Extruder calibration

We have a new TAZ 5 that we got at the beginning of the week. One of our plans for this machine is to print out some check gauges and calibration jigs for parts. Since we want the maximum available resolution and precision from this machine, we’ve been going through some of the calibration tutorials online.

We decided to try to dial in the extruder first, since that seems like it can affect the X, Y, and Z calibrations. Our first trials were done extruding 30mm, and trying to measure things with a simple scale. We weren’t able to get anything that seemed even reasonable this way.

Our second trial is done using a set of digital calipers. We set them to 120.00mm and lock them, then position them above the extruder head and mark the filament with a razor knife. Next, we use Pronterface to extrude 100mm of filament, then use the calipers to measure the height of the cut, using the razor knife as a guide. If everything was working perfectly, we would measure 20.00mm every time.

We’re seeing very inconsistent numbers. Here’s the data from this morning:
Trial 1: 18.76 mm
Trial 2: 19.57 mm
Trial 3: 20.04 mm
Trial 4: 20.21 mm
Trial 5: 19.58 mm

Has anybody else tried this and gotten better results? Is this as good as we can get? BTW: we’ve got the extruder rate set to 100 mm/min.

Thanks for any tips.

Here are couple of links to the recommended methods for setting your extruder calibration:



The OHAI guide says to set extrusion speed at 100, but it is recommended to use a normal speed or 30-40 for more accurate results.

I`m glad to see this numbers are in the heads of the users here instead of the 100mm/s :slight_smile:

CoParaTech,try this values and you will get better results. Also check the tensioner screws are not too loose.

Thanks Sebastian, I think I’ve got mine dialed in pretty well now. :wink:

Well, we ran some more tests, and they’re slightly more consistent. We changed our default marking length from 120mm to 60mm, and our feed test from 100mm to 50mm, because it seemed like we were introducing significant measurement error through the bending of the filament. We ran some more tests at 30mm/min feed rate, and got 10.08, 10.08, 9.73, 9.74. So it seems like maybe that is as accurate as we’re going to be able to get with this equipment.

I’ll run some more calibration samples tomorrow, and see what the results look like.

Strange that the filament movement is so different… I’d give the idler a few turns to ensure consistent “bite” into the filament.

I had the same thing when spending ages trying to fine tune my e steps. I just played about with the values until the +/- was about the same each way.

I have dealt with and used machinist measuring gauges and I don’t think your going to get a 3D printer, printing plastic to make gaging blocks with great accuracy. And if you did get one you wanted, the plastic expands and contacts with moisture and temperature over time.