18 replies to this topic

[Victor Poulin]

Hey guys,

Yes, I have yet another question for you. I've been getting very heavy into motor building, and was wondering if any body makes anything that measures motor RPM? I would think with all the motor building tools out there today, that someone may know of a company that makes or sells something. I feel that would be a great asset to motor building.

Vic

[HarV Wallbanger III]

Pro Slot used to make one but I think they stopped. You can find them every once in a while... good luck!

[Ralph Thorne]

Pro Slot and Trinity both made motor dynos that read RPM, every now and then they can be found on eBay. JK also used to sell a power supply that read RPM.

[Rick]

Vic, you can buy a hand held tach, they are pretty reasonable. I saw one of the Eruopean power supplies with a tach display built into it, I think they are rather expensive...............

[Victor Poulin]

Vic, you can buy a hand held tach, they are pretty reasonable. I saw one of the Eruopean power supplies with a tach display built into it, I think they are rather expensive...............

Good idea Rick, Do you think a 12volt automotive tack would work? I know the ones I used to use years ago really bounced around alot, and it was sometimes hard to get a good reading on them.

Vic

[idare2bdul]

I've been using the Trinity version. Works great. They should have their new one out soon hopefully.

[Dante]

Try this on Ebay
http://shop.ebay.com...-All-Categories
Dan

[Phil Irvin]

Mmmmm. They use a reflective tape to bounce a lazer beam off the spining object. A polished arm might work but you have 3 poles and that should make it read 3 times the actual rpm. I may be wrong BUT......

OLPHRT
PHIL I.

Just thought. Take and put a small flat spot on the arm shaft & paint it a flat black so that the flat black will not reflect the lazer might work??

[idare2bdul]

RC airplanes use some motors our size. If you made a test stand to hold the motor and put a small propeller or even a back and white disc on a prop adapter the airplane tachs might work.

prop adapters

[JerseyJohn]

here goes Motor Dyno--amps /volts/ rpm/ break in

[Guy Spaulding]

If you have money coming out of your nostrils, this is the closest thing you'll find to a real dyno.

https://www.ssl-stor....pl?pn=FAN60622


I have one for RC Motors. It's the real deal. (but much cheaper for RCs because brushed motors are all but dead)

[Victor Poulin]

One of our members on here just made me an offer I couldnt refuse for a trinity dyno.
Thanks for all the help. I really like some of the set ups some of you posted, but man !! you gotta have some real deep pockets for some of them Im sure the trinity will be good for what Im doing. I know a few other racers/builders that have them, and they love them. Thanks for all the help guys.


Vic

[HarV Wallbanger III]

Victor,
Mikes prop type dyno is a real good way to test torque. Just adjust the size of the "fan" till you get something that is repeatable. You don't need props either just make different size fans till you get one that puts about 10 0r 20% load on the motor and then read RPMs. The one with the most RPMs has more torque. Clue: look at a good windup mantle clock and check what they use as a fan. Real simple. You can use props but if you make your own you can keep cutting down the size and weight till you get whats needed.

I built one years ago and it worked great! Just takes some time to dial it in. That one had a driven slave motor that drove the fan. Since I got back into slots again I still have not built another one.... but I need to.

more help:
Remember these motors we use have max torque at 0 RPMs! This means "locked rotor torque"

Run test motor at 6V- 8V check rpms say 30,000 rpms (pic any #)

Put load on and test for a short time and see what RPMs it reads (try to get a fan that will show a 10% (3000) or
a 20% drop in RPMs = 6000) Higher loads means more heat. You can use more % of load but watch out.

Test all the same motors wind type to each other. (ie: 12's, 15s, 20s, Falcon 7, TSR etc.) The one with the most rpms has more torque but there are other things as well to think about.....

Watch for motor to heat up and check temp often.

If you build it so you can watch rpms constant you can also do run up tests to see how fast it gets to the max rpm as well and confuse yourself more. Just use a stop watch unless you have a good bud to build a custom circuit for you!

Remember its all info and how to deal with it is what makes it fun!

Then just when you think you are done... start checking motor brushes in the same motor and see that some of those are better than others!

[Victor Poulin]

Victor,
Mikes prop type dyno is a real good way to test torque. Just adjust the size of the "fan" till you get something that is repeatable. You don't need props either just make different size fans till you get one that puts about 10 0r 20% load on the motor and then read RPMs. The one with the most RPMs has more torque. Clue: look at a good windup mantle clock and check what they use as a fan. Real simple. You can use props but if you make your own you can keep cutting down the size and weight till you get whats needed.

I built one years ago and it worked great! Just takes some time to dial it in. That one had a driven slave motor that drove the fan. Since I got back into slots again I still have not built another one.... but I need to.

more help:
Remember these motors we use have max torque at 0 RPMs! This means "locked rotor torque"

Run test motor at 6V- 8V check rpms say 30,000 rpms (pic any #)

Put load on and test for a short time and see what RPMs it reads (try to get a fan that will show a 10% (3000) or
a 20% drop in RPMs = 6000) Higher loads means more heat. You can use more % of load but watch out.

Test all the same motors wind type to each other. (ie: 12's, 15s, 20s, Falcon 7, TSR etc.) The one with the most rpms has more torque but there are other things as well to think about.....

Watch for motor to heat up and check temp often.

If you build it so you can watch rpms constant you can also do run up tests to see how fast it gets to the max rpm as well and confuse yourself more. Just use a stop watch unless you have a good bud to build a custom circuit for you!

Remember its all info and how to deal with it is what makes it fun!

Then just when you think you are done... start checking motor brushes in the same motor and see that some of those are better than others!

Wow, Now you my friend, have done some home work And you are so right, all this work and planing/building is all part of the fun of slots. If it were to easy, would it be as fun? Sure wish you lived closer to me so we could wrench together I think I could learn alot. My true love is building motors. Dont know why, but I just really enjoy it.

Vic

[HarV Wallbanger III]

That's just a redneck dyno Victor. I'm cheap and needed to git-er-done so I worked it out. I was going a real involved direction and after talking to my Uncle ( a old Kansas farmer and plant electrician) and a few others it was the best way for me. It took some time but it worked real good. Now with PC's it may be better to do it that way if you have a electro geek to build the board.

[HarV Wallbanger III]

Oh I got asked about the slave motor on the one years ago.... I just used a small hobby motor AND the fan to add flywheel to the mass. If I do another it will be different with no motor. Like I said .... redneck dynos take time to figure out. Hey maybe I'll market one.....
Oh also the clocks I told you about use what I call a fan but it's not used for that.... figure it out...

The Team CORT Waz'zu Dyno and drink mixer! Anybody up for Wallbangers!

[Cop Cake]

Mmmmm. They use a reflective tape to bounce a lazer beam off the spining object. A polished arm might work but you have 3 poles and that should make it read 3 times the actual rpm. I may be wrong BUT......

I think if you have a pinion gear on your motor that you could affix the tape to the face of the pinion, or......

There was this note:

It comes with two contact tips that can be used to touch the rotating shaft. This is great when a reflcetive tape can not be attached, e.g. due to grease or water.

[Horsepower]

Try this on Ebay
http://shop.ebay.com...-All-Categories
Dan

This is really interesting! I wonder if they actually work? Price is cheap enough.

[Dante]

It works.
You may have to make (sometimes it works by painting a flat black spot on the shaft) a light weight disc that the motor can spin; paint 1/2 the disc flat black and away you go.
Dan