Posted by Janna.
Student on team #349, The RoBahamas, from International Academy and Ford Motor Company.
Posted on 2/1/2000 4:26 PM MST
Hi,
We have been having difficulty making the gears we need to have on time. Does anyone know of a good place online or in the metro Detroit area that we can buy some from? One of the gears we need is 16 diametral pitch and 36 tooth…any ideas? We’d appreciate any help you can give us! Thanks a lot!
Janna
Posted by Daniel.
Coach on team #483, BORG, from Berkeley High School and NASA Ames & UC Berkeley.
Posted on 2/1/2000 4:35 PM MST
In Reply to: gears…? posted by Janna on 2/1/2000 4:26 PM MST:
Use the link below (http://www.mcmaster.com/)
Do a quick search for spur gears in the box at the upper left and browse the catalogue of gears. They’ve got 16-32s in all sorts of materials. Good luck!
Posted by Joe Johnson. [PICTURE: SAME | NEW | HELP]
Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.
Posted on 2/1/2000 5:00 PM MST
In Reply to: Re: gears…? posted by Daniel on 2/1/2000 4:35 PM MST:
McMaster sells 14 1/2 degree pressure angle gears.
The gears on the window motors are NOT 14 1/2 degree pressure angle gears.
You don’t have to understand the exact theory of conjugate action of gear teeth, but you must at least know this much: 20 degree pressure angle gears and 14 1/2 degree pressure angle gears DO NOT LIKE EACHOTHER!
I would suggest that you call Berg (wmberg.com) or Stock Drive Products (sdp-si.com) or PIC Design (pic-design.com) or if you are in a REAL hurry and have buckets-o-cash you can call Rush Gears (rushgears.com).
One nice thing about rush gears is that they have NO stock on hand but for the right amount of money stuffed in their palms they will cut (not wire EDM, cut, I say) you almost ANYTHING you want in any material you want and have it on your DOCK in 3 days. Very impressive company. I wish I could afford them more often 
Anyway… Bottom Line: If you are looking for a mate to the gear on the window motor, don’t get a 14 1/2 degree pressure angle gear (which I believe is the only pressure angle gears that McMaster sells).
Joe J.
Posted by Justin Stiltner.
Student on team #388, Epsilon, from Grundy High School and NASA, American Electric Power, Town of Grundy.
Posted on 2/1/2000 7:09 PM MST
In Reply to: DANGER, DANGER, DANGER! WARNING ALL FIRST TEAMS! posted by Joe Johnson on 2/1/2000 5:00 PM MST:
I have a tip and a question first the tip
The drill motors will mount to the fisherprice gearboxes with the pre drilled mounting holes
Now the question
What do I need to know about the gear on the fisher price motor in order to order one exactley like it but with a bigger shaft hole to fit the drill motor also how are these attached to the motors ??
Justin Stiltner
Team 388
Posted by Joe Johnson. [PICTURE: SAME | NEW | HELP]
Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.
Posted on 2/1/2000 7:41 PM MST
In Reply to: More gear questions posted by Justin Stiltner on 2/1/2000 7:09 PM MST:
Justin,
I can answer your question, but I am a bit afraid to.
The Fisher Price gearbox is designed for the motor that it comes with. Specifically the Mabuci motor with a stall torque of about .36 N-m.
I am far from convinced that the geartrain is sufficiently overdesigned to take the .65 N-m stall torque of the Johnson Electric motor used by Bosch.
Also, there are other considerations. The Johnson Electric motor is much bigger and has a higher free speed. Both of these factors mean that more kinetic energy will be stored in the armature as the motor reaches high speeds. If the output shaft is stopped rapidly (e.g. your arm hits a hard stop or your robot runs into a diamond plate wall ;-), the much larger kinetic energy of the armature can provide very much larger impact loads to the gears in the gearbox.
Bottom line: I STRONGLY urge you to reconsider using the drill motors on the Fisher Price gearboxes.
But… in my spirit of giving teams the rope needed to hang themselves if they REALLY insist that they know what they are doing…
The gear is basically a standard ‘full depth,’ 16 tooth, 20 degree pressure angle, 32 diametral pitch gear.
Note: this is close to the 0.7 module (approx. 36 Diametral Pitch) gear on the drill motor, but is not the right pitch. While Raul tells me from experience that the drill motor pinion is sufficiently hard to ‘wear in’ a 28 D.P gear, I cannot in good conscience recommend it.
Joe J.
Posted by Justin Stiltner.
Student on team #388, Epsilon, from Grundy High School and NASA, American Electric Power, Town of Grundy.
Posted on 2/1/2000 11:57 PM MST
In Reply to: Hey, Be careful out there… posted by Joe Johnson on 2/1/2000 7:41 PM MST:
Joe
Thanks for the advice manily what I wanted the information for is just in case of one of our fp motors going down and not having a spare we are not using the drill motors at all and it was just a ‘I wonder if…’ type of thing but I think we have already decided aginst it.
Justin Stiltner
Team 388
Posted by Joe Johnson. [PICTURE: SAME | NEW | HELP]
Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.
Posted on 2/2/2000 5:08 AM MST
In Reply to: Re: Hey, Be careful out there… posted by Justin Stiltner on 2/1/2000 11:57 PM MST:
NOT USING THE DRILL MOTORS! ? ! ?
These are easily the most powerful motors in the kit. It is difficult to understand a decision not to use them.
Is there nothing you would prefer to do have the same output force only to move faster?
How about something you would like to do at the same speed but with more force?
Both of these things boil down to wanting more POWER.
If you don’t put it in at the motor side, you can’t get it out at the output side.
Word from Joe J, ‘USE THE DRILL MOTORS!’
Joe J.
Posted by Andy Baker.
Engineer on team #45, TechnoKats, from Kokomo High School and Delphi Automotive Systems.
Posted on 2/2/2000 6:12 AM MST
In Reply to: Re: Hey, Be careful out there… posted by Justin Stiltner on 2/1/2000 11:57 PM MST:
Justin,
I agree with Joe. Definitely try to use your Drill Motors. These great motors have driven our robot for every year that they have been available. And before that, we used the previous drill motors to drive our 'bot.
We even abuse them by using the 3:1 gear changer to go from low to high gear, without even altering the gearbox (yep, Joe, we use it AS IS). BUT, be warned… it takes some pretty tricky software. One of those unseen aspects of a good 'bot.
Anyway, if you want some F-P gearboxes, we would love to trade for your drill motors. Heck, we might even throw in some other goodies.
Good luck,
Andy B.
Posted by Justin Stiltner.
Student on team #388, Epsilon, from Grundy High School and NASA, American Electric Power, Town of Grundy.
Posted on 2/2/2000 8:44 PM MST
In Reply to: Need Drill Motors, Don’t Want F-P Gearboxes posted by Andy Baker on 2/2/2000 6:12 AM MST:
we might be interested in trading our drill motors for van door motors or the f-p motors but it is still possable that we could use them but I doubt it
I wanted to use the drill motors to power the bot but our engineers had different ideas.
Justin Stiltner
Team 388
Posted by Daniel.
Coach on team #483, BORG, from Berkeley High School and NASA Ames & UC Berkeley.
Posted on 2/2/2000 8:54 PM MST
In Reply to: Re: Need Drill Motors, Don’t Want F-P Gearboxes posted by Justin Stiltner on 2/2/2000 8:44 PM MST:
I think you should push your original suggestion.
I have yet to see a successful drivetrain that uses FP motors. It may work in a sterile back room, but under competition those suckers’ll buckle. Watch out!
One BIG thing to remember: half of engineering is experience. A lot of successes our built on the successes of others…
-Daniel
Posted by Dan.
Student on team #10, BSM, from Benilde-St. Margaret’s and Banner Engineering.
Posted on 2/2/2000 9:26 PM MST
In Reply to: Re: Need Drill Motors, Don’t Want F-P Gearboxes posted by Justin Stiltner on 2/2/2000 8:44 PM MST:
If you use the FP motors for locomotion they WILL burn out and they WILL be slow. It’s very likely you’ll grind some of those plastic gears as well. You’ll be saving your team from a lot of disappointment if you can convince them to use the drill motors.
:-Dan
Posted by Daniel.
Coach on team #483, BORG, from Berkeley High School and NASA Ames & UC Berkeley.
Posted on 2/1/2000 7:35 PM MST
In Reply to: DANGER, DANGER, DANGER! WARNING ALL FIRST TEAMS! posted by Joe Johnson on 2/1/2000 5:00 PM MST:
On page 2 of the spur gear section of the McMaster catalogue you’ll find gear stock with a pressure angle of 20. These are nice in that they allow you to machine your own gears without fancy machines. Hubs and bores can be the size of your choosing. Kinda nice, eh?
Only catch is they make you buy a foot.
-DL
Posted by Daniel.
Coach on team #483, BORG, from Berkeley High School and NASA Ames & UC Berkeley.
Posted on 2/1/2000 7:38 PM MST
In Reply to: Good point…try page two. posted by Daniel on 2/1/2000 7:35 PM MST:
oops, no 32
Posted by Joe Johnson. [PICTURE: SAME | NEW | HELP]
Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.
Posted on 2/1/2000 7:59 PM MST
In Reply to: oops, no 32…(EOM) posted by Daniel on 2/1/2000 7:38 PM MST:
Daniel,
Thanks for finding the 20 degree pressure angle gears in McMaster.
I LOVE that company, but I have never purchased gears from them because I have been basing my decisions on the gears I can see in Catalog 101.
Since McMaster’s lastest is 106 I think it is about time I got a new ‘Big Yellow Book’.
By the way,One of the reasons I think McMaster is so great is that I can place an order on there website at 5:00pm (sometimes LATER) and still have the stuff on my dock by 10am the next day (without paying extra for overnight shipping by the way – they ship to me from a location in Ohio and the stuff just comes regular UPS from there in about 18 hours – go figure).
Anyway, I highly recommend McMaster-Carr for all your robot needs (perf. aluminum sheet is my current favorite product – you’ll see it soon enough).
Joe J.
Posted by Bill Beatty.
Other on team #71, Team Hammond, from Team Hammond.
Posted on 2/2/2000 8:26 AM MST
In Reply to: DANGER, DANGER, DANGER! WARNING ALL FIRST TEAMS! posted by Joe Johnson on 2/1/2000 5:00 PM MST:
Joe
Isn’t the gear on the tape drive a stub tooth? If so. I would think it would be tough to buy a stock gear to mesh properly.
Bill B
Posted by Joe Johnson. [PICTURE: SAME | NEW | HELP]
Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.
Posted on 2/2/2000 3:14 PM MST
In Reply to: More Warning posted by Bill Beatty on 2/2/2000 8:26 AM MST:
Bill,
Good catch, I knew this fact, but I forgot to mention it.
For those who don’t know the difference, ‘stub’ teeth have lower mountains (addendems) and less deep valleys (dedendums) and ‘full depth’ teeth. The problem with mating one with the other is that the valley of the stub toothed gear is not deep enough to allow the mountain of the full depth gear to pass.
However, life is bad, but it is not too bad. Recovery is possible.
Two paths can be followed:
(not as nice as #2 but it will work) Increase the center distance by 0.2 / Diametral Pitch. In the case of the window motor gear this works out to be .2/16 which is 0.012 inches. Not a big deal, but if you don’t do it, the gears will just not spin with eachother. One bad thing about this is that you are increasing the amount of ‘backlash’ in the gear train (beyond what would normally be designed into the gears). All in all , this should be an acceptable work around the stub tooth gear problem.
Chuck up the full depth gear in a lathe and take remove 0.2 / Diametral Pitch from the outside RADIUS of the gear (0.4 / Diametral Pitch off the Diameter). This will effectively make the full depth gear a ‘half stub’ gear in that the mountains will not be as high as a full depth gear even though the valleys are still just as deep as ever. This is my preferred method to make a full depth gear mate with a stub gear. One problem with this method is that you have to be carefull to remove the burr on the top of the gear teeth without damaging the rest of the tooth form. It is tedious, but with a fine file it and patience it can be done.
Good luck.
Joe J.
Posted by Dan.
Student on team #10, BSM, from Benilde-St. Margaret’s and Banner Engineering.
Posted on 2/1/2000 4:39 PM MST
In Reply to: gears…? posted by Janna on 2/1/2000 4:26 PM MST:
Check out Rush Gears (link below.) Never used them, but many have recommended them.
G’Luck
:-Dan