GNG, 1000W 48V BB-drive, $400

I'm going to try printing an 80 to 110t sprocket tonight that I want to try with 19t on the primary. 110t seems to be the limit for my main 3d printer, I should be able to do a 120t sleeve (in nylon!) on my second 3d printer but I haven't finished putting it together yet.

I posted the openscad source for the pulley a few pages back, check out my post history.

I'm still working out the right gear ratio. I don't think the 20mm belt will work well with overhanging printed pulleys, I think it'd be better to try that on an all metal pulley. Printed parts are weak across the horizontal layers (they can delaminate under stress).

I think my stock 80t pulley might just have too much wobble to get a good tension on the belt.

If you guys can find a source for those 120t sprockets then I can send out a few 19t sleeves to test with it.

I've ordered parts for the chain conversion because it seems like the way to go for a higher powered GNG conversion and I'd like to push this motor as hard as possible.
 
gestalt said:
I'm going to be heading to the hackerspace at MIT on Friday and there might be somebody there who can arrange to have one of your slip on cogs printed for me. Is there any kind of file I could bring with me on a flash drive that would help the process? I would be much obliged and it would keep me from begging you for one :lol:

I think I'm going to be upgrading to the driven pulley to the 95 tooth from electricscooterparts.com, I'm thinking the ratio will be alright on the stock 48v.
Click to expand...
just bring the openscad source code I posted. There's a constant for outer_teeth that you can change to adjust the number of outer teeth.

I recommend printing on an FDM printer like reprap or makerbot in ABS plastic, I don't think PLA or wax will work unless you're casting with the print.

I print the pulleys with a handle so I can dip them into acetone for 5-10 seconds which soaks into the tiny holes in the print and melts the plastic, strengthening the inter-layer adhesion, and smoothing the ridges off the outer surface of the part. After removing from the acetone shake off excess acetone, and blow on the pulley to evaporate any excess acetone quickly stop the melting (don't want to warp the print surface!) after a few minutes the pulley surface should be hard and dry enough to put it down. I've found that it can take a few days for the acetone to evaporate completely and for the part to completely harden all the way through.
 
Hey Bee, have you thought of uploading your .stl file from openscad to shapeways and pricing the 20T print in stainless steel? You might be able to hollow some out and get the price down...

What density percentage and layer thickness did you print your ABS ones at - 100% infill and 0.1mm?

Cheers.
 
Actually forget the shapeways.nl stainless 3d print - it's 75 bucks!

ABS could be quicker to print with a low inner fill percentage but lots of outer shells...
 
.3mm layer height with .5mm nozzle

100% infill, 3 shells.

I don't think any infill happens with how thin these are though.

got $100 back from aliexpress because of the damages to my kit, making it a much better deal :)
 
speedmd said:
My new kit just got here. ... It has been fitted with a new little adjustable idler on the primary belt.
Click to expand...

A new adjustable idler? Could you send a photo? If it's a good design I could try to make similar for my kit.
 
WTF happend to all of the pages? This thread was sitting on 102 pages the last time I looked, now its 62.

(I actually commented back on page 100, which is now page 60?) :pancake:

Anyhoo. Managed to do some nasty damage to either the chain or rear sprocket - under power, the chain slips between two gears - annoying. I found that while the battery over the front forks keeps the front wheel on the ground, it messes up the weight balance on the bike. Time for a backpack battery - fine for onroad, painful in technical singletrack. Oh and found that it is entirely possible to lose traction with 2.7" wide maxxis minions DHR Pro 60's on a steep enough incline :)

Need to find a downhill tyre for uphill :mrgreen:
 
heathyoung said:
WTF happend to all of the pages? This thread was sitting on 102 pages the last time I looked, now its 62.

(I actually commented back on page 100, which is now page 60?) :pancake:


Need to find a downhill tyre for uphill :mrgreen:
Click to expand...


Yeah, what did happen to all the pages? lots of good info lost if not recovered.

I'm running a 3 inch MX tire on the rear and can still spin it, having the battery and motor/drive unit in the middle of the bike has kept the bike feeling nuetral.
 
full-throttle said:
Denisesewa said:
Yeah, what did happen to all the pages? lots of good info lost if not recovered.
Click to expand...
It seems the number of posts per page changed from 15 to 24. Everything is still there.
Click to expand...
Whew !! :D
 
That's kind of odd...I wonder if MRVass did an update? That posts-per-page setting is an admin-level thing AFAICR, although sometimes it can be set so users can control it, I don't see that option in our UCP here.

There is a mod for PHPBB to allow it:
https://www.phpbb.com/community/viewtopic.php?f=70&t=2146757
 
If any aussies are hunting for gears/chain/sprockets/belts/pulleys you might find something here: http://www.smallparts.com.au/products/
 
3d printed pinions not too bad at 0.3mm. Openscad generation seems to have quite a taper tho at the top of the internal teeth. Might be weak?
 
heathyoung said:
Time for a backpack battery - fine for onroad, painful in technical singletrack.
Click to expand...

These are great if you want to use a backpack battery, really comfortable and well padded. I use an R35 which is a little big but allows me to carry a load of other stuff as well. The R25 would be perfect.

http://www.kriega.com/categories/Rucksacks/
 
gestalt said:
please don't eat the pinions...

they'll give you a stomach ache.
Click to expand...
Oh, I thought it was short for pickled-onions! :shock:
 
We'll I'll take a helping!

I don't think the local guys are going to help me out on the 3d print front, but they are letting me use the super sweet soldering station. I can't believe how long it took me to do just seven 10p cell groups!

If there is a silicone based casting material that would be good I do live just about a mile from a place that sells all the casting supplies. The place is super legit and has same casts of at least a hundred different materials. I have some pretty good experience doing plaster and latex casting, it can't be that much more complicated.
 
Openscad generation seems to have quite a taper thogh at the top of the internal teeth. Might be weak?
Click to expand...

Since the small motor-pulley is the highest-RPM/lowest-torque piece in the drivetrain, I suspect these 3D printed plastic parts will perform better than their resume might at first suggest. If the tooth-count, surface finish, and loaded performance is acceptable, the part can be permanently bonded to the shaft-pulley with DP-420 (or similar product) which I believe will add additional support when fully cured.
 
Get out and put some kilometers on those pickled onions! We can theorize forever as to how they will hold up. The best test is real world use.

The laser cut/cnc finish in steel approach is looking like a fail. Because there are two shops involved it came back at $50 US apiece. I told them in advance that we needed a cost of $30 or less.

It's looking like 3D printed and cast resin from 3D printed are the best solutions for the chainaphobics. I've asked Bee to make a 23mm wide version for me with a sold slug of plastic at the end where the extension and flange are. The stock spindle is actually 20mm long minus the added flange. I'm hoping that extending the teeth 3mm past the spindle won't weaken the drum too much. The flange section on the very end really isn't loaded by the belt. I agree with SpinningMagnets that the use of DP-420 or similar will help the drum stay in one piece under load.
 
beefed up my shunt, the turnigy meter captured a peak of 1935w @ 35.4A. Motor and controller didn't get warm (it's 0 degrees out tho). The 3d printed sleeve flew off after few km of heavy riding but is undamaged. Gonna try gluing it on next.

The bolt on the adjustable plates is an M6x90 and you should get some nylon lock nuts to replace the thin square nut before it destroys the bolt threads like mine did.

Ordered a few different belts for a ~120 tooth gear, and nearly finished putting together my larger 3d printer to print the large sleeve adapter.

That taper on the 3d model is there so that it's easier to start off the press-fit ABS sleeve. For resin casting I would recommend commenting out the taper and using a file on the print so that it fits snugly, but can still be pulled off by hand.
 
The bolt on the adjustable plates is an M6x90 and you should get some nylon lock nuts to replace the thin square nut before it destroys the bolt threads like mine did.
Click to expand...

All of the GNG kits have those thin square nuts on the bearing blocks since they came with the kit. I only provide nuts with the lower BB sheets. Those are 5mm nylon lock nuts.
 
Yeah those square nuts are garbage - they are actually the captive nuts used in server racks. (eg. http://www.jaycar.com.au/productView.asp?ID=HP0310)

Not sure why they are used, maybe they were cheap :) But M6 nylocks fit well in their stead (not 5mm).
 
heathyoung said:
Yeah those square nuts are garbage - they are actually the captive nuts used in server racks. (eg. http://www.jaycar.com.au/productView.asp?ID=HP0310)

Not sure why they are used, maybe they were cheap :) But M6 nylocks fit well in their stead (not 5mm).
Click to expand...

The jackshaft bolts are the only M6 bolts in the sheets area. The two shorties on the primary side are M8s and the rest are M5s.
 
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