a cheap motor..

i'm writing here (wish that's the right place) to ask this:
i've seen a series of video on the tube explaining how to use a car alternator as a brush DC motor.
it can be a very cheap way to have powerful motors to build an experimental machine.
what do you think about that? did anyone try this way?

thanks for ideas..

How about a new 7KW motor for $99.99?

hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=5139

Not sure how long it will hold together at 7KW...

Im pretty sure a treadmill has a dc brush motor and you can find them on ebay pretty cheap.
May not be large enough for your purposes but .....

PCW wrote:

How about a new 7KW motor for $99.99?

hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=5139

Not sure how long it will hold together at 7KW...

intersting, but...mmm.. if you read in the posts, someone says it became very hot in a minute.
after all they are meant to be used on airplanes, so no force but air should be applied on the motor..

an alternator should be powerful. maybe not fast..
or another idea could be a motor from a washing machine?

dewey525 wrote:

Im pretty sure a treadmill has a dc brush motor and you can find them on ebay pretty cheap.
May not be large enough for your purposes but .....

thanks! i needed google to understand what a treadmill was!
but since i'm looking to a cheap way to find 4 identical motors, i'm sure i can't find 4 used identical treadmills to take motors from!!!
anyway, is it right to say that i can use i.e. 7i29 mesa cards to drive such motors? (under a 7i43?)
of course with an encoder per motor..
thanks!

Yes the 7i43 will drive the 7i29 although limited by the amount of I/O, but that is according to what you are trying to accomplish. What are you looking to do anyway?

hi, and thanks for answering.
i just want to improve my stepper inverted tetrapod, and to do that, for sure i'll change to servo motors.
but since my only experience is with cheap steppers, i wanted to find a not expensive way to learn how to use servos and drives..
i like very much all that i've read about mesa drivers, so maybe in a first step i can buy the drivers needed and use costless used surrogate of motors..then with practice i will feel i could spend lot of money for 2kw motors, or something like that and hardware.

in a first configuration, with mono-phase motors, i just need one 7i43, two 7i29 driving 4 motors, 4 encoders (differential?) and 4 limit switch (maybe 8..)..and of course a fisical e-stop..
do you think a configuration like this will be possible?
the 7i43 comes in 4 configurations: with or without USB and 200k or 400k gates..
do emc2 users need the USB kind?
then from the manual i couldn't find info on what changes from the 200k and 400k. is it the number of logical i/o?
how many do they have?
how many i/o do one 7i29 use?
any idea of the cost of the 7i29 and 7i43?
thanks and sorry for so many questions and for my possible english-writing errors.
ciao, davide.

1st I wanna see a pic of that tetrapod... Sounds cool !!!

I have looked at other emc2 compatible hardware and yes the mesa to me seems to be a better choice as it is a modular system. Now the 7i43 will only drive the 2 7i29 boards so that leaves no availability for limit switches or an e-stop. Im just not sure how to configure the e-stop or limits to kill main power to the servos with just the 7i29 but i havent read through the manual or really thought that through. Off my head id guess relays powered with a series circuit of the limit switches and e-stop, but Id still want that as an output monitored by emc2.

So Id suggest the next best priced solution of 1-5i20 2- 7i29 and 1 7i37ta which would allow you to run the 4 servos and have 16in 8 out for limits and e-stops ( Im still learning these boards and how to integrate also )The 7i43H is the 400k the 7I43-p is the 200k and from my understanding emc2 does not work well with usb (7i43H) just parallel and pci (7i43-p) . Honestly the 7I60 may provide you a better solution , but you would need to read the manual as it has a lot of options available.

The 7129 do not hold their peak current rating long as they are derated as they increase in temp so you will need to cool the heatsink by mechanical means for running large loads for extended periods of time.

The 5i20 is listed at 199.00 usd the 7i29 are listed at 299.00 usd and the 7133ta is 79.00 usd they say something about another 20% charge but as I have yet to order my boards Im not sure.

dewey525 wrote:

1st I wanna see a pic of that tetrapod... Sounds cool !!!

you can see here. sites.google.com/site/kedefly/home/Lavor...erimonia-volley-2010
the flying ball is the vertex of the tetrapod.

I have looked at other emc2 compatible hardware and yes the mesa to me seems to be a better choice as it is a modular system. Now the 7i43 will only drive the 2 7i29 boards so that leaves no availability for limit switches or an e-stop. Im just not sure how to configure the e-stop or limits to kill main power to the servos with just the 7i29 but i havent read through the manual or really thought that through. Off my head id guess relays powered with a series circuit of the limit switches and e-stop, but Id still want that as an output monitored by emc2.

So Id suggest the next best priced solution of 1-5i20 2- 7i29 and 1 7i37ta which would allow you to run the 4 servos and have 16in 8 out for limits and e-stops ( Im still learning these boards and how to integrate also )The 7i43H is the 400k the 7I43-p is the 200k and from my understanding emc2 does not work well with usb (7i43H) just parallel and pci (7i43-p) . Honestly the 7I60 may provide you a better solution , but you would need to read the manual as it has a lot of options available.

The 7129 do not hold their peak current rating long as they are derated as they increase in temp so you will need to cool the heatsink by mechanical means for running large loads for extended periods of time.

The 5i20 is listed at 199.00 usd the 7i29 are listed at 299.00 usd and the 7133ta is 79.00 usd they say something about another 20% charge but as I have yet to order my boards Im not sure.

another way coul be having a second parport to plug all the switches and e-stop in. is it right?
then the 5i2x series is wonderful, but works on pci.. i prefer parport because i can use one notebook, since i'll use the system in different places..but effectively i cannot add another parport on the notebook..