Fiber Rotary Table - Marking off and different inconsistent results

My Rotary table woes continue. Please see video regarding issues Im having getting my rotary table setup on my fiber laser.

I forgot to mention in the video that the slots in the aluminum foil were tested both ways cutting the foil in focus, and cutting the foil in focus with the brass. Both ways produced the same end results.

Same deal with circles, some are ok, others are way off without any explanation.

Are you using a beta of Lightburn? I’m using the current version and couldn’t find support for a rotary table?
Thanks, David

Repeat marking tool was introduced in 1.4.00. More information here:
Repeat Marking Tool - LightBurn Software Documentation

Yes I’m using the current version of LB , 1.4

This is the first time i see a rotary table working.
Bu the problem, seems to me, kind of offset problem. Did you check if dimensions check precisely. It looks like you need to do some adjustment to mach dimensions on screen with real cut dimensions.
As I don’t have a device connected to this seat I can´t point you corresponding $ sign numbers… :unamused:

The brass blanks are CNC cut, accurate and measured with digital calipers.

The slots that are cut in the jig are accurate as the brass sits snug and properly in it, also measured with calipers.

Even if I were to adjust the framing for the first jig / brass it doesn’t seem like it would matter since they all wind up different in the end anyway. Inconsistent.

Two things, did you re-focus adding the thickness of the blanks?
When your table is stationary and on, if you grasp it can you get any wiggle?
Also,
I would use the sticky back HVAC foil tape to assure your tinfoil is not moving around a tiny bit.
Seems like you have some play in your setup.

How many steps is your rotary per 360 degrees?

This was my next question. :+1:

Yes.

I actually tried both ways to eliminate those variables.

It didn’t matter if I cut the foil while focused with the foil, or cut the foil focused with the brass. It gave me the same end results. But any time I cut brass I’m focused with the brass.

My driver is currently set at 6400, so the table is set at 25,600.

I’m going to experiment increasing the driver steps to 12800 to see if at makes any sort of difference with accuracy, I doubt as much - but never know.

No wiggle, everything is firmly secured , the foil is actually doubled up to increase thickness. I also run the table at slow speeds to ensure that the momentum of the rotation doesn’t shift the blanks

It shouldn’t matter, 10 positions/ 36 degree works with every driver configuration. Maybe even go lower, more torque per microstep. I think these rotary tables don’t benefit from such large belt/gear reduction, just introduces more backlash. Also, any deviation from perfectly parallel to lens will cause issues.

I could possibly see being off-centered being an issue but I’m pretty close. I have it pretty close but do you have any recommendations how to precisely align it? I project it out a framed straight line from North to South and lined it up with the center screw as best I could with a straight edge

One other thing if you have a dial or digital gauge device i would check table for runout, up and down primarily. I do a lot of machine work and you would be surprised how something can look perfectly flat that really isn’t, and a galvo really needs to be close due to angle of beam not perpendicular to workpiece. (Except at one spot.)

I’ll give that a shot. Would a slight off center or run out really give this large of an inconsistency you think ? I mean we are talking close to a 1/16" off in some cases.

How would you go about making sure its perfectly centered with the center axis of the table?

If your work area was large enough you could use the laser to project a line down the center. I don’t think it’s an off center issue as you cut the foil with the same layout as the borders. My guess is your table moves up and down and / or flexes a little bit, and has just a bit of backlash, maybe changes a bit after you loaded the labels. Because the laser is coming out of the lens at an angle, it can make a difference. Of course, I could be totally wrong.
Question: What lens focal length are you running?

You are the second poster on the forum in the last 2 weeks with maybe similar issues. I am in the process of building one for myself so have been studying these things and asking a lot of questions. Following the forums. One thing I don’t understand the need for all the reduction, it’s not like tumblers where you are rotating set surface distances that are very tiny, even 800 steps would do anything I’ve seen so far on a table, unless you wanted odd counts other then 5. I’m building mine direct drive to eliminate any backlash from pulleys or gears.

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i’m the same guy as the other post, I had lose set screws on both gears that caused back lash. I got it tight now and 90% solved, but still dealing with this now.

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Yes you are. Thought it was Jack Wilborn, my mistake. That was an odd one, for sure.