Horizontal wave patterns on bottom of print

I’m trying to print a small projectile for a shooting toy on Form1. The projectile is mainly made up of a cylinder. The cylinder is supposed to be smooth but I get this wave pattern on the bottom half of the cylinder.

What can be the cause of this?

Picture of the print repositioned on the supports:

Bottom side of projectile with wave pattern:

Top side is smooth:

I also tried to print the projectile standing up straight vertically with the half sphere tip facing down. I only put support on the tip to keep the cylinder smooth. This got rid of the problem with the wave patterns. It also got rid of the left overs from support connection points on the cylinder. But it resulted in the cylinder being oval and not round. Why is this?

I found someone with a similar problem here:

But no info on it being solved or not.

Actually they asked for the original person to contact them almost immediately.

Also found this on that thread, thought it was useful:

Aug '13

Hey Leo,

Check your resin tray. I bet it’s loose. This happened to me too, and the resin tray was moving from vibrations of the printer motor. Do not shove the tray in all the way, but instead make sure the clips are holding it in place. You can wiggle it a bit to make sure the clips are holding. After I did that the problem went away

Hi, I started the original thread a long time ago.
Actually, after several direct messages between support, finally I send back my Form1 to be repaired, and then this problem had been fixed.

Thanks for the replies.

I’m pretty sure that the tray is not loose. But I will check that it’s not in contact with the backend. Vibrations sounds like something that could cause waveforms.

I hope I will not have to repair the printer…

LeoA, did they tell you what the problem was?

If you have a Form1 then you need to clean the dust off the mirrors inside every 6 months or so

1 Like

Thanks for the advice. Is it hard to open the case to get to the mirrors? Is there any instructions anywhere?

I tried to make sure that the tray was not pushed all the way in and did another print. Still the same result.

I will try cleaning the mirrors next.

Contact support and they can send you the guide on how to do it. The big mirror is pretty straightforward but the ones that have the biggest impact are the galvo mirrors inside which require removing the back to access.

Thanks, I found it online already! : ) Didn’t have time to get it done yet!

Now I’ve tried cleaning the mirrors and it didn’t change the results at all.

I also tried adding more support.
Making sure the printer is placed on a level and stable surface.
Changing the angel of the object on the layout so that it’s 90 degrees contra the hinge side of the tank.

Still get the same result.
The only thing that seems the change the print is that 0.1mm layer thickness produces better result than 0.05mm and 0.25mm.

The problem is horizontal lines, they are not really wave formed as I first thought.

I will try testing the laser spot next. Anyone got any other idea?

Another thing I noticed is that the support structures seem to be OK. It’s just the object itself that has these protruding lines.

Is the STL a single shell?

See this thread: http://forum.formlabs.com/t/print-has-ridges-that-are-not-found-on-the-original-file/15361

Thanks for the input. Interesting threads that you linked to.

I think it is a single shell or object. I made it in Autodesk Fusion 360. The whole thing was made by sketching a flat profile that is then rotated around one full turn. This creates the cylinder and the sphere.

I hope that was understandable…

Here’s the result of the laser spot test. I think it looks OK. No flares at least.


I’m giving up on this printer now. I can’t come up with anymore ideas on what can be done to improve the print quality.

We have another abandoned Form1 printer standing on a shelf in the makerspace. I’ll give that one a try know. The problem with that one is that it has a lot of liquid resin inside of it and one of the ball springs is glued shut.

I tried another print yesterday with the first printer. Tried to print a sphere. The bottom of the print has the horizontal lines and the sphere is not round either.

The top is smooth and nice though. I wish I could get prints of that quality…

I notice that the supports are very badly formed too, similar to the results that I got with expired resin.