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MPCNC Drilling Jig – Printed and Accurate

mpcnc drilling jig

Cutting holes in a steel conduit is easy with the MPCNC drilling jig.

The Mostly Printed CNC machine is built with vertical steel pipes (Z axis) that hold a cutting tool. The tool holder is attached to the machine using two 5/16 inch holes in each pipe, spaced 3” apart.

Preparing these pipes presented me with three requirements. First, holding the round pipe firmly down. Second, accurate placement of the holes. And third, actually drilling the holes with my limited workshop. I had never drilled a hole in a pipe before.

Previously, I have discussed how easy it is to create little jigs or “helpers” with a 3D printer. For this drilling job, I got the idea of printing an MPCNC drilling jig that would help with all of my requirements: work holding, accuracy and drilling guide.

The MPCNC drilling jig is shown in the top left picture above. It is basically a plastic cube with a 23.5 mm hole in the middle, which is the outer diameter of the EMT conduit pipe. The smaller holes on the edges are 8 mm in diameter (close to 5/16 inch) to serve as positioning the drill and guiding it.

I was able to slide these jigs over the pipe and position them accurately to place the holes where I wanted them. The MPCNC drilling jig also provides flat surfaces for clamping the pipe down firmly. This is shown in the bottom picture. The walls of the drilling holes are high enough to help position and keep the power drill vertically while boring the holes.

MPCNC Drilling Jig Helped a Lot

Everything worked together like a charm. The final product is shown on the top right, the end of one of the pipes with two accurate holes for mounting the tool holder.

The drill used was my cordless power Skil drill with a 5/16 inch bit. I used a touch of WD-40 to lubricate as I drilled, which kept the smoke to a minimum. My wife bought me this drill as part of a set of tools from Costco a few years ago and I have been pleased with the performance of this Lithium Ion battery powered tool.

By the way, since I had to drill four holes in the pipe, there were enough holes in the jigs to use a new hole for every drilling operation. I had thought that the drilling might damage the plastic, but that turned out not to be the case. I guess I have a steady hand.

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