Rotary rollers

Rotary Roller Particulars

Considerable effort was required to align the Roller's straight bar with the bed, as it was to get the motorized and free spinning wheels to be in the same horizontal plane. i/e. changing their Z axis position relative to the laser chamber bed (the Roller apparatus has spin knobs to do this).  Careful work is also required to get the center of the cylindrical drinking vessel aligned and centered on the laser head position; this is best done while standing at the side of the laser and looking in the Y direction (the same direction as the gantry).

Depending on the rim and base shapes of your drinking vessel, you also want to remember to give clearance between the rim and/or base of the vessel to avoid touching against the wheel base on the other side so they don't scrape the wheels of the vessel while it is turning.

Be aware that there is a rotational equivalent to hitting the Y stop limits within your chamber bed; you can only do so many rotations in either the clockwise are counterclockwise direction before the roller becomes unresponsive and its position does not change. This will also result in tests activated by the software that do not rotate the wheels.  You'll get some clues that you are at your limit point if you see an error message on the view port for the on-board laser control panel that you have "Y slop over" error: 

Also see this link for more details on error messages on the Boss Laser's LCD panel related to using the Rotary Roller

When everything is working well, here is an example of the intricate artwork you can engrave into a tall drinking glass (the bird is 5 inches tall): 

When you try to frame your design and you'll also see that it is unrealistically narrow in the one direction.  If you find yourself near such a limit, just manually move away (either within software or using the on-board arrow keys) a number of steps to clear open Y space so you can properly frame your design.

While working in rotation mode you will likely need to drop your scan gap interval by a factor of three to eight lower than working on flat materials. For example whereas a scan gap of 0.067 mm is good for flat materials, your likely should set a scan gap closer to 0.015 mm while in rotation mode. 

Click here to see more photos and videos of the Rotary roller apparatus in action 

Rotary Roller Tool Warning

It is important that the laser is first completely off and powered down BEFORE disconnecting the Y-axis controller cable and replacing it with the cable to the rotary roller accessory. Failing to do so will result in the X/Y/Z limits to be incorrectly set when you have returned to linear mode after removing the Rotary Roller tool. 

Rotary Roller Examples

Boss Laser recommends that on some occasions when shallow etching glass, whether on flat or rounded materials, you will be better served by first attaching wet non-shiny newsprint to the glass. The challenge is that the laser chamber is dry and with air flowing briskly during operation, the engraving run must be paused periodically to take a brush to re-wet the newsprint.

Here is a video showing Seth's engraving and the use of wet newsprint

I have attempted to engrave a very detailed 5 inch bird onto a cylindrical 7 inch tall glass. I am now also engraving the main parameters of power %, scan gap interval in mm, and laser pulse frequency in kHz. This way when I engrave up to four birds on one glass, after several cycles of hand and/or machine washing, I'll know which set of parameters holds up the best.

Right now,  I am experiencing inconsistent results, even in back to back runs on the same laser with no change of tool position. I speculate that air flow consistency and possible soiling of the optical head on the relatively long 25 minute runs may cause deterioration of engraving performance. I tried to improve the former by standing attendant to the control knob on the compressor to even out the air flow manually as needed, but some flaking issues persist. I may also try wet newsprint. You can compare the two back-to-back engravings below.

First run ... relatively clean 

Second run that same day, ... aborted due to excessive flaking. 

coated aluminum and wood etching

Today we etched a logo into the painted surface of a thermos mug and a wooden sign.

Try to use the lowest power possible and only move up in power if the paint on your aluminum surface is very thick. We want to avoid reflecting the laser beam back in the direction it came from off the metal surface, as this could potentially damage the optics and laser tube by energy redirection.

A good choice for wood is 1/8 inch Birch which can be purchased for about $14 for a 5 by 5 foot square.

The rep rate range for our lasers is between 4 and 150 kHz. Use lower rep rates for smoother edge along cut lines and depths, and higher rep rates to cut all the way through thicker (> 1/4 '') materials.

A trick Seth taught us is to purposely defocus the laser after and autofocus by backing the the Z direction by 1-2 mm (move the bed downwards). This can save you time by making your cut lines purposely not go all the way through, while at the same time broadening ("bolding") the line. This will have roughly the same effect as a medium single pass scan, but much faster.

Flaking of etched glass

When I was doing a slow shallow etch of the waxwing bird on a cylindrical glass, I was having lots of flaking. I asked Boss Laser Tech Support what to do to improve the process and they recommended the following. 

"We have seen a lot of people have success by placing masking tape over the glass on the area that they are wanting to engrave over. This typically helps them a lot with the flaking on the glass. Also the air flow seems to be too high for that material it would probably be better to be around 20PSI.

Lastly, some lasers have a hard time firing at 14% power or below, I definitely recommend trying to up the power to at least 15 each and every job so we can ensure the laser is consistently firing for you."

I'm not sure I agree that this will help:

1. The masking tape will be hit many times in a small area and may cause lots of debris issues near the laser head.

2.We prefer pressures more like 60  psi for a reason, again, to get the debris out of there.

3. We have good experience with dependable firing at as low as 10%.

 I will consult with Seth to see if any of the suggestions from Boss Laser make sense.