Spinningmagnets' RC Friction-Drive Build-log

Hi Spinner, did the 2 pix arrive OK, are they the ones you wanted, when you said you could do it without pix it made me think that the pix didn't arrive.
Robbo

I finished the first production version, and I am pleased with how it's turned out (pics to be loaded tonight). It looks the same as the prototype mule, but it has steel nutserts instead of tapped threads in the aluminum. Also, all the bolts now use a 5mm hex-wrench. Most of the bolts are M6 (very close in size to 1/4"), and the center bolt in the sliding slot is a larger M8-bolt, but I found an M8 that still uses a 5mm wrench.

The stems bar-cap uses bolts that require a 4mm hex-wrench, but once I tighten them down onto the cross-tube with a dab of lock-tite, they never need to be wrenched. All that is needed to attach and adjust everything on the drive is a 5mm hex-wrench.

A thought recently ocurred to me, I was wondering if anyone here would like to buy one of these? My focus has been on developing this with an eye towards selling a few units to the local college students. I have a full-time job, but I could easily make one unit per week-end.

I have also taken efforts to fully disclose every stage of the build with details and pics, so that anyone else who wants to build one of these, can make one while avoiding my R&D stumbles.

I've ordered a throttle kit from Matt that incorporates his new improvements, but AJs report on them was so positive, many other people ordered one too! Matts existing shelf stock and parts bin were cleaned out, and to make a throttle for me, he had to order more parts. I should be getting it soon, but to be frank, I have not driven my drive at all! so it is still in the experimental stage.

I have an extra drive sitting in front of me right now, but I would have to order a motor for it (your choice of available kVs) and once arrived, I would have to shorten the shaft 1/3rd of an inch and also cut two parallel flats on the shaft sides. Once thats done, and fitted, I could ship the drive.

I can also make any part of the drive as a separate piece, such as the 1.0" diameter roller with two one-way clutch-bearings, and also an optional 1-1/4" diameter (they both slide onto a 1/2" diameter case-hardened shaft). I hope to find a knurled-steel roller solution within a few months, but I can't guarantee if that will happen, so for now I am using the sticky-backed sandpaper, just as the Kepler-drives are using. I'm told it does wear out occasionally, but it is available and cheap when it needs to be replaced.

If there is any interest, I will start a sale thread and calculate the costs. My thanks to everyone, for all the generous help and advice I have recieved.

edit: I have recieved PMs of interest, so I will put together a sale-thread for the "new items for sale" section, and link it here to make it easy to re-find later. Also, I have started a sale-thread for the rollers by themselves for experimenters:

http://endless-sphere.com/forums/viewtopic.php?f=31&t=23089

Good thread Ron,
congrats on getting it all refined & built. I know how the devil is in the details & respect the effort to get to this point.
Good luck & i hope once its out there the prospects flock your way to "get some"
T

Thanks for the encouraging words, Thud. I really like this design. If somebody was already making these, I would just buy them and resell bench-tested turn-key systems to the local students.

When I showed the LBS a pic of Todds drive, I was about to buy a 9C for myself, but they sounded so interested...and now here I am! Its been fun, and I'll be glad if I just break even. Edit, added pics, I like the steel nutserts and I recommend them. If anyone wants a couple M6-1.0's to play with, PM me. I have plenty as McMaster sells them in bags of 25.

spinningmagnets said:

I finished the first production version, and I am pleased with how it's turned out ....
.... but to be frank, I have not driven my drive at all! so it is still in the experimental stage......

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As Thud said, the devil is in the detail, and you may yet find many "details" to deal with once you start to use the drive ...(but i hope not !)
I found the design , manufacture , and build off my drives to be very satisfying too, but those areas of the drive ( ESC, etc) that are not totally under my control , became sources of immense frustration ! ...and much time wasting.
Spinner, ... test your drive thouroughly, find its weaknesses (if any). It is better for you to fix any issues now , than have to deal with problems from a disappointed user in the future.
good luck.

very clever design!!

the trick is definately limiting the need of custom parts to be made, using readily avaiable parts that can be sinmply assembled!! great effort!!

what milage do you expect to get from the 6S pack?

Geared to the appropriate wheel size it would be interesting to see tests of a 10S battery to a 1.5" roller and a 700c wheel!!

spinningmagnets said:

Thanks for the encouraging words, Thud. I really like this design. If somebody was already making these, I would just buy them and resell bench-tested turn-key systems to the local students.

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Really? If I recall I was going to give you a drive for free and start working on pricing! It's all good though. I know I've been dragging my feet on getting anything into production with my design. I've been trying to get a couple thousand miles of testing done before selling them.

Looks good Spinner, I will be interested to hear if you have any sync problems, I hope not.
Good luck.

Hey, Todd! The big frustration back then was my inability to get as many steel EV warrior rollers as we would need. I expect some potential customers will still be reluctant to buy a drive knowing that they will occasionally need to put on another abrasive tape strip (customers are a funny bunch). You also sounded very busy, and I felt I was probably pestering you too much.

Either way, I have only gotten one PM about a possible sale and thats only for part of a drive. Its a big country, millions of potential customers. But, I could only handle making a few for the local college. The drive I'm making is somewhat limited in the frame choices that it will fit. If I were you, I'd market your GFs mount and drive, the fact it mounts to the rear brake bosses (possible while still leaving the rear brakes operational), it will work on over 90% of bikes made!

Edit: Todd, whenever you are able to go into production, PM me. I have to be riding what I'm selling. That's another thing customers are funny about.

I will indeed let you know when I get into full swing. I have a new design I'm playing with. Gonna hold off posting anything about this one until I test it a bit.

I think the mount I made for my gf's bike would be pretty limited on it's applications too. I still picture myself making drive pieces for people to put together themselves but from the responses I've gotten (also a very small number like you said) most people want a full drive they can just throw on the bike.

I guess my big issue isn't making them but having the time to properly answer all the questions I will get from customers. I'm kinda with you. If I could produce a couple of drives per week it would be something to consider.

I am able to spin my two motors on the bench now (unloaded, sync issues unknown yet). So far I am using a very tiny E-Sky Servo-Tester (it will eventually fit inside a black box), and a 120A ESC from Miking. The default settings work immediately upon plugging them in, without any programming (once you figure out which sockets and which orientation!), so that is handy right now.

Now that I have been draining my single LiPo brick, I had to finish up my charging system (AKA "can-of-worms"). Heres my initial charging system effort. The menu navigation is difficult, the PDF manual is confusing, and I'm having difficulty actuating the 4.1V per cell "LiLo" setting. Even for an affordable LiPo charging starter kit, I recommend several small upgrades in the thread at a minimum.

edit: my charging system died. I had cycled the LiPo brick a few times to break it in (shallow cycle, low 2A charge) and the power supply was getting very warm. When I adjusted the charger to charge up my battery using a higher 5A rate, it died halfway to the battery being charged. The PS was VERY hot (the black box in the foreground thats labeled "AC adapter 15V"). After it cooled down, it still didn't work.

Back again: hooked it up a 12V car charger, the Turnigy 7A charger is still working, the cheap power supply died when I tried to use it at its labeled rate of 5A. I will likely buy this $60 Meanwell, 23A (15V/350W)
http://epbuddy.com/index.php?main_page=product_info&cPath=5&products_id=28

http://endless-sphere.com/forums/viewtopic.php?f=16&t=23465&p=341300#p341300

I made a rear wheel stand so I could spin the wheel in my room: http://endless-sphere.com/forums/viewtopic.php?f=2&t=12303



ES member Rearengine wanted a friction-drive with some mods to fit his personal spec, so I made him one: http://endless-sphere.com/forums/viewtopic.php?f=28&t=22551#p343772 and he also wanted an ESC and a Servo-tester to experiment with, so I sold him my extra set (Turnigy 85A with added caps).



I am trying out the Miking 120A ESC (so far, only found on Ebay, http://myworld.ebay.com/mikingstore/ click on "items for sale"). It was an affordable $38 for parts and shipping [edit: they just opened a web-store 01/05/11 http://www.hobbyred.com/esc.html ]. On the down-side, there is no manual provided, and no way to adjust any of the settings. On a positive note, it worked right out of the box with the default settings. The tips came tinned, and I soldered-on the 4mm bullets and Heat-Shrink insulation. The 4mm bullet sockets came packaged with the motor.

WARNING: this ESC doesn't seem to have a Low-Voltage-Cutoff (LVC). I only stopped riding when I began feeling the power drooping. I 'thought' it was the LVC ramping down power as a warning. When I pedaled home and put on the voltage meter probes, the pack read 5S voltage! Theres a chance I may have damaged my pack by discharging it too low. Thats one of the reasons I am starting small and slow. Annoying to fry one pack, worse to fry 3 of them!



The capacitors are labeled: KZE, 35v, 1000uF, (M) 105C, 9T, NM,... and it is unlikely that they are the desireable low-ESR type. If they blow, I will get another ESC and swap in several of these caps: ( http://endless-sphere.com/forums/viewtopic.php?f=30&t=22194&start=15#p325273 )



The [very tiny] E-Sky ST ( http://www.toysonics.com/esky-servo-tester-adjuster-ek2-0907.html ) I’m trying out as a throttle worked without any fiddling, once I figured out the wiring color-codes ( http://endless-sphere.com/forums/viewtopic.php?f=16&t=23554 )



So….I’m bench-cycling the battery 3-times to break it in, and I’m about to make a long servo-wire to reach the handlebars for the ST-throttle. My plan is to get a bike speedometer this weekend, and start logging data.

Three steps forward...two steps back! Progress, but very slow. Got the $11 Schwinn speedo/odometer purchased and mounted.

The stair-traction-tape is an absolute waste. (probably works quite well on stair-steps, but...) I should have used the money to buy a good cup of coffee instead. I am trying out the thick two-sided carpet-tape and a cloth-backed wet-dry sanding belt. its definitely 'better', but I can't say 'good' until I've had a few more days on it.

I've temporarily mounted the E-Sky servo-tester as a throttle, it will be modded soon with some type of trigger and will be inserted inside a black box with a more professional-looking bar-clamp. At the moment, it has no return-spring, so, it works like a cruise control.



Finally got some speed numbers. Using the 63mm Exceed 295-kV motor, using 6S and hauling an 180lb curmudgeon around with no wind on flat ground...I got 13.X-MPH on the 1.0" roller, and 15.X-MPH on the 1-1/4" roller. This was after the initial charger voltage had burned off and the speeds settled in to a steady state.

The Exceed 295-kV was noticeably quieter than the Turnigy 250-kV, I'm sure it was because the Turnigy has a skirt bearing.

Plenty of torque, as when I tried to accelerate briskly, I could hear and feel it slipping (I may need to angle it down for a little more 'bite' when it slides into the tread). Motor and 120A ESC were barely warm. This is slower than I had calculated (anticipated 17/21-MPH), and I was hoping I could move on to finishing a box-drive. I would have loved to get 20-MPH, as most of the students here want to stay legal. Edit: I 'may' have a bad cell, which would explain why I'm getting 5S speeds from a 6S pack. I certainly abused this poor brick the last few days. I over-discharged it at least once, and my charging system is a little sad (soon to be upgraded).

The 295-kV is the fastest winding I could find in the 63mm diameter motors (the size of a coffee cup). The smaller 50mm's have faster windings (see chart here http://endless-sphere.com/forums/viewtopic.php?f=28&t=21365&start=30#p316470) so when I get some spare time, I will try one out. Hopefully, when they are driven hard, there will be no heat issues with the smaller motors.

I know I can go to 8S or 10S for higer speed, but each step up requires a more expensive ESC, charger, and battery. An 'adequate' system that 12 students buy is better for me, than a 'GREAT' system that nobody buys.

Hey spinner .. Leme know how your trigger ,and return spring works out .. I'm planning on using the turnegy ST mounted as you have , only with Velcro on the back if I can find a flat spot.. That stuff holds pretty good... Bill

Looking good SM.. but..
you have me beaten on figuring out where exactly you have mounted that servo tester/throttle . ??
which part of the bike is that ? :? :lol:
Merry Xmass, by the way 8)

Looks like a stem clamped to the end of split-bars to give a vertical handle (kind of like my CrazyBIke2 has).

Although it also kinda looks like the seattube part of some of the split frames I've seen, his saying that it is up on the bars tends to negate that. If he was welding stuff, he could've made handlebars out of two bikes like that, though,

I have some quirky preferences (handlegrips among them), not so much better, its just that they suit me. Yes you are right AW, the handles are from the back when I had this as a long-bike (which it will be again soon). Throttle dial is by my left thumb.

I have gutted the black plastic box from my dead cheap HK 15V power supply. I knew they had a bad reputation (under-age drinking, always driving too fast, smoking out behind the school gym, went to Mexico to get a tattoo...). I will add a bigger gear so that a two-inch trigger-stroke will give me a 180-dgree ST shaft rotation. I 'might' be able to use a lever from a seat-post clamp as a trigger.



The bad news is, I did fry my battery...and now I have to order more and wait for them. The good news is, that it explains my lower-than-expected speed.

Hillhater, I may have hit sync-loss for a second. I didn't have to go back to zero on the throttle for it to re-sync, but it did screech for a second with a loss of power. I had angled the drive more, so it would dig-in deeper and would slip less, and the screech happened when I tried to accelerate hard at half-speed.

The original prototype drive with 5/16 bolts instead of metric is for sale. $280 with one of two motors included.

http://endless-sphere.com/forums/viewtopic.php?f=31&t=23809

what do you mean when you say you fried the battery.

Nice, you got that Exceed going, it seems like a quality motor to me, i had mine going on the bench the other day and it did seem like a quiet enough motor. I gotta say, you have my vote for strangest handlebars of the year. I can see how it could be comfortable mounted above the cruiser bars, but below them seems awkward a little. Ah, the throttle, how to go from 270 degree rotation to about an inch of thumb motion.... I wonder if you couldn't do a plunger style rack and pinion of sorts. Similar to those toy cars you spin up with a piece of plastic with teeth on one end to spin up the rear wheels, maybe have the thumb throttle be attached to a stick with teeth on one end that rotates the servo tester gear, and instead of rotating, it plunges in and out. Or you could try to fashion one like Matt's, you know, that is if you happen to have a CNC laying around and such. :?

I really like the handlebars, SM. If my alloy tube trick doesn't work for my trike extensions will try the stem arrangement. Thanks.
otherDoc

what do you mean when you say you fried the battery

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Its "puffy", I will have to read up on those, there are some puffy-LiPo threads around here somewhere...It is 6S, I deeply discharged them to low-5S voltage by accident. The Miking ESC has a high-amp rating for a low price, but it really has no features, and apparently the LVC doesnt work. Then, I decided to charge them up (I figured it was already shot, and it might be educational)

I can see how it could be comfortable mounted above the cruiser bars, but below them seems awkward a little

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Yes, they are just a personal preference. I am getting old, and I've never really been comfortable with the conventional bike posture...especially after all those years pole-dancing at the ladies club.

Thanks, etard, for the rack-and-pinion suggestion, that might work for me. I saw some limit switch arms at work, and I may make something similar to attach a trigger to a rotating shaft, something like this

16.x-MPH on a new battery with 24.6V (I expected 20-MPH). Level ground, no wind, 180-lb rider, Exceed 63mm/295-kV motor, 1.25" roller, Miking 120A ESC, E-Sky servo-tester as a throttle.

edit: 13.x-MPH using Turnigy 63mm/250-kV motor with everything else the same as above. I now believe there's nothing wrong with the motors. They are labeled correctly as to the kV they are, because the speeds and kV scale to each other.

I shortened the power wires between the battery and ESC, as much as is practical. I made some phase-wire lengtheners, as I have read the 3 phase-wires can be as long as you like without any issues.

I get sync-loss if I try to accelerate suddenly, (screeching noise, loss of power) but if I accelerate at a gradual rate, no sync loss. I will try some hills and also different voltages and kVs, and a different throttle. I just ordered a 50mm/400-kV which hopefully will be about 1/3 faster (21-MPH?).

The Exceed motor seem to be made with more care. It was very well packaged. It doesn't have a skirt bearing, and it seems to run a little quieter than the two Turnigy motors I've tried.

spinningmagnets said:

16.x-MPH on a new battery with 24.6V (I expected 20-MPH). Level ground, no wind, 180-lb rider, Exceed 63mm/295-kV motor, 1.25" roller, Miking 120A ESC, E-Sky servo-tester as a throttle.

I will try some hills and also different voltages and kVs, and a different throttle.

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Do you have a HV ESC? EVTodd ran his CH HV 85amp @ 36v with no issues. You would get much higher mph w/higher volts just to learn what it could do in comparison to another similar design, EVTodd's.

Yes, an ESC that can handle 37V is the next step, one is on the way (slow boat from China). I am just perplexed about the speed. Maybe the ESC isn't working well (it IS a cheap model), maybe my speedometer is off (if, I didn't program it right). Rearengine reported 25-MPH from 26V on a 280-kV, which seemed a little high.

I forgot to add, I borrowed a cheap SLA set since I'm waiting for LiPo to arrive. I used a 24V bulb to drain it down to 24.6V, which is what I'm told a full 6S pack should be (4.1V per cell). Grandpa was mad when he found out his wheelchair wouldn't run. He said he needed to ride down to the clinic to get his medication, but I know he just wanted go to the casino...I'll put the batteries back when I'm done with them. I'll just have to wait until he's drunk enough to pass out, so he won't shoot me in the leg...again.