has anyone built their own encoder system to work with step motors and mach3

[cwiliam]

has anyone built their own encoder system to work with step motors and mach3?

Ive looked in the forum but I haven't found any thing

any recommendations or webpage that can give all the details of building one
I will appreciate it



thank you

[ger21]

You can wire the encoders directly to a second parallel port or breakout board. Then you'll need to write a plugin or macro to read the encoders and tell mach what to do. However, the only thing you can really do is pause or stop the machine if you detect an error.

There is a commercial product that does this, at www.rogersmachine.net

[cwiliam]

I emailed Rogers twice but haven't gotten a response yet
so I thought with all the creative people in this forum (except for me)
I would be lucky to find something

[opusinwood]

I have no answer for u but I am also interested in exactly this. maybe if two seek they shall find

[keebler303]

Why exactly do you want feedback from your steppers? If they are properly sized and not overloaded, they will never miss a step. Seems like wasted effort for the most part.

My $.02

Matt

[opusinwood]

yes nice logic but as they say ... the best laid plans... And I have had issues due to miss judgement and other unforseen. An encoder would be the simplest form of reset / feedback control method.




as far as wasted effort - why do humans do? isnt it all (90%) wasted effort?

I mean really as far as effort goes this diy cnc is not a stroll before lunch anyway.

I think, 'how much effort involved' is part of the search anyway. An encoder doesnt seem too difficult - every ball mouse has two a wheel mouse has another.

Matt

[Monte]

GeckoDrive is developing such a system. Here is a link to a thread on cnczone describing it

http://www.cnczone.com/forums/showthread.php?t=43359

Sounds like summer/fall ETA maybe?

Monte

[Golden1ce]

There is a note on the rogersmachine page that says the encoders can also be used as a DRO to manual machine.

G1

[keebler303]

Originally Posted by opusinwood yes nice logic but as they say ... the best laid plans... And I have had issues due to miss judgement and other unforseen. An encoder would be the simplest form of reset / feedback control method. Matt

All I'm saying is an encoder would be a band aid to a poorly designed machine. For the cost of a standard us digital encoder (~$40) you could just buy a bit bigger motor to overcome any overload situation,which is the only time when a stepper motor should miss a step.

The encoders would not provide realtime feedback, not to mach anyway, so that it could send extra steps to correct for the problem. It would not realize the difference until it is too late, and then add then on later, which probably means your part is ruined anyway, so I say why bother. If you're stuck on a closed loop system, get some servos, that will give you the most bang for your buck.

Originally Posted by Monte GeckoDrive is developing such a system. Here is a link to a thread on cnczone describing it http://www.cnczone.com/forums/showthread.php?t=43359 Sounds like summer/fall ETA maybe? Monte

Read the thread, this is not a stepper with an encoder for feedback. Gecko is essentially running a stepper as a brushless servo. With this new drive, there will not be any feedback to mach3 and the motor will not be operated by stepping. The drive will feed a sinusoidal current to the motor so that the motion is continuous. The encoder here is used just as on a servo.

It will be a great drive for sure, but has little relation to this threads topic.


Matt

[Monte]

Originally Posted by keebler303 sniped Read the thread, this is not a stepper with an encoder for feedback. Gecko is essentially running a stepper as a brushless servo. With this new drive, there will not be any feedback to mach3 and the motor will not be operated by stepping. The drive will feed a sinusoidal current to the motor so that the motion is continuous. The encoder here is used just as on a servo. It will be a great drive for sure, but has little relation to this threads topic. Matt

It is still a stepper motor with an encoder. If you run the new drivers with the G100, the G100 will read the feedback from the encoder and make corrections real time. Sure, Mach doesn't know about it, but the feedback from the encoders is being used for corrections for lost steps and such. It would do what the OP was asking for as far as I can tell. Maybe in a slightly different manner, but the end is the same, real time encoder feedback with stepper motors.

Why doesn't it relate to this thread/topic?

Monte

[keebler303]

Monte

It is indeed a stepper motor with encoder, but it is not used as one. The encoder feedback is used directly by the drive itself. The G-100 is not needed at all. The drive makes corrections real time, just like in the G320. The main difference is it is outputting a sinusoidal waveform to the motor instead of an on off step pattern, think of it as a stepper motor with super small microsteps. The encoder is needed because the microstepping performance of stepper motors is not completely linear. Each motor will perform slightly differently so you need the encoder to maintain accuracy.

I said that the "new Gecko" doesn't relate to the thread because:

1) Its not "built your own"
2) Its not "really" a stepper motor anymore, but it does use an encoder.
3) Mach is in no part involved in the performance of the "new Gecko", unless you decide to use mach to send step/dir commands to it. Even with this drive, there is no sort of closed loop back to mach, which is what the OP was originally looking for.

The "new gecko" would prevent "missed steps" but it is not really a stepper motor drive, I guess it is just a matter of semantics. I say its not a stepper drive, more a brushless drive. You say its a stepper drive because its using a stepper motor. Either way, it would provide closed loop performance from a stepper motor, so I agree on that regard. But I think the main purpose of this new drive is to pull more power from a stepper motor, it is just necessary to have an encoder as well. If Mariss' intention was to add an encoder to a stepper, he would have made a "G204V" or something like that. This is a whole new type of control algorithm.

Cheers
Matt

[ger21]

Isn't the G380 the replacement for the G320? I don't think the stepper / servo drive has a number yet, does it? Or am I wrong?