Wheel Building - Tongxin in Brompton wheel

[mapman]

jerrysimon.
Use a pipe cutter on the shaft, use a file first on the shaft to make a small indent so the cutting wheel can sit flush. Good luck

MAPMAN.

 

[jerrysimon]

Yer thanks Mapman I had also thought about using a pipe cutter.

Regards

Jerry

 

[mapman]

Jerrysimon

Just realised shaft has 2 flat bits so may be difficult to use pipe cutter but would still have a go.

Mapman

 

[daniel.weck]

 

[barrycoll]

Jerry, the thumb throttle is the same as the one fitted by EWC....

it works well enough, but because the thumb does not tend to fool the arc of the lever, but sort of push it sideways, there is a tendency for the lever to stick 'ON'...and the thumb has to nip underneath and 'pull' it up...I have given it a squirt will silicone spray, but no difference, so must be the mech rather than the plastic of the lever
..it also tends to only 'work' during the last one third of its travel, so not as sensitive as one might wish...
the Red button, is an On/Off switch, for leaving the battery live, but not accidentally pushing the throttle
and the last 'complaint' is that if its mounted on the right hand side, changing gear is a pain, and on the left, covering the rear brake doesnt feel intuitive...

but after all that, your kit looks great, and I watch with bated (baited?) breath for the next instalment

all the best barry c.

 

[daniel.weck]

Jerry, would you be able to open-up the controller to reveal the MOSFETs and other key components ? It would be good to see how these recently-built controllers are laid-out inside. Many thanks if you can. I added the image diagram above hoping that it's the correct one (from the Dongguan Desheng Industrial Development Co website). PS: there's normally an aluminium bar that connects the back of the MOSFETs to the case, with some sticky paste to ensure thermal conductivity. A few screws should keep them in check on one external side of the controller.

That's just my opinion but I'd like to say it again: my e-Brompton build includes a more discrete, simple black thumb throttle which blends quite nicely amongst the other controls on the handlebar. I'm convinced that the 3/4 LED battery indicator is a waste of space (not an efficient way of monitoring the remaining battery capacity anyway) and it compromises the sleek looks of the Brompton (by adding bulk and extra wires). Let's not even talk about the full handle-grip throttle, which is an abomination ! (I'm harsh, I know)
PS: the Brompton handlebar is curved in a few places so it is difficult to find a flat spot where the throttle can go without "sticking". Double/triple check that the action is smooth before tightening the Allen bolt.

Good luck with the motor Jerry, it must feel like a mountain of work !

 

[jerrysimon]

Thanks for the replies. I had seen that diagram on their site thanks Dan. It seems like one for the Halls sensor one though. That is the company who my contact seems to work for yes. I must say apart from the mix up in the motor spec, they do seem genuine and reliable. I felt it was a bit of a gamble when I wired them my money

I will take apart and photograph the controller later in the week.

The thumb throttle can easily be replaced as they are not expensive but this one will allow me to at least test it all out.

I agree its a lot of work but I am in no rush, as I have my Cytronex to carry me to and from work

I guess in hindsight I have to admit that I would probably have gone for the EWC one now, but this is still quite a big saving and I have two motors to play with should one fail in a year or two.

I will work on it steadily over the Christmas/New Year break.

Still waiting for the battery cells to arrive too.

Regards

Jerry

 

[daniel.weck]

I had seen that diagram on their site thanks Dan. It seems like one for the Halls sensor one though.

I thought maybe the cut wires are the ones normally used for the Hall sensors ?

Good luck with it all !
Don't worry about the EWC, your build will be miles better !

 

[jerrysimon]

Ok as promised pictures of inside the controller.

Back of circuit board.

I will update the above now that I know exactly what colour the wires are. I noticed there does not seem to be any connector for re-programming the controller.

I also had chance to put the motors in some spare wider forks and test them both. They ran fine so its looking good

Regards

Jerry

 

[daniel.weck]

In the row with the thermal alloy bar, there is one separate component on the left end, and there are 6 identical MOSFETs. What does it say under "NEC" ?

I think that the programming header can be soldered on the 4 pins just between the big blue and (even bigger) red/wine components. But that's just a wild guess !

 

[jerrysimon]

Well another slight mishap.

The nipples I ordered were too long, 20mm instead of 12mm. Anyway I have some off the rim I dismantled and more coming from our Tawain contact. Great value £5.70 for 150 incl p&p.

A couple of pics Dan did for me to show the problem

Nipple lengths

12mm

20mm

Tongxin hub motor (36V 180W 190rpm 80mm-wide), 1-cross laced into a 36 holes Sun-Ringle CR18 rim (16" 1-3/8 349mm ERTO), with 14G 112mm stainless-steel spokes (2mm diameter) + 12/14mm nipples, and with an extra 20mm nipple that doesn't fit properly (too long, not enough thread on the spoke to provide tension).

I do plan to get this project finished by the end of the Christmas/New Holidays lol

Regards

Jerry

 

[jerrysimon]

Ok progress has been slow, life is getting in the way.

Anyway spent a couple of hours in the worshop so here is an update.

I took it really slow taking off metal evenly from each side of the fork lug both sides of the the fork. I used my dremel to open up the fork lugs to 10mm

Next it was time to widen the forks. This shows the spacing at the beginning i.e. around 75mm.

Like most here I used the method shown i.e. using a threaded bar to expand the forks. You have to be VERY careful here to make sure the bar does not spring out the forks as you expand them. You need to keep pusing it back in to to the forks as it tries to wind itself out. I used a pair of pliers to hold the threaded bar still whilst I turned the nuts evenly on both sides.

I took it out to just over 100mm to allow it to spring back hopefully to 80mm. Its quite a scarry process but I took it slow.

Finally unwinding the nuts the forks return to an acceptable 84mm.

Ok lets try the motor in.

 

[jerrysimon]

Ok finally the motor goes in

The other side

Temporarily I have put a few washers on one side to try and get it even. At this point nothing fowls though I may take 1-2mm off the roller brake bushing.

It does seem that the Tongxin seems slightly tighter up on the non wire side where it touches the fork frame without a washer or three!

It would be great if another Nano Brompton owner could post a picture of this side for me. Maybe its because the forks are not opened up evenly on both sides, comments

Anyway its all going well. I have another couple of pics I will post tomorrow showing the anti tonque washers that seems a little short to fit into the holes where the little nipple goes. This is probably why Carolines was bent slightly, see here. I am not sure yet whether to enlarge the length of the torque washer of take some more off the fork lug so it goes deeper into it.



Regards

Jerry

 

[daniel.weck]

Looks great Jerry !!

 

[jerrysimon]

Thanks Dan. How many washers are you using either side of your Tongxin motor ?

Ok so here is the motor shaft fitted in the Brompton forks. As you can see its right down with no gap.

Here is the torque washer. As you can see the nipple does not quite reach the the hole in the forks where it locates

So three options :

1. Elongate the torque washer
2. File the fork cut out deeper
3. Elongate the hole where the little nipple fits.

Comments

At the moment I favour 3. Don't want to weaken the torque washer or cut the fork lugs any deeper to push the motor further into the forks.

PS Just found Dan's pic and his shows him using two washers here Also it looks like Dan took a little more off the fork lug itself to allow the motor to drop down further so the nipple goes in the hole here

Jerry

 

[daniel.weck]

It looks like you need to grind down a further 1.5mm down into the dropout "well", not a big issue

You've done a really neat job so far, well done !

 

[daniel.weck]

Temporarily I have put a few washers on one side to try and get it even. At this point nothing fowls though I may take 1-2mm off the roller brake bushing.

It does seem that the Tongxin seems slightly tighter up on the non wire side where it touches the fork frame without a washer or three!

It would be great if another Nano Brompton owner could post a picture of this side for me. Maybe its because the forks are not opened up evenly on both sides, comments

This problem was even worse with the Bafang on my e-Brompton, due to the extra bulk / bulge and to the impossibility to use spacers on the axle (because of the custom lock / anti-rotation washer).

After spreading the fork arms, I then straightened the lugs / dropouts so they were parallel again (I imagine you did the same).

But the forks essentially remain too straight, they need to bend outwards a bit more, to open-up just like the famous cowboy stance

I needed to grind 1mm off the inside of the right-hand fork arm (and I now have a 1.5mm clearance), but that wouldn't be necessary with the Tongxin (especially because spacers can be used on the axle to increase the gap between the fork and the motor).

Cheers, Dan

 

[Northern Irelander]

Good job, nice to see the old thread bar trick being used

 

[daniel.weck]

Good job, nice to see the old thread bar trick being used

LOL Mine was the "deluxe" version, with extra nuts on the other side to keep the whole thing springing back out of the fork lugs !

http://www.pedelecs.co.uk/forum/electric-bicycles/4737-diy-stage-3-motor-testing-fork-photos.html#post60041

 

[Alex728]

where are you people getting those digital calipers from? Saw a set on Screwfix but they don't look as good..