Motor speed Checkers ?

[dr fabio]

Next time you're having India takeaway don't throw away the takeaway container. Using your son's compass, punch a small hole in the middle and scribe a circle about the size of a 10 cent piece on one of the lids. Cut a circle using and paint the disk using flat black paint. Cut a small strip of reflective tape (that comes with the opto tacho) and add to one half of the disk. I use a bit of blue tac to hold the disk in place on the motor shaft. Make sure you push on the disk so that about 2-3mm of shaft pokes out from the disk, otherwise you'll be losing a lot of disks.

cheers
dr fabio

[boopiejones]

Whenever my boys have broken motorized toys, I take them apart before throwing them away. Many times they have motors with large press fit gears or pulleys. Paint one black, install a small piece of reflective tape and you've got a nice round speed check disk.

[SpeedyNH]

here's what i've been doing:
first i take an old press-on plasic sidewinder pinion. cut a quarter-sized circle of plastic business card- like material (even file card will work if you're careful with it), punch a little hole in it to center it easily and superglue it on the end of the pinion. then throw it on a motor and true it up with a file/knife/ sandpaper. then black magic-marker the front side. as below, cut a small trapezoidal piece of the reflective tape that comes with the tach, a little less than the radius and maybe 5/16 wide and stick it on along the outer edge.
press the pinion on the end of the motor shaft and aim the laser at the reflective tape as it passes by. slightly off-axis works the best to avoid saturating the receiver, and also not under direct intense flourescent lighting.
when you have a reading, you can slide it off the shaft with your fingers but sometimes i use needle nosers so i don't bend it. being heavy on one side, even if it hits the floor it won't go too far.
i've made several of these for friends and they seem to like 'em. anyway, it works for me and is a pretty simple fab.
speedy

[waaytoomuchintothis]

That's the same tachometer I have, and more or less the same method I use (by the way, the narrower the reflective tape strip, the more accurate the reading). I also was curious about final rpm under load at the tire surface, and I rigged a fairly elaborate driven dynamo/voltmeter to do it. Funny how that rig just popped into my head, but the simple disk on a motor shaft took me weeks to work out!

[LanciaB]

I use the same speed checker, with just a large black sidewinder slotit crown with reflective tape on it.

[Abarth Mike]

I use a modified Tamiya Speed Checker and an excel spread sheet. Close enough for my needs.

[Abarth Mike]

Simple or obvious really, it needs a slot. So remove the front rollers and add a slot, I used future board and solder wick for the rails. The key is as with all speed or rpm testing is to measure the voltage fed to the car/motor and incorporate that into the results. My cars range in speed from a low of 16 kph to a high of 38 kph. Resolution is only 0.5 kph which is appreciable but good enough for me as in the real world most cars never reach maximum speed anyway.

[Abarth Mike]

No i didn't take any pictures. But this is what I posted on SCI some years ago

"What I did to mine was:

Not necessarily in the correct order.

Removed the 6 screws and took the bottom off.
Removed the front axle and rollers
Turned over the top. in place of the front rollers I put a piece of 4 or 5mm Future Board (corrugated plastic like a box). Fixed it in place with double sided tape
This has a 1/8" slot cut in the centre to allow the guide to sit in. On mine the future board at the rear is lined up with the shaft of the two arrows.
Then I drilled two holes in the top behind the future board at the apexes of the two "shapes" in the centre. Then fed two pieces of solder wick (braid) through the holes and stapled them to the future board to act as "rails" The front of the wick is wrapped under the front on the future board and stapled from below.
I then drilled a hole on the front passed two wires through for power and soldered then to the solder wick. ( I made a mistake on mine and fed the power wire through the top not the front)

I lubricated the rear roller shaft and put the thing back together. Couple of alligator clips and a power source and you are away. Some cars run in between the rollers some ride up on the rear roller because they are long. I left the blue folding stop in place."

There might be something on SF.

[Abarth Mike]

You'll have to start thinking outside the box ;) Not everything in life is perfect.

I use mine for ALL my cars. You only need one wheel on one roller. (Fortunately my Vanquish is wide enough!). Move the Escort to one side a bit.
I was even going to also remove the rear rollers but as it works for me I let it be. As you know 10 seconds is good enough to get a reading. I usually take three or more.

Even a Quad will work on mine. Agreed the guide doesn't fit into my slot as it needs to be a bit longer but the braids make contact and that is good enough. My SCX Citroen has a track of only 40 mm and I can get one wheel to make contact. 8-)