High power RC motor and drive unit production

[swbluto]

It sometimes means "That's obvious!" (sometimes meant as in, "...in hindsight!") depending on the context and the tone.

See: O Rly.

Other times, it can be an attempt to confirm the person isn't making a joke as in, the thing said is unbelievable again depending on the context.

 

[Miles]

Thanks SW :wink:

 

[johnrobholmes]

In this context, I would say that Matt is saying "No Kidding!" to mean- Yes I agree! or Quite So!

 

[TylerDurden]

Indeed.

 

[swbluto]

With multiple alternatives, maybe Matt should be asked?

The "I agree" meaning makes sense and it seems to share some similarity with something that's obvious. At least in this case, it's not exactly a non-obvious solution.

 

[nomad85]

I want to see the 40 series motor Matt was going to post about

I have an idea to mount this drive on an xtracylcle(making it transferable to any number of bikes if my preference changes.)
I figure on using a single speed disk brake hub for simplicity and more load carrying ability(since dished wheels aren't as strong) is it possible to still use the disc brake if I put a sprocket on that side?
I'm hoping the drive could mount somewhere on the xtracycle attachment and not be in the way. My goal is a top speed of 40-45mph although I would use it at 30-35 mostly, and to be able to use my ping lifep04 pack,so no crazy high amp draw. its capable of 40Amps continuous with 60 max for a few seconds, but I would like to keep it about 15-20 amps with 45 amp spikes for acceleration. its a 48v pack. Is this possible?

here are some pics of the kit. any ideas on how to mount it would be great. I think it would be cool to have it all within the dropouts, but I think the drive is a bit to thick for that? I want to be sure I can transfer it to another bike fairly easily as I figure I'll be putting in on a recumbent when I can afford one.
http://www.kk.org/cooltools/xtracycle2web.jpg
http://store.xtracycle.com/_e/Xtracycle_Conversion_Kits/product/FR-BASE-/Free_Radical_Base_Kit.htm

Thanks,
Kyle

 

[recumpence]

Miles,

Absolutely, couldn't agree more, I love it, very true, my thoughts exactly, we think alike, etc, etc, etc,

These all mean, simply "I agree".

Kyle,

I would assume it should fit fine in the X-Tra cycle. However, the pictures aren't perfectly oriented to know for sure.

Matt

 

[etard]

Kyle,
The Xtracycle seems to be an ideal setup for Matt's kit, fit it (triangle folded) in the drop outs. As for mounting a left side sprocket, the easiest bolt on approach is the way the ICE bikers do it, by bolting it directly to the spokes. It may seem rudimentary and archaic, but this method works quite well without having to fab anything. Hopefully somebody comes up with an adapter to mount directly to a disk soon.

Matt,
I have been brainstorming to somehow adapt a quick release system to your drive and I think I might have something. If you look at the Cyclone drive, keep only the sprocket and idlers. Then mount only a toothed shaft on final stage of your drive that inserts into that sprocket to drive the chain. It seems this system would only need two bolts to dismount. Is this possible?

 

[Miles]

Miles,
Absolutely, couldn't agree more, I love it, very true, my thoughts exactly, we think alike, etc, etc, etc,
These all mean, simply "I agree".

Ok

Let me know if you need any advice on CAD.

 

[MitchJi]

Hey, Mitch and Gary want a series drive (chainring to motor with one chain, then motor to cassette with a second chain). This will make the shaft overhang from the reduction bearing kind of far. I am concerned about shaft flex. Also, the pedal sprocket on the output shaft should be the outer most sprocket and the motor drive sprocket to the rear cassette should be the inner. This would reduce the load on the shaft considerably.

Thoughts?

Matt

Hi Matt,

Now I'm worried

The pedal sprocket should be the outer sprocket for chain alignment so thats good. So the extra distance will only be about 1/2" and it will be the pedal sprocket so it might be Ok. On the other hand the additional 1/2" is doubling the length of the overhanging shaft.

If the extra 1/2" with the pedal sprocket is an issue one sprocket might be borderline.

Are there any engineers reading this who can figure the forces applied vs the shaft strength?

Use stronger shaft material?

Would the shaft be less likely to flex if it was supported over a longer distance? At the connection between the first and second stage (shaft with the big belt sprocket) has almost twice the length of shaft support. It looks like the second stage could be doubled up without increasing the overall size. Use two identical second stage pieces (the second one would be on the right side in the picture above). Then use longer shafts. The middle shaft would then have the thickness of 3 "links" for support and the final shaft on a dual stage would have 2 "links' for support. This would also make the second stage body massively stronger.

The strongest (and most complicated) option would to support the end of the shaft. This might not be too hard by doubling up the second stage but mounting it outboard (be nice to trim the thickness). They could probably be connected in the middle (between the sprockets).

 

[Miles]

Are there any engineers reading this who can figure the forces applied vs the shaft strength? Use stronger shaft material?

Mitch, it's not the strength so much as the stiffness and the additional stress on the bearing. You could use the strongest steel available and it still wouldn't be significantly stiffer - it wouldn't deform permanently, though...

 

[recumpence]

A couple things;

#1 The bearing tubes are crazy strong. They also are made one at a time and can, therefore, be cut to any length desired.

#2 Wait till you see the frame mount! It is 1 and 1/4 inch thick same as the stage two dog-bone link. The drive will be insanely strong. No problems there.

Yes, it is possible to support the output shaft on the outside. It is all a matter of how much time is needed to do it.

Lastly, width becomes an issue for crank (and ankle) clearance. Two freewheels already add width, an outer support bearing would add even more.

The drive (with one freewheel) will be roughly 4 inches wide. That is just enough to clear cranks. Part of that width is for shaft bearing support and part is for physical room to fit components.

Matt

Matt

 

[recumpence]

One last thing;

I can have Jason make some adaptors with virtually no shoulder and no set screws. That adaptor can be simply welded to the output shaft (I have a MIG welder). That would reduce the width further.

Matt

 

[lawsonuw]

Regarding freewheel adapters I'd prefer keyed with a set screw hidden under the freewheel. Another critical feature is wrench/vice flats on the back shoulder of the adapter. The wrench flats make it possible to remove a freewheel to change tooth count, etc. Keyed with a set screw is nice because it will allow the adapter to be put on backwards letting a right handed freewheel drive CW or CCW.

ACS claws makes a 12T BMX thread Freewheel. Only issue with it for me is that it's LOUD. The attached .PDF should fit any BMX thread freewheel, and offsets the teeth of the freewheel so they're centered on the adapter. The whole assembly is 7/8 inch wide. I think several of the 18 tooth and higher 1.375 x 24tpi "standard" freewheels are narrower.

Marty

P.S. Matt, It's WELL worth your time to learn an MCAD package. Parametric drawings rock! (basically as you draw you can add geometric constraints and dimensions, if a dimension is wrong, change it and everything else updates) All the packages also give effortless weight estimates. And verifying the kinematics of a linkage, range of motion, or interference is a breeze.

 

[GGoodrum]

Nice, Marty.

What is the second set of threads for, the one marked "30mm M1/26TPI"?

EDIT: Nevermind, I see now that those are the main threads to go into the FW, right? Isn't that supposed to be 1.375 and 24 TPI?

 

[boostjuice]

Nice, Marty.

What is the second set of threads for, the one marked "30mm M1/26TPI"?

EDIT: Nevermind, I see now that those are the main threads to go into the FW, right? Isn't that supposed to be 1.375 and 24 TPI?

The smaller tooth count freewheels(usually <15T) use a 30mm metric bore with a 1mm thread. This smaller bore is needed to give enough room for the bearings between the inner and outer rings due to the smaller tooth count reducing the diameter of the outer ring closer to the bore. The 1.37" x 24TPI singlespeed/BMX freewheels are the most common because most riders are happy with >15T, in fact the most common sizes used are 16T/18T. Some BMX's run 'Flip-Flop' hubs which have two freewheel mounts, one on each side of the wheel and usually the different diameters/threads. This allows the wheel to be taken off and flipped over so that a different tooth-count freewheel is selected from the opposite side. That allows riders to have two different gear ratios, low gearing for high torque in the skatepark, taller gearing for getting around town at a higher cruising speed.

BMX selective diameter Flip-flop hub and front wheel hub

Singlespeed 700C with matching diameter Flip-flop hub

Eno freewheel with dual ratios

Possibility for RHS drive?

Random inspriation

 

[recumpence]

I have gotten several requests for various adaptor designs. We should discuss them to find the best design.

I agree a keyway has better power handling than set screws, but, keyways require keyway shafts to be used. Also, a double set screw arragement is plenty on my recumbent. So, I am leaning toward no keyway.

I like the idea if a thin adaptor, but I think most people would not be happy with hidden set screws. So, I am leaning toward double set screws at 90 degrees from each other, and an exposed shoulder holding the set screws.

I like the idea of flats for a wrench or vise to hold onto. I had already thought of that myself as well.

Matt

 

[MitchJi]

A couple things;

#1 The bearing tubes are crazy strong. They also are made one at a time and can, therefore, be cut to any length desired.

2. Yes, it is possible to support the output shaft on the outside. It is all a matter of how much time is needed to do it.

Lastly, width becomes an issue for crank (and ankle) clearance. Two freewheels already add width, an outer support bearing would add even more.

The drive (with one freewheel) will be roughly 4 inches wide. That is just enough to clear cranks. Part of that width is for shaft bearing support and part is for physical room to fit components.

3. I can have Jason make some adaptors with virtually no shoulder and no set screws. That adaptor can be simply welded to the output shaft (I have a MIG welder). That would reduce the width further.

Matt

#1 Does that mean that doubling up the "links" to offer more shaft support wouldn't help?

2. I think that supporting the end of the shaft is the "if nothing else works" option. If we need to pursue it I think using an existing 'link' milled down to about 1/4" thick wouldn't be too hard to do and wouldn't add too much to the width.

3. Great! Reducing the additional length as much as possible is the best first step, which hopefully will resolve the issue. I would prefer hidden set screws, or a key slot, as compared to welding the adaptors to the shaft. If its welded to the shaft how would the sprockets be adjusted to fine tune the chain line?

I have gotten several requests for various adaptor designs. We should discuss them to find the best design.

I agree a keyway has better power handling than set screws, but, keyways require keyway shafts to be used. Also, a double set screw arrangement is plenty on my recumbent. So, I am leaning toward no keyway.

I like the idea if a thin adaptor, but I think most people would not be happy with hidden set screws. So, I am leaning toward double set screws at 90 degrees from each other, and an exposed shoulder holding the set screws.

Matt

I think we should be sure that White FW's thread all the way against the shoulder.

If there is a slot for the Key in the adaptor, plus the set screws, then the Key becomes an optional feature. I don't see any advantage to not including a slot for a Key. Thinner is a good argument for eliminating the set screws but I'm not sure its a good idea. I don't think there is any argument for eliminating the Key Slot.

If it looks like there is a need for thin adaptors it might be a good idea to have a few made with no set screws if that reduces the width substantially.

Thanks!

Mitch

 

[Miles]

I don't think there is any argument for eliminating the Key Slot.

Well, cost for a start. Also, broaching is an operation that not every machine shop has the ability to handle.

How about the option of two shallow 90deg. grooves in the gearbox shaft to match the point profile of a set screw type, or even just two flats?

 

[recumpence]

That was my thought as well. Two setscrews with two shaft flats.

I do like the keyway layout. It is just more machining to worry about and I have not found it needed on my recumbent drive.

Matt

 

[recumpence]

The ball is rolling on the FW adaptors!

It looks like $11 each for manufacturing is the final cost.

Good deal!

I am sending Jason a White freewheel for thread fitting purposes.

Matt

 

[recumpence]

More bling!

You can see CNCAdict's 40mm motor here along with some more drive pics. Also shown is the secondary chain drive adjustable idler.

I have almost all CNC machining for the first 12 drives completed. There are frame/swingarm mounts to be made yet along with the FW adaptors.

Fun, fun, fun!

Matt

 

[The Stig]

Beautiful! Amazing! Magical!
Those are some good looking parts.

 

[Miles]

8)

 

[Hangdog98]