Building a rotary attachment

[pontiacg5]

Hello everyone! First post in this subforum!

The company I work for just bought a 48x36" 80W laser from Full Spectrum laser. This laser is mainly for engraving part numbers or serial numbers on parts we make in the shop. We didn't order a rotary attachment from FSlaser because most of our parts are not completely round and would be better suited for a chuck style rotary instead of the roller rotary that FSlaser sells.

So, I had planned on building a rotary attachment since I couldn't buy anything that I thought would be beefy enough. I was planning on waiting till the laser actually arrived to start so I could plan better but now we have an order for a few parts to be engraved by the 8th of December and the laser isn't even supposed to be here till sometime the first week of December

The parts needing engraved are brass rings around 6" in diameter with a 4" through hole around 1" thick. I know that won't work on a roller setup and I'm pretty sure it's way too big for most rotary attachments sold. I'm planning on using a Chinese mini-lathe headstock/spindle as the actual rotary part with a simple timing belt.

I have no idea what motors these Chinese machines use but I've searched quite a bit and couldn't find anything. Does anyone know what motors they use? I'm hoping it's a standard size as I guess epilog uses some weird non-standard steppers.

Is there any reason such a thing wouldn't work? Does the software allow you to compensate for rotary attachments not necessarily using the same gear ratio as the original?



Another thing, slightly off topic I guess but, if I don't manage to get this rotary built in time would I be able to engrave a 3" string of tiny numbers on the circumference of this part? I figure it would go out of focus too fast and half of my letters would be left blurry. Then again I guess I could probably split the engraving into 3 sections and just raise the table a little to compensate...

[underthetire]

I just did a rotary on our laser.
You will need either C axis or A axis control, a motor and timing belt will work, but you need to be able to control (sync) it with one or both of the other axis. Why do you need heavy duty? It's not like lasers put any pressure on anything. You could just mount a fixture right on a stepper motor (if thats what yours uses). Ours is a 5C collet set up, with servo control, but we ordered our machine with a 4th axis interface.

You could probably get a Sherline on an angle plate and make it work even.
CNC Rotary Indexer

[pontiacg5]

The way the 4th axis works on chinese lasers is very bad in my opinion. The control does not have an open amp or "spot" for the 4th axis, to do rotary work you center the rotary fixture directly inline with the Y axis and then you just unplug the Y axis and put the rotary in it's place. After that you calculate a few things out and change the setting for pulses per revolution of the "y" axis.

The whole deal doesn't need to sync with the other axis, well I guess it does but that's all done with software. The only things I need to worry about are that the stepper I pick is compatible with the amp/controller of the laser and that I don't pick a gear ratio too steep for the software to compensate pulses per revolution.

That sherline deal really wouldn't work either, the mechanical side might work but the electronics it comes with are redundant. I also don't think it is big enough, I need as big a chuck as I can find and that thing doesn't look too big. The mini-lathe headstock I plan on using will fit 5" chucks easy plus there are a lot of other chuck options out there. I need heavy duty because some of the parts I'll be running are really heavy, some of the cheap china rotary deals look like they would fold over on top of themselves if you put anything bigger than a wine bottle on them.

I really just need to know what the specs for the x and y motors are. Also, does anyone know if the "genuine" rotary fixture has any limit switches?

[pontiacg5]

Anyone? I just need to know the voltage and current. I know they are 4 wire two phase motors and I assume they are the standard 1.8/step.

Thanks!