This forum my last hope?
 

Greetings, one and all,

I'm posting here because the folks seem genuinely helpful. I need a pinion gear. It's not for a truck but a Maxon coreless motor to go in a big German train I have. I've done a lot of research, but haven't found a match. I'm hoping that someone here might tell me how to proceed. Here's the info about the needed gear:

10 tooth
2 mm bore
7 mm outside diameter (might have once been 7.5- it's now worn.)
5 mm inside diameter (base of teeth)
5 mm length

Detailed picture at:

http://www.flickr.com/photos/28638959@N08/5303819296/

Thanks,
Tom Cox

PS: I have looked at dozens of vendor sites and found close matches. But I just don't know how to proceed. I know that it's a very dicey thing to try to replace a pinion and get good mesh. But I want to try. The engine has nostalgic value to me. Train forum folks haven't been able to help.

we are and here you go

https://sdp-si.com/eStore/

i would need to know alot more about thr pinion you need to find you the right one, but if it can be found it will be at sdp-si

10T @ 7mm diameter = 43.54p (Mod 0.58). Calculated from http://scriptasylum.com/rc_speed/gear_calc.html

Not much help, but you can get an idea...

sdp-si are very good. I have seen all kinds of gears there. Give them a call or send them an email and I am sure they will be able to help.

Many, many thanks. I can furnish whatever information you need about the pinion in question. BTW- it was installed on a beautiful 1970's vintage large scale German train. I sent the original motor with gear intact to a dealer of coreless motors. He said he'd pull the old gear off and put it on a new Maxon corelss motor for me. But he tore the old gear up really badly with his gear puller. It had meshed very smoothly and when I got it back, it just locked up.
I may have made a big mistake by trying to gently remove the burrs with a dremel. It meshed a bit better. But it's still not right. And I'm just at a loss on what to do next. Should I buy several gears that are close to this one and hope for the best?

I can furnish pictures of the pinion, pictures of the spur gear it meshes with, measurements, whatever is needed. I appreciate very much your help, believe me.

Thanks,
Tom

On the contrary, this is a huge help. The available literature was confusing on how to calculate the modulus. This url converter is a big help. I knew that the modulus was close to 0.6. But it's better to know that it's exactly 0.58. That's of course assuming the original diameter was 7 mm. But if it was 7.5mm, then I know that the modulus is 0.63. If I need to, and if they're available, I can order pinons in 0.58 and 0.63 modulus.

Again, many thanks,
Tom

Thank you very much for the recommendation. They contacted me and I've replied. I'm beginning to feel like there may be hope!

Regards,
Tom

Cool, glad it might help. Along with just the pitch/modulus, also pay attention to the tooth geometry (pressure angle), as there can be variation there even with identical pitch gears. I have a feeling a very large/detailed picture will be needed for sdp-si to make sure they provide the exact match.

The Duratrax Vendetta 1/18 RC car uses Mod 0.6 pinions if I remember correctly, but I believe the stock bore is 2.3mm. Might be worth a try looking at those

Brian's website shows that if the gear was originally 7.2 mm then the pitch would be mod 0.6. That's 48 pitch isn't it? I think that might be it.

Maybe look in the slot cars area?
http://www.ncphobbies.com/arp-1/24-g.../arp4810strts/

Or could this fit?
http://store.rc4wd.com/10-Tooth-48-P...ear_p_597.html

Or maybe find something on ebay?
http://cgi.ebay.com/Losi-Night-Crawl...item20b6214e1b

Scan and fax exact size copy
 

I just thought of something. Would it be of any help to scan and fax an EXACT 1:1 image of the gear? Accurate to .10 say.??

I also have taken a great many photos and measurements.

Thank you,
Tom

It might also help if you had dimensions for the gear this pinion meshes with, if it is not too worn.

Man I love scriptasylum. Brian you have done the RC community something that they will for ever be in debt to you for. Couldn't count the number of times I have used it and it just seems to get better with more features and calculations.

+ 1 as well. I direct my friends to the link constantly when they have a question

I would try a 48 pitch gear, there are 2 types of these, if memory serves me correctly. tamiya use a gear that is very close to 48p in most of their tourinc car line. It is slightly tighter pitch than regular american 48p. Not 2mm bore, but 2.3 (1/8").

Just being pedantic

yup. meant 3.2 which is 1/8...

[QUOTE=tommyheadleycox;392060]Greetings, one and all,

I'm posting here because the folks seem genuinely helpful. I need a pinion gear. It's not for a truck but a Maxon coreless motor to go in a big German train I have. I've done a lot of research, but haven't found a match. I'm hoping that someone here might tell me how to proceed. Here's the info about the needed gear:

10 tooth
2 mm bore
7 mm outside diameter (might have once been 7.5- it's now worn.)
5 mm inside diameter (base of teeth)
5 mm length

Update: Please excuse me if this is a duplicate message. I found a source in England that has a 10 tooth, module 0.6, 2 mm bore pinion gear. I also talked with SDP. They did not <think> they had this gear in stock. So I'll try out the gear from England.

I did find some gears that were close. But the fewest number of teeth was 12, not 10. Question: Am I correct in assuming that I can switch from 10T to 12T, as long as I stay with the same module? I understand this will affect top end speed and put more power demand on the motor, but that's not an issue. I just need to achive proper gear mesh.

Last question: Does anyone know if there exists a module between 0.5 and 0.6? I ask because my measurements and scriptasylum tell me the pinion and spur gears are 0.58 module.

Thanks again for all your help.

Tom

Yeah, thats fine- so long as you can adjust the motor side to side to allow for smaller and larger gears then there wont be an issue using 10t or 12t- does just affect the speed and current draw of the motor a little. I think anything between mod .5 & .6 would be very rare or custom/ bespoke for a certain use- an imperial gear might have the equivalent pitch when converted to metric units of measurements.

Thank you very much - this is really useful to know.
Tom

i thought there was metric and imperial .6 though...

See here for metric 0.6... http://www.robinsonracing.com/catalo...tchpinion.html

and losi/duratrax use the other 0.6

http://www3.towerhobbies.com/cgi-bin...?&I=LXUFE5&P=M

We run Mod0.8 and 32p (31.75p) all the time without issues, and that's a pitch difference of 0.25. Using a mod 0.6 for 0.58 is a pitch difference of 0.02.

Have you considered replacing the spur and pinion as a matched set? You might be able to modify the existing spur mount to fit something much more common. Just a thought...

Press fit vs set screw
 

Greetings everyone,

I've found a source for the gears I need. They use set screws or as the English apparently term them, grub screws. But my Maxon motor has no flat on the shaft and is meant to accept press fit pinions as far as I can tell. The shaft is hardened to a Rockwell designated number so creating a flat might be difficult. Have the folks on this forum deal with this problem before?

The source by the way is RW Racing, Mr. Neil Stubbington. Here's the link:
http://www.rwracing.co.uk/about.html

Thanks,
Tom

depending on the amount of torque that will actually be required to get the train moving you may not need to grind a flat spot for the set screw, it will still bite into the round shaft and stop it from spinning. However if you wish to make a flat spot there are a few ways to do it. Start by getting yourself a plastic bag such as a sandwich bag. put the motor in the bag and poke the shaft through, this keeps any metal filings from getting in the motor. If you have some quality files and the shaft isn't to hard you can do it that way. Or you can use a dremel tool with a grinding stone on it to grind a flat spot.

Thanks for the advice. This is helpful. I'm glad to know I can proceed. BTW, the baggie idea is particularly helpful. I was wondering how to protect the motor!

Regards,
Tom