Need help deciding if Granite Devices will work with my servos

[gavztheouch]

Hi im in need of some advice, Im planning on fitting a new set of electronics to a 20 year old mechanicaly sound machine. The system is not making the most of the machine and I would like to run it with Mach 3 or similer.

The idea is to use a Granite driver for the two West amp servos and Encoders ( Not motor mounted ). And a third drive with a smaller stepper motor for the Z-axis. All drivers to be connected to a granite devices Breakout board and all driver will have there own power supplies.

The large servo motors are rated at 140v max is this too large for the standard Granite devices driver to handle?

The motors are made by WestAmp, the model number is MT233

The encoder is made by Dynamic Research Corp, Model number: 25-F010-B06-2048-AXZ0

Cheers
Gav

[JerryFlyGuy]

The Vsd-e drives are only rated to 80 [or is it 90vdc] so you'd only be getting 80/140=57% of the max speed of the motor at this reduced voltage. Tero used to sell a higher voltage drive, but has since dis-continued them. There was talk of producing a high voltage version of the Vsd-e drive.. but I've not seen any talk of it since.. [or know if it's been done].

If your wanting to run those motors at 140vdc then I'd think your limited to a more commercial level drive [AB or some such].. which is too bad as the Granites are very nice drives [I love mine ]

J

[keebler303]

Tero is supposedly working on a 160V version, but it has been delayed several times. If that gets done, it would be a good fit, otherwise you will not be getting top performance from your motors.

Where are your encoders if they are not on the motor?

A VSD-E is overkill for a small stepper motor. I would go with a gecko for that, but a VSD-E would work fine as well if you want all matching drives.

Maybe Tero will chime in and let us know when(if) there will be a 160V version available.

Matt

[gavztheouch]

You can see the encoder mounted on the underside of the y-axis in the photo below, the x-axis encoder is tooth belt driven straight off the servo.



I've started a build thread elsewhere, Steel Gantry Wood Router

I stupidly thought I would be alright just fitting a Gecko or Granite device driver for each axis, now its looking like my motors are too big to drive and the machine to heavy to accept some smaller motors

[H.O]

If the VSD-E won't do it and if you're interested in a kit you might want to have a look at the HP-UHU. It's not a plug-n-play drive, you'll have to assemble it yourself so you need some knowlege about electronics. They should be good for your 140V motors and are capable of ~25A or there abouts. (I've run mine with a 160V supply during testing without trouble).

It doesn't come even close to the VSD-E when it comes to features - it's just more power. Again, if you know your way around electronics you'll be fine, if not it's still very much doable but you're in for a ride and a learning experience.

Another option is to look at the Viper200 from Larken. Threre are a couple of guys around here that uses them so you can read up on performance and suitablillity.

I'm sorry for bringing up other products on the Granite forum but I'm pretty sure that Tero would like you to have the most suitable drive for your application even though it means it's not his. I have a set of VSD-A and I'm very impressed with them, hopefully the VSD-E will come in a 160VDC version, I'm sure it would be a killer drive.

[JerryFlyGuy]

Grav first, I'd get rid of the seperate encoder and put one on your motor. I think having it seperate down there is just asking for problems.

As far as fitting smaller motors I don't think you need worry. I've got a router which has a gantry which weigh's well over 2000lbs and I drive it w/ two 70vdc servo's [Nema 34's] through a 10:1 reducer and into a 1.5" pinion. I can accellerate at 22in/s/s in Mach 3 and have a top speed up in the range of ~1200ipm [I've got it limited to 500 as I'm not comfortable w/ it being any faster]

If your system was mine, I'd buy a VSD-E drive and power it up w/ the max allowed voltage and run it that way, you may experiance some slower rapids but you'll get all the same cutting power down low. Before you right it off, look at the actual numbers of performance you'll get. [ie do the math on the motor speed and reducers and gearing etc to see what your real world performance numbers will be]

Lastly, as Henrik mentioned if you still feel your going to need the 140vdc drive buy a HP-UHU kit[s], if your not comfortable soldering them together I'm sure you'd have no problem getting someone to do it for you for a few dollars..

Anyway, at the end of the day your not in that bad of a corner, and there are still viable options available to you.. don't lose heart... this is the 'fun' part of getting a machine up and running [there's always a few hills to climb.. just as Henrik about encoders he can tell you lots of stories about his 'hills' ]

Keep us posted..

J

[gavztheouch]

Thanks for the info guys, it does sound promising .

I would like to have a go at the HP-UHU, I have etched a few circuits with press n peel paper and feel confident enough in my soldering and diagram reading skills that I could populate the pcb. There is some doubt as to whether I can actually make it work, but it is by far the cheaper option avaliable and might be an intresting project

I did notice someone was selling kits, this could be the way to go, instead of making my own pcb's.

If I got one kit and a breakout board I could start experimenting with the motor. One possible problem I can see already is the encoder has SIX wires not FOUR? Could be older technology?

[JerryFlyGuy]

If you've done your own pcb's before you'll not have any issue soldering together your own boards. I'd buy the kits they come w/ the heavy traces where you need them etc.. less hassle and I don't think I could produce my own for the price of the kit..

Your encoder is most likely a differential encoder [guess] IIRC my differential ones came w/ 6 wires [well 8 but the extra's are just grounds]

[H.O]

I'll second everything Jerry wrote. The PCB in the kits has thicker copper (70um) compared to normal (35um), and it's double-sided with plated thru holes. You can get the PCB or a complete kit from Paul (tenmetalman here on the 'zone) and/or from Irfan Ulla who's also a frequent user here. If you get the kit you'll get all the hard to get parts (in particullar the inductors) but you need to supply some mountig hardware, connectors etc.

The encoder is, as Jerry also said most likely a differential type, which is a good thing. It has two wires each for the A and B signals. Both the VSD-E and the HP-UHU supports this type of encoder.

[Al_The_Man]

Originally Posted by gavztheouch One possible problem I can see already is the encoder has SIX wires not FOUR? Could be older technology?

The common encoder connection count is either 8 for differential encoders and 5 for single ended. if you have 6, it could be the 5 plus a shield or case ground.
If they are DRC encoders like the one in your picture, the connections should be readily available.
I assumed you have included the encoder power connections in the wire count?
Al.

[gavztheouch]

I was wrong on the encoder wires it looks like 7 just checked and took a photo see below. This might mean 2 power, 2 each for the A and B signals and 1 earth? Problem is I dont know which is which. Do you think DRC might be able to provide a schematic I see they are still in business

What info do I need on the motor? The datasheet is unavailable online, there is an info plate on the motor itself but it seems a little vague, I will post a photo a little later on to show you what I mean.

[Al_The_Man]

At 20yrs old, that encoder is probably obsolete, but you may get the info by sending an email to DRC. It looks like 2048 p/rev. Also they have AXZ which could indicate marker pulse also.
The motor will be the larger red & blk is the armature and the small red & blk the tach. and green/yellow ground.
Al.