steering arms and calliper mounts to make. These are as simple as it's possible to be being just two tubes welded together. One to take the kingpin and the other the axle. I'll take 140mm off the track with these. They're a massive improvement and will give 40 degrees steering on the outside wheel and more on the inside.





 
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Finished both uprights. All steering arms and calliper brackets now attached to them. Steering link in. I've made a small start on the handlebars too.
I managed to make a schoolboy error in that when I'd welded the steering arms to the first upright I'd welded them in a place where I couldn't withdraw the kingpin bolt. More grinding and welding and the bolt now goes in from underneath!





 
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Finished the steering today. I'll add a carbon tube over the side rods to disguise the threaded bar. I also checked the big T bar under the chassis for how well it supports the front suspension. The answer is very well indeed as the T part runs direct to the bottom of the suspension mounts and welds solid so I think I can do without any further bracing up top. Looking at the pictures it doesn't seem like much progress for 5 hours work! I still need to cut / grind the excess off the pivot bolts. I may need to cut the mech post off the bottom bracket too as the Tongsheng won't need it for a mech but I'll wait until I offer it up as mods may be needed for clearance etc.

 
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one "maybe" issue is the threaded rod bends easier than a tube. I found using 1/2inch box tubing works great and you can adjust using a 1/2inch end wrench plus it won't bend or flex as a threaded rod will.
curious how well does the suspension work?
 
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