[Sanghera]

Hi all,
I was just wondering what some good servo motor sources are, I want to run the motors off of a Gecko G320. Does this board drive brushless and brushed motors? I found some motors at homecnc.info but I'm not sure if there are any other good deals. I have been looking around and am a bit lost on what type of encoder and motor to get.
Thanks for the help.
I really appreciate it. :wee:

[snaggletto]

Hello,
Ebay is the most popular/affordable source, but takes some time and searching. Gecko G320/G340 will operate brush servos only, NOT brushless DC or AC servos. Brush servos have small round caps around the rear of the body of the motor. These screw in and out to allow replacing the brushes. So, look for these in pictures if the seller doesn't advertise it as brushed or brushless.

Rutex.com has brush and brushless drives. They also allow for larger servos than the Geckos as they go up to 200V @40A where Geckos are limited to 80V and 20A. However, this will still drive a large NEMA 34/42 servo effectively.

Geckos have a bit wider user base, so it's easier to get information for troubleshooting. Also, Mariss, the owner/creator of Geckodrives, makes himself commonly available for support and he is great to work with. There is nothing wrong with Rutex, they have nice products and support right here on cnczone also. Geckos are just a bit cheaper.

You will need 5V optical encoders, Renco and US Digital are popular. You can buy encoders yourself from US Digital for decent prices and install them yourself. But you would be good to buy servos with proper encoders already fitted, like at homecnc. These encoders are "quadrature", meaning 4X. So 250 count per rev encoders will give 1000 pulses per rev etc... This is important as Mach2 or other step/dir software can only output so many pulses. High count encoders can limit your speed.

Older servos commonly used analog resolvers for feedback. These will NOT work. You need digital, optical encoders, these are very common on newer motors.

[Sanghera]

Thank you soo much for the help. How many oz-in do servos go up to? I'm guessing as big as you want to pay, but I have seen lots of stepper motors above 1000oz in on the internet from home cnc builder stores, or other stores on the internet, but I'm not sure because I can't find many big servo motors other than on ebay, other than the www.homecnc.info website. Is this because the cost tends to go way up, and they become more for industrial use?
Thank you so much for the help.
I really appreciate it. :wee:

[Al_The_Man]

The largest I have used is 40Nm = 5624oz-in = 354lb-in
Al

[Sanghera]

How much is a servo like that worth, although a bit overkill for a home cnc machine. OUCH THOSE ARE BIG. What were they for? Also, what size servo could you expect from a 20 A 80 Volt limit? I know it depends a lot on the motors themselves aswell but it's alright.
Thanks. :yee:

[Al_The_Man]

$3,500.00 used on a 30ft bedmill table.
Al.

[HomeCNC]

Sanghera

I have looked into getting larger servo motors to sell. I have a connection direct from the factory. I looked at a Nema 34 size servo that was 1110 oz/in running at 48VDC with a 20 amp peak. Even selling them at $200 each with an installed encoder would just barely make me any money AT ALL! There is a guy selling a slightly larger servo motor now one Ebay that is asking slightly less than $200 each. I just can't compete with that! I can't spend close to $10,000 to get the quantity of larger servo motors down in price to compete with him when I would not even know if I could get them all sold!

[Sanghera]

I think I know which person on ebay your talking about, but I do understand where you are coming from. Thank you all soo much for the help.