Hole Error Test Plate, 5 to 22 mm

General

A 5mm hole and a 22mm hole don't print the same amount off nominal.

On the five printer setups I measured, the 5mm holes came out 0.09 to 0.25 mm undersized and the 22mm holes 0.05 to 0.10 mm undersized - so a single correction number is wrong for at least one of them.

This is the plate I used in that experiment. It goes with the main calibration model for FitCheck: Hole Sizes & Fits, an app I develop. That calibration model gives the app the two sizes it needs, 5mm and 22mm, and if you just care about calibrating the app, use that one.

This plate has those two plus the four sizes in between, so you can see what your own printer does across the whole range and chart its linearity

Details

• Six through-holes: 5.00, 10.00, 13.00, 14.00, 16.00 and 22.00 mm

• Every size is engraved next to its hole

• 0.5 mm chamfers top and bottom on every hole

• Nominal sizes with no compensation built in

• About 157 x 40 mm. Fits a 180 mm bed.

10, 13, 14, 16, and 22 are the catalog bearing sizes (623, 695, GE5C, 625, 608)

Print Settings

• Slice with the same profile, nozzle and material you usually use

• Layer Height: 0.2 mm

• Infill: 15%+

• Walls: 3+

Leave slicer XY size compensation OFF (your slicer may call it hole horizontal expansion)

How to measure

Let it cool to room temperature first on the plate. 

• Use the caliper's inside jaws and aim for the middle of the bore, between the 2 chamfers.

  • Try not to lean on the jaw as it will deform the wall and a slight tilt will read larger.

• Measure each hole twice, rotating the caliper 90° between readings, and average the two.

Write down measured minus nominal for each size. That's your hole error at that size. Negative means the hole came out small, positive means it came out larger.

What to do with the numbers

• 5 mm - the round-hole number FitCheck asks for, enter it in the app.

• 22 mm - the optional large-bore number. Enter it and the app scales the correction with diameter instead of applying the 5mm number everywhere.

• 10 mm to 16 mm - not entered anywhere. They show you whether your printer follows a straight line between the two numbers you did enter. Enter it into excel or Google Sheets to chart how your printer scales holes linearly

Enter them into FitCheck (free app for iOS and Android - more info here), and the clearance and pocket sizes it shows are corrected for your machine. Calibration is free, and saved machines stick around.

No app?

You can still use these numbers. Measured minus nominal at each size is your printer's hole error at that size, which is usable directly as slicer XY hole compensation. Note though that XY hole compensation compensates all internally-cut geometry - hex nut holes, skeletonization, bores, etc. And as I've found, a single compensation number does not truly cover the full range of possible bore sizes

Prefer to just look a number up?

All references are  free on the web, no app needed - including bearing pocket sizes for every size on this plate.

Why the sizes in between

On my printers, a correction from the 5 mm holes alone over-corrected larger bores, so measuring a small and a large hole lets the app scale the correction with diameter. The app draws a straight line from your 5 mm number to your 22 mm number and reads the correction for the sizes in between off that line. The four holes in between are the check against that line. If they chart nicely along it, those two numbers describe your printer. If one of them is well off the charted line, that's the size to test print before you trust the correction there.

Re-measure when your process changes. These numbers describe one machine with one nozzle, one material and one profile. Change any of them - including turning slicer compensation on or off - and print the plate again.

Happy printing!

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