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Love your enthusiasm for such a DIY project!

But:

The overwhelming power draw for a EUC is wind resistance. So a treadmill will in no way give meaningful range numbers.

You would actually have to ride that fast, or own a wind tunnel that matches the treadmill speed while you ride on the treadmill (the wind resistance is mostly from the rider). A treadmill alone won't tell you anything useful about range. You can merely measure your rolling resistance, which is the small part of the overall power usage.

Edited by meepmeepmayer
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Love the concept and analytics of your treadmill. When I use to experiment with EUC related gadgets a prototype relating to your idea did emerge from my mad lab.
 

If you can can build one for $50 I say go for it. :thumbup:  FYI, I used parallel bars to maintain my balance. 

 

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57 minutes ago, Rehab1 said:

Love the concept and analytics of your treadmill. When I use to experiment with EUC related gadgets a prototype relating to your idea did emerge from my mad lab.
 

If you can can build one for $50 I say go for it. :thumbup:  FYI, I used parallel bars to maintain my balance. 

 

Somehow this reminds me of the coyote and roadrunner acme gadgets aka @Rehab1s contrapments 😉 

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1 hour ago, meepmeepmayer said:

Love your enthusiasm for such a DIY project!

But:

The overwhelming power draw for a EUC is wind resistance. So a treadmill will in no way give meaningful range numbers.

You would actually have to ride that fast, or own a wind tunnel that matches the treadmill speed while you ride on the treadmill (the wind resistance is mostly from the rider). A treadmill alone won't tell you anything useful about range. You can merely measure your rolling resistance, which is the small part of the overall power usage.

Agreed .. such an EUC treadmill does not allow for wind resistance portion of energy consumption to be individually adjusted .. it's just a controlled load.

Riding outside is very far from controlled conditions .. The only way I can think of for controlled wind resistance testing .. all require a much more expensive wind tunnel.

 

Fortunately other people have already paid for that kind of wind resistance CdA information.

Depending on rider size (some are bigger than others) and body posture of course.

See attached CdA from professional wind tunnel testing.

 

The other part that will be shown from such EUC treadmill controlled testing , is about the EUC itself .. under __ watts of load one gets __ wh out of it .. energy wh is the capacity to do work .. soo , in the real world , part of those wh will go to wind resistance , some goes to rolling resistance , gravity , lights , sounds , radio , electronic losses , etc .. but such testing still allows for measuring the wh output (no matter what it will be spent on later).

Electronics have efficiency curves .. and batteries also have an efficiency curve (aka Wurburg equivalent circuit) .. one gets different total wh output at 300w rate than one gets at a 1000w rate from the same battery.

The 5Ah LG 21700 cells (used in the V11) have been tested by others already .. attached are some tests others have done .. I could always do my own tests as well .. but that would be a separate thread / project .. in any case .. we can use the battery cell data (for whatever battery cell a particular wheel is using) to account for the battery side .. any significant difference in performance from the batteries alone comes from the EUC's own efficiency (electronics and such).

For example if batteries alone give 1.4kwh under constant __ watt load .. but under that same __ watt load of use the EUC being tested only gives ~1.2kwh output .. then the difference (roughly ~200wh in that hypothetical example) was spent by the electronics themselves.

https://lygte-info.dk/review/batteries2012/LG 21700 M50T 5000mAh (Gray) UK.html

 

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Edited by IamIan
phrasing
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8 hours ago, Rehab1 said:

Love the concept and analytics of your treadmill. When I use to experiment with EUC related gadgets a prototype relating to your idea did emerge from my mad lab.
 

If you can can build one for $50 I say go for it. :thumbup:  FYI, I used parallel bars to maintain my balance. 

 

OhMyGod! That is just amazing, REhab1. Thank you for sharing that, though it makes me feel like I I need to get to work on something — anything!

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4 hours ago, Yellowjacket said:

OhMyGod! That is just amazing, REhab1. Thank you for sharing that, though it makes me feel like I I need to get to work on something — anything!

Thanks. It was fun while it lasted.:) 

 

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My 2 rollers came in .. $33.36 so far spent.

I got some scrap (drops/trash) 18mm plywood from work. just big enough to cut down to 8" x 8" squares. Then I cut those into 8" diameter circles. I used my table saw .. There are lots of other (better) ways to cut out circles , but it was easy and done .. Gave me 2 stacks that are ~5" thick each (more width than I'll probably ever need for any EUC tire). That leaves me about ~1" clearance on each side of the ~7" roller.

The building facilities manager at work (a friend of mine) made me a set of brackets for the rollers out of some of his metal scraps .. they are just a basic steel angle thick enough to handle the torque , with a hex on one side (for the roller to fit into) and a bolt/screw hole on the other to attach the bracket to a stand/fixture .. one can of course just buy such brackets ready made .. but I think they charge too much for them, considering how basic and simple of a thing they are to make for far less$.

 

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8 hours ago, Yellowjacket said:

Rubber tracks?

Yes.

7 hours ago, IamIan said:

My 2 rollers came in .. $33.36 so far spent.

I wish you much success on this project. Like Yellowjacket stated this will be fascinating project to watch come together..

Edited by Rehab1
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The rollers are about ~1-15/16" OD.

I used a 1-7/8" hole saw bit to drill the center ID out .. using the same center pilot hole I used for cutting their ~8" OD.

A little light sanding , and they pass the hand snug dry fit test.

 

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A firmer seat on the inner roller could be achieved if I cut each disk in half .. and used tite joints to snug down each one on the ID.

 

but ..

Being a little lazy , I thought I would just try to glue them as is.

I lightly sanded/scuffed (then cleaned) the smooth roller surface .. for better glue adhesion.

To minimize the loss of ID epoxy while sliding disc onto roller .. 1st disc to center , then each disc after slide onto each side.

Apply ~2oz JB cold weld epoxy to ID .. $5.68

Apply ~7oz TB-III wood glue between each disc .. $4.18

Clamp together .. let cure over night.

A little out of balance .. would have been more 'true' if I had used a drill press for ID.

It might be ok as is .. But I think I might sand / balance the OD a little.

Total Thus far $33.36 + 5.68 + 4.18 = $43.22

 

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I'm using scrap/waste plywood/wood from the carpentry company where I work on this project .. Other people might have to pay for some of these bits (raising the project cost some for them) , but there are plenty of common fairly low cost suitable materials .. and it doesn't have to be these specific materials , other materials might be better in one way or another .. I'm using what's free to me, that I think will work.

 

I cut out some scrap wood pieces for the wood base .. with ~8" OD rollers , I needed more than 4" of base height to clear the roller to floor .. 6pc 3/4" thick each ~4.5" overall .. because the L bracket has some height from roller center as well , I probably can go down to 5pc thick instead or 6 .. Hardwood drops should be plenty strong enough for any load I'll put on them .. I don't think I will need it .. but if needed I can add weights to front and back cross pieces to anchor the base down more.

I'll probably nail or screw the pieces together tomorrow.

 

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Edited by IamIan
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You definitely have my attention. Waiting to see how your masterpiece actually functions. :popcorn: 

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19 hours ago, Yellowjacket said:

A dyno for EUCs. Very cool.

I am more interested in the project itself than the outcome of testing. 

 

However

 

I do think using the data to factor in wind resistance will work here. 

Question is how do you cruise control?  OP mentions manipulating the rollers so the device stays at a specific speed. This will need to be overall precise so must keep speed precise. Hook into some sort of vice contraption that holds the tilt at a predefined speed?  Very interesting...

Edited by EUChristian
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3 hours ago, EUChristian said:

Question is how do you cruise control?  OP mentions manipulating the rollers so the device stays at a specific speed. This will need to be overall precise so must keep speed precise. Hook into some sort of vice contraption that holds the tilt at a predefined speed?  Very interesting...

Might not need to stay at a constant speed.

Would setting up some sort of measurable resistance and then going to full acceleration with a full battery tell us anything? I'm thinking about a belt from rollers to an alternator, and a recorder of power generated over time. Perhaps could be used to compare two wheels, with the caveat that individual wheels will vary.

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I lowered the height a little .. 1.5" (two 3/4" blocks) .. Still has about ~1/2" bottom clearance.

Soo, a total of 4blocks x ~3/4" = ~3" raising the side roller brackets up will provide clearance up from ground for a ~8" OD roller.

I settled on screwing it together .. might take another day or two.:rolleyes:

 

3 bit tip for anyone else:

If you ever decide to work with a wood as hard and dense as IPE .. even if they are free drops given to you for a EUC treadmill.

1> Nails do not work very well .. steel is too soft and the nails bend constantly .. you have to pre-drill every hole.

2> If you want screws or nail heads to finish flush to the surface .. you can not rely on the nibs of flat head wood screws to cut into the material enough .. nor can you rely on just hammering the head of a nail flush into the wood .. you pretty much have to pre-countersink all the holes.

3> Corded drills might be better to use .. as battery powered drills burn up their charge quickly when working so hard .. forcing you to wait while they recharge.

 

 

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Many Battery Charge cycles later slow progress continues .. 20/20 hind sight , I think a wood as dense and hard as IPE is overkill for this .. I think other easier to work with woods would be adequate for the compressive and shear strength needed .. especially for cheapie old cordless drills like mine.

I've Pre-Drilled , counter sunk , and screwed in all the pyramid like build ups .. 2 screws on each to lock in and prevent any possible rotation.

I've Pre-Drilled and counter suck 2 holes each side of the cross / support front / back pieces .. I I'm using bolts and nuts (wing nuts for now) on those because that is about the two sides come together onto the axle of the two rollers .. I could have screwed them as well , but I wanted that part of the assembly to be easier to open up again if adjustments later are needed to the wheels.

During down time waiting for drill battery to charge , I used my dremel to make a notch for each of the roller brackets .. might be overkill .. but I thought I had the time , and it would help lock in the bracket , preventing it from being able to rotate on that one bolt it anchors down with , if such a rotational torque gets applied to them.

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Edited by IamIan
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Finally got the last of the pre-drilling and countersinking done .. the 4 main roller brackets.

The bottom under sides counter sinking means that the entire base lays flat on the ground.

Basic assembly is now complete.

Although , it would probably work as is .. I'm just not happy with the slight imbalance , from my hand drilling , and hand (straight by eye) assembly .. I think I want to try and balance both wheels a bit more as my next step.

I am just a novice , just fumbling / tinkering through .. a skilled carpenter would have no doubt had this all start to finish done in just a few hours.

 

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2 hours ago, IamIan said:

a skilled carpenter would have no doubt had this all start to finish done in just a few hours

If, and only if, they had access to the correct tools! Battery powered hand drills and dremels are much more challenging for precision work. As was said (jokingly) long ago at the kite factory: hammer to fit, paint to cover.

Edited by Tawpie
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On 2/10/2021 at 4:52 PM, IamIan said:

Real world anecdotal riding examples include too many uncontrolled variables .. changes in ride weight , changes in tire PSI , changes in speed , changes in terrain , changes in  operating weather (temp , wind , etc) , changes in elevation , changes in SoC , etc .. etc .. the same device can get significantly different results reported.

Local gym type human walking treadmills max out 15-20MPH .. and still need to do the side to side balancing.

I'm considering making a small EUC specific treadmill to measure in a more controlled way the usable range vs various conditions , for an EUC .. not crazy science lab , or rolling road in a wind tunnel kind of level .. just something basic that can get more controlled repeatable results .. controlled speed , controlled tire PSI , controlled weight / load.

I estimate I might be able to build such basic one for less than $50.

Some bearings that can handle the weight / load / RPMs , a little jig (made from scrap wood) to help balance the side to side.

Grainger sells Item # 24K727 .. $16.68 each ... it's a replacement roller for industrial conveyor systems .. ~7" wide roller surface .. ~1-15/16" OD .. each one is rated to hold up to 1,760Lbs (more than would ever be needed for EUC testing) .. and up to 2,000 RPMs .. at up to 220F.

Back of napkin math .. I figure if I aim for about a ~8" OD wheel to fit onto the roller .. 8xPi = ~25.13" Circumference x 2000 RPM = ~50,265" / m x 60 = ~3,015,928"/hr / 12 = ~251,327 ft/hr / 5280 = ~47.6 MPH maximum (faster than I will ever ride) .. if someone wanted to test even faster than that .. all they would have to do is just make one with a bigger OD.

Two such rollers with EUC in the middle might let the EUC self balance itself in that forward - backward axis , and the up - down axis .. only remaining axis balance needed would be the side to side.

 

pretty neat. Reminds me of the old treadmill back in the day. Basically a human powered conveyor belt. When running the treadmill meant... pushing the mat. I had a test roll device made up for mine, that looks similar to what you're doing. Fun project, but i think mine made it into the burn pile. All you need is an adjustable stand/clamps for width/height/tilt and a friction modifier by belt, to make the wheel earn it.i guess you could always tilt the entire device rather than just the wheel pedal clamp support.

Edited by ShanesPlanet
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