Motor RPM testers
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1,864 Posts
search for "laser rpm" on ebay
These laser tacho's comes with a reflective tape that you cut and place on the wheel (from center of hub to tire edge), then measure the RPM and multiply the result with the cars gear ratio to find the motor RPM.
These laser tacho's comes with a reflective tape that you cut and place on the wheel (from center of hub to tire edge), then measure the RPM and multiply the result with the cars gear ratio to find the motor RPM.
Are these cheap digi tachos any good? EBay is full of an orange and black model for about ten pounds. I will have one if they work consistently. I have been disappointed with cheap digital verniers before with the reading fluctuating wildly!
Thanks
Thanks
Ive used a Sampo DT2234B and it seems to do the job very well. Just make sure it can sample well above 20k rpm.
http://cgi.ebay.com/DIGITAL-PHOTO-TACHO-TA...=item35b3fe6f69
cheers
rick1776
http://cgi.ebay.com/DIGITAL-PHOTO-TACHO-TA...=item35b3fe6f69
cheers
rick1776
I have one and instead of using reflective tape i just painted an aluminium hub black and scratched a line about 2mm wide in one part of the hub. Works a treat. They are pretty handy if you are racing a control motor class. Not good if you spend hours building a car to find out you put in a dud motor.
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4,637 Posts
If you are going to test motors before you put them in a car you need to make an adapter that will easily press on the motor shaft. I use a short length of thick tubing from my local hardware store. I put reflective tape on that. If you run out of the tape that comes with the tachometer the sort of silvered tape that is used on HVAC ductwork works well.
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1,081 Posts
As an alternative you could try a speed checker see link.
http://www.tbirdslotracing.com.au/itemdetail.php?id=3026
If gearing and tire dia. are equal you get a comparable RPM just put the car an the checker and power up.
Regards Ray
http://www.tbirdslotracing.com.au/itemdetail.php?id=3026
If gearing and tire dia. are equal you get a comparable RPM just put the car an the checker and power up.
Regards Ray
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3,411 Posts
The speed checker is made for RC cars, the two I have seen have been modified for slot cars use. But the results we got d were not in proportion to the results we got using a tachometer. I think it may be that the speed checker provides some load to the car. So the results car only be compared to other results taken from the speed checker.
hi all, that speed checker [tamya] is way to dear, check usa ebay, you can buy them for £18 inc P&P. i use a chinese made optical lazer its a DT2234A, no makers name, range 2.5-99999rpm its got an 18in piece of sticky back reflective 12mm wide tape supplied, i use a small tyre tube cap painted matt black and drilled 1.8mm hole in the dimpled centre, this gives a nice tight push fit on the 2mm motor shaft. its best to have a pinion on to but against the disc to sqare it up. but not all that important. cost! £7.99 inc free P&P from china 2 yrs ago. works superbly and i cant imagine being without it now. john
QUOTE (Pioneer @ 27 Jul 2011, 15:46) <{POST_SNAPBACK}>search for 'Digital Tachometer'. You need a non-contact optical type that shoots a laser beam, as 356speedster suggested.
Jules
Jules, if your motors lack a bit of top end Ive found that if you place two reflective strips on the disk you double the RPM of your motor. Worth a try.
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cheers
rick1776
Jules
Jules, if your motors lack a bit of top end Ive found that if you place two reflective strips on the disk you double the RPM of your motor. Worth a try.
cheers
rick1776
QUOTE (stoner @ 30 Jul 2011, 07:14) <{POST_SNAPBACK}>hi all, that speed checker [tamya] is way to dear, check usa ebay, you can buy them for £18 inc P&P. i use a chinese made optical lazer its a DT2234A, no makers name, range 2.5-99999rpm its got an 18in piece of sticky back reflective 12mm wide tape supplied, i use a small tyre tube cap painted matt black and drilled 1.8mm hole in the dimpled centre, this gives a nice tight push fit on the 2mm motor shaft. its best to have a pinion on to but against the disc to sqare it up. but not all that important. cost! £7.99 inc free P&P from china 2 yrs ago. works superbly and i cant imagine being without it now. john
The speed checkers on ebay haven't been modified for use with slotcars though. Seems an excessive amount added to the price for what is really just a bit of plastic track in the front. The speed checker is a good tool though as Phil points out the car is under a little load and gives a better indication of how the car will actually go on track. I have had good revving motors before that in a car were ordinary because of a lack of torque.
Speed checker also has a function to test the time over a given distance so you can tell if the motor/gear combination has the right "punch". I think its only useful for hardcore racers though.
The speed checkers on ebay haven't been modified for use with slotcars though. Seems an excessive amount added to the price for what is really just a bit of plastic track in the front. The speed checker is a good tool though as Phil points out the car is under a little load and gives a better indication of how the car will actually go on track. I have had good revving motors before that in a car were ordinary because of a lack of torque.
Speed checker also has a function to test the time over a given distance so you can tell if the motor/gear combination has the right "punch". I think its only useful for hardcore racers though.
I also have a Digital tachometer (the black and orange one with the blue pocket, reflective stripes furnished) I bought two years ago on Ebay for less than 10€, P&P included, from China of course.
as i check the motors alone, i just glued a piece of reflective tape on a sidewinder black Slot-it crown (the biggest i think) : then screw the crown on the motor axis (99% of the time I even don't have to remove the pinion on long cans) and check speed.
It's accurate and easy to use.
It's really worth the try.
Another - far more expansive but far more technoligically advanced - solution is the tool developped and built by my favorite french dealer, SP-Collectable :
http://sp-collectable.com/boutique/descrip...11&path=428
...if you need some translation or more info i may help.
Regards.
as i check the motors alone, i just glued a piece of reflective tape on a sidewinder black Slot-it crown (the biggest i think) : then screw the crown on the motor axis (99% of the time I even don't have to remove the pinion on long cans) and check speed.
It's accurate and easy to use.
It's really worth the try.
Another - far more expansive but far more technoligically advanced - solution is the tool developped and built by my favorite french dealer, SP-Collectable :
http://sp-collectable.com/boutique/descrip...11&path=428
...if you need some translation or more info i may help.
Regards.
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1,987 Posts
I've never understood why people rpm test motors with the motor removed from the car
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Is it just a fascination with yet another piece of kit and another excuse to fork out another load of cash on a fancy gadget?
Surely testing a motor on a gadget takes the motor away from its running context 'on the track' with car weight/magnets/tyre drag/gear drag/influence of gear ratio and so the reading is always going to be false to how the motor behaves in the car under race conditions.
Surely the best type of rpm tester is to use a perfectly set-up car and simply pop each motor into that and simply time the laps?
Keep it simple and keep it accurate
![]()
Is it just a fascination with yet another piece of kit and another excuse to fork out another load of cash on a fancy gadget?
Surely testing a motor on a gadget takes the motor away from its running context 'on the track' with car weight/magnets/tyre drag/gear drag/influence of gear ratio and so the reading is always going to be false to how the motor behaves in the car under race conditions.
Surely the best type of rpm tester is to use a perfectly set-up car and simply pop each motor into that and simply time the laps?
Keep it simple and keep it accurate
sorry i gotta disagree srewneck, say youve got a bunch of 130s or johnston 111s you can at least pick the best motor to start with, and theres nothing to stop you putting the reflective tape on the tyre to see what happens with gear changes. i do agree nothing beats running them on track, but you do have that base line to see what the changes actually do do. the stop watch is the most important ,it doesn,t lie but at least you know how you got there. ive got 2 good johnstones that both turn just over 27000rpm ,itook one and managed to turn the com to 20 advance. it lost brakes but a gear change sorted that, its now turnig 31000rpm and its quicker and easier to drive than the 27000rpm one . as an aside ive got johstones that run from 14000 to 21000 rpm, there due for a clean and blueprint to bring them up to scratch. this is where the rpm checker is invaluable, food for thought and their so cheap now under £10 inc p&p. john
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