Posted by Raul at 1/7/2001 12:57 PM EST
Engineer on team #111, Wildstang, from Rolling Meadows & Wheeling HS and Motorola.
Did I miss a section in the manuals or am I correct in saying that it does not say how many off-the-shelf gears we are allowed? In the “Additional HW” list (appendix C) it says 6 “timing pulleys” and it says 20 feet of “Timing belt”. But it does not say anything about gears or chain.
Last year, we were allowed to use as much chain and as many gears as we wanted. Please don’t tell me this decision was reversed. Someone please enlighten me.
Raul
Posted by Frank at 1/7/2001 8:32 PM EST
Coach on team #97, Psychedelics, from CRLS and MIT.
In Reply to: Gears? Chain?
Posted by Raul on 1/7/2001 12:57 PM EST:
Raul,
There is no mention of gears or chain. So I guess that means you can use as much as you want, but the chain has to come out of Small Parts and the gears do too…or be custom made out of raw material that is on the list.
Frank
: Did I miss a section in the manuals or am I correct in saying that it does not say how many off-the-shelf gears we are allowed? In the “Additional HW” list (appendix C) it says 6 “timing pulleys” and it says 20 feet of “Timing belt”. But it does not say anything about gears or chain.
: Last year, we were allowed to use as much chain and as many gears as we wanted. Please don’t tell me this decision was reversed. Someone please enlighten me.
: Raul
Posted by Ken Leung at 1/8/2001 2:45 AM EST
Student on team #192, Gunn Robotics Team, from Henry M. Gunn Senior High School.
In Reply to: Gears? Chain?
Posted by Raul on 1/7/2001 12:57 PM EST:
It seems like this is only a matter of typo in the manual. But it won’t be sure until FIRST have another team update clarifing all these mess in the manual. What is the e-mail address to ask FIRST about these kind of questions? (if it’s not appropiate to post the address here, can you please e-mail me?)
Until then, we can only have small-part gear/sproket. Guess that’s why the budget for SPI is $1200.
Posted by Elaine at 1/8/2001 5:20 AM EST
Student on team #368, Kika Mana, from Mckinley High School and NASA Ames/Hawaiian Electric /Weinberg Foundation.
In Reply to: Re: Gears? Chain?
Posted by Ken Leung on 1/8/2001 2:45 AM EST:
The address are in the manual under the administration section. It depends on what your question is to know who to contact. There are several e-mail addresses listed.
Elaine
: It seems like this is only a matter of typo in the manual. But it won’t be sure until FIRST have another team update clarifing all these mess in the manual. What is the e-mail address to ask FIRST about these kind of questions? (if it’s not appropiate to post the address here, can you please e-mail me?)
: Until then, we can only have small-part gear/sproket. Guess that’s why the budget for SPI is $1200.
Posted by Jim Meyer at 1/8/2001 3:04 PM EST
Engineer on team #67, HOT Team, from Huron Valley Schools and GM Milford Proving Ground.
In Reply to: Gears? Chain?
Posted by Raul on 1/7/2001 12:57 PM EST:
It looks to me like the restrictions on gears chain and sprockets were intended to make the pneumatics more appealing so that everyone would use them, thus making their donating sponsors happier. It saddens me to see the restrictions. It wouldn’t be as big of deal if we could use our allowance at McMaster-Carr. SPI doesn’t carry squat in comparison and their parts take forever to get!
I guess we’ll just have to get used to waiting a week or so for delivery of a high cost limited selection of gears.
On the pneumatics, has anyone figured out how to controll the position of the piston other than mechanically limiting its range? It’s supposed to be so much better for robot arms but it seems you could only have two positions of your arm.
Posted by Jason Iannuzzi at 1/9/2001 8:58 AM EST
Engineer on team #11, Marauders, from Mt. Olive HS. and BASF, Rame Hart, CCM.
In Reply to: Re: Gears? Chain?
Posted by Jim Meyer on 1/8/2001 3:04 PM EST:
For once, I really think there is a conspiracy.
I imagine last year, with the rules on gears and chains relaxed as they were, SPI saw a significant drop in the amount of items ordered. Honestly, we barely ordered a single part from them last year. It was so much more economical NOT to. Combine SPI and the Fluid Power coalition, and you probably have the roots of the gear/chain rule change.
It saddens me. Life was so easy last year.
Posted by Elliot Johnson at 1/9/2001 2:19 PM EST
Student on team #218, HP Robotics Team, from Highland Park High School and Double-E Inc…
In Reply to: Re: Gears? Chain?
Posted by Jim Meyer on 1/8/2001 3:04 PM EST:
: On the pneumatics, has anyone figured out how to controll the position of the piston other than mechanically limiting its range? It’s supposed to be so much better for robot arms but it seems you could only have two positions of your arm.
There are at least two different ways I know of to slow the cylinders down to a controllable speed.
The first (easiest & most reliable) is to put one of the little pressure valves inline with the cylinder’s feed. I’m not sure the exact name for them, they look like little 90 degree elbows and have a screw coming out of them, like a small water faucet. You adjust the screw until the cylinder moves at a comfortable speed. To move it to a certain position, just turn on the pressure switch for the cylinder until it is where you want it and turn off the switch. The air pressure will remain in the cylinder so it will maintain it’s position. You can also use two valves, one for each entry into the cylinder, to have different speeds in different directions.
The other way I’ve read about it to use a model like PWM for controlling motors. The solenoid valve is quickly pulsed on and off rapidly. The pulses begin at a constant frequency (the solenoid is turned on every x milliseconds) but the length of the pulse depends on how fast you want the cylinder to move. The length of the pulse can be between 0 (not moving at all) and the full period (full power). Anywhere in between should give a proportional speed. This setup is more complicated, but the speed isn’t fixed like with the pressure regulators. For a better description of PWM, check out this article in the SRS newsletter: http://www.seattlerobotics.org//encoder/apr98/68hc12pwm.html
Hope that helps!
Elliot Johnson
Team 218
Double-E Inc & Highland Park High School Robotics
Posted by Nate Smith at 1/9/2001 4:41 PM EST
Other on team #66, GM Powertrain/Willow Run HS, from Eastern Michigan University and GM Powertrain.
In Reply to: Gears? Chain?
Posted by Raul on 1/7/2001 12:57 PM EST:
: Did I miss a section in the manuals or am I correct in saying that it does not say how many off-the-shelf gears we are allowed? In the “Additional HW” list (appendix C) it says 6 “timing pulleys” and it says 20 feet of “Timing belt”. But it does not say anything about gears or chain.
: Last year, we were allowed to use as much chain and as many gears as we wanted. Please don’t tell me this decision was reversed. Someone please enlighten me.
: Raul
Update