Sloppy model print


Last night we printed four dental models. Problem: they are sloppy, see picture:

We used a resin tank that is quite new. The last print before this one was last thursday. Meanwhile we stored it with its cover in a dark closet.

Also, the connection for our articulator does not fit (the model is slightly too big), see picture:

Can anyone help me trying to find the cause?

Thanks in advance!!!

Gr Koen

Can you post closeups of the “sloppy” part? I see what I think are maybe “flakes.” Have you had any print failures previously? Do you ever filter your resin?

The new tank would rule out fogginess on the bottom of the tank.

I don’t do dental, but I have gotten in the habit of filtering through a paint cone into a quart container and storing that in a dark cabinet. I use castable, which is really hard on the tanks, so I store the resin and tank separately…this might not be necessary with dental resin. But the filtering my help in your case.

There is also an XY adjustment in the settings on the Form…on the printer, not the software. Perhaps you could print a smaller test block and use calipers (digital) to make sure that it’s printing accurately. Make adjustments as necessary.

Thanks for you input! I think there is a high chance that it is the filtering process we did not know about. Do you maybe have a picture of the quart container or a reference number? We would like to start filtering as well.

just go to any paint store and ask for fine mesh filter cones- they come in packs and are disposable paper with a mesh section.
At the same store, buy a supply of disposable paper buckets that are about pint or quart sized- just take out one o the filters and open it and find a paper bucket that has a rim slightly smaller than the cone that will support the cone and still have the tip of the cone well off the bottom of the bucket.

Back at the lab you stick a cone in the bucket, and dump the tray resin into the cone… do this in a room with low artificial light- no windows admitting daylight- it will take a while for the resin to filter thru. you might check it once in a while and use a popsicle stick or tongue depressor to gently scrape the inside of the filter screen in case tiny bits of resin are clogging it up.

while this is going on, gently scrape the inside bottom of the tank with a spatula like tool to see if any very thin sheets of resin are adhering to the tank surface. Sometimes a single printed layer will stick to the tank… but usually that would cause much more dramatic flaws than you are seeing.

Prints coming off size and with muddied detail usually points to a problem with the focus of the laser.
Also check the UNDERSIDE of the tank window for debris, fingerprints, or grease.

And then check the optical window he tank sits on top of in the form2- make sure its clean and with no dust, fingerprints etc.

Another thing to check is that the file was exported from Preform with the correct resin selected,
different resins have different shrinkages that Preform adjusts the file to compensate for… and printing dental resin with a file prepped for, say durable, would result in an offsize or less distinct print.

I use something like this for the cones. The kind I get are from Home Depot, but I’ve also ordered them from Amazon. They sit nicely in the quart containers mentioned below.

I get these quart cups from Home Depot. They are in the paint department, and come with lids.

I place the cone in the quart container, then use the wide putty knife that came with the printer to gently clean the tank. Remove the tank from the printer, then pour the resin out of the spout at the back of the tank through the filter cone and into the cup. Start at the furthest corner from the spout with the putty knife, carefully and gently scraping the PDMS surface and pushing the resin toward the spout. I don’t really fuss with it much or leave it too long…I can usually see if there are flakes. It might be a little more difficult with the dental resin.

Because I’m using castable resin, and that’s hard on the tanks, I leave the resin in the quart container in a dark cabinet. When I start printing again, I pour the resin into the tank, and not back into the cartridge. . The printer senses the level of the resin in the tank, and will add resin if the printer needs more. You will lose a tiny amount of resin while filtering, but the printer will accommodate.

I do this in my studio with regular lighting on…it goes fast enough that I don’t have a problem with any of the resin curing.

I followed this article the first time I filtered:

It was a little intimidating at first, but now it’s just part of the process for me.

Another thing…in PreForm, there is a feature to “View Minima” in the “Printability Display” section under the View menu I’m guessing your software generates a file and then you import it into PreForm? Make sure that everything is supported correctly, and go through the layers to ensure there are no parts of your model that are unsupported. Even if you let PreForm generate the supports…check the layers with the Slicer Slider under the view menu or on the right-hand side of PreForm. Edit supports and add more if necessary.

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