Fat Marvin

While I was fiddling with the acceleration settings on my Printrbot JrV2 to get less shaking and perhaps more accuracy, I discovered that reducing the acceleration below 1000 mm/sec^2 pretty reliably caused the machine to stop working  partway through a print. (I can imagine Marlin getting into a situation where it can’t look ahead enough moves to get the acceleration numbers down and quitting in disgust, but that’s probably not the reason.)

So I figured “Two years since the last firmware update, maybe it might be time,” and borrowed my spouse’s MacBook, because there’s a really cool app for OS X that gets the right file for your particular printrbot, handles the twiddly DFU syntax and generally reduces cognitive load.fatmarvin2

And then this happened: Everything displayed fine on Repetier’s layers-in-progress visualization, but the result was, er, not exactly the alien my 7-year-old has come to know and use in games.

So I whipped up a 20x20x10mm calibration cube in openscad and printed it. Hmm, just shy of 25mm on a side.  The M501 command to list settings tells me that X and Y steps per millimeter are the 80 standard for a JrV2, but apparently my JrV2 isn’t quite standard (and since it was kindly calibrated at the factory after assembly, who needed to know?).

A few micrometer checks of Y travel later, it looks like steps/mm is about 62.99, which looks suspiciously close to the number listed on Printrbot’s site for the JrV1. Did someone have a few old pulleys in the bin? Do I really care, as long as I can get the right number dialed in?

But I have to say, once I do get the right number I’m probably going to go back to the scale control in Repetier and make some more fat Marvins. They’re kinda cute.

This entry was posted in probably boring and tagged . Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s