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View Full Version : What makes a rotary device proprietary?



Neville Stewart
07-19-2015, 10:24 AM
Other than having the right type of connector on the cable and appropriate driver , why couldn't you use one manufacturers rotary device on another's machine? It's just a stepper isn't it?

Gary Hair
07-19-2015, 1:19 PM
Other than having the right type of connector on the cable and appropriate driver , why couldn't you use one manufacturers rotary device on another's machine? It's just a stepper isn't it?

You are quite right that it should be possible. Steppers have various specs and you should find one that closely matches what the manufacturer used, oz.-in., torque, voltage, mH (phase inductance), etc. One big consideration is that if you connect it up incorrectly it will not likely damage the stepper, rather, it will fry the drive on your -very expensive- mainboard rendering it useless. If it were me and I had a nice, new, speedy 400, I would spend the $1,500 and buy the one from Trotec - just sayin...

Here is a link to a pdf that tells you all you ever wanted to know about steppers, but were afraid to ask.
https://www.geckodrive.com/gecko/images/cms_files/Step%20Motor%20Basics%20Guide.pdf

Dan Hintz
07-19-2015, 5:02 PM
Other than having the right type of connector on the cable and appropriate driver , why couldn't you use one manufacturers rotary device on another's machine? It's just a stepper isn't it?


Yes, and no. There are different styles of steppers with different numbers of coils, different current ratings, etc. Plugging one rotary into a machine it wasn't designed for is a complete hit or miss (likely miss) proposition, and in many cases can damage either the rotary or the system it's plugged into.

Michael Hunter
07-20-2015, 8:09 AM
Most rotaries use some sort of belt drive between the motor and the rollers.
As well as having the correct specification motor (which gives the right number of steps per rotation), the belt drive pulley ratio needs to match the manufacturer's one.
Basically, unless everything about the drive chain matches EXACTLY then the engraving will be distorted*.

Given that the proprietory rotaries have about 1000% markup, some research and experimentation could be well worth while!

* This may be possible to correct by distorting the original artwork to match, but what a pain!

Steve Morris
07-20-2015, 8:43 AM
yep got agree about getting the spec and steps right but if you are fitting the driver as well as the motor and not using the one on the main board then it should be doable as it is just taking the digital signal from the logic board.
Also bear in mind the Trotec is a closed loop servo system so a different kettle of fish altogether.

Richard Rumancik
07-20-2015, 10:27 AM
If you could buy the exact motor that the manufacturer uses (Trotec in this case) then you might have a chance at making it work. But a lot of time the motors are custom-made for the application with specific characteristics, manufacturer's options, custom encoders, as well as connectors. The connector problem can be overcome but chances are you won't be able to buy a motor from the motor manufacturer as it will be considered custom and they would not sell single units to end users. As far as taking a rotary from another laser and trying to make it work - I wouldn't even attempt this.

Neville Stewart
07-20-2015, 2:41 PM
I guess when you buy an Aston Martin, you have to buy their driving gloves too...

Joel Ifill
07-27-2015, 7:14 PM
* This may be possible to correct by distorting the original artwork to match, but what a pain!

we usually had to play around by printing a grid and adjusting the diameter in software until it came measured out right, a pain but could be done in maybe 15 minutes.

Mike Null
07-27-2015, 7:50 PM
I've been bragging on my Trotec for years and I would for sure buy another--BUT--their rotary device is wanting. At least in my opinion. I could not get repeat-ability from it and ended up sending it back. The device is well designed and well made but the software and firmware is lacking. It is obviously not a priority with Trotec Austria as this has been an issue for several years.

I hope this little nudge will put some priority on this matter as I keep turning away work.

Joe Hillmann
07-27-2015, 8:11 PM
On ULS's rotary they have a sensor in it to tell it where home is. Without it I don't think the laser would be able to find home when you first turn it on and if it did you wouldn't be able to repeat multiple passes on an item because it appears to go back to home rather than counting back the steps.

Mark Sipes
07-27-2015, 8:33 PM
My Trotec has a Cam shaped much like a baseball diamond with a limit switch to tell the software where home is at start up. As stated "repeatability is wanting" with this set-up.

I attempted to purchase the drive motors from the manufacturer and as stated they deal with one customer direct Oh well $800 per pop!


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