laser etching on the curve with this add on

[Tug Wilson]

                                                                    WILSON’S ROTARY ADD-ON

Welcome to the Rotary add-on for laser users, I invented this add on because I had a contract to supply my old regiment with flask having the hat badge etched on them, and as there was nothing affordable on the market sat down and designed what you see today.
This unit can hold items from about 10mm dia to 100 mm using the two step motor positions on the back plate. The length of the unit is now fixed at 300 mm so this will be able to accommodate quite a large range of items such as bottles tumblers and wine glasses, I know because I have done them all using this unit.
The kit comes part assembled to make it easy for anyone to assemble along with the dreaded “instructions” which none of us read, but as I had some spare paper laying around thought I’d draft one anyway.
The step motor you fitted to the unit has a lead and this goes into the control board in place of the Z motor at the back of the laser unit.
The only thing your going to have to do is work out how you elevate the machine to enable the add on to fit under it and gain focus with the laser. I suggest 5” or 120mm or there about. I have uploaded pictures to show how I got over it, but I have a milling machine so was easy to cut slots out of blocks and pin the lot together with ply strips.
I might come up with something a bit more professional later but thought you’d like something to think about in the mean time.
If like me your using the brilliant T2 laser program you will find in the second  “settings” the option “Rotary Axis Enabled” this will be activated once you have loaded your design to be etched and created the G-Code, all you have to do is enter the diameter of the object and the program sort it all out.
A word of warning try to remember to cancel the option once you have finished, or your flat job that you put under next is going to look a bit sad as it will be one big blob, yes I talk from experience.
I hope this has been interesting and if you need to know anything else or of course place an order please contact me on email at tugwilson206@gmail.com
Thank you for viewing. Tug

[mattm58]

Just a question, as I'm looking at rotary devices now.  It looks like the three jaws on your chuck are not connected in any way, so how do you guarantee the object is perfectly centered in the chuck?

[Tug Wilson]

mattm58,  the chuck back plate is transparent you can aline it over the work to be held on it, before offering it up to the step motor shaft. and although it helps to have it dead center a small amount of deviation is not harmful. the main thing is to ensure the support rollers are doing the job they were designed to do and that is support the work so as to keep the item as movement free and parallel as possible.
Hope that helps.
Tug

[sapling]

Yeah Tug I think what he is talking about is that the grips arent connected together in a way to make sure that each are even. I believe the style Thotloki built has two pieces on the end that as you rotate it the connections slide together to make sure they are even.
https://www.thingiverse.com/thing:2565273
I think thats more what he is getting at if I am correct on how thotlokis works.
I am curious have you posted any pictures of things you have done with your rotary axis?

[Zax]

There's more info and pictures over at http://forum.eleksmaker.com/topic/2507/laser-etching-over-a-curve (some of these may be earlier prototype pictures). I see advantages to both designs, in some cases have the flexibility to move the chuck grips independently can be a benefit but for quick and accurate centering having them connected helps. I like the simplicity of Tug's rotary attachment and it obviously gets the job done.

[Tug Wilson]

There's more info and pictures over at http://forum.eleksmaker.com/topic/2507/laser-etching-over-a-curve (some of these may be earlier prototype pictures). I see advantages to both designs, in some cases have the flexibility to move the chuck grips independently can be a benefit but for quick and accurate centering having them connected helps. I like the simplicity of Tug's rotary attachment and it obviously gets the job done.

Yes Sapling, I did print out a self centering chuck, it's very cumbersome and heavy, and I found that my three jaw chuck is easy to center to the degree of accuracy you need to get good results. because it has a see through material.
One of my customers has already found out how the different options make such a difference to the work to be done, he moved the support arms to the side and that gave him an even bigger choice of jobs to be etched.

[ggallant571]

I built a fixture some time ago and it sits idle. How do you:

  1. Compensate for differences is diameter (curves)?
  2. Prepare glass for etching?
  3. Etch small diameter items such as pens?

Please post some pictures of finished projects.

[Tug Wilson]

with the T2 laser program the diameter is set when selecting the Rotary Axis Enabled option, I have found that as long as the deviation in diameter along the 'Y' path is not too great the image comes our fine.
Preparing the glass for etching once again is simple, as the laser would fire straight through the glass I paint a water based white coloured paint on the area to be etched and let it dry, it then cuts trough the paint and etches the glass, once finished I wash the paint off and the job is done.
Etching small objects, I have designed the unit with two step motor position options the lower one along with the roller support arms can shut down to 5mm this being more then enough to accommodate a pen.
my facebook page has some of the items I have done and can be seen at https://www.facebook.com/Wilsons-rotary-laser-add-on.
hope that helps.

[ggallant571]

Thanks. Couple more question about the paint:

  1. Type - oil acrylic.
  2. Applicator - spray vs brush.
  3. Depth an uniformity.

If you can't tell I have been frustrated in getting repeatable consistent results.

[Tug Wilson]

I understand and had the same problem, I use a Dulux white paint, not sure what you can get where you are. I use a brush and apply it in one direction first, I had 12 glasses to do so it was a kind of assembly line, get to the end and cover it the other way, just to make sure. the laser will shine through and not etch the glass if it is too thin a cover. now the first one is dry apply the design, you can see by the burn on the paint if it has been etched evenly, if not I press start again and etch a second time, I only have a 2500 laser so yours might do it in one every time, I found only now and then did it need to be done twice. I have only used a mat finish type paint so not sure if gloss would do better or not.
Not easy taking picture of etched glass but think you can see what I mean from this effort.
 

[ggallant571]

I also have a 2.5W on the rotary fixture. Suspect it sits idle because I do not have a reliable recipe for etching.

I bought some non-contact distance sensors that are supposedly good in the 100 to 200 mm distance range. Planned on adding a Z axis and having the fixture do a "profile" scan prior to the etching. Then have it adjust the Z to maintain a specified distance. Perhaps having someone post results will get that project in motion.

[ThothLoki]

Ggallant
I use black acrylic paint. I buy the $0.50 bottles from Walmart and brush them on. Just try to make the thickness uniform. I have done spray paint before but it was a huge pain to clean up and remove. The acrylic paint just comes off with some warm water.

For the correct steps, I don’t know. Zax takes care of that for me in t2. I bet ya he knows the formula for setting the diameter.