[Larken]

Welcome to the new forum for the Viper servo drive.
Its available in two models
Viper 100
80 volt @ 20 amps

and
Viper 200
180 volt @20 amps

These drives are loaded with the features you need to control cnc routers, mills and lathes etc.

For more info on Larken's servo drives check them out on the website
http://www.larkencnc.com/viper/index.shtml

Larry kenny

[turmite]

Hi Larry,

Good looking product. I would like to offer a little bit of gentle advice!

Your website is somewhat difficult to navigate. If all pages were vertical it would be much faster to read everything. I don't know if it's just my pc, but I had to navigate both vertical and full page horisontal to get all the info.

I also noticed you posted about customers with Mach giving feedback. Would it be possible to get a little more detail.....since I use Mach?

Mike

[Larken]

Thanks, i will check that . It should be no more than 800 pixels wide.

The customer manufactures cnc routers and Lasers. They commented that they could run faster and smoother with the viper than the other 2 popular servo drives.
One reason is because on the other drives they overshoot when the Derivative is increased to settle the motor. The viper's enhanced PID control settles without overshooting. This makes it follow Mach2's contouring more accuratly and you can run faster.

[turmite]

Thanks for the info. I got your pm as well. I currently am using steppers but my next machine will likely have servos on it. I hear so many good things about speed,smoothness etc.

Mike

[DennisCNC]

Will the motor runaway if the encoder signal is lost?

[jamma]

Very interesting product. I'm fixing a broken Bridgeport clone retrofit that has a 115VDC power supply. The old drives are shot, so I was thinking of trashing everything and setting up a 80V Gecko-based system. Your 200V viper would simplify my job a lot, although the parts cost would actually be more expensive ($239 x 3 = $717 vs $114 x 3 + $150 for PS = $492).

I like that it can use single or differential encoders, and am intrigued by the storage of multiple motor configurations. I've dreamt of building one controller box for a mill, lathe, & router (since in a garage setup like mine, you only have one machine active at a time) with a selectable switch on the front for the appropriate machine. The multiple motor config makes this possible (although still not simple - lots of relays required).

Have you ever used these drives in conjuction with a Geckodrive G100 motion controller?

[faststeve]

I'm setting up Viper servo's on my mill. They are working real well. Are they size 34 or 42 motors on your mill ?

[Larken]

Will the motor runaway if the encoder signal is lost?

No, it won't, Ive added that feature in the latest version.

It also has current protection to protect the drives incase you crash into a hard stop.

[automationtechinc]

The KL34-150-90 Servo Motor is working good with Viper servo drive.
If you are looking for the Servo Motor, pls check
www. http://www.kelinginc.net/ServoMotor.html

[N4NV]

Will the Viper drive run a DC brushless motor? How much power is available for the encoder? (the Gecko drive is limited to 50mA).

Thanks

Vince

[Larken]

Will the Viper drive run a DC brushless motor? How much power is available for the encoder? (the Gecko drive is limited to 50mA).

No, just Brushed motors for now.
The encoder power has a separate 7805 regulator, so it can supply as high as necessary.

[bcromwell]

Have you tested your drives with the Geckodrive G100 motion controller? I would love to use mach3 + the G100 + Viper drives.

[Larken]

Have you tested your drives with the Geckodrive G100 motion controller? I would love to use mach3 + the G100 + Viper drives.

Should work fine.
One question, why do you need the G100, if you have Mach2 that outputs step/direction ?

[turmite]

The G100 produces a much smoother pluse train at a lot higher frequency than the the engine used by Mach.

Mike

[sbalder]

I took the plunge and ordered 3 Viper 200 Servo drives this morning. I plan to use them on 140Volt-11AMP dc servo motors on a Milltronics Partner Mill that I am trying to bring back to life. My only hesitation is that the product is new so there isn't a lot of feedback I have been able to find.

[JerryFlyGuy]

I'm also interested in these [the 80v /20a] drives and would use them w/ a G100. The other concern I have is how fast a pulse train the drive can accept. The G100 can output up to 4Mhz step and direction pulse streams. Can your drive accept these? Also does your drive accept differential encoder signal's?
What encoder count speed has it been tested to?

[Larken]

I'm also interested in these [the 80v /20a] drives and would use them w/ a G100. The other concern I have is how fast a pulse train the drive can accept. The G100 can output up to 4Mhz step and direction pulse streams. Can your drive accept these?

Its easy for a counter based board (like Grex) to output 4mhz or 100 mhz, but it doesn't mean its useful.
If you even ran 100Khz, your machine would be flying faster than you could use.

Also does your drive accept differential encoder signal's?

Yes.

What encoder count speed has it been tested to?

2 Mhz

[JerryFlyGuy]

Larken thats true to a point. However I'd planned to use a 1800 line encoder. My servo can hit 3000rpm so that ends up being 360,000Hz on the encoder line. And the drive would have to handle that pulse speed to make it all work. Now, am I going to run it up there all the time.. no, but if I ever get things tuned out so that it gets close I don't want to have to worry about the drive missing steps or faulting out because of it.. these are just question's I ask before I buy.. they're kinda useless to ask afterwards

So if the drive will accept up to 2Mhz on the encoder side, does that mean they'll take 2Mhz on the step/dir side?

[Mariss Freimanis]

Let's see here: 100kHz or abve isn't useful. Your drive accepts 2MHz so it is useful.

It's not useful, it's useful. It's not useful, it's useful. My brain vibrates dangerously. Cognitave dissonance warning! Arggg!!!

Why as a circuit designer would you expose a port to 2MHz and its attendant 150nS noise pass-band if the intended resonse is limited to sub 100kHz step pulse rates?

About step pulse rates: Say you have a 6,000RPM motor equipped with a 2,000-line encoder; it's not an entirely unreasonsable proposition. The encoder results in 8,000 counts per revolution and there are 100 of them per second. This requires an 800kHz step pulse frequency and that's just a tad above the stated 100kHz to "make it fly".

At 100kHz that motor would reach 750RPM and only deliver 12.5% of the power it has available. It would take an 800kHz step rate to have it deliver 100% of the power the client paid for in buying the motor.

Mariss

[Larken]

Say you have a 6,000RPM motor equipped with a 2,000-line encoder; it's not an entirely unreasonsable proposition.

Thats a bit of a mismatch for most applications. Maybe in a space shuttle guidance system or semiconductor wafer fab, but i doubt they would be using a drive that costs under $200.

Why as a circuit designer would you expose a port to 2MHz and its attendant 150nS noise pass-band if the intended resonse is limited to sub 100kHz step pulse rates?

Two words > Step multipler

For now the viper has a step input of about 100,000 steps/second which is about 2x what Mach2 can output and satisfys about 99% of applications. (Encoder pulse rate can be up to 2Mhz.)

Probably in a year or so, I will have a drive that can take a 1-2mhz step-rate using newer DSP technology.