Go to Post Robotics competitions take place in the same "perfect" environment that basic physics equations take place in. :rolleyes: - Branden Ghena [more]
Home
Go Back   Chief Delphi > Technical > Motors
CD-Media   CD-Spy  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
Closed Thread
 
Thread Tools Rate Thread Display Modes
  #1   Spotlight this post!  
Unread 22-11-2004, 23:19
Solace's Avatar
Solace Solace is offline
Head Hurts. Coffee. More. Now!
AKA: Jake
#0571 (Team Paragon)
Team Role: Alumni
 
Join Date: Feb 2002
Rookie Year: 2001
Location: Windsor, CT
Posts: 569
Solace is a splendid one to beholdSolace is a splendid one to beholdSolace is a splendid one to beholdSolace is a splendid one to beholdSolace is a splendid one to beholdSolace is a splendid one to beholdSolace is a splendid one to behold
Send a message via AIM to Solace
Re: Advices on FP Motor

a single lesson learned from 2004.

Do not use FP motors in your drive train unless you are comfortable basking in the aroma of sizzling plastic.
__________________
...What is a man,
If the chief good and market of his time
Be but to sleep, and tool? A nerd, no more.

2004 UTC New England #2 seed
2004 UTC New England Champions with 716 & 230
2004 Archimedes #2 seed, undeafeated in Qualifiers (for what its worth)


Jake
Team Paragon #571
  #2   Spotlight this post!  
Unread 22-11-2004, 23:26
Elgin Clock's Avatar
Elgin Clock Elgin Clock is offline
updates this status less than FB!
AKA: the one who "will break into your thoughts..."
FRC #0237 (Black Magic)
Team Role: Mentor
 
Join Date: May 2001
Rookie Year: 2001
Location: H20-Town, Connecticut
Posts: 7,773
Elgin Clock has a reputation beyond reputeElgin Clock has a reputation beyond reputeElgin Clock has a reputation beyond reputeElgin Clock has a reputation beyond reputeElgin Clock has a reputation beyond reputeElgin Clock has a reputation beyond reputeElgin Clock has a reputation beyond reputeElgin Clock has a reputation beyond reputeElgin Clock has a reputation beyond reputeElgin Clock has a reputation beyond reputeElgin Clock has a reputation beyond repute
Send a message via AIM to Elgin Clock
Re: Advices on FP Motor

Quote:
Originally Posted by Solace
a single lesson learned from 2004.

Do not use FP motors in your drive train unless you are comfortable basking in the aroma of sizzling plastic.
I remember that smell @ the Jersey regional. I thought the stands were on fire or something.
I guess I was upwind of it.
__________________
The influence of many leads to the individuality of one. - E.C.C. (That's me!!)

  #3   Spotlight this post!  
Unread 23-11-2004, 00:10
Unsung FIRST Hero
JVN JVN is offline
@JohnVNeun
AKA: John Vielkind-Neun
FRC #0148 (Robowranglers)
Team Role: Engineer
 
Join Date: May 2001
Rookie Year: 2000
Location: Greenville, Tx
Posts: 3,159
JVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond repute
Re: Advices on FP Motor

  • The FP motor windings have insulation that gives off a distinctive odor when combusted.
  • The magic white smoke leaves these motors much easier than most.
  • The motor will burn before the 30A breaker trips.
  • Gear down to reduce motor load accordingly.
Seriously...
Try to keep these motors from EVER running at stall while drawing 12V. This will minimize their strain over the course of a match, and prevent them from smoking.

If you EVER stall these motors during a pushing match...
... hope you have some spares ready.
__________________
In the interest of full disclosure: I work for VEX Robotics a subsidiary of Innovation First International (IFI) Crown Supplier & Proud Supporter of FIRST
  #4   Spotlight this post!  
Unread 23-11-2004, 00:17
Tytus Gerrish's Avatar
Tytus Gerrish Tytus Gerrish is offline
IGAB, ADHD, and Dislexic
AKA: Ty
FRC #0179 (SwampThing)
Team Role: Tactician
 
Join Date: Feb 2003
Rookie Year: 2001
Location: West Palm Beach, Florida
Posts: 2,017
Tytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond repute
Re: Advices on FP Motor

:wiffs the air: Smells like... fisher Price,
  #5   Spotlight this post!  
Unread 23-11-2004, 07:33
Unsung FIRST Hero
Al Skierkiewicz Al Skierkiewicz is offline
Broadcast Eng/Chief Robot Inspector
AKA: Big Al WFFA 2005
FRC #0111 (WildStang)
Team Role: Engineer
 
Join Date: Jun 2001
Rookie Year: 1996
Location: Wheeling, IL
Posts: 10,798
Al Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond repute
Re: Advices on FP Motor

The FP motors are really pretty strong motors but like any of the motors we use there are some flaws. FP's need to be run at the RPM they were designed for. Low RPM on these motors spells disaster as the fan that pulls colling air through the frame is very inefficient. At low speeds the heat from the motor will melt the fan (which is just pressed on the armature shaft) and it will stop working altogether. Remember that this motor is designed to power a drive around kids car in almost continuous duty until the batery dies, without failure. Keep the RPM up, and the motor ends unobstructed to allow cooling air to flow through and you should have no problems. Stall current is above 90 amps, so more than 100 watts can be dissipated in that little package.
__________________
Good Luck All. Learn something new, everyday!
Al
WB9UVJ
www.wildstang.org
________________________
Storming the Tower since 1996.
  #6   Spotlight this post!  
Unread 23-11-2004, 07:43
David Guzman's Avatar
David Guzman David Guzman is offline
Registered User
AKA: Dave
FRC #1251 (The Techtigers)
Team Role: Engineer
 
Join Date: Nov 2004
Rookie Year: 2004
Location: Broward, FL
Posts: 522
David Guzman has a brilliant futureDavid Guzman has a brilliant futureDavid Guzman has a brilliant futureDavid Guzman has a brilliant futureDavid Guzman has a brilliant futureDavid Guzman has a brilliant futureDavid Guzman has a brilliant futureDavid Guzman has a brilliant futureDavid Guzman has a brilliant futureDavid Guzman has a brilliant futureDavid Guzman has a brilliant future
Re: Advices on FP Motor

Thank You every one for your input. From what i have heard, it isnt very reliable to use them in the drive train. What has your team used them for? How did it go?
  #7   Spotlight this post!  
Unread 23-11-2004, 07:50
Unsung FIRST Hero
Al Skierkiewicz Al Skierkiewicz is offline
Broadcast Eng/Chief Robot Inspector
AKA: Big Al WFFA 2005
FRC #0111 (WildStang)
Team Role: Engineer
 
Join Date: Jun 2001
Rookie Year: 1996
Location: Wheeling, IL
Posts: 10,798
Al Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond repute
Re: Advices on FP Motor

Quote:
Originally Posted by David Guzman
Thank You every one for your input. From what i have heard, it isnt very reliable to use them in the drive train. What has your team used them for? How did it go?
Dave,
I should add that we have used FPs for many years in our drives including our 2003 Championship winning design. They are as reliable as anything in the KOP if used as intended.
__________________
Good Luck All. Learn something new, everyday!
Al
WB9UVJ
www.wildstang.org
________________________
Storming the Tower since 1996.
  #8   Spotlight this post!  
Unread 23-11-2004, 08:16
Unsung FIRST Hero
Mike Betts Mike Betts is offline
Electrical Engineer
no team
Team Role: Engineer
 
Join Date: Dec 2001
Rookie Year: 1995
Location: Homosassa, FL
Posts: 1,442
Mike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond repute
Re: Advices on FP Motor

I will not be as harsh on the motors as others in this thread. They are powerful and compact actuators. We have used the FP motors in quite a few key applications over the years (we have avoided using the FP gearbox since the first year). I don't think that we have ever failed a motor.

Prolonged stalling of any DC motor is something we try to avoid by design. Beside heating effects, the larger motors (drill, CIM, van door) will trip circuit breakers and the smaller (window, seat) will rapidly slow (internal PTC resistor). All of these are undesirable in a competition robot...

Another note: I usually inspect the FP motor wires where they attach to the motor rather carefully. I have found the integrity of the connection at that point to be lacking...
__________________
Mike Betts

Alumnus, Team 3518, Panthrobots, 2011
Alumnus, Team 177, Bobcat Robotics, 1995 - 2010
LRI, Connecticut Regional, 2007-2010
LRI, WPI Regional, 2009 - 2010
RI, South Florida Regional, 2012 - 2013

As easy as 355/113...
  #9   Spotlight this post!  
Unread 23-11-2004, 08:16
David Guzman's Avatar
David Guzman David Guzman is offline
Registered User
AKA: Dave
FRC #1251 (The Techtigers)
Team Role: Engineer
 
Join Date: Nov 2004
Rookie Year: 2004
Location: Broward, FL
Posts: 522
David Guzman has a brilliant futureDavid Guzman has a brilliant futureDavid Guzman has a brilliant futureDavid Guzman has a brilliant futureDavid Guzman has a brilliant futureDavid Guzman has a brilliant futureDavid Guzman has a brilliant futureDavid Guzman has a brilliant futureDavid Guzman has a brilliant futureDavid Guzman has a brilliant futureDavid Guzman has a brilliant future
Exclamation Re: Advices on FP Motor

Ok now im confused because firt John V says that the motors will burn before the 30 amp breaker trips. However Al says that their stall current is over 90 amps. I don't know if im understanding correctly but if the motor burns before it trips the 30 amp circut breaker then that would mean that it would burn before it gets to its stall current?
  #10   Spotlight this post!  
Unread 23-11-2004, 09:15
Unsung FIRST Hero
Mike Betts Mike Betts is offline
Electrical Engineer
no team
Team Role: Engineer
 
Join Date: Dec 2001
Rookie Year: 1995
Location: Homosassa, FL
Posts: 1,442
Mike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond repute
Re: Advices on FP Motor

Quote:
Originally Posted by David Guzman
Ok now im confused because firt John V says that the motors will burn before the 30 amp breaker trips. However Al says that their stall current is over 90 amps. I don't know if im understanding correctly but if the motor burns before it trips the 30 amp circut breaker then that would mean that it would burn before it gets to its stall current?
Dave,

Please refer to the chart labeled "time vs. current" on page 2 of this document Snap Action Specification then read on...

Any fuse or circuit breaker uses heat to trip. Heat is related to current by ohms law. When you plot the time versus current required to trip the device, you get a characteristic curve called an inverse time curve.

All current interrupting devices are made to pass the specified current (what is called 100% rated current) forever. Therefore, a 30 amp circuit breaker will not trip at 30A.

Referring to the curve for Snap Action, at 90 amps (300% rated current), the device will take between 1.5 and 4 seconds to trip. The range of values is due to variations in manufacturing.

Two factors further mitigate this operation point. (1) You never get to 90A because of voltage drops in the speed controller and wiring. (2) The internal resistance on the Exide battery will drop your voltage under load. As such, the voltage seen at the motor is closer to 8 or 9 volts during a stall.

It is likely that it could take 5 to 10 seconds for a FP motor st stall conditions to trip the breaker.

Now let's give the system a second or two to cool, the breaker resets and it starts again... During a two minute match, this can happen many times... The thermal mass of the FP is large compared to the breaker. Heat builds up in the motor and, after a while, the motor wires smoke.

The breaker tried to do it's job. If we had used a fuse or a non-self resetting circuit breaker, the motor would have been stopped after the first stall and the interrupting device would have protected the motor.

Note here that the FP is not unique. I have seen many smoking drill motors in my 10+ years of doing this...

Engineering is all about trade offs. Most teams would prefer a self resetting breaker which allows you to continue playing the match. The down side is that you run the risk of frying a motor.

You can try and educate your drive team to avoid motor stalls. Even better, you can try and design systems which do not stall...

Bottom line... Read and understand the spec sheets.

Peace.
__________________
Mike Betts

Alumnus, Team 3518, Panthrobots, 2011
Alumnus, Team 177, Bobcat Robotics, 1995 - 2010
LRI, Connecticut Regional, 2007-2010
LRI, WPI Regional, 2009 - 2010
RI, South Florida Regional, 2012 - 2013

As easy as 355/113...
  #11   Spotlight this post!  
Unread 23-11-2004, 09:32
Unsung FIRST Hero
JVN JVN is offline
@JohnVNeun
AKA: John Vielkind-Neun
FRC #0148 (Robowranglers)
Team Role: Engineer
 
Join Date: May 2001
Rookie Year: 2000
Location: Greenville, Tx
Posts: 3,159
JVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond repute
Re: Advices on FP Motor

Quote:
Originally Posted by Mike Betts
Bottom line... Read and understand the spec sheets.

Peace.
Mike is absolutely right.
I was in a goofy mood, and probably overly harsh on the FP motor. We have had some bad luck using them, despite my best efforts as a mechanical designer to minimize the loads they see.
  • It is a good motor.
  • 3rd most powerful motor in our kit. (Following Drills then Chiaphuas)
  • Many teams have used them with great success. (My favorite usage has been by team 60. They use 2 of these to power their 2-jointed arm.)
I still recommend investigating another motor for drivetrain, and possibly saving the FP (and it's premade, 147:1 gearbox) for an arm or other mechanism.

Good Luck in whatever you do,
John
__________________
In the interest of full disclosure: I work for VEX Robotics a subsidiary of Innovation First International (IFI) Crown Supplier & Proud Supporter of FIRST
  #12   Spotlight this post!  
Unread 23-11-2004, 10:10
Andy Brockway Andy Brockway is offline
Engineer
FRC #0716 (Who'sCTEKS)
Team Role: Engineer
 
Join Date: Apr 2002
Rookie Year: 2001
Location: Falls Village, CT
Posts: 459
Andy Brockway has a reputation beyond reputeAndy Brockway has a reputation beyond reputeAndy Brockway has a reputation beyond reputeAndy Brockway has a reputation beyond reputeAndy Brockway has a reputation beyond reputeAndy Brockway has a reputation beyond reputeAndy Brockway has a reputation beyond reputeAndy Brockway has a reputation beyond reputeAndy Brockway has a reputation beyond reputeAndy Brockway has a reputation beyond reputeAndy Brockway has a reputation beyond repute
Re: Advices on FP Motor

We used these in our winch last year with great success. The key has been stated above, use as intended, run near full speed for cooling.

If you do a search through the archives you will find a drawing for replacing the final gear with a metal one. Bill Beatty was kind enough to share his design and it is still available at http://www.beattymachine.com/gear.htm.
__________________
Andy Brockway
Team 716, The Who'sCTEKS
  #13   Spotlight this post!  
Unread 23-11-2004, 10:19
Unsung FIRST Hero
Al Skierkiewicz Al Skierkiewicz is offline
Broadcast Eng/Chief Robot Inspector
AKA: Big Al WFFA 2005
FRC #0111 (WildStang)
Team Role: Engineer
 
Join Date: Jun 2001
Rookie Year: 1996
Location: Wheeling, IL
Posts: 10,798
Al Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond repute
Re: Advices on FP Motor

Quote:
Originally Posted by David Guzman
Ok now im confused because firt John V says that the motors will burn before the 30 amp breaker trips. However Al says that their stall current is over 90 amps. I don't know if im understanding correctly but if the motor burns before it trips the 30 amp circut breaker then that would mean that it would burn before it gets to its stall current?
David,
Mike refers to the current trip point in the breaker but we also must add into the variable mix the fact that your speed controller is not at full up all the time. That means that there are current pulses being fed to the motor that could be at full stall current but the average is actually less. What makes the situation worse is the fast rise times at the switch points do produce some significant back EMF when the motor is heavily loaded. These add to the heat in the motor due to eddy currents and arcing brushes that the circuit breaker will not react to. As to the circuit breakers, they are usually out in the open getting cooled off by moving air and the large diamter wire will draw heat away from the breakers as well. However, when these self resetting breakers start to trip under heavy loads they do get extremely hot and reset times can be under a second, so fast that the breakers actually buzz. When this occurs, do not allow anyone to get near the breaker panels until they have had time to cool. The temperatures are beyond the point of producing second cegree burns.
Other things that are beyond our control that affect whether a motor winding burns are the uniformity of the varnish coating and bending and nicking of the wire as it is wound on the armature. A wire that is bent and/or pulled tightly around a sharp corner will become the weak point in the winding, having the highest resistance and therefore the highest heat. Add these variables to the mix and winding failure is inevitable at the weak point(s).
Again, running this motor at normal design speeds will let the fan move air through the motor minimizing the heating factors.
__________________
Good Luck All. Learn something new, everyday!
Al
WB9UVJ
www.wildstang.org
________________________
Storming the Tower since 1996.

Last edited by Al Skierkiewicz : 23-11-2004 at 10:21.
  #14   Spotlight this post!  
Unread 23-11-2004, 11:03
Woodie Flowers Award
Bill Beatty Bill Beatty is offline
Registered User
#0071 (Team Hammond)
 
Join Date: Sep 2001
Location: Hammond, IN
Posts: 175
Bill Beatty has a reputation beyond reputeBill Beatty has a reputation beyond reputeBill Beatty has a reputation beyond reputeBill Beatty has a reputation beyond reputeBill Beatty has a reputation beyond reputeBill Beatty has a reputation beyond reputeBill Beatty has a reputation beyond reputeBill Beatty has a reputation beyond reputeBill Beatty has a reputation beyond reputeBill Beatty has a reputation beyond reputeBill Beatty has a reputation beyond repute
Re: Advices on FP Motor

F P Caution

We have used the FP motor and gearbox every year since it has been in the KOP. Not the most efficient, but easy and economical to use.

Our gear mod will not work on the newer FP gearboxes. The final gear set is much heavier than before. The weakest link now appears to be the gear cases. Don't have a fix for it yet, but if we come up with something, we will post it.
  #15   Spotlight this post!  
Unread 23-11-2004, 11:30
ChrisH's Avatar Unsung FIRST Hero
ChrisH ChrisH is offline
Generally Useless
FRC #0330 (Beach 'Bots)
Team Role: Engineer
 
Join Date: Jun 2001
Rookie Year: 1998
Location: Hermosa Beach, CA
Posts: 1,230
ChrisH has a reputation beyond reputeChrisH has a reputation beyond reputeChrisH has a reputation beyond reputeChrisH has a reputation beyond reputeChrisH has a reputation beyond reputeChrisH has a reputation beyond reputeChrisH has a reputation beyond reputeChrisH has a reputation beyond reputeChrisH has a reputation beyond reputeChrisH has a reputation beyond reputeChrisH has a reputation beyond repute
Re: Advices on FP Motor

The BeachBots have used the Fisher Price motors with great success ever since they were introduced. But we have never used them as a drive motor. when combined with the supplied gearbox, they make a pretty good winch. You can even use the supplied wheel adapter for your winch drum. Two plates with a hole in the right spot and a couple of scraps of aluminum angle and you have a really powerful winch. Our winch for pulling us on the bar last year was one of the fastest around, and we had enough pull to lift a second robot, in case somebody should have accidentally gotten hooked on us. It used two FP motors and gearboxes with a custom drum. The only problem we have had was a failed limit switch. It allowed the winch keep pulling beyond its normal travel and bend our lift. Fortunately it was during a demo and not the competition season

As Al S mentioned earlier, it is important to keep them operating at the correct speed. We always design our systems so that the motors are running at 75% of free speed and 25% max torque under a normal load. Those rules pretty much apply to all motors. Follow them and your motors will live long and you will prosper.

ChrisH
__________________
Christopher H Husmann, PE

"Who is John Galt?"
Closed Thread


Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Gas powered engine horsepower equivalent to electrical motor horsepower? Elgin Clock Motors 30 22-08-2004 20:44
Multiple Motors phrontist Motors 12 21-06-2004 23:05
Mounting the drill motor Veselin Kolev Motors 11 26-04-2004 14:27
Parallel Motor Connection Don Wright Electrical 12 30-03-2004 21:23
Thermal Protection archiver 2000 1 23-06-2002 23:27


All times are GMT -5. The time now is 15:45.

The Chief Delphi Forums are sponsored by Innovation First International, Inc.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright © Chief Delphi