Laser Engraving Carpenters Pencils – Setup to Engraving

Ok I’m going to do a final project with my CNC machine. If you follow the second channel you might be aware that I’m building a new CNC machine, which I’ll just point at it. It’s over there. That’s called big red. But that machine is not ready yet and I’ve got something I want to work on so I’m going to use this thing.

So this machine has a attachment which I 3D printed, which has a mounting bracket for an Opt Laser engraving module. I’m planning to migrate all the electronics over to the new machine, but I wanted to do one last project using the laser in conjunction with the router spindle. I’ve bought a load of carpenters pencils which I planning to personalise using the laser engraver. The laser was sent to me by a Polish company called Opt Laser, and if you want to know more about the module there’s a video on my second channel – which I’ll link to in the description and information card.

So the first thing I need to do is measure several the pencils, to make sure they are all consistent. With that information I can then design a jig to hold them in a known position on the CNC machine.

Ok, so if I zoom in you can see the pattern I’ve created with the dog bone effect so that the pencil could fit within that gap. This is a little bit elaborate to be honest. Really what you could do is just cut a 90 degree angle out (with a dog bone in the corner) and push the pencils against the edge. Coz if you’re laser engraving your laser doesn’t move the material. This option is probably more for routering, so if you were to use a V bit and engrave something onto the pencil. I kinda like the option to do both so I’m going to use this template. I’ll just explain how I created it. If I just go backwards and… And then go forwards.

So I made a rectangle first and I gave it the dimension of 290 and 240 and I created a rectangle within that initial rectangle of 178 by 13.5. It’s a little bit bigger than the pencil so it should fit in. Oh no… damn it.

Then I’m going to position this so it’s in the centre, so I’m making an equaiton. 240 minus the pencil width which is 178 divided 2, and then I’m going to orientate this to the top, and I want that to be about 30mm.

Then I’ll create the dog bone effect. Circle > two point circle. And I drag across, and I’m going to use a 6mm bit so I write 6.1mm and I’m doing that for each one. When I want to repeat I right click and select. I’m going to now trim – press t – the additional lines I’ve created. Essentially what I want is an outside vector line that I can follow. If I got to sketch I can go to rectangular pattern and I can select the lines that I want to do the pattern to. If I change quantity to 1 (along one axis) and expanse is going to be 290 take away 60, because of the position of the top and bottom and 13.5 because it’s measuring from one side of this object, and now in distance I can write 216.5 and if I zoom out you can see the magic happening. If i write minus it will go in the right direction. And I can now just increase the quantity until it populates that spaces between the points. When I’m happy with that I press ok.

I can then export this and send it to my CNC software. And the way you do that, is you go to the sketch folder, find the sketch, you right click and save as a dxf file.

So I’m now going to art cam – this happens to be what I’ve got. This software isn’t supported anymore as it was bought by autodesk and they amalgamated it into their packages. It doesn’t exist anymore so I’m heavily considering moving to vetrics when I can afford too.

So the height is 290 the width is 240. My point that I’m referencing my home is the top right corner of my CNC machine. Press ok,

I now go to import. The board I’m using is 9.3mm And material set up 9.3. So this is quite a simple one, so just select all of those and go to toolpaths, and area clear. I’m going to add the 6mm bit. I haven’t used this CNC machine for so long. 6mm soft wood. I’ll select that. Offset > conventional. Giving it a name. Calculate. And that’s kind ready now.

I put a 6mm up-spiral single flute o-cutter, and then screwing down a pieces of 9mm MDF to my wasteboard.

I’m going to make sure I’m quite close to the edge. If this was something I’d do over a long period of time, I’d try dig up the file for the wasteboard with the positioning of the mounting holes and try mill this out so that I could bolt this down instead. But as I know I’m only going to do a limited run and then I’ll get distracted, I’m only going to screw this down.

I home my machine and then move the router spindle to what will be my origin position, at the corner of the 9mm MDF.

I’m just going to move this across so I can get a screw in this corner here.

Here I am using my probe attachment to set the z origin to the MDF itself. I’m not going to go into the details, but I have a lot of videos on my second channel about some of these steps and what I’ll do is try link to the relevant video in the information card if your curious.

To recap: From fusion 360 I went and imported that DXF file into art cam, and then applied the toolpaths onto that, exported the Gcode and now what I’ll be using to do the cutting is another piece of software called bCNC. This one is an opensource thing. It’s quite a workflow of software and it will get further complicated when I get to the laser engraving bit as well.

I cut one groove out first and checked the fit, and then I cut the rest.

Pretty good. There’s a little bit of a wobble in the x axis but I think it’s fine.

The next thing I need to do is work out the offset of my Laser – so how far the centre of the laser beam is to the centre of the spindle. The simplest way I decided I could do that was to laser engrave a cross while keeping the gantry in the same origin position. And then measuring that mark to a known mark made previously on the 9mm MDF while routering the jig.

I exported the g code from inkscape using the Jtech plugin. I’ve added a header and footer which I’m having to watch my own videos to remind me what I was doing.

I make sure that there’s no power going to the laser, so I don’t have any accidents.

I measured that with a callipers but I could have also put a v cutter into the collets and moved to the laser engraved point, measuring the movement in bCNC. I took note of that and then offset the DXF file in the next software – this time within inkscape. So the jig had shifted to compensate for the position of the laser. The new origin was now on the 0-0 coordinates of the canvas within inkscape.

I set the engraving toolpath this time using a Jtech plugin for inkscape, exported the gcode, opened that in bCNC and press play.

While cutting, I had an inline extractor venting fumes form the engraving process to the outside of the workshop, and I was also wearing laser safety goggles that were provided with the OptLaser Module.

Ok so I think I’m quite happy with this design, so I will do a batch of them – only 20 or 30. I’m not sure.

So that was my laser engraved pencils projects. If you liked that video please let me know in the comments or by scarifying a thumb to the algorithm gods. There are links to the usual things in the description and to similar or related videos in the information cards. Thanks again for watching and you’ll catch me in the next one.

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