Form1+ Lead Screw (Z Screw)

I’m looking for info on the Form1+ lead screw. The short version of the story is that the refurbed replacement that Formlabs sent me for my machine has never printed properly (there is a repeating wave in all prints) they had me try cleaning mirrors, replace mirrors, new vat, new resin, old vat and so on. I told them about a visible wobble in the lead screw but this was dismissed by them. So, after having it basically collecting dust for another year I’ve decided to fix it myself.

Formlabs said they don’t have the specs on the lead screw and to check here. I’ve removed it from the stepper motor and now just need to buy a replacement, but there is some info I need on it to get the right replacement.

I know it’s a T8 screw with 2 degree thread pitch, but I need to know the lead and if it’s single, double or 4 start? Anyone know?

Better yet anyone have a Form1 or 1+ they are parting out?

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No one knows anything about the leadscrew?

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You sure it’s the lead screw? Is there any play in the build platform at all? The Build platform has a small screw on the lever to make sure it snugs down when locked down,
For the screw to create a wave it would have to be out of round which I think is pretty unlikely as if your machine had this problem many others would have the same problem.

If the head is sticking a little you could put a tiny drop of light machine oil on the screw, very little as I had a horrible grunt sound as the head would raise or lower at end or beginning of print cycle. I used 3:1 oil and just the tiniest drop on the top of the build head where it meets the screw when the head was in it’s lowest position and that did the trick.

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Support had me try everything, including tightening that screw on the build platform as well as greasing the lead screw. All prints have a repeating wave of about 3-4 mm which looks to be what the lead (linear distant traveled for one full rotation) of the screw. Given I tried everything else and other printers like the photon and moai, which use more or less the same setup, have exhibited similar problems without a straight lead screw it doesn’t seem to be coincidence. The wave is there left right not front to back. Since the platform rides a rail it would be very hard to affect the front to back motion, but a bent lead screw could cause some axial twist to the bed left to right.

If others have a lead screw that isn’t straight and have no print problems I’d be quite interested to know.

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My form 1+ lead screw wobbles a bit. You can’t see it when it moves under normal use, but when the lead screw moves fast at the beginning and end of a print, you definitely can see the wobble at the tip of the screw.
An no, I don’t have a wave pattern.

I also have a couple of FDM printers, and the wavy pattern is a symptom of a loose guide rod. As long as your guide rods (or in the case of the Form 1, the rail is straight, it doesn’t really matter if the screw is slightly out of whack. Just make sure the guides are tight.

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