i am nuts a nutty question

[pcmad]

I'm currently developing a 3D model to print out on a 3D printer and I'm wondering how do you measure hex nuts to go into the 3D printer model do you measure it from the point to point of each of the angles or do you measure it from the flat side to the opposite flat side

[sleemanj]

Measuring flat to flat is easier with your calipers, but you can do it either way depending on your modelling program.

[ledtester]

Maybe this page will help -- for US sizes:

https://www.aftfasteners.com/finished-hex-nuts-dimensions-technical-information/

This says the diameter is "across the flats. It is also the size of wrench to use."

https://www.boltdepot.com/Fastener-Information/Nuts-Washers/Metric-Nut-Dimensions.aspx

[beanflying]

Depending on the application my preference has been to use knurl nuts in a design over trying to capture a nut in the plastic to fasten something.

Depending on if you want to stick standard nuts with cold fitting them you may also need to add 0.1-0.2mm in your model too. The knurl nuts have a similar 'fudge factor' but you will need to have a bit of a play with both until you get a number for your particular size and or printer.

[Infraviolet]

Measure across flats, thats how it is done in datasheets where you buy nuts from. Also note that hex nuts have the corners of the hexagon somewhat rounded off, so a corner to corner measurement would end up giving too small a hexagon to encompass the actual nut if used. Recesses to take hex nuts should be shaped according to the hexagon with flats measured (or read of the datasheet for that nut type, they are standard for the M series metric thread sized nuts), then offset by 0.1 to 0.3mm to widen it. The amount of offsetting epending on printer accuracy and whether you want a tight fit (struggle to force the nut in) or a looser one (nut at risk of falling out until screw tightened in to it and maybe at risk of turning in the hex recess if sufficient torque is applied to the screw). 0.15mm to 0.2mm (added on each side of the flats, so 5mm across flats becomes a 5.3 to 5.4mm hole across flats) usually gives the bext balance of tolerance considerations.

[Warpspeed]

Open ended spanners are measured between flats, and so are the nuts.