newbie electric rider
100 W
Wow, I have been absent for a month!! Enjoying the waning days of summer. Very nice job Beagle!!!! 
Eric's Project #002
- Thread starter Beagle123
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dirty_d
10 kW
id get this http://www.out2win.com/catalog/img/rlv0702.gif and chop the sprocket off of it and weld your original unite sprocket in the center of it.
dirty_d said:
If the sprocket itself is closer to the narrow end of the tapered bore, you could rebore to 12mm, as dirty_d suggested earlier. The short taper sprocket that I have here is 14mm to 10mm but the sprocket is at the wide end of the taper.
You can bond your sprocket onto the shaft with Loctite 603
safe
1 GW
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TylerDurden said:
As I said before the case you are pointing to is AC power and not DC power. So they're keeping the voltage the same and fiddling with the frequency. In this example it's going from 100 Hz to 300 Hz.
TylerDurden, you tend to take things too literally... you seem unwilling to grasp similiarities in the "abstract". The "re-rating" process is conceptually similiar to "over-volting" because you are increasing the maximum rate at which the motor spins. The powerbands will expand in the same way whether you are using AC and "re-rating" or DC and "overvolting". The basic themes are the same. Same basic idea.
But I suppose it's good to have "detail oriented people" around because when some of us get to too relaxed it's good to have someone to call us on it...
dirty_d
10 kW
this is another solution for the drive sprocket http://www.mfgsupply.com/m/c/4-462.html?id=zmojQSia a 11 tooth #35 sprocket for a centrifugal clutch. take the bronze bushing out and cut all the bullshit off it so its just a flat sprocket with a 7/8" hole in the center, trim your stock sprocket down to 7/8" diameter and put it in the center and have it welded in.
TylerDurden
100 GW
The re-rating method applies to PM motors too. Dumbing it down to your level and calling it "overvolting" is a gross oversimplification of one of the most significant developments in electric motor engineering.safe said:
re-rating = 300%+ performance
dirty_d
10 kW
in a DC motor i believe re-rating would be like rewinding a 48V motor with less turns of thicker wire so that the winding resistance is less and less backemf is produced, the end result at say 36V since there is less resistance you get more current than before(less windings so same torque) and there is less backemf so that even at 36V you get the same rpms as the original motor at 48V. now this doesn't really mean all that much essentially its the same motor with the same power as before just built for a different voltage(unite does this), but if you run it at 48V like it was originally wound for then it is essentially over-volted and is going to put out more power.
safe
1 GW
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TylerDurden said:
Relative to what?I did go through that pdf and they are talking about how to make motors work better for specific rpm demands. When a motor is running in it's low rpm inefficent range then it can have terrible performance charactoristics and when you "re-rate" the motor so that it's voltage (or frequency) and gearing are such that they finally get it right then you could see a big improvement compared to the original configuration. But it's not REALLY a 300% improvement in the peak efficiency of the motor but a big reduction in error from how things were being done before.
It's like with gearing... gearing "fixes" a problem. The motor doesn't really change, but the gearing "fix" corrects a problem that the natural motor has to deal with. "Re-rating" could show a 300% improvement... but only because it's improving on poor previous performance.
The "bottom line" is still that any motor with a permanent magnet is "permanently" bound by that magnet for it's performance. It's only through Tesla's Induction motor that you can escape the "permanent motor trap". "Re-rating" does not really escape anything... it's an "evolution" of the permanent magnet motor, but not a "second revolution" like the Inductance motor was. (in 1887)
safe
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From the re-rating pdf:
"Many workers have advocated a wide constant power
range as a way to avoid a transmission in an electric traction
application. However, the need for a gear ratio means that at
least a “single-speed transmissionâ€￾ is in place. A special
advantage of electric machines is the possibility of precise
control. One can envision an “automatic gear boxâ€￾ that
delivers the performance and efficiency of a simple multispeed
manual transmission with full automation of the gear
shifting process. This was successfully implemented with
our motor [12], and showed that the transmission does not
impose cost or performance limitations."
So they are in agreement with our observations here on the messageboard:
1. Use a smaller motor and re-rate (overvolt) it.
2. Reduce the high rpms down to lower more usable rpms.
3. Add gearing to widen the powerband. (use a CVT if possible)
I agree with their conclusions...
"Many workers have advocated a wide constant power
range as a way to avoid a transmission in an electric traction
application. However, the need for a gear ratio means that at
least a “single-speed transmissionâ€￾ is in place. A special
advantage of electric machines is the possibility of precise
control. One can envision an “automatic gear boxâ€￾ that
delivers the performance and efficiency of a simple multispeed
manual transmission with full automation of the gear
shifting process. This was successfully implemented with
our motor [12], and showed that the transmission does not
impose cost or performance limitations."
So they are in agreement with our observations here on the messageboard:1. Use a smaller motor and re-rate (overvolt) it.
2. Reduce the high rpms down to lower more usable rpms.
3. Add gearing to widen the powerband. (use a CVT if possible)
I agree with their conclusions...
hmmm...
According to this weather map, there seems to be a high pressure system blowing a lot of hot air out of Missoora.
(as indicated by the arrow pointing to safe's house)
KEE-ding!
:lol:
xyster
10 MW
Toorbough ULL-Zeveigh said:
:lol: A sucker for a chart is a fool for a test.
TylerDurden
100 GW
Toorbough ULL-Zeveigh said:
I believe that is called a "plume".
:lol:
Beagle123
10 kW
Newbie: Thanks!
Dirty, Miles: I'm going to try the #25 chain set-up because I already have the parts (see pics). The sprocket looks tiny to me, but steel is well... "strong as steel." I don't think I could weld another sprocket onto this one because the shaft is so small at that part and I think It's sure to wobble.
My plan B is to take your advise and bore out a 3/8 #35 sprocket, or attempt to center the sprocket I already have. Then For the back, I can buy a 72 or 80 tooth #35 sprocket blank. Then I could take it to the machine shop and have them put a hole right in the center of it to fit over the 22t bicycle freewheel. I think that's a good solution.
I agree with Miles that #219 might be optimum, but that would involve two adapters for the back. I"d rather just make two pieces in the back.
I'm starting to think that #25 might work becasue #219 isn't that much bigger, and the small links may be more efficient.
Thanks to both of you, you've come up with very interesting and original solutions to this problem.
Att: Thanks, I love the aluminum look too. I'm trying to figure out if I can just leave it unpainted. I guess it would oxidize. I wonder what it would look like. I guess we'll find out.
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xyster
10 MW
Beagle123 said:
If you're talking about aluminum metal oxidizing -- it does, but that's not a problem:
http://en.wikipedia.org/wiki/Aluminium_oxide
Beagle123
10 kW
Cut Panel, Installed Kick-stand
I don't have much left to do on the frame. I should really be spending my time thinking about batteries.
This kick-stand is great. Its a standard aluminum kick-stand that bolts onto the bottom of a bicycle. Eventhough it bolts onto bike tubes, its flat. Its perfect for my bike because the bottom of my bike is flat. I just drilled a hole in the bottom and bolted it on. Hopefully this bike will weigh about 80-90lbs. A bike kick-stand should be plenty strong enough to support it.
I don't have much left to do on the frame. I should really be spending my time thinking about batteries.
This kick-stand is great. Its a standard aluminum kick-stand that bolts onto the bottom of a bicycle. Eventhough it bolts onto bike tubes, its flat. Its perfect for my bike because the bottom of my bike is flat. I just drilled a hole in the bottom and bolted it on. Hopefully this bike will weigh about 80-90lbs. A bike kick-stand should be plenty strong enough to support it.
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Beagle123
10 kW
Miles said:I would use one of these: http://www.whiteind.com/ENO-free-specs.html
The 22t version has weight-saving slots milled into it that you could easily bolt a custom adaptor to #219 spec to. That was my solution to the freewheeling cranks problem... :wink:
Hi Miles: I found that product used on ebay. I wanted to get a silent freewheel. The one on my current bike makes a clicking sound that gets really loud when going fast. Is this ENO one a silent one? I noticed that my cheap freewheel adapter clicks too. uuh.
newbie electric rider
100 W
Hey Beagle,
Aluminum oxides over time and gives a dull silvery finish, look at sailboat masts. If you want it to remain shiny, I am pretty sure, that you could spray a clear coat epoxy on it. Epoxy is a very durable finish.
Aluminum oxides over time and gives a dull silvery finish, look at sailboat masts. If you want it to remain shiny, I am pretty sure, that you could spray a clear coat epoxy on it. Epoxy is a very durable finish.
Beagle123
10 kW
Hi Miles:
I've been googling "silent freewheel" etc, and I think you're right about the ENO freewheel being about the best you can do. I don't know how you know about all these things like "sprag clutches" etc. But its great that you have all this info.
Unfortunaately it doesn't look like they make sprag clutches for bikes. I think the silent bikes use a silent hub. I know old single speed bike sith a coaster brake (pedal backwards to brake) are silent, but it is done in the hub.
AN interesting fact I learned is that the ENO hubs are rebuildable. That means you could take them apart and weld a sprocket onto them, then reassemble them.
Hi Newbie: I want a flat finish because the sun make it like a mirror. It might be bad even with flat. I'm sure I'll take the lazy approach and leave it until it oxidizes. If I don't like it, then I'll do something.
To get it flat, I'm going to go over it with a wire brush.
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