CNC Router X & Y Axes Zero Block

I needed to make a number of rectangular plates each with 50 holes, I do not have the facility to 3D print them in one piece so I bit the bullet and invested in a FoxAlien Masuter pro CNC router. Long story short having built an enclosure/dust extractor/demidifier for it, the time came to carve something.

Zero on the Z axis was easy, as simple as a piece of paper or I could have use the provided setting block.

I set zero for X & Y by jogging the tool to the corner of the plate to be cut and sent the router on its way.... well part way through something went wrong and I heard a noise that said to me something had slipped so I stopped the cut. I returned to zero and sure enough the cutter was in the wrong place.

Not a problem, just reset X & Y zero and away we go again...... my zero was around 0.3mm out in one direction and though the plate was rescuable, I realised a more accurate method would be required for setting up to carve.

As I stated above. the router came with a Z setting block but that was not suitable for the other two axes, I found various setting blocks that didn't look like they could be integrated into the FoxAlien and they were pretty expensive.

I decided to design and build my own.

3D resin printer and resin

Soldering iron

1mm thick brass sheet

8mm diameter brass (not essential)

Battery holder with 2 0ff CR2032 batteries

https://www.amazon.co.uk/Jsdoin-20s-LED-String-Lights

5mm LED

480 Ohm resistor2 off M2 dia x 10mm countersunk screws and nuts

2 off M2 dia x 16mm cap head screws and nuts

1 off M3 dia x 6mm cap screw ( not essential)

A length of flexible insulated wire with an alligator clip at one end

Thin plastic card for insulating

In Tinkercad I designed a 2-piece block, the base having a cutout to locate on the corner of the work piece.

The upper has cutaways for electrical contact plates, a battery holder and an indicator LED.

There is a hole 8mm in diameter right through, centred on the corner of the workpiece.

Out of 1mm brass sheet I cut a piece 12mm wide x 46mm long and another piece 12mm square that you only need if you want to have a Z contact.

2 holes were drilled and countersunk for M2 dia screw heads, the centreline was notched with a square file to assist with bending.

Once bent at right angles you could leave it there for just XY.

I silver soldered the 12mm square plate in place to add the Z contact, then the assembly was checked and adjusted for square.

The brass was cleaned up ready for trial assembly.

The 3D print was adjusted to allow the brass piece to fit nicely in place, 2mm holes were drilled through and it was screwed together.

One of the screws will be used for electrical connection, the other one has a trapped nut dropped into the slot next to the battery cutout.

I went the Z axis route because I can, I have a lathe, I turned a piece of brass down to fit the 8mm hole and drilled a 2.5mm diameter hole, (M3 tapping size) into the end. I then parted off a piece around 3mm thick to use as a drilling button, once inserted in the hole in the 3D print I could drill through the brass contact plate.

I didn't manage to photograph making the actual contact but the drawing is self-explanatory, dimensions are shown as nominal as the diameter needs to fit the hole and I adjusted the length to get a nice simple Z offset figure.

Using a mini linisher I adjusted the contacts, I was aiming for offsets of 10mm on X & Y and 15mm on Z

Using my vernier height gauge, I got the following results:

X = 10.05mm

Y = 9.96mm

Z = 14.95mm

For what I am doing that is 10mm, 10mm & 15mm. For those working in imperial that is an error of around two thousandths of an inch.

This will put the edge of the cutter against the corner of the work piece. Adding the raduis of the cutter to the jogging will put the centreline of the cutter on the corner, whichever you prefer.

One wire of the resistor wrapped around a screw and a bit of solder added to keep it in place when attached to the contact fixing screw between a pair of washers, the other end of the resistor was soldered to the LED.

The battery pack had its LED string removed and the wires were scraped to remove the insulating laquer and the wires were tinned. The polarity of the battery pack was worked out and the correct wire soldered to the other side of the LED.

The wire with the alligator clip was knotted and the end bared and tinned, this was soldered to the other wire from the battery pack.

A piece of thin plastic was placed between the LED/resistor and the flying lead for insulation and then the two resin parts were assembled with M2 screws and nuts.

Set the block on the corner of the work piece and connect the alligator clip to the cutter,( some coated cutters may be non conductive, you can check at this point by touching the block contact to the cutter, the LED should light).

If you set the block slightly away from the corner of the workpiece as the cutter comes in contact the LED will flash as the block is pushed along, jog again until the LED fully lights.

The video shows the setting cycle that zeros X & Y axes, Z axis is possible but less user friendly. so I have left it out of the video.

This doesn't automate the procedure but it does make zeroing repeatable which was my original aim.