Darkly Labs Community

E1 Fine tuning the laser height, with repeatable results


The above images represent my recent modification to my Emblaser One. I had the laser carriage and slide module crack, requiring re-printing and replacement. In the process, I learned just how difficult it is to snap the sliding part onto the carriage. I eventually had to heat the slider in boiling water for a few moments, turning the plastic into short-duration form-able putty, then snapping it into place. In the process, I think the spring button under the slider got jammed in the retracted position.

I was not about to destroy the part by attempting to open it up and had to come up with another way of keeping the now-easily-sliding laser module in the proper location. Pursuant to another discussion on this forum, I also devised this modification to provide for more precise height adjustment along with repeatability.

The original fan shroud was downloaded and the top face was extruded 6mm in meshmixer. I then imported that STL file into OpenSCAD and added the ledge with a hole for the screw. My original plan was to use an M6-1.0 screw but could not find any. I did find some nylon #8-32 screws but the hole was too large to tap. Aha! I have #8-32 threaded inserts.  Great. That gets installed and the nylon bolt won’t go in cleanly. A trip to the hardware store for a metal version and I’m good to go. I realize now that since I had to make the trip, I could have collected an M6 instead.

I have a 3/4" (18mm) tall vacuum table under the laser. The laser shroud sits cleanly on the table when the screw is fully retracted. If one does not have an equivalent spacer under the workpiece, this mod will not work. I expect that one could simply add a ledge to the fan to accomplish the same thing if the extra depth is needed.

As my laser module slides quite easily, it’s a simple matter to get the focus tool at the exact location. I expect I’d have a problem if it was properly sticky and if it returns to that condition, I’ll slide off the entire module and carve away at the button underneath, to remove any possible friction in the future.

https://www.dropbox.com/s/ut8uwuzmx7nes02/fan_shroud_extended.zip?dl=0 

The link above contains the 6mm extended fan shroud, the extended fan shroud with the ledge and too-large hole, the OpenSCAD file for those who might want to modify the file and the pretty OpenSCAD picture shown above. I did not create this OpenSCAD in a parametric manner, I used the TLAR method which came out well on the first shot.

If you download the file from the dropbox link, please let me know.

1 Like

This is a very clever solution.

If you are having trouble with friction, then carefully removing some material away from where the laser carriage bracket rubs against the heatsink fins would help. If done carefully, the spring loaded pin in the bracket should be enough to give you just enough friction.

Very well done and BIG thank you from the Darkly Team and community for sharing this information and the files.

 

At first, when I attached the newly printed components to each other, with the spring and button in place, the friction was nearly perfect. A week later, no friction at all.

I’m hopeful someone can benefit from my efforts. I know I have!

1 Like

Hi Fred.

I take it that the height adjustment came from our previous posts. (Well do by the way)

I will be interested in any experiments you might do to using the height adjustment to lower the head for each successive cut to reduce the number of passes required. (This is assuming my theory about depth of field of the pass is correct and not some crackpot idea)

I will watch this tread for any more excellent ideas.

John

John, you’re correct, our conversation was certainly a good part of the motivation. My motivation was enhanced by the friction failure of the button, leading to this modification.

In the magic world of 3D printing, one can insert a g-code command to pause a specific number of seconds. If such an option is available in the Emblaser firmware, one could plan to “be there” and generate a 30 second pause, adjust the screw and allow the program to continue. I know from experience that the g-code sender dumps a large number of commands to the emblaser into a buffer, which means a console pause is not guaranteed to be where you want it. You’d be able to see the pause in the terminal window, however.

Had I stuck to my plans of using an M6-1.0 thread, it would allow for a precise adjustment, one millimeter per turn. Even with an 8-32 bolt, one can get a 1/32" change with each turn, or even a 1/128" change on a quarter-turn!

It’s astonishing to think that one could cut 1/4" (6mm) plywood using your suggested method. I can cut 3mm in five passes at five mm/second. Advancing the depth adjustment and continuing from there may allow for this operation.

Fred, not having access to a 3d printr to try out you mods I am lookong at maybe a filler flat piece of say 10mm aluminium tyo fit between the topof the laser head and fan.(As your mods)

What do you think of making the code for cut2d to be a single pass. when the head returns to home position you could lower the head say 1 turn of the screw, select reset and then run the code again.(The workpiece should be firmly fixed in place)

I have found on occassions that the emblaser is accurate enough to cut the second cut in the exact same position

Maybe a thought

John

In order to keep the weight down, I would suggest something plastic rather than aluminum. If you use aluminum, cut as much away as possible. Turn it into swiss cheese with more holes than cheese. Inertia is not your friend when it comes to good performance and accuracy from our lasers. You could get away with a shape like the letter A with the legs of the A being parallel and engaging the holes on the top of the fan. No need for a cross-piece for the letter A and at the apex of the A, barely enough material in which you would tap your thread. It’s more of an upside-down V than an A, but I’m hoping you get the idea.

If you don’t have a 3/4" vacuum table or equivalent spacer, placing the ledge under the fan will prevent you from dropping the module far enough to focus. You should be able to put the ledge atop the fan to permit greater travel than my unit provides.

If you are considering to send the code a second time, I suggest to remove the homing code (G28) from the last line of g-code. That will prevent the head from re-calibrating the home position which would add a bit of deviation to the second burn. If you remove the G28, be sure to be in evidence when the code stops running. The laser does not turn off fully on the last line and will create a burn. Running it a second time, you have a moment or three to get in there to restart and not have to press/hold the laser button to activate it. This could be an anomaly of my laser or it could be in the design and operation.

Unless you modify your laser shroud, you’ll have only one millimeter leeway before the shroud hits the workpiece, as you turn the screw. Of course, you could remove material from the shroud and create a new focus tool to compensate for the change.

Because we can cut 3mm plywood, you might be able to carve 3mm off the shroud and use the “vernier” to go as deep as 6mm. That would be an impressive accomplishment.

Fred, I have been watching this thread and wondered what if any results you may have gotten from adjusting the height of the laser when cutting thicker material. I am away from my workplace and cannot try anything out so I thought you may have experimented. I have the steps in my mind , but sometimes theory does not equate to practice

John

I have not had any projects which require me to perform a multiple pass with adjustment. My primary purpose for this mod was to deal with the loss of module friction and to enable more certainty in my focus. Now that I have a CO2 laser, the Emblaser is delegated to small, thin projects. The Emblaser comes out ahead for preparation requirements, though.

Prior to using the monster laser (60W) I have to turn on the water pump, the air pump, the anti-condensation fan. I have to place the exhaust duct in the window, open an input air flow window and turn on the exhaust fan. The main switch goes on, the laser switch goes on, then I have to connect the laptop.

WIth my “toy” laser, the Emblaser, I connect the shop vac and the laptop and away I go. Smaller cutting bed, sure, but a good bit easier for setup, especially now that I have the focus problem solved.