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Glen Monaghan
05-21-2011, 10:09 AM
Several months ago, I started gathering information with the intent to build a rotary attachment for my Epilog laser engraver and found a lot of good information on SMC. But, in February, I took a detour and bought a laser rotary attachment through ebay from a guy in North Carolina because the price I paid was about what parts and shipping were going to cost me for making my own.

Although I never received anything but excuses, another SMC member recently informed me that he has finally received a rotary attachment after months of delay. However, he says it is non-functional. He gave me the model number of the stepper motor used in the unit he finally received.

According to the motor manufacturer, it is a discontinued NEMA 17 motor that is only rated for 6V. Epilog uses a larger NEMA 23 motor rated at 24V and drives it with 48V. One of the motor manufacturers told me they don't warrant the motors when over driven with constant current sources. Although it is common to overdrive steppers when you have current limiting circuitry, Epilog apparently doesn't use active current limiting so the 6V motor would be over-driven by a factor of 8 with Epilog's 48V driver, seriously exceeding the motor's I^2R rating. I'm not sure what max current Epilog's circuit can provide, but these 6V motors will try to pull four times as much as the OEM motors and eight times their own rating. Power dissipation goes up by the square of current. Anybody know how much a new Epilog driver board costs?

So I'm back to rolling my own chuck-based rotary attachment around a custom-wound NEMA 17 motor that is designed from the get-go for 48V operation. It draws less current than Epilog supplies to their 24V motors without overdriving (or overheating) either the motor or the driver. My thanks to Kim, Peter, and Dave for their kind help.

-Glen

Neil Pabia
06-29-2011, 11:55 AM
The guy that sells them in NC seems to not be willing to ship anything or refund money, he was great at sales, but is terrible at delivery. I guess it's time to build my own.

Dan Hintz
06-29-2011, 1:37 PM
Yeah, it's been so long since I saw anything about it I plum forgot his name...

Neil Pabia
06-29-2011, 2:05 PM
His name is William (Bill) Blais of LaserworkNC.

Glen Monaghan
06-29-2011, 4:43 PM
His name is William (Bill) Blais of LaserworkNC.

Blasi, actually, and LaserworksNC, but I heartily recommend you don't go there! I eventually got a refund through ebay, and he was booted off there for failure to deliver at least a couple of rotaries as well as using a shill in his auctions to drive up the price. A couple of people did eventually get deliveries from the guy, but they were non-functional due to mechanical problems. Apparently you didn't get even that much, Neil?

I'm awaiting a custom-wound 48V stepper to "roll my own". It's going to take a while to arrive so I opted to order an extra, just in case... Cheaper than Epilog's OEM stepper, physically smaller, and actually rated for the applied voltage & current, just slooow delivery...

-Glen

Neil Pabia
07-03-2011, 1:19 PM
No, I didn't get anything, I bought directly from his website and guess I learned another lesson about dealing with civilians. It's too bad because it seemed like a good product and I have a number of people waiting to see what happened with this deal before they bought, so at least I saved some others from the same fate. If he had come through with a decent product, we probably could have done a lot of business together.

Bruce Dorworth
07-03-2011, 9:26 PM
There are a lot of smart here on this forum. I wonder if we couldn't do a group build? Here is a picture of one that I saw on ebay. There is not a lot to it.

B200326ruce

Ken Shea
07-03-2011, 9:43 PM
Not a bad idea, likely have most everything here to build one which does not appear to be all that complicated.
The problem I would have is proper wiring to the control.

I had asked about whether the control (at the time a MPC6515) had a input for a rotary down they road and they indicated it was built in.

Does LC 5.3 have output for that?

Ken

Bruce Dorworth
07-03-2011, 10:51 PM
I don't think that is a big deal. I am sure there are only three wires. With all the users here we should be able to come up with the correct wiring.

Like you said there are not that many parts. It won't take much of a stepper motor.

Bruce

Rodne Gold
07-03-2011, 11:25 PM
Ken , either of these rotarys will work with your card , they are less than $200 each. You would need to change your Y axis parameters in software for them to work or check to see whether you have an enable rotary section , you unplug your Y axis and plug the rotarys into your Y axis stepper motor driver.

Ken Shea
07-04-2011, 10:38 PM
Bruce,
Had not looked at the few steppers here for a while, thought they had six wires, there are a few servo's as well, could be them I am thinking about.
I'll have to check.

Rodne,
yeah, for $200 bucks it would be hard to justify building unless you just wanted to for kicks, and I don't really, but it does look simple enough.
The one with the chuck on it, what is the end plates and base material?

Ken

Glen Monaghan
07-05-2011, 1:16 AM
I don't think that is a big deal. I am sure there are only three wires. With all the users here we should be able to come up with the correct wiring.

Like you said there are not that many parts. It won't take much of a stepper motor.

Bruce

The vaporware rotary mentioned earlier was specifically for Epilog laser engravers and so is built around a .09 degree/step, 6-wire, unipolar stepper motor, geared down 6:1. Other engravers may use servos rather than steppers, bipolar vice unipolar, different gearing, etc. and I can't speak to that.

Many people have said their Epilog rotaries run hot, some say too hot to handle after a while, and that's because they are NEMA 23-sized 24V motors being run at 48V without proper current limiting to keep the power dissipation within specs. Stock 24V steppers with the fine step angle are hard to come by and will run just as hot as Epilog's, or you can try more common lower-voltage motors which will be even hotter unless you add current limiting circuitry (power resistors as a bare minimum, but then you are just wasting power by transferring the heat to the resistors).

I've opted to have a couple of smaller NEMA 17-sized 48V steppers custom wound so they will be plug compatible but rated specifically for the Epilog drive circuitry, and they cost about half what Epilog charges for spare/replacement steppers. Still scratching my head as to why Epilog didn't do that in the first place...

Rodne mentioned some Chinese rotaries that sell for a mere $200. That would be great if they are compatible with your machine, but we'd need to know quite a bit more about the motors, gearing, and connectors in order to determine whether they can easily be made to work with our various engravers...

-Glen