Moderators: Dave Moll, Steve Anderson
gary wrote:Hi Harry I hope this makes it a bit clearer:
gary wrote:Shipping is the killer...
gary wrote:Strangely though, I look all the time (I want to upgrade from a measly 35 oz to 200 oz) and have yet to see the killer deal that forces my hand...
Viewmaster wrote:Harry, other than using bellows or rubber there is another type of coupling that was used on tuning for short wave receivers etc, where zero back lash was essential.
Eddystone Radio made them many years ago and they are seen on ebay
from time to time.
Consisted of a two pieces of brass mounted either side of a circular plate. riveted each side (or use bolts). Coupling boss each side in centre.
The Eddystone one took a 1/4 inch dia shaft.
You could easily make one to suit requirements using 2 pieces of spring steel etc. or something along this principal design.
See piccy of the Eddystone one here.
gary wrote:Harry, I have addressed this before but you mustn't have got the reply, but the NEMA rating is to do with the physical size of the motor not it's holding torque. For instance a NEMA 17 has a diameter of 1.7" if round or has a side length of 1.7" if square shaped.
Now obviously the larger the casing the more copper you can get in it so the more powerful motors are the larger sizes.
But, my steppers are NEMA 23 but are only 35oz-in so you can't assume the larger the motor the more powerful.
Having said that if you want 200 oz-in (generally recommended for your size machine) you would need to go to NEMA 23.
Floppy disk drive motors are NEMA 14 I think with very very low holding torque.
Yes if you are using a recycled motor and it doesn't have the holding torque written on it the only way (if it doesn't have a model no you can look up - many do) is to measure it the way you mention - there are some tuts on how to do that on the net. Persoannly I think it would be just as easy to hook them up and see how they go - if they don't have enough grunt then you need to source other motors.
But if you buy new motors the holding torque is always specified.
Users browsing this forum: No registered users and 20 guests