Dave's 80:1 RC mid drive kit build log

john61ct

1 TW
Joined
Dec 18, 2018
Messages
8,758
morati said:
Curious if anyone has tried the Nucular 6F? It can run sensorless motors as well and the buy-in price isn't bad.
Unobtainium these days Vasili is only ramping up production of the 24f

 

Driveless

10 mW
Joined
Jul 19, 2015
Messages
24
Ham said:
Bearing shot or gears cracked. Best to pop it open and have a look....

Spot on, bearing looks like it exploded pieces all ground up in there. Hopefully its not needing new gears too...
There was plenty of grease. What would cause this?

Also do you have Dave's contact # or email to get replacement parts?
 

Ham

1 kW
Joined
Feb 18, 2016
Messages
498
Not unheard of for the bearing to fail. Pretty sure it's off the shelf size... should be written on it somewhere. If not then someone here will know which it is or take calipers to it for internal and external diameters and race width....

Dave hasn't been responsive on here for some time. I hope he is OK.
 

Ecyclist

1 kW
Joined
Apr 1, 2016
Messages
475
Location
San Diego, California
Ham said:
Not unheard of for the bearing to fail. Pretty sure it's off the shelf size... should be written on it somewhere. If not then someone here will know which it is or take calipers to it for internal and external diameters and race width....

Dave hasn't been responsive on here for some time. I hope he is OK.
500 miles is nothing. These bearing should be good for few thousand miles. Cycloidal shape of Tangent is way off and bearings can't take that. I'm sure bearing size is right on it. My own build cycloidal drive has about 3K miles and not a single bearing problem, but also no heat, vibrations or nose.
 

briangv99

1 kW
Joined
Jan 15, 2008
Messages
338
Location
Canberra, Australia
Dave did progressively update the gearbox over time, including larger/stronger bearings and more refinements to the cycloidal profile.

I had a bearing explode on my first gearbox too, which I replaced ,sorry don't recall the size, but by the time I did that Dave had sent me a v2 (or a was it a v3?) gearbox, free of charge. The v2 box is much more refined, quieter and smoother.

Like so many cottage industries Dave moved onto a new job (aerospace I think) working long hours and had no time to support the Tangent Drive business anymore. Such a shame his craftmanship was beautiful, but honestly I don't think the Astroflight motors were doing him any favours developing his drive. So little torque and heaps of rpm needed to get decent power, the poor 3220 gets to scorching temps even at 3kW.
 

Driveless

10 mW
Joined
Jul 19, 2015
Messages
24
[Update]

Got in touch with Dave, he's super helpful and walking me through the teardown process and said he's got parts to get it up and running.

Dave said that likely some grit worked its way into the bearing and caused it to fail, which judging by the outside mud on my drive is totally likely.
Said that if you're always over-lubing them the gears in these drives should be nearly indestructible, since they are sourced from industrial an application.

The bearings are standard bearings, {update} I opened the drive up there are going outside to inside the bearings seem to mirror each other. There are two large bearings on both outsides that I am not pulling the numbers on since I am not trying to make more work for myself, but working your way in on the layers of this onion are two bearings (6003Z) and the two mirroring each other on what Dave referred to as the camshaft at the very center are (6806Z). Going to try and source a few of these and work on cleaning and putting this onion back together. Gears and internals all look to be good condition.

-N
 

knurf

100 W
Joined
Aug 28, 2016
Messages
129
Yeah? Dave's actually responding again? I'd love to get my dead late gen Tangent back and running. Just an expensive paperweight right now.

The freewheel's whats always messed up my units, they break and cannot be replaced, since they tend to cold weld to the output screw. In my final breakdown the whole transfer part broke before the freewheel. Can't even use the motor for anything since its the version with the motor epoxied to the shell.
 

Ecyclist

1 kW
Joined
Apr 1, 2016
Messages
475
Location
San Diego, California
knurf said:
Yeah? Dave's actually responding again? I'd love to get my dead late gen Tangent back and running. Just an expensive paperweight right now.

The freewheel's whats always messed up my units, they break and cannot be replaced, since they tend to cold weld to the output screw. In my final breakdown the whole transfer part broke before the freewheel. Can't even use the motor for anything since its the version with the motor epoxied to the shell.
Motor glued to the shell? Is this one of the progressively update gearboxes with aluminum gears? :shock:
I know that Tangent was at first with chromoly steel gears and later with aluminum gears. Presumably to make it lighter. In reality because it was easier (read cheaper) to machine. Hopefully you will get a new part and will be able to use it again. Throwing away $2k is not fun. :( Was you motor 3210?
 

briangv99

1 kW
Joined
Jan 15, 2008
Messages
338
Location
Canberra, Australia
knurf said:
Yeah? Dave's actually responding again? I'd love to get my dead late gen Tangent back and running. Just an expensive paperweight right now.

The freewheel's whats always messed up my units, they break and cannot be replaced, since they tend to cold weld to the output screw. In my final breakdown the whole transfer part broke before the freewheel. Can't even use the motor for anything since its the version with the motor epoxied to the shell.

I did manage to get a freewheel off so I could swap from a 16t to a 20t. It didn't budge for a while, but eventually the cordless electric impact driver broke it free. Any chance that would work on your Tangent?
 

knurf

100 W
Joined
Aug 28, 2016
Messages
129
Ecyclist said:
knurf said:
Yeah? Dave's actually responding again? I'd love to get my dead late gen Tangent back and running. Just an expensive paperweight right now.

The freewheel's whats always messed up my units, they break and cannot be replaced, since they tend to cold weld to the output screw. In my final breakdown the whole transfer part broke before the freewheel. Can't even use the motor for anything since its the version with the motor epoxied to the shell.
Motor glued to the shell? Is this one of the progressively update gearboxes with aluminum gears? :shock:
I know that Tangent was at first with chromoly steel gears and later with aluminum gears. Presumably to make it lighter. In reality because it was easier (read cheaper) to machine. Hopefully you will get a new part and will be able to use it again. Throwing away $2k is not fun. :( Was you motor 3210?
I think I’ve run and broke all recent revisions of this concept. My last one was indeed the aluminum geared one with the alternate motor (can’t remember the name but it wasn’t Astro) fused into the shell. It was comparable to the 3220. The output part that connects the freewheel thing is removable now (to quickly swap freewheels) but it was made much too weak and the aluminum piece has sheared instead. Getting one made in a random shop here using just the part without any blueprints costs 50% of the Tangent itself.. also there’s some real play in the gears at this point anyway so limited life left in it I think. Super fun unit while it worked, thought I’d never find anything to fill that void (but I did).

I also have a broken 1.5(?) revision with a 3210, which has the unscrewable freewheel problem. It had a lot of miles on it and also rusted. After I had my way with it, I handed the thing in to my local motorbike shop and they couldn’t get it off with their air driven industrial tool (ofc I showed them and told them about the pins etc). So in frustration I just cut the whole fw off with a angle grinder, trying to keep as much of the threads as possible but ofc that didn’t hold up long.

So it’s all just expensive paperweights at this point but was real fun while it last!
 

Ecyclist

1 kW
Joined
Apr 1, 2016
Messages
475
Location
San Diego, California
knurf said:
Ecyclist said:
knurf said:
Yeah? Dave's actually responding again? I'd love to get my dead late gen Tangent back and running. Just an expensive paperweight right now.

The freewheel's whats always messed up my units, they break and cannot be replaced, since they tend to cold weld to the output screw. In my final breakdown the whole transfer part broke before the freewheel. Can't even use the motor for anything since its the version with the motor epoxied to the shell.
Motor glued to the shell? Is this one of the progressively update gearboxes with aluminum gears? :shock:
I know that Tangent was at first with chromoly steel gears and later with aluminum gears. Presumably to make it lighter. In reality because it was easier (read cheaper) to machine. Hopefully you will get a new part and will be able to use it again. Throwing away $2k is not fun. :( Was you motor 3210?
I think I’ve run and broke all recent revisions of this concept. My last one was indeed the aluminum geared one with the alternate motor (can’t remember the name but it wasn’t Astro) fused into the shell. It was comparable to the 3220. The output part that connects the freewheel thing is removable now (to quickly swap freewheels) but it was made much too weak and the aluminum piece has sheared instead. Getting one made in a random shop here using just the part without any blueprints costs 50% of the Tangent itself.. also there’s some real play in the gears at this point anyway so limited life left in it I think. Super fun unit while it worked, thought I’d never find anything to fill that void (but I did).

I also have a broken 1.5(?) revision with a 3210, which has the unscrewable freewheel problem. It had a lot of miles on it and also rusted. After I had my way with it, I handed the thing in to my local motorbike shop and they couldn’t get it off with their air driven industrial tool (ofc I showed them and told them about the pins etc). So in frustration I just cut the whole fw off with a angle grinder, trying to keep as much of the threads as possible but ofc that didn’t hold up long.

So it’s all just expensive paperweights at this point but was real fun while it last!
I guess I could make a new output post for you just for fun, but considering that this kit has aluminum gears I don't see a point.
They will be gone soon after you get a new part going. It's a dead end. :cry:
Maybe Dave can send you new steel gears and an output post. Assuming all parts are made to the same tolerance and fit without any problems. :roll:
 

knurf

100 W
Joined
Aug 28, 2016
Messages
129
Ecyclist said:
knurf said:
Ecyclist said:
knurf said:
Yeah? Dave's actually responding again? I'd love to get my dead late gen Tangent back and running. Just an expensive paperweight right now.

The freewheel's whats always messed up my units, they break and cannot be replaced, since they tend to cold weld to the output screw. In my final breakdown the whole transfer part broke before the freewheel. Can't even use the motor for anything since its the version with the motor epoxied to the shell.
Motor glued to the shell? Is this one of the progressively update gearboxes with aluminum gears? :shock:
I know that Tangent was at first with chromoly steel gears and later with aluminum gears. Presumably to make it lighter. In reality because it was easier (read cheaper) to machine. Hopefully you will get a new part and will be able to use it again. Throwing away $2k is not fun. :( Was you motor 3210?
I think I’ve run and broke all recent revisions of this concept. My last one was indeed the aluminum geared one with the alternate motor (can’t remember the name but it wasn’t Astro) fused into the shell. It was comparable to the 3220. The output part that connects the freewheel thing is removable now (to quickly swap freewheels) but it was made much too weak and the aluminum piece has sheared instead. Getting one made in a random shop here using just the part without any blueprints costs 50% of the Tangent itself.. also there’s some real play in the gears at this point anyway so limited life left in it I think. Super fun unit while it worked, thought I’d never find anything to fill that void (but I did).

I also have a broken 1.5(?) revision with a 3210, which has the unscrewable freewheel problem. It had a lot of miles on it and also rusted. After I had my way with it, I handed the thing in to my local motorbike shop and they couldn’t get it off with their air driven industrial tool (ofc I showed them and told them about the pins etc). So in frustration I just cut the whole fw off with a angle grinder, trying to keep as much of the threads as possible but ofc that didn’t hold up long.

So it’s all just expensive paperweights at this point but was real fun while it last!
I guess I could make a new output post for you just for fun, but considering that this kit has aluminum gears I don't see a point.
They will be gone soon after you get a new part going. It's a dead end. :cry:
Maybe Dave can send you new steel gears and an output post. Assuming all parts are made to the same tolerance and fit without any problems. :roll:
I would have begged you to help me out if it wasn't for the fact that I've already found something better. But you're right; it will just keep breaking even if I probably could get a few hours more time out of it.

The Tangent kit was my way into ebiking and I've had a lot of fun on these kits already. Also Daves been more than helpful and I've definitely lost count on how many packages he's sent me with replacement parts over the years. He wouldn't even let me pay for the shipping.
 

giblet

1 W
Joined
Sep 23, 2012
Messages
54
I would have begged you to help me out if it wasn't for the fact that I've already found something better. But you're right; it will just keep breaking even if I probably could get a few hours more time out of it.

The Tangent kit was my way into ebiking and I've had a lot of fun on these kits already. Also Daves been more than helpful and I've definitely lost count on how many packages he's sent me with replacement parts over the years. He wouldn't even let me pay for the shipping.

Be interested to know what you went to after the Tangent - I've not found anything that was as fun yet?

Also Dave was very fair and also sent me multiple units and revisions at his own cost. When the unit worked - it was epic.
 

Ecyclist

1 kW
Joined
Apr 1, 2016
Messages
475
Location
San Diego, California
giblet said:
I would have begged you to help me out if it wasn't for the fact that I've already found something better. But you're right; it will just keep breaking even if I probably could get a few hours more time out of it.

The Tangent kit was my way into ebiking and I've had a lot of fun on these kits already. Also Daves been more than helpful and I've definitely lost count on how many packages he's sent me with replacement parts over the years. He wouldn't even let me pay for the shipping.

Be interested to know what you went to after the Tangent - I've not found anything that was as fun yet?

Also Dave was very fair and also sent me multiple units and revisions at his own cost. When the unit worked - it was epic.
knurf is using now GNG / CYC X1 Pro 3000w.
You can see it here:
https://endless-sphere.com/forums/viewtopic.php?f=28&t=95704&p=1657580#p1657580
 

Mugenski

10 W
Joined
Aug 2, 2015
Messages
67
Location
Toronto
Dave was always helpful and I still have a running tangent Gen2 with the waterjacket and I believe steel gears. I don't ride it as hard as I use to. What I'd really like is to get a torque sensing BB and pair the kit with a smaller battery. No longer do I need to test the limits of this kit. It easily twisted the frame of my 2010 glory :roll:

Turn the tangent into a mile munching and calorie burning machine, I think this is a good plan.
 

antares924

10 µW
Joined
Aug 27, 2018
Messages
6
Had a 3210 1:40 kit a few years ago, it was awesome which I sold unfortunately, now I got a gen 2 with 3220, 0 miles on it. Making an even better build now than before. Can’t wait to finish it in the next weeks. Frame is a specialized demo 9 from 2004, restomod.
Wish Dave was still active, imagine what a Gen 3 would be like. Wonderful engineering.
w9NNBVG.jpeg
 

Azalin

100 µW
Joined
Jun 20, 2023
Messages
7
Location
Ankara
New round of units going out, these include some changes I've been working on over the winter.

6806+vs+16005


Old on top, new on the bottom. The 6806 bearings are a bit small, so in with 16005 ZZ C3, oh yea. These are twice the strength, C3 clearance for high speed and temps. They're a touch wider so I had to re-do the other pieces. These gears are 7075 Aluminum running against a steel ring gear. Steel for the eccentric gears is overkill, thousands of miles and they look brand new. Shown here is the eccentric assembly with steel gears blued from hardening.

View attachment 213510

I'm going to produce the 40:1 ratio for all the kits. This ratio is a great starting point as we can easily achieve overall ratios to the crankset of 44:1 all the way to 95:1 using commonly available freewheels and chainrings. This updated design fits all existing gearboxes. If someone has an issue with their 6806 bearings, they'll get the new design.

1492141670133


By reducing the turn count of the Astro motors by 1, we can shift more work to the gearbox and generate less heat in the motor, by quite a bit. A 4turn 3220 has winding resistance of 0.032ohm while a 3turn is 0.019ohm, almost half. The previous 3220's were 4turn and overall 40:1 ratio; the 3turn will run at 55:1 overall to produce identical performance figures, but for longer because of less heat. Same goes for the 3kW kit, instead of a 7turn at 55:1, we'll use a 6turn at 75:1. Another upside is 12s packs work great. 14s is bonus now.

Aluminum gears are 40% the weight of steel but as strong as a mild steel. New gear profile has quieted things down and 10% more output pins increases efficiency and robustness.

[youtube]8DYuSvJ-CUw[/youtube]

Oh, new spring loaded tensioners too.


-dave

I'm not interested in bicycles but I've come to say that you did a terrific job on these cycloidal drives. I'm currently building one for my CNC mill as the 4th axis. Steel 1:33 disks, aluminum housing with hardened roller pins, etc..

Anyway. Names Suat. Hello all.

Dang. I'm just 1 µW. I can't even shock an ant.
 
Last edited:

Ecyclist

1 kW
Joined
Apr 1, 2016
Messages
475
Location
San Diego, California
@tangentdave did you use GearTrax for the cycloidal gears or hardcoded equations?
Just so you know, any software including GearTrax will only design theoretical shape. Practical shape require some adjustments.
 
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