24 replies to this topic

[mgerbetz]

Who makes a nice spur gear sizing gauge ?
Or how do you determine teeth count ?
So many gears, so many brands, so many colors and sizes.

[Racer36]

There is a sizing tool available for 64 pitch gears. Mark can get you one. That’s the only one I know of.

[Matt Sheldon]

Problem that I found is that there is a considerable o.d. inconsistency between brands. 

[MSwiss]

Minor thing.

Sizes will vary between brands.

IE -JK 38 .618
Cahoza 38 .621
Koford 38 .625

[Matt Sheldon]

Minor thing.

Sizes will vary between brands.

IE -JK 38 .618
Cahoza 38 .621
Koford 38 .625

Except when you are using a gauge that is cut to .626 for 38T to try to determine if your 38T JK is really a 38T when it fits perfectly into the 37T spot. Most are color coded these days thankfully.

[mgerbetz]

Any color code/ brand charts out there ?
I could start with Mikes measurements for the 38t and go from there.

[mreibman]

Vanguard wpeedlab makes these for 64 and 72 pitch. Nice. Available direct or through distribution. Ask your raceway, but they sell them in 10 packs.
https://www.vanguard...ucts/gear-gauge


I have another kind from RM Racing that's different, but never see it anymore. They made ones machined from aluminum for 48 and 64 pitch and included pinion sizes.

[Highnoon]

I measure my favorite gears and use that. I mainly use cahoza, hp and s&k.

[HarV Wallbanger III]

Problem that I found is that there is a considerable o.d. inconsistency between brands. 

Yes even with a gear guide different brands are all different.... It would be nice if they were all molded in.... Big enough for us old farts to see easy

I have old gears that do not have T count so being color blind I have to count them.....

[Eddie Fleming]

The big problem with counting and I expect I am not alone, is I get up to 30 or so and get messed up and need to start over. 

[Big_John]

I just use a pair of dial calipers. 

 

Measure the OD, multiply that times the gear pitch and subtract 2. 

 

For example, if my gear measured .594 and I had a 64 pitch gear. 

 

.594 x 64 = 38

 

38 - 2 = 36 

 

36 tooth gear. 

 

This is a gear formula that you can find just about anywhere and not something I made up.

 

I've printed out a small copy of the sizes of the gears I use (or may use) and stuck that on my spare gear parts box. 

 

 

 

[Dave Crevie]

The big problem with counting and I expect I am not alone, is I get up to 30 or so and get messed up and need to start over. 

 

Mark a tooth with a magical marker, then count off ten teeth and mark that one with the marker. Count ten more and mark it. Go all the way around. Count up the tens and add the leftover teeth between the starting tooth and the last tooth of the last group of ten. Easy breezy. 

[HarV Wallbanger III]

I just use a pair of dial calipers. 

 

Measure the OD, multiply that times the gear pitch and subtract 2. 

 

For example, if my gear measured .594 and I had a 64 pitch gear. 

 

.594 x 64 = 38

 

38 - 2 = 36 

 

36 tooth gear. 

 

This is a gear formula that you can find just about anywhere and not something I made up.

 

I've printed out a small copy of the sizes of the gears I use (or may use) and stuck that on my spare gear parts box. 

 

 

 

Will give it a try thanks

[Zippity]

Do you measure tooth to tooth, or between teeth to between teeth?

 

Just asking for a friend  

[Big_John]

Do you measure tooth to tooth, or between teeth to between teeth?

 

Just asking for a friend

 

You are measuring the outside diameter as shown here. 

 

 

 

A couple caveats:

 1. As was said, this outside diameter is going to vary a little between manufacturers/vendors and probably even gear to gear. These aren't really precision gears, just little plastic gears for our toy cars. 

 

2. You have to round off some of the measurements because of caveat 1

 

3. Gears with odd number of teeth need a little understanding that you can't measure to from the outside of one tooth to the outside of another tooth. The "jaws" of the caliper are flat. See caveats 1 and 2 and the illustration below. 

 

4. It's harder to do this as the gears get smaller and have less difference between OD (obviously)

 

Gear measurement is a science in itself and someone that mops the floor in a gear factory QC department would be more knowledgeable than me. I have slept in Holiday Inns though.

 

A couple of things that might help understanding gears. Note the "pitch diameter" in the above picture.  A 64 pitch gear with a 1" pitch diameter will have 64 teeth. Same for a 48 pitch gear with a 1" pitch diameter. It will have 48 teeth.

 

There are much more accurate ways of measuring gears and I would suggest looking into measuring the pitch diameter with a seat of appropriate gear wires if you really want to get into what gear is better quality and that really just scratches the surface. 

 

This also illustrates how measuring gears with odd numbers of teeth could be difficult. 

 

[Nonfractal]

Thanks for that John,
A very useful pair of graphics to explain the terminology.
Companies like NSR vary the pitch to keep the same OD for differing numbers of gear teeth.
Calculations based on knowing the pitch just don't work for those types of gears.
Alan W
London.

[Sean Mikuen]

Vanguard wpeedlab makes these for 64 and 72 pitch. Nice. Available direct or through distribution. Ask your raceway, but they sell them in 10 packs.
https://www.vanguard...ucts/gear-gauge

Hey that's me! I appreciate the recommendation! I got tires of counting teeth like any sane person does, and originally made something like what RM has. Then I thought I'd have to take a gear off and on every time to look. After some considerations and different designs, I settled on what I have now. And now I sell it in packs of 5 to raceways, as 10 was a bit much.

As far as size goes, I haven't had any issues with any brand of gear, including angle spurs. (With angle spurs, you will want to measure at the larger edge) I have used cahooza, proslots, JK, SK, and others These are also great for raceways running a stock or spec class, which allow for different brands of gears. Especially since every brand has its own color code.

I'll be adding new products in the future, I've just been very busy with other facets of life, as this is just for fun

[Tim Neja]

I placed an order on your website and sent paypal?  DId you get it?  Tim Neja

[Sean Mikuen]

I placed an order on your website and sent paypal?  DId you get it?  Tim Neja

Thanks for the order Tim! I did get your order and it was sent out a few days ago. Did you receive an email with the tracking number? If you want, send me a PM or an email, as I don't want to make this seem like an ad

[Pablo]

Gentlemen, these posts should be Private Messages

[Zippity]

Why should they?

 

They are no worse than some of yours I see in this forum.

[Big_John]

I went to sort some gears and realized my chart that I posted (taped to my box  o gears) had a pretty drastic mistake. The 48 pitch gears were listed having the same OD as the 64 pitch. 

 

Here's the corrected version. 

 

I guess no one was watching me the day I did this, so I blame whoever's turn it was. 

 

[Zippity]

Who races 48p gears these days?   

[Jay Guard]

Who races 48p gears these days? 

Everybody that races under IRRA rules does.

[Big_John]

Who races 48p gears these days? 

We do.