my new cheap servos

[Dan S]

I found these servos on the net, and they are dirt cheap, so I just had to get them.

the website where i got them

http://www.cnczone.com/gallery/data/...85myservos.jpg

I posted a message on the gecko forum asking if they where any good and Marriss replied with the following.

“
Use a 36VDC power supply.
No-load RPM at 36VDC = 3,130
(Ke = 11.5, KRPM = 36V / Ke)
80% of no-load RPM = 2,500 RPM
Leadscrew RPM @ 120 IPM, 5TPI = 600RPM
Reduction Ratio = 2,500 RPM / 600 RPM = 4.1666:1, Use 4:1
Kt = 1.351 Ke = 15.5 in-oz / amp
Maximum continuous current = 3 Amps
Maximum continuous torque = 3A * Kt = 46.5 in-oz
Torque on leadscrew = 46.5 in-oz * 4:1 reduction = 186 in-oz
Leadscrew thrust = pi/8 * TPI * in-oz = 365 lbs
Maximum speed at full load = 2500RPM /(ratio * TPI) = 125 IPM
Maximum speed, no-load = 3,130RPM / (ratio * TPI) = 156 IPM
Power delivered to load = RPM * in-oz / 1351 = 86 Watts

Mariss
“

If these servos are even half that good I will be happy.

-Dan

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[ezland00]

I don't think they have encoders. Do they?

[HomeCNC]

I just got my one servo that I ordered to check it out. It looks like they can be modified to hold an encoder. I'm going to reverse the end caps because I like the cap where the wires connect as the front. I will turn off the knurl as well.

[Dan S]

If your using belt drive isn't it better to hook the encoder to the screw, and not the servo?

Jeff

whats knurl??

-Dan

[barbwirebi]

Jeff & Dan

I'm still in the conception phase of my router design and don't really know what I exactly need yet. But I could not pass on this deal!
I bought five.
Guees this resolves my Stepper versus Servo Issue

So how much can I expect to pay for encoders?(.001 resolution)

I want my router to handle 4' x 8' sheets of 3/4" MDF
If I slave two motors together do you guys think I will have enough torque to move a (aluminum)gantry along @ 60 IPM
cutting .500 depth of cut in MDF?

If thesse motors cant do it, perhaps I should build a small mill first.


Thanks in advance
This is a great forum!!
Barbwire Bill