LightningRods
1 MW
Miles said:
No, you wouldn't need a cap if plate metal is the final product. Definitely a good open source solution for people who have a water jet or good laser cutter at their disposal.
GNG, 1000W 48V BB-drive, $400
- Thread starter spinningmagnets
- Start date
No, you wouldn't need a cap if plate metal is the final product. Definitely a good open source solution for people who have a water jet or good laser cutter at their disposal.
spinningmagnets
100 TW
I am not a trained engineer, but the thought occurred to me that going from 14T to 18T (a good thing) would increase the engaged teeth from (about) 7 to 9 (roughly). Adding two teeth out of seven is about a 27% improvement in holding power. Going from 15mm wide to 20mm wide would also add 5mm out of 15mm for a 30-ish % in belt-traction improvement. I think this is really worth the effort, and using stacked sections is quite clever!
LightningRods
1 MW
Miles said:
So an inexpensive fix that solves for too sharp a belt bend, too few drive teeth engaged, sharp pulley teeth and also lowers the reduction ratio. Sounds perfect!
LightningRods
1 MW
Miles said:
It's very close with the current version. There is maybe 1/2" (12mm) between pulleys with no adjustment left. Unfortunately that was with a 14T drive sprocket. The 120T has a nearly 1.25" longer radius. An 18T has a 1/8" longer radius than 14T. Getting close. I made my first plates .75" longer than stock. At that point I was thinking 14/90 pulleys. If I need to make longer plates, I'll make longer plates.
I just physically measured the drive with the sheets at max extension. 115mm center to center. Like I said, close.
bee
100 W
Should we upgrade the motor wires as well if we're upping the volts really high, rather than the amps?bzhwindtalker said:
Anyone know how to open the motor up for this? I've taken out the screws but the motor parts seem stuck together.
Would slapping a 3rd 7s onto my bike for 21s be too high a voltage for the stock controller?
Miles said:
I should be able to do the 18t adapter on my neighbors CNC in a few weeks. What would be a good material, steel?
Close is ok, but will it fit? I don't have the kit in front of me to measure. I can take a few teeth off to be safe.LightningRods said:
LightningRods
1 MW
This is how the 14 to 18T conversion looks. There are still some scary thin spots where the 14T teeth line up with the 18T. This will probably work in metal but I'm wondering if the resin will hang in there. The solid end cap will help, and an inside flange would help. Anything to get some extra meat supporting those thin spots.
Bumping up to 20/120 is still 6:1. Lower reduction than stock and more outside diameter to work with.
Bumping up to 20/120 is still 6:1. Lower reduction than stock and more outside diameter to work with.
bzhwindtalker
100 kW
Who knows where to get the 800w gang inrunner? Would be the perfect motor for my next build.
christerljung
100 W
You mean: 800w GNG inrunner i suppose.bzhwindtalker said:
From what i will remember there was an aliexpress or mrTao link to motor only, a bunch of pages back. The price was low, about 35$.
Haven´t found it yet, been scanning this thread about 3 months back.
speedmd
10 MW
SlA plastic in general is mechanically very poor stuff. Good for touchy feel and mock ups, but IMO way to weak for what your expecting from this drive. Would be very surprised if it lasted a few minutes. The aluminum composite may last a bit longer but thin sleeve design would be a challenge in strong material. Would be good possibly to work out ideal ratios possibly.
Cyclebutt
100 W
That's it! The solid end didn't occur to me but I like it. I would love this in steel, teeth profile would have to be spot-on. We could use "doctorbass"'s Scotchweld DP420(?) to glue these things on. Between steel and the ScotchWeld glue, I wouldn't even care if it had a solid end, thin as it is in places. That motor is going to be spooled up anyway, no real grunt work to it. I've already gone to a smaller inner chain ring on my final drive and intend to use this as a commuter with occasional off-road rides, ratio change not critical. Nice work guys! Bike on!LightningRods said:This is how the 14 to 18T conversion looks. There are still some scary thin spots where the 14T teeth line up with the 18T. This will probably work in metal but I'm wondering if the resin will hang in there. The solid end cap will help, and an inside flange would help. Anything to get some extra meat supporting those thin spots.
Bumping up to 20/120 is still 6:1. Lower reduction than stock and more outside diameter to work with.
LightningRods
1 MW
I really like the look of the 14/20T conversion. Cast in the type of resin that construction hard hats are made of this thing should be pretty bulletproof.
Bee- I'll take some careful measurements of the sheet travel. I'd say I'm headed towards making a +1 length set. You have access to a 3D printer, correct? Are you thinking of printing both the 120T sleeve for the driven and a drive pulley sleeve? I can get this printed, but it's not free.
On a side note, do any of you engineering types know where the 5mm pitch is measured once it's laid out on a circle? If you measure at the root of the teeth the pitch of the teeth is larger and the diameter of the pulley larger than if you measure at the tips of the teeth. It seems logical to go through the midline to stay consistent through different pitches but I don't know for certain what the standard is. Miles?
Bee- I'll take some careful measurements of the sheet travel. I'd say I'm headed towards making a +1 length set. You have access to a 3D printer, correct? Are you thinking of printing both the 120T sleeve for the driven and a drive pulley sleeve? I can get this printed, but it's not free.
On a side note, do any of you engineering types know where the 5mm pitch is measured once it's laid out on a circle? If you measure at the root of the teeth the pitch of the teeth is larger and the diameter of the pulley larger than if you measure at the tips of the teeth. It seems logical to go through the midline to stay consistent through different pitches but I don't know for certain what the standard is. Miles?
LightningRods
1 MW
Awesome! Thanks, Miles.
LightningRods
1 MW
So if you've been CADing up some 5mm HTD pitch pulleys and you didn't scale the pitch based on an imaginary circle .0225 inches LARGER than your pulley's outside radius (measured from the tips of the teeth), you've been making your pulleys too big. The bad thing about that of course is that the scale of the belt teeth and pulley teeth will not match. I wonder if GNG went to all of this trouble?
spinningmagnets
100 TW
Just for discussion purposes, PaulD's race bike was rocking a lot of watts through an 80-100 motor. His primary reduction was only 15mm wide, but the motor-pulley was 26T. 15mm times 12 fully engaged teeth equals an arbitrarily made-up tooth area engagement quotient number of 180, increase the width to 20mm and the tooth-count can be reduced to 18T and still have the same holding power?
http://endless-sphere.com/forums/viewtopic.php?f=28&t=37729
http://endless-sphere.com/forums/viewtopic.php?f=28&t=37729
LightningRods
1 MW
I think 18T x 20mm wide is plenty of holding power for the GNG. In steel I think that the sleeve profile is even adequate. I personally like the perfectly smooth finish of one piece of resin. It sounds like a bunch of folks are on the steel plate hunt and have the equipment to execute it. I think I'll go for the lowest possible belt wear combination, even if it costs me a bit of primary reduction. No sense in all of us rushing the same door at once.
bee
100 W
I have two 3d printers at home for PLA/ABS printing and I have access (or I can upgrade one of my printers) to one capable of printing nylon.LightningRods said:I really like the look of the 14/20T conversion. Cast in the type of resin that construction hard hats are made of this thing should be pretty bulletproof.
Bee- I'll take some careful measurements of the sheet travel. I'd say I'm headed towards making a +1 length set. You have access to a 3D printer, correct? Are you thinking of printing both the 120T sleeve for the driven and a drive pulley sleeve? I can get this printed, but it's not free.
On a side note, do any of you engineering types know where the 5mm pitch is measured once it's laid out on a circle? If you measure at the root of the teeth the pitch of the teeth is larger and the diameter of the pulley larger than if you measure at the tips of the teeth. It seems logical to go through the midline to stay consistent through different pitches but I don't know for certain what the standard is. Miles?
I can print up like half a dozen various pulleys for you to try out, just give me the specs.
The ABS printed pulley required some filing and I pressed it on with a vice, it's stuck on there really well and I might need to destroy it to remove it. Take that into consideration if you're making some very hard casts that won't flex/conform like the ABS does.
I generate my pulleys with http://www.thingiverse.com/thing:16627
Which cites http://www.sdp-si.com/D265/HTML/D265T016.html for some pulley diameter measurements
A quick look at the math in the script indicates that this particular one seems to take into account the issue you mention:
function tooth_spaceing_curvefit (b,c,d)
= ((c * pow(teeth,d)) / (b + pow(teeth,d))) * teeth ;
function tooth_spacing(tooth_pitch,pitch_line_offset)
= (2*((teeth*tooth_pitch)/(3.14159265*2)-pitch_line_offset)) ;
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