JTech Laser Mag Mount Improvement

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Tex_Lawrence
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Model of CNC Machine: Shapeoko3XXL; JTech7W; V-CarvePro 11.554
Location: Dayton, Texas (Don't Mess With My Texas!)

JTech Laser Mag Mount Improvement

Post by Tex_Lawrence »

Well, its been about a year since I performed this procedure on my JTech mag mount. The only problems that I have had with it are when I run into something, where it releases from the mount without anything getting broken. But, it doesn't release as easily as with the magnets (and that's a good thang.)

I don't have time or inclination for adding this to a YouTube video, but I wrote a procedure and provide a couple of photos in explanation. If you don't use a similar JTech laser, then won't be much help to you.

When I first started dialing in the offset between the J TECH magnet mount and my Shapeoko router zero, I ran into trouble with the easily-removable feature of the magnets --- they move. So, there's really no way to get repeatable tracking of the zero points (albeit probably more than most folks need to worry about.)

I set about finding the reason for this in the design of the mounting system. The first thing I did was to move the laser mounting bracket to the center line of the router. My thinking here was to reduce the leverage that could allow the laser to move. (In hindsight, I'm not sure this is required.) The way this assembly goes together with four screws makes it as tight as if it were molded as one piece.

There was only one weak link in the system; the registration screws. Those two screws that have their heads inside of the housing where the laser is. A few millimeters stick out and help align the laser to the mount. The magnets hold the assembly in place, but due to the glossy meeting surfaces, the laser is easy to bump out of set zero. Those two screws are there, but they perform no more than a pointing function at best.

The goal was to create a tight fit of the registration screws to the holes in the mount, and then the magnets will ensure that that assembly stays put. My solution eliminates the motion of the laser, but still allows the laser to be removed.

The first step in the procedure is to enlarge the holes in the mount to 5mm diameter (fits M3 standoff). The tolerance here needs to be tight to maintain the dialed in offsets. The offsets are coded into the post processor with the G92.1 and G92 XnYn commands. Some precision is required, in the drilling, so the hole centers still match the laser screws. I was easily able to do this on my drill press by clamping the mount in place while drilling. I started with a bit that was one size smaller than 5mm and the came back with a 5mm bit to size the hole. The plastic mount likes that two step process. (Note that the enlarging of the hole does not change the way the mounting works today. That means that the standoffs can simply be an included option.)

The second step in the procedure is to screw the M3 (5mm diameter) x 8mm aluminum standoffs onto the two M3 screws sticking out of the laser. Hand tight seemed to be OK, but I have a strong grip. I thought there might be some advantage to grinding a small chamfer on the edge of the standoffs to
aid getting them into the mount holes, but I added a touch of silicon juice and forgot all about doing that.

The third (and last) step in the procedure is to push the two parts together. My tolerances were almost non-existent, but I don't find any reason to change the fit of the standoffs into their holes.

The result of this process was that I was able to match the offset of the laser cut to within 1/64" of the router zero. I think I'll be able to get that a little better, but I stopped so I could test what happens when the laser is taken off and put back on.

There are two methods to remove the laser from the Shapeoko. You can remove the laser from the magnet mount or from the router mount. After taking it off and on with both methods, I confirmed that the offset maintained the 1/64" tolerance. However, that 1/64" did shift across the router XY center a couple of times, which is fine for my purposes.

Anyway, that's my solution. It is solid, reversible, removable and repeatable. I'm calling it solved. If you need or want further information (or solutions), just please ask.
JTechLaserMount_0090.jpg
JTechLaserMount_0092.jpg
PS. I did receive an award of a pair of laser spectacles after JTech received this same procedure.
Tex — Crooked Wood Products
Now there's a man with an open mind – you can feel the breeze from here.

wb9tpg
Vectric Wizard
Posts: 453
Joined: Tue Sep 04, 2018 2:49 pm
Model of CNC Machine: Shapeoko 3 XL

Re: JTech Laser Mag Mount Improvement

Post by wb9tpg »

Nice modification to the mount.
Gary Mitchell
Kentucky, USA

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