Focal jigs/guides

Does anyone have a cut file for a focusing jig ? I want to cut one, but can’t find a file to do it. My lense is a 2.5" 18mm

I use a stepped piece I downloaded from Russ’ files on RDWorks user forum. Don’t know if there is anything like it here. A pair of stair step pieces with 1mm increments. One 1mm to 20mm, the other 1.5mm to 20.5mm. It had a .5mm but it broke off.

Put something that won’t scratch your lens up the nozzle, like a zip tie, and mark it. Subtract that length from your 2.5" and you have a rough tip to work distance. Take a short piece of scrap, put something around 3/8" thick under one end to angle it, and set your rough tip to work distance in the middle of the angle. Run a low power line to mark the scrap.

The finest point of the line is your sweet spot. Most engraving setups put the nozzle tip around 18mm above the work, most cutting setups are down around 5 - 8mm. For cutting you generally set your focal point one or two mm into the work.

I can’t recall where this file originated and I may have modified it a bit. It is a free download, though, as I recall not purchasing it from the source. It’s somewhat of a compromise, as I think it was originally created for 6 mm stock and I butchered it for 3 mm stock. The bottom is not flat but that could be easily corrected by trimming the feet/tabs.

focus ramp 3 mm.lbrn (348.8 KB)

The shelf at the mid-point is used as the zero reference. It may be necessary to adjust the model to match your lens. Of that I am unsure.

That is Russ’ focus test ramp. works great to find your foal point. The only difference I see in that vs his dxf file, is that center piece is set flat to the bed instead of in the plane of the test angle. The reason for keeping it flat to the test angle is to set your initial focus on the test paper, and not have it pressing down or sitting loose.

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