Determining unknown nozzle bore size.

[Qdeathstar]

Hi guys.

I have a cyclops hot end and was dissapointed that they did not have a 1mm nozzle for printing t-glase. So, i got myself a 1mm drill bit and made myself one. The issue is, however, im sure that despite using a drill press i'm sure its not exactly 1mm in size so im wondering what the best method is for determining the size. I assume the errors with mistatiting the bore size are simular to "over extrusion"?

Thanks!

[Eric]

It won't be smaller than 1.0 mm, if that's the hole size you drilled, so it follows that it's larger by some tiny amount. See if a 1.1mm bit* will hand-fit in the hole. If not, it's still somewhere between 1.0mm and 1.1mm, and that's probably the best measuring tool you're likely to have handy. But other methods come to mind, such as a measuring microscope or air gauging (measuring nozzle air flow at a specific pressure).

The extrusion will expand after it passes through the nozzle under pressure, so measuring that will give you a larger number.

* Or other sizes, if you've got an extensive expensive set of drills. Between standard and metric, there are probably 5 or 6 sizes between 1.0mm and 1.1mm available.

[Xenocrates]

Optical comparator? If it's a 1mm nominal, it is likely to be slightly undersized, as well as tri-lateral. Perhaps get a 1mm reamer like this, and see what you get after that.

Don't try using a typical drill for "precision" work. If you need it more accurate than ±5%, use a reamer or boring bar. If round is important, the same advice (Take a look at a freshly started hole some time, unless you have a good pilot it has a 3 lobed profile). Also, if you need hole properly positioned, use a centerpunch or spot drill to start it, and for hand drilling, think of investing in a good set of split point bits. Long story short, drill bits, and especially home despot or lowest bidder bits aren't much better than Horrible Fraud's. For nozzles, I would got for centerpunching, drilling out undersize, then reaming, to make sure it's round, smooth, and accurate.

[Qdeathstar]

The nozzle was aready bored to .4mm, so i'm assuming it would automatically center in the hole. I'm not looking for methods to measure the bore, persay, but more, how to dial in the printer to the proper bore width if you do not know it.

[mhackney]

Gage wires is the best way. Get a set of tiny metric drills and use the shaft side as the gage or buy a specialty set.

And as Xenocrates correctly stated, you can not drill precise holes with a standard drill. If you don't have reamers, drill undersize and sneak up on it in at least 2 increments. Not perfect but better than a single pass. I don't know of reamers this small so the sneak up method is probably the best. And always spot drill too, most drill wander at the entry point will impact the roundness of the hole.

[Andre B]

If you tell the slicer you have a 1.1mm nozzle but your nozzle is actually 1.03mm the amount of plastic pushed thru the hole will be the same as if the nozzle really were 1.1mm. It is just that it will take a little bit more pressure to do it but not so much that it will cause problems.
Then as long as there is still a reasonable flat on the nozzle around the hole the plastic will get flattened out to a layer thickness and width you wanted.
In other words the actual size of the hole can be off a fair bit but as long as it is a clean round hole it should work ok.

[mhackney]

There are other issues though, the molten plastic "die swells". Die swelling is a function of a lot of things and nozzle diameter is one of them. Your dimensions will be off a bit in finished parts. For my parts, that would cause problems, for a Yoda statue it wouldn't. Of course, the smaller the ration of desired vs actual, the smaller the effect so for a 1.0 mm desired, 1.03 is only 3% and most likely will not be an issue at low print speeds.