Spinningmagnets' RC Friction-Drive Build-log

Discussions related to motors other than hub motors.
This includes R/C motors, botttom bracket, roller and geared drives.

Re: Spinningmagnets' RC Friction-Drive Build-log

Postby Hillhater » Thu Sep 30, 2010 9:28 pm

spinningmagnets wrote: The other option for designers who crave an RC-motor is to add hall-sensors and use a larger 6-FET Infineon controller,....!


SM, I have also considered this option, however,i am having trouble finding a sensored controller that will happily work on the 18-22v range and cope with the high current 60-70A, needed for these friction drives.
do you know of any ? i suspect it would be another "custom" built unit.
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Re: Spinningmagnets' RC Friction-Drive Build-log

Postby spinningmagnets » Thu Sep 30, 2010 9:45 pm

As far as controllers for the amp-load, I "think" it depends on what your build is drawing, so you may even need the 9-FET or even a 12-FET controller (even larger and more expensive).

If you contact Lyen, I'm sure he could set you up with an Infineon that will use the voltage range you need. I've been given the impression the voltage range is a minor change, but I don't know. Edit: Gwhy is using a Keywin-E-crazyman controller with $30 mods (= $55 total) on an RC motor using hall-sensors, and he sounds pleased with the performance.

I haven't done much homework on those options, once I determined that I wanted to explore the 85A ESC on a small diameter roller as my first RC project. There may be several unforseen roadblocks to using an Infineon/halls that I don't know anything about. He did mention that the lower kVs (170/130) were more doable for those units for some reason.
Last edited by spinningmagnets on Sat Oct 30, 2010 10:44 pm, edited 2 times in total.
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Re: Spinningmagnets' RC Friction-Drive Build-log

Postby spinningmagnets » Sat Oct 02, 2010 2:36 pm

My first shipment from online metals arrived by UPS, took 4 days, prices are reasonable for small pieces, I'm happy with them so far.

http://www.onlinemetals.com/merchant.cfm?step=2&id=60

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Re: Spinningmagnets' RC Friction-Drive Build-log

Postby EVTodd » Sat Oct 02, 2010 5:50 pm

Try to find a local supplier for aluminum. Any of the online places are 2 to 4 times higher than they should be. Seriously, their prices are nuts.

My local surplus warehouse says I'm their biggest aluminum customer and I know I'm even getting a bit screwed there but man, those online prices are WAY out there.
New Tidalforce friction drive build: viewtopic.php?f=28&t=28029

My Friction Drive Outrunner Setup: viewtopic.php?f=28&t=9652&start=330
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Re: Spinningmagnets' RC Friction-Drive Build-log

Postby D-Man » Sun Oct 03, 2010 10:34 am

Lowes , Home Depot, and OSH will happily screw you on metal prices.

One thing I don't see anyone talking about is that there must be something felt with a drive connected to the seatpost while your sitting on it. Maybe vibration or the seatpost fore and aft movement? Seems like that would be annoying.
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Re: Spinningmagnets' RC Friction-Drive Build-log

Postby EVTodd » Sun Oct 03, 2010 10:41 am

D-Man wrote:Lowes , Home Depot, and OSH will happily screw you on metal prices.


I didn't really mean national retail chains. I'm talking metal suppliers.

I've personally never felt the motor even though I have it mounted via seat post rack. I don't think it's a big issue.
New Tidalforce friction drive build: viewtopic.php?f=28&t=28029

My Friction Drive Outrunner Setup: viewtopic.php?f=28&t=9652&start=330
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Re: Spinningmagnets' RC Friction-Drive Build-log

Postby spinningmagnets » Sun Oct 03, 2010 5:56 pm

Yes Todd, I agree. I am in a remote region two hours from Kansas City, and one hour from Topeka, currently surrounded by beef ranches and farms (what the hell is Sorghum and Milo?). I did find a small local supplier called "Custom Cut Metal", and I was pleasantly surprised at how affordable the pieces in the first pic of this thread were. Plus not having to wait 4 days for UPS is nice. (CCM, 8989 Green Valley Dr, Manhattan, KS 66502-9005, Ph# 785-537-0441 ) ‎

The local supplier has half the stuff I wanted, and the shipping cost from Online-Metals was cheaper than the gas to go to Topeka/KC for hard-to-source bits. I'm not done fiddling around with the final design yet (now trying to incorporate the adjustable stem above), I only wanted one foot of the odd-dimension stuff.

If anyone wanted to copy what I've done so far, I think Online-Metals might be a viable option to build one drive. However, I'm sure anyone in a major city could find a better source with a little effort. Find a local fabrication and welding shop (especially if they make aluminum trailers, their recycle scrap-bin is wonderful and cheap), then just ask where they buy small orders of metal.
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Re: Spinningmagnets' Friction-Drive Build-log

Postby daveo » Tue Oct 05, 2010 2:27 pm

Kepler wrote:ESC is a bit light on. The 100 is a better choice but out of stock. (The 20 I recently bought might have contributed :oops: ) That being said, I am hammering an 85 at the moment and doing all I can to smoke it. Bloody thing wont break :twisted: I have hit the high temp limit on it a few times though.


Noobie question: If the 85A is a bit light, couldn't you just use a 80 or 100 amp fuse between the ESC and the motor to keep from cooking the ESC? Maybe like these:

https://www.vtewarehouse.com/content/electromech/fuse/html/maxi/maxifuse.php

Replacing a $0.70 fuse is a lot cheaper and wouldn't leave one stranded.
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Re: Spinningmagnets' Friction-Drive Build-log

Postby dontsendbubbamail » Tue Oct 05, 2010 3:59 pm

daveo wrote:
Kepler wrote:ESC is a bit light on. The 100 is a better choice but out of stock. (The 20 I recently bought might have contributed :oops: ) That being said, I am hammering an 85 at the moment and doing all I can to smoke it. Bloody thing wont break :twisted: I have hit the high temp limit on it a few times though.


Noobie question: If the 85A is a bit light, couldn't you just use a 80 or 100 amp fuse between the ESC and the motor to keep from cooking the ESC? Maybe like these:

https://www.vtewarehouse.com/content/electromech/fuse/html/maxi/maxifuse.php

Replacing a $0.70 fuse is a lot cheaper and wouldn't leave one stranded.


Maybe you mean between the battery and the esc. I not sure what would happen if you tried to fuse the three phase wires between the esc and the motor. Most likely nothing good. The folks at Castle Creation told me not to put a fuse between the esc and battery. They said that blowing the fuse could also blow the esc.

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Re: Spinningmagnets' Friction-Drive Build-log

Postby Hillhater » Tue Oct 05, 2010 4:04 pm

dontsendbubbamail wrote:The folks at Castle Creation told me not to put a fuse between the esc and battery. They said that blowing the fuse could also blow the esc.

Bubba


Hmm ?, i would like to understand the explanation for that statement,
I know several battery packs have fuse protection built into them as standard !
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Re: Spinningmagnets' RC Friction-Drive Build-log

Postby amberwolf » Tue Oct 05, 2010 4:38 pm

If the ESC were capable of regen, and the motor was in regen mode and not freewheeling, I could understand that if the fuse blew the voltage would have no load anymore and could spike very high, potentially damaging the controller.

The only other situation I can think of is similar, in that if the controller does not have enough capacitance to suppress the switching spikes on the input side without the battery connected, then bad stuff could happen for the same reason.

THe former is not likely, as I doubt these controllers do regen, but using a freewheel would eliminate the problem anyway.

THe latter is fixable simply by adding more low-esr capacitance.
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Re: Spinningmagnets' RC Friction-Drive Build-log

Postby daveo » Tue Oct 05, 2010 6:46 pm

Thanks for the replies. Apparently the answer is a big NO on the fuse idea. Figures. It was too simple.
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Re: Spinningmagnets' RC Friction-Drive Build-log

Postby spinningmagnets » Tue Oct 12, 2010 8:30 pm

Making progress, waiting for more parts and time to fiddle with them...



There's two things I will change on the next one. The motor is so close to the back edge, I had to install one of the motor-plate bolts with the head on the inside. I will move the roller closer to the center so the motor mount bolts (4 of them eventually) will all allow the motor removal with an allen wrench from the outside, and it won't disturb the roller.

Also, I was forced to use a chamfered flush-head bolt under the roller. After the roller is moved closer to the center, I can use the same 5/16"-18 bolts as the rest of the drive (all using a 1/4" allen wrench, the single flush-head bolt uses a smaller wrench). With the current arrangement, the roller can also be changed out without disturbing the motor.



Finished the motor-shaft slotter (similar to the scrap-wood roller-shaft slotting machine, but with two discs). I re-read Grinhills second build, and he has successfully used this style of joint after remembering that older cars drove the distributor with a similar joint. I left 'just enough' slop to allow for heat expansion between the parts. The shaft shortening and cutting the two flats went easier than expected, thats a relief...

The motor mount-plate is 1/4" thick. I tried to use 20mm long screws, but they bottomed out against the skirt bearing. I needed at least 13mm to get full thread engagement, and I was able to find some chamfered flush-mount M4-0.7 screws that are 16mm long. I am somewhat annoyed the 4 motor screws use a 2.5mm wrench, but thats just the way it goes...
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Last edited by spinningmagnets on Wed Mar 30, 2011 9:20 am, edited 2 times in total.
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Re: Spinningmagnets' RC Friction-Drive Build-log

Postby drifter » Wed Oct 13, 2010 1:08 am

Looking good Spinner, I will watch for further progress.
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Re: Spinningmagnets' RC Friction-Drive Build-log

Postby Hillhater » Wed Oct 13, 2010 1:30 am

spinningmagnets wrote:Making progress, waiting for more parts and time to fiddle with them...
...The motor mount-plate is 1/4" thick. I tried to use 20mm long screws, but they bottomed out against the skirt bearing. I needed at least 13mm to get full thread engagement, and I was able to find some chamfered flush-mount M4-0.7 screws that are 16mm long. I am somewhat annoyed the 4 motor screws use a 2.5mm wrench, but thats just the way it goes...


Why didnt you just use the alloy X motor mount that comes with the motor ?? .. complete with csk screws ?
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Re: Spinningmagnets' RC Friction-Drive Build-log

Postby spinningmagnets » Wed Oct 13, 2010 2:52 am

Xmount.jpg
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Using the stock X-mount would have been faster and easier...but where's the fun in that? Several other builds have implied that whatever the motors stator-face is bolted to will act as a heat-sink, so I thought I'd start out with an aluminum plate that was bigger than needed. I am hopeful that these parts, and the application that they will be used for will not have any heat issues. That being said, I'd rather start out too cool, and work my way towards warm.

I also had some ideas that I might explore later, concerning a fan-cooled cover to make the motor quieter. I don't know if that will work at all. Or, if it does work 'a little', whether it will be worth the effort. Thats one of the reasons for the larger plate, as a base for a cover (I can always make the plate smaller later).

edit: just remembered, another reason I attached the motor to such a wide baseplate is that I am still in the R&D phase, and if I needed to attach another motor with a different bolt pattern, I wanted to be able to swap in another motor base plate, rather than drill more holes in the side of the drive.

I also HATE the tiny phillips screws that come with it, I have already stripped one the cross-slots that the screwdriver turns, without much effort (and I was being careful). After a close examination, I now believe they are made from an unusually stiff form of butter that is covered with aluminum paint. The allen-socket screws feel much better, and it was only $1.60 for 4 of them. If I bought a box, they'd be 1/3rd that price.

On a side-note, I no longer have any reservations about the 5/16"-18 bolts I'm using. I tried to purposely strip out the threads in one hole of a 1/4" aluminum plate. Two side-by-side attached plates that had been drilled and tapped at the same time (for alignment), one hole to remain threaded.

I wanted the plate on the shank end of the bolt to have a smooth hole, but still snug to keep alignment. I had to keep side-milling the threads I had cut by using a drill bit (rather than order a 19/64" drill from McMaster-Carr). There were almost no threads at all, before I was finally able to strip the hole smooth.
Last edited by spinningmagnets on Mon Oct 25, 2010 7:55 pm, edited 4 times in total.
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Re: Spinningmagnets' RC Friction-Drive Build-log

Postby Hillhater » Sat Oct 16, 2010 12:24 am

Hey SM, you need to get off the fence and decide to go either all metric or stay "old school" .. :lol:
You are building a real "multi-national" / multi- dimensional drive there..not good in the long term ...just pick one team and support it full time ! :lol:

I used to build everything with 5/16 UNF cap screws as i had boxes of every length imaginable together with tap sets & matching "nutserts" (threaded inserts for fixing to plate /sheet or blind tubing etc.
I still have a few , but i try to stick with metric stuff now as its more readily available.
5, 6, and 8 mm is all you need on this scale of build .. and of course a full range of drill sizes..inc number and letter scales. :roll:
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Re: Spinningmagnets' RC Friction-Drive Build-log

Postby spinningmagnets » Sat Oct 16, 2010 11:36 am

Yes, my friend, I should go all metric soon. The local store has a good selection of the SAE black-oxide socket-head bolts, plus drillbits and thread-taps. If I could just stop changing the design every two days!...too many new good ideas showing up. With bicycle parts, metric is definitely the way to go.

edit: noticed today that my bikes have a lot of bolts using 5mm and 6mm hex-sockets (handlebars, seat-post, brakes, etc), so I am likely to use those in future builds.

I just hate to order a whole box of a certain bolt, then realize that a design change demands a different size. I'm just using whats quickly available until all the bugs are worked out.

With the motor mounting screws, I only meant that, I wish the wrench for them was 3mm instead of 2.5mm...much like trying to buy a 19/64" wrench. BTW, I definitely like the nutserts as an option. Fast too, drill a smooth hole in aluminum, press-in a steel-threaded nutsert. Ridges on the nutsert OD grab the hole, and once you insert a bolt and tighten it down, its good to go!

edit: I tried two nutserts on the small holes I had to drill for the longer bolts that compress the two clamps. The seat-post mount uses a 5mm wrench to install and adjust the drive, so I will use bolts on the two rotation-clamps that also use a 5mm wrench, and nutserts!
http://www.fastenal.com/web/products.ex?N=0&Ntk=Search+All&Ntt=nutsert&Ntx=mode+matchallpartial&Nty=1&searchBox=1

edit 11/01/10: A package of M6 nutserts just arrived in a padded envelope, 4 working days from their US warehouse to Kansas. The smooth part of the tube-OD is 0.388", but oddly, the ribbed portion seems to be about the same diameter? It struck me as strange for a moment, as they have recommended a 10mm drill (0.394") to make the insertion hole, and I assumed the ribs would be an interference-fit.

Went back to the web-catalogue and found that these are intended to have the neck collapse and by doing that, it expands outward into the hole (using a special tool). For that reason, the flanged and ribbed half of its length has no threads.

I collapsed one just now with just a bolt, and when this is done outside of a hole, the collapsing neck forms a thicker flange lip (0.118"). The insertion length is reduced to 0.266". The engineering drawing seems to indicate that when inserted into thin sheet-metal, the created flange sandwiches the sheet-metal between the two flanges. Or, when collapsed inside a hole thats made in thicker metal, the wall collapse forms a sideways-fold that expands outward and also inward.

I still plan to use them, but the closest drill size seems to be 10mm (0.394") so it looks like they will need a thin smear of JB / Devcon

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Re: Spinningmagnets' RC Friction-Drive Build-log

Postby Bluefang » Sat Oct 16, 2010 8:19 pm

Hey mate, those steel inserts look great. Do they need to be pressed in or can they just be hammered in? Also with your bearings, did you press them in or drill the hole big enough that they just slipped in?
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Re: Spinningmagnets' RC Friction-Drive Build-log

Postby spinningmagnets » Sat Oct 16, 2010 8:53 pm

Nutserts are installed into a smooth hole made by a drill-bit, then they tap in halfway with little effort, and tightening a bolt into them fully seats them (edit: depends on the diameter of the hole, I have found its hard to get a perfect fit). They can even be flush-head if you spot-face (make a smooth shallow recess) on the the insert side with a bigger drill bit by shaving off just a hairs thickness in depth. If you do get a single hole that was drilled a little too loose for the nutsert to grab properly, pull it back out and a smear of JB/Devcon will set the loose one for good.

These M6-1.0 nutserts call for a hole made with a 10mm drill, but that does not provide a tight fit. I have been using a smear of JB-Weld/Devcon with good success. As an option, you can put a bolt inside the nutsert to prevent collapse while you clamp the nutsert OD in a steel vice (in several places around the OD), and the rough vice jaws faces 'knurl' the OD of the nutsert just enough that they then have to be forced into a 10mm hole.

The nutserts that are made to insert into wood holes have fairly big spikes, but the steel ones that are made to insert into aluminum holes get by fine by just using some ribs (oops, see paragraph above). The nutserts cost more than common nuts (50 cents each?), but if you're only doing 5 or 6 holes and you don't have the $5 tap to cut threads (or, you don't want to risk breaking a tap, especially on a small hole), its not a bad option to consider.

With the two roller bearings, I got lucky and found a long tube in the pile ( 1.000" OD / 0.748" ID) at the metals supply place that had an ID that was 0.002" smaller than the OD of the bearings. The precise tubing dimensions vary a little from one piece to another.

I put the aluminum tube in boiling water, and the ID expanded 0.010", and at that point I could pick it up with long pliers and tap the tube onto the bearings with a hammer. You must move quickly, as once they touch, the temps equalize rapidly. Its called an interference fit. Too loose or too tight, and it won't work well.

viewtopic.php?f=28&t=21365&start=15#p313906

If I can only find tubing (in the future) that has the same ID dimension as the Bearing shell (0.750" ID -0.750" OD) I will have to glue them in with JB or Devcon to prevent slippage.
Last edited by spinningmagnets on Sat Nov 27, 2010 12:27 pm, edited 2 times in total.
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Re: Spinningmagnets' RC Friction-Drive Build-log

Postby spinningmagnets » Tue Oct 19, 2010 10:16 pm

FD_015.JPG
110mm long, Good news, it has a stronger joint than I expected!
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FD_020.JPG
95mm length Kalloy Uno from JensonUSA
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Some parts finally arrived, and I am pleased! It took 11 days from Niagara Cycle, most parts were marked “Taiwan”. Quality and strength looks very good. http://www.niagaracycle.com/

I placed a bet on the Dimension adjustable-angle stem for $28, and I think it’s a winner. It has a wide adjustable angle, but that can also be increased quite easily with a file, by cutting back the stops a little if needed.
http://www.niagaracycle.com/index.php?cPath=129&sort=2a&page=8

The three lengths listed are 95mm, 110mm, and 125mm, which is the measurement from the center of the quill-clamp (QC) hole to the center of the handlebar-clamp hole. The QC (on the left) has an Inside Diameter (ID) of 1-1/8”. You can mate the 1-1/8" QC to the common 27.2 seat-post with a $7 shim from "Problem Solvers", part # ST0214 / 27.2mm-28.6mm (or, also a tin can and a pair of shears! the wall thickness is only 0.7mm/0.027")
http://problemsolversbike.com/products/seatpost_shims/

The center of the QC to the center of the pivot is 30mm on all three choices, so the three arm lengths (center to center) are 65mm, 80mm, and 95mm. I am listing this, so that those who are interested can mock up a paper dummy before purchase.

Concerning the arm length, it has a hollow center with an oval cross-section that is 30.7mm tall X 27.8mm wide. If someone needed a longer arm, you could cut its length in two, and then epoxy (JB-Weld / Devcon) a section of very common 27.2mm seat-post to any length you needed.

The hinge-bolt is 6mm X 1.00, Standard-Thread (std), 30mm long (5mm hex-wrench)
The two QC-bolts are 6mm X 1.00 (std), 18mm long (5mm hex-wrench)
The four handlebar-clamp bolts are 5mm X .80 (std), 15mm (4mm hex-wrench)

The bar clamp is available in several diameters. This first one I chose to try is 31.8mm, the other optional diameter I am interested in is the 25.4mm (1.0”). By ordering a stem with a handlebar diameter in one of these two sizes, you can use a very common aluminum or steel seat-post in the clamp as a cross-bar ($12 new, 31.8mm here:)
http://www.niagaracycle.com/product_info.php?products_id=600559

edit: added the Kalloy Uno 95mm. The Kalloy stem-arm also has a hollow center through its length, with a circular-cross section of 0.912” diameter, and a 62mm length from center-to-center. Its QC length is 33mm CTC. Bolts are the same as the Dimension stem.

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

I want to try using two seat-tube clamps (set on the two ends of the cross-bar) that are thick aluminum with flat sides like the one pictured below, from Dimension. These clamps are $6 each, and this model is available in the 31.8mm ID that I am interested in. They are thick enough that the bolt-hole can be bored out to accept a ¼â€, 7mm, or 5/16” diameter bolt (if needed).

Niagara Cycle carries the 31.8mm unit, and JensonUSA also carries it. Jenson claims to have a USA warehouse in California, so ordering from them may be faster for US customers. Here's a link to a similar unit that also has flat/parallel sides from Sunlite, but with the smaller 25.4mm/1.0" ID :
http://www.niagaracycle.com/product_info.php?products_id=11832
http://www.bestbikebmx.com/catalog/product_info.php?cPath=23_49&products_id=786&osCsid=5226f2aebaa0f80c1db3956938e80a32

By swapping in a longer bolt, the clamp can have protruding threads that insert into the top-plate of my drive. If you want to use a larger diameter bolt in order to source a long enough bolt locally, the bolt-head may not fit inside the stock recess, so be aware the outer width of the clamp is 40mm (1.57”). The seat-tube clamping-bolt is a 6mm X 1.00 (std), 34mm long, using a 5mm hex-wrench.

As a side-note, this very strong clamp would also be useful for attaching a DIY rear cargo rack to a bike, (while still performing the duty of a seat-tube clamp), perhaps bored-out slightly to use ¼â€ all-thread rod, so threads extend on both sides.

http://www.niagaracycle.com/product_info.php?products_id=417672
http://www.jensonusa.com/store/product/SE308F01-Dimension+Seatpost+Clamp.aspx?SSAID=214987
Image

I also bought this $8 lever-clamp by Origin-8, and I am very happy with the strength, quality, and the very long handle. I plan to attach the drive to the seat-post and remove the whole drive/seat/post all together on a regular basis.

http://www.niagaracycle.com/product_info.php?products_id=431881
Image
Last edited by spinningmagnets on Mon Nov 01, 2010 8:24 pm, edited 4 times in total.
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Re: Spinningmagnets' RC Friction-Drive Build-log

Postby spinningmagnets » Mon Oct 25, 2010 2:22 pm

There are three lengths of stem-arm (if you buy this model). This is the medium 110mm length, the other two are either 15mm longer or shorter. For seat-height comparison to your bike (to see if this type of drive will fit), my pants inseam is 34" and I am 6-foot tall.

The cross-tube is a seat post (31.8mm dia), so, that is also the diameter of the stems bar-clamp, and also the two seat-tube clamps. You have the option of using one inch dia (25.4mm) for these parts. In order to get a full range of angle adjustment rotation on the square part of the drive, I had to add some 3/8" aluminum as a riser-plate under the two side clamps.

Now all I have to do is figure out the electrical half of this,...thats the easy part,...right?

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Last edited by spinningmagnets on Tue Mar 29, 2011 12:34 pm, edited 5 times in total.
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Re: Spinningmagnets' RC Friction-Drive Build-log

Postby spinningmagnets » Mon Oct 25, 2010 2:24 pm

Friction-Drives
Volt / kV-speed chart
For available 63mm motor kV's
1.0" and 1.25" roller diameters


The kV that is listed for a motor, is the RPMs resulting per volt applied. Many factors affect the actual road RPMs in use. The weight of the bike, rider, and cargo is a major factor, and also wind resistance and system friction. In the past, many have found that reducing the kV number by 15% can be a useful (though approximate) way to arrive at a calculated speed which is close to the actual resulting road-speeds.

I have compiled this chart as a rough guide to selecting a motor kV and system voltage. The top number is a 1.0" diameter roller and the bottom number is a 1-1/4" roller. LiPo and LiMn cells have a nominal voltage of 3.7V (and 4.1V when fully charged). Six of them connected in Series (6S) creates a cell-string that will have a nominal voltage of 22.2V; When fully charged, the string will have a voltage that is closer to 24.6V

Edit: I still have the original chart, but it has proven to be off some. I have developed two drive systems that both operate at arount the federal speed limit for unlicensed mopeds, which is 20-MPH (of course, the federal limit does not apply in those states where a higher speed is allowed)

Both are using the Exceed 295-kV motor. For flat land I am using 24V of SLA and the 1.25" roller, and for hill climbing, I am using 37V of LiPo and the 1.0" Roller. For the hill-climber, I am also adding more capacitors and a heat-activated air-cooling fan.

If you chose to use 44V-48V, the available kVs of the 63mm motors would provide you with a very wide range of top-speeds, with the 295-kV providing an estimated 27-MPH.
Last edited by spinningmagnets on Wed Mar 30, 2011 9:37 am, edited 18 times in total.
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Re: Spinningmagnets' RC Friction-Drive Build-log

Postby D-Man » Sun Oct 31, 2010 8:45 pm

Looks good. Got it running yet?
408 front hub
12000+ miles on sla's.
Michelin pilot sport 2.3 tires
Miles 1400
Flats 2
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Re: Spinningmagnets' RC Friction-Drive Build-log

Postby spinningmagnets » Mon Nov 01, 2010 10:08 am

Thanks! not quite yet. Like many here, my personal life is full enough that it restricts time for the things I enjoy. I've found when learning something new and testing a complex system, its best to go slow and isolate any unproven parts. Towards that, I have parts-in-hand for several affordable throttle options, but I am waiting for a complete throttle kit from Matt. That is a proven throttle system, so I'll know that if I encounter problems, it is somewhere else in my system.

If it was only for myself, I'd just buy Matts throttle and be done, but polling of my potential customers shows that many of them need a lower purchase price, and they are willing to accept a cruder throttle.

I am anxious to test out the $40 turnigy 85A ESC, as Todd has posted that his peak amp-draw on acceleration is very reasonably low. It was what I expected, and it was a relief to hear it verified. A one-inch roller on a 26" tire loads the motor like a 26:1 reduction.

I really like Keplers drive, and he has heaps of road-data. Since his motor-shell is the roller, its 2"-ish diameter should result in higher peak-amp loads than my kit, and his data led him to recommend the 100A ESC from Castle Creations (resulting in many satisfied customers!). If his 2" roller works well at 100A, I am confident that my 1" roller will be fine at 85A.
http://powerslideracing.com.au/index.ph ... 8f8a4c3b9c

I spent about a week of my spare time researching capacitors (I'm a caveman when it comes to electronics). Bigmoose, Fechter, LFP, and mwkeefer (among others) were very generous and patient with their expertise when helping me. I now believe the first 2 caps I bought will be adequate (I just copied others), and I have now added them to my ESC. Also, I have identified what I believe may be slightly better cap options based on the new info I have been provided.
http://endless-sphere.com/forums/viewtopic.php?f=28&t=21197&start=15#p325342

I have decided to try LiMn cells and make my own battery pack, based on posts by Docbass (waiting for parts to arrive). I have a brick of LiPo in-hand and I will continue in my plan to use it. I never planned to make any battery packs, but...if the LiMn packs work out well, that may prove to be a key element in selling a dozen kits to the local college students (which is my ultimate goal). I am not nervous about the added precautions with LiPo, but the college students are.
Last edited by spinningmagnets on Sat Nov 27, 2010 12:32 pm, edited 1 time in total.
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