QS 138 70H with Gearbox

[Jordan325ic]

Any mechanical engineers familiar with this sort of shaft dimensioning? What are the extra digits following each nominal dimensions (14 -.03 / -.04, 4 -.01/-.02)?



My hunt to understand brought me to this, which I have found replicated (appears to be ISO 14 splined shaft standard, DIN 5463).
https://roymech.co/Useful_Tables/Keyways/Spline.html

If I am understanding this correctly...
The OD could be: 16.98mm to 16.99mm
The ID could be: 13.96mm to 13.97mm
The tooth could be 3.98 to 3.99mm

So would that same tolerance (in reverse) apply to the sprocket?

 

[speedmd]

The spec shows what is commonly referred to as minus stock. Typical machining and heat treating would require some final finishing that would normally bring dimensions down a bit from rolled stock dimensions. The cog hole and shaft diameter tolerances would vary depending on the spec'd fit. Your link shows the slip, close and fixed "fit" tolerance codes that spec the allowances (play) between parts. Most of the moto apps I have run across are slip fits.

 

[Clueless1]

In case anyone was wondering, I ordered this from Ali express, motor only, March 6th 2021, received it today, April 2nd to my house in the Seattle area.

Didn’t have any tracking pop up on the FedEX system for the first 3 weeks, then all of the sudden it said it would be here April 4th, but then arrived early. So... thanks?!?!? Having said, I emailed some technical/application questions to QS motor prior to purchasing and they were actually quite responsive for me being a DIY one man show.

Package was slightly banged up (picture below, AFTER removing it from the cardboard box), otherwise the motor seems to be in good shape. I checked for oil leakage like previously mentioned and it seemed to be dry. Gasket was Protruding a little bit, not sure what that means yet...

No sprocket came with the motor. I thought that might be the case but it’s likely different depending on what kit/package/vendor you go with on AliExpress.

 

[spinningmagnets]

Do you have any pics of the rotor pulled out of the housing, or the stator coils?

 

[XSRe]

In case anyone was wondering, I ordered this from Ali express, motor only, March 6th 2021, received it today, April 2nd to my house in the Seattle area.

Hi folks,

My first post and apologies if it’s to take and ask for information, but I hope I can contribute once I have my setup working.

I have a EM150 (non SP) and I was wondering if anyone has got the this motor working with this controller. If so, what settings have you used. In particular the number of ‘pole pair’ and ‘phase shift angle’

Thank you

 

[larsb]

5 pole pair, phase angle + or - 60. can't remember. it's in the Votol controller thread. I think the geared motor is basically the same as the non geared since it's name is 138 70H so plenty of people have gotten it working.

 

[larsb]

Is this motor using 60° or 120°Hall sensor phase angle? I hate that the information about QS motors are so limited.

Always 120 these days. with 60 degrees it's harder to diagnose a hall sensor problem so it's not used in quality motors.

 

[XSRe]

Always 120 these days. with 60 degrees it's impossible to diagnose a hall sensor problem so it's not used in quality motors.

This sounds interesting. So if I understand correctly the ‘hall phase angle’ is simply the angle between the sensors. And the ‘hall shift angle’ is this the angle between the sensor centreline and the magnet/pole centreline?

one more question, how does it become impossible to diagnose a hall sensor failure if the phase angle is 60?

Devan

 

[larsb]

the ‘hall phase angle’ is simply the angle between the sensors. And the ‘hall shift angle’ is this the angle between the sensor centreline and the magnet/pole centreline?

Yes, sort of.
The hall shift angle sets the triggering of the coils in relation to the hall sensor switch point. It doesn't have to be center to center, there's an optimum for each rpm.

I think the way it works normally on controllers that have this setting is that the coil is triggered very slightly before the hall sensor switching actually takes place based upon an estimation of the previous hall switching position and rotation speed. It’s triggered before to remove the delay caused by controller processing and the time to build up the current and coil field.

the hall shift angle 120 deg 60 deg 0 etc is based on the winding and is unique to each motor (and possibly also each controller).

hall spacing angle 60 vs 120 degrees:
60 has 111 and 000 in the commutation table, means that a shorted hall sensor (always ON/1) or a dead hall sensor (always OFF/0) is not seen as a fault. for hall spacing 120 deg the signal states are 101, 011 etc and all hall states are shifting as the motor rotates, a state of 111 or 000 caused by a faulty sensor will immediately show as an error and controller can use this to stop the output.

 

[Clueless1]

So from what I can tell, the shaft fits a 420 chain with a JTF249 sprocket from JT Sprockets. Same sprocket for Honda 125 Grom.

Does it need a retaining clip of some sort? If so, where do you find that? Or does that come with a JT249 sprocket when you order one...?

***update***

This post is full of BS. This sprocket definitely does not fit. Check the username...

 

[hugok]

So from what I can tell, the shaft fits a 420 chain with a JTF249 sprocket from JT Sprockets. Same sprocket for Honda 125 Grom.

Does it need a retaining clip of some sort? If so, where do you find that? Or does that come with a JT249 sprocket when you order one...?

***update***

This post is full of BS. This sprocket definitely does not fit. Check the username...

Are you talking about the V3 now? Because JT249 should fit.

 

[Jordan325ic]

***update***

This post is full of BS. This sprocket definitely does not fit. Check the username...

Are you talking about the V3 now? Because JT249 should fit.

+1. The JT249 does fit. I would be curious to see a picture of this sprocket not fitting...

Edit: Although from eyeballing it seems nothing bigger than 16T will fit without some slight modification (chain hits the gear case)

 

[Clueless1]

So I tried to fit it again just now. Left it outside at about 32degF last night and even put the sprocket in the oven for awhile. Seems like it starts to fit differently depending on how I rotate the sprocket (60,120,180 etc) so maybe one or more of the teeth is out of spec?

Do I need to press this thing on?

Made a video below in case this helps.

https://youtu.be/XgKJICfzmyw

I have another 17mm splined sprocket in the mail that fits a “pitbike”. Hoping this will do the trick.

Any help would be greatly appreciated

-Check the username

 

[jhoexp]

Mine is this one from Amazon:
https://www.amazon.it/gp/product/B077XTC7KX/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&th=1

It fits ok, a bit loose but not too much.

 

[Jordan325ic]

https://www.amazon.com/gp/product/B08RCJ68GD?pf_rd_r=1XPMXSCC6CAN6JHDPM3Y&pf_rd_p=5ae2c7f8-e0c6-4f35-9071-dc3240e894a8&pd_rd_r=5b2cc338-ea10-485c-8af4-3142692faafd&pd_rd_w=htuoN&pd_rd_wg=SxaxF&ref_=pd_gw_unk&th=1

I used this one.

 

[Clueless1]

New sprocket came in and it fits.

Thanks Ebay!

 

[Jordan325ic]

Just FYI I have had a batch of 520 12T sprockets made up for the 17mm/14mm shaft for the QS138V3 motor. Anybody with a complete or near complete project want to test them, send me a PM.

 

[philjk2007]

Jordan325ic i just pm'd you

 

[hugok]

Derbi Senda sprocket seems to fit nice if you're using 420 chain. I will use 420 now in the beginning. Guess I will switch over to 520 when I find matching sprockets.

 

[Greggio_f]

So what are people’s recommendations for the front and rear sprocket ratios for this motor with the built-in gear reduction?

Am I correct that QS says 1:3?

I’m looking to use the QS138 70H in a vintage scooter, with a 12” wheel. Scooter will probably weigh around 130-140kg (285-310lbs). Scooter would be mainly for commuting, but my commute includes a bit of motorway, so want to be able to do 100km/hr (65m/hr). Was thinking I’d probably just use the Votol EM150 or may EM200. Looking at CALB CAM72 batteries in a 23s 1p config for 72V 72ah, but should handle 150A continuous.

The scooter has a 40 tooth rear sprocket originally - which would be the easiest option. So the standard 14 tooth front sprocket that QS ships these with should be pretty close to 1:3. By my calculations, though, that’d only get me something like 75km/hr at, say, 5,500 motor RPM?

It seems like I’d need more like a 1:2 ratio (19 or 20 tooth front sprocket with a 40 tooth rear) to get 100km/hr at that sort of RPM. (This assumes a rolling wheel circumference of about 1529mm (for a 130/70 x 12 tyre).) Or am I calculating this wrong?

Is 5,500 motor RPM a reasonable assumption? It looks like that may be what QS has used to calculate the 100km/hr for their QS138 70H motor kit (with swingarm and belt drive).

 

[Jordan325ic]

So what are people’s recommendations for the front and rear sprocket ratios for this motor with the built-in gear reduction?

Am I correct that QS says 1:3?

I’m looking to use the QS138 70H in a vintage scooter, with a 12” wheel. Scooter will probably weigh around 130-140kg (285-310lbs). Scooter would be mainly for commuting, but my commute includes a bit of motorway, so want to be able to do 100km/hr (65m/hr). Was thinking I’d probably just use the Votol EM150 or may EM200. Looking at CALB CAM72 batteries in a 23s 1p config for 72V 72ah, but should handle 150A continuous.

The scooter has a 40 tooth rear sprocket originally - which would be the easiest option. So the standard 14 tooth front sprocket that QS ships these with should be pretty close to 1:3. By my calculations, though, that’d only get me something like 75km/hr at, say, 5,500 motor RPM?

It seems like I’d need more like a 1:2 ratio (19 or 20 tooth front sprocket with a 40 tooth rear) to get 100km/hr at that sort of RPM. (This assumes a rolling wheel circumference of about 1529mm (for a 130/70 x 12 tyre).) Or am I calculating this wrong?

Is 5,500 motor RPM a reasonable assumption? It looks like that may be what QS has used to calculate the 100km/hr for their QS138 70H motor kit (with swingarm and belt drive).

The QS138V3 will not fit a 420 19t or 20t front sprocket without modifying the front case. I have a 16T and it is pretty close. With such small tires it doesn't seem like the V3 (built in gear reduction) is the best choice. You could run a QS138V2 (non-geared) and achieve 100kmph without spinning the motor up to 5500rpm (which is achieved by heavy field weakening which pulls more current).

 

[jhoexp]

So what are people’s recommendations for the front and rear sprocket ratios for this motor with the built-in gear reduction?

Am I correct that QS says 1:3?

It's 1:2.35

 

[jhoexp]

Just FYI I have had a batch of 520 12T sprockets made up for the 17mm/14mm shaft for the QS138V3 motor. Anybody with a complete or near complete project want to test them, send me a PM.
20210501_104544[1].jpg

Is the 12z the largest one in 520 size that can fit? (without cutting the case, I assume)
I12 t's too small for me, but 13 will be doable...
I am not in a hurry, cause I have already a new 428 combo to try, but count me in for a 13 (or 14, if it fits!)

 

[Greggio_f]

Thanks! That’s helpful.

So what sort of RPM range should I be working to with these motors? More like 4,000?

 

[jhoexp]

Thanks! That’s helpful.

So what sort of RPM range should I be working to with these motors? More like 4,000?

I think you can go much higher, depends on the voltage you want to use and the controller field weakening. If you search for j bjork ktm build, he reached 7000rpm or more, if I remember correctly, with a 137 70H (not geared).