16 replies to this topic

[Alchemist]

I presume motor dyno's are relevant to this forum, if not, please pardon me and would expect it to be relocated.

 

I have a bunch of motors that I have been wanting to test to determine their rpm and torque capabilities.

 

So, with a bunch of scrap aluminum from other projects, I decided to build one.

 

I had an old Harbor Freight Gram Scale and put it to use.

 

Just wanted to share.

 

Thank you.

 

Ernie

 

 

 

 

 

[Charley]

Nice little tool. Where did you purpose the gear with the setscrew?

[gotboostedvr6]

Great way to find stall torque.

Also a great way to kill a good motor.

[Alchemist]

Greetings Charley,

 

I discovered that a rear axle gear for a 1/8" axle,  can be sleeved with a 1/8" aluminum pop rivet and the I.D. of the rivet fits a 2mm axle or motor shaft perfectly!

 

No play at all!

 

I used a countersunk head pop rivet because the head is flat - which is what I like.

 

I've used a dome head without any problems but I prefer the look of the countersunk head.

 

I'll provide a photo later.

 

Thanks for asking!

 

Ernie

[Alchemist]

Hi David,

 

I check the torque applying only 4 volts for a quick moment - then multiply by 3 to get an approximate 12 volt reading.

 

I do that a few times and take that average and then multiply by 3.

 

Close enough for me to get an idea - just for the entertainment of it.

 

This doesn't seem to affect my motors.

 

Ernie

[Alchemist]

Here is photo of a crown gear for a 1/8" axle next to a 1/8" aluminum countersunk rivet.

 

Rivet inserted into the gear barrel.

 

Shaft removed from rivet and installed - but I did not tap the rivet to make it flush against the gear - just for example.

 

 

Of course, you'll need to drill a hole through the rivet for the set screw to penetrate and then ream the hole to eliminate any burrs.

 

I've also done this on my 1/8" wheels so I could run them on 2mm axles - better wheel/tire selection for my purposes.

 

You could always file away the head if you're shy on clearance, which is what i've done.

 

 

Thank you.

 

Ernie

[Clyde Romero]

Very cool
A nice piece of engineering
Good luck with it

[Racer36]

That could be called a smoke generator as well, depending on how it is used.

[Alchemist]

This little device looks like an accurate method of reading RPM.

 

If only I knew how to wire up a connector for an electronic Tach - LOL!

 

 

Ernie

[MarkH]

Are you finding testing with this method allows for the separation / ranking of real track performance?

[Alchemist]

Hi Mark,

 

For me, it does provide a way to determine what motor I would use for a particular chassis I've built, based on the torque findings and not necessarily rpm.

 

My "experimental" chassis builds are all different in weight and depending on what I'm trying to achieve, will determine which motor I've deduced would work well.

 

I don't participate in sanctioned races, only in friendly "race what you brought"  skirmishes - LOL!

 

This exercise provides me something to enjoy, as well as trying to engineer something purposeful for keeping me occupied.

 

The slot car track that I use to visit has permanently closed, and since I really enjoy slot cars, I try and "engineer" stuff for myself which helps to keep my mind sharp!

 

Besides, it gives me something to "play with" - LOL!

 

Ernie

[MarkH]

OK, what kind of difference are you seeing in your final values?

[Alchemist]

Hi Mark,

 

 

 

OK, what kind of difference are you seeing in your final values?

I'm not fully understanding the question.

 

I have a variety of motors I've collected.

 

I have FK130's, FK180's, Kyosho RC car motors etc., .

 

From the handful I've tested for torque value, some FK130's have very close torque readings to some of the FK180, and vice versa;  while some of the very low cost "mini" FK130 motors have very low torque readings.

 

So, there are vast differences.

 

I'm just curious as to what the torque values of the motors that I have.

 

I prefer "torquey" motors for my scratch built chassis.

 

As I mentioned, it is just something I prefer to do, for the fun of it.

 

Ernie

[MarkH]

I assumed you were testing a whole bunch of the same motor and then track testing. Then moving on to different motors and repeating.

I understand what you are doing now. Keep us posted.

[John Luongo]

great and useful project! being able observe stall torque and rpm would be a good indicator of motor performance. your test data and graph would indicate which motor/chassis set ups to use for both flat, twisty tracks and high speed banked tracks. very well done!

[bbr]

Cool tools to check motors, very useful to weed out the bad ones when you just bought 50 motors to find that bullet motor

[Alchemist]

Wow!  I had forgotten about this thread!

 

 

Thanks John, Mike for the compliments!

 

It is very much appreciated.

 

Ernie