Hello
I recently bought a formlabs 2 printer and is printing my own surgical guide for implant procedures.
I am designing the guide using a software called blue sky plan. I will get a stl file from the software and print with formlabs 2 (with preform).
The printed guide was somehow loose. Pic below showed the hole to be around 5.2mm, but in software the hole was designed to be 5.0mm.
When I fitted on a stone model it was loose too (different guides but all same issues). IMG 7518 - YouTube
It seemed the whole surgical guide had been enlarged by about 5-10%
I had try printing with different layer thickness, did not resolve the problem.
I tried putting the print objet either flat or at an angle.
I tried changing the support material, but did not changed the result.
Since you have a set of calipers, print a few simple cubes of different sizes and see how they measure up. You’ll be able to quantify both the scale and direction of the dimensional error. I suspect there’s a secret way of adjusting the printer’s calibration. Though you could always brute force it, knowing the error on each axis you could scale your object accordingly before printing it…
I don’t know what the post-print cleaning procedure is for the dental resin. Is it possible you “over soaked” it and that’s why the holes have opened up?
It is soaked in alcohol for 10 min, twice, followed by light curing.
But that measurement is taken right after the alcohol cleaning. Dimensional change should be at minimum.
Is it possible you’re deforming the print when measuring it? Like I said, I haven’t used the dental resin, But especially for thin walls, until final curing is completed the shape can be easily deformed. If you pull on the caliper too hard, you might just be spreading the opening a bit.
The best way to figure this out is to print some solid cubes and measure them outside-to-outside. You won’t have to worry about deforming the print while making the measurement, and you’ll be able to calculate exactly how much error there is (if there is error).
I noticed that you are printing with Grey resin, and that you also haven’t post-cured your print. The post-curing process will cause some shrinkage to occur. Perhaps you could try that and re-measuring?
Also, our grey resin isn’t tuned to be as accurate as our Dental SG resin. Have you tried printing with Dental SG and post-curing according to the IFU?
Finally, if you’re making implant guides you really should be doing it with a biocompatible material. Our Dental SG material is Class I biocompatible (ISO 10993-1) and designed specifically for dental surgical guides. If you are going to use these in surgeries please use Dental SG, not grey resin.
Again, I’d strongly encourage you to get the Dental SG resin. It’ll get you much better results for this application, and also gets you the biocompatibility you need.
Also Dr. Huang, do you have a support ticket open with our team? If so please let me know – I’d like to make sure you’re getting the help you need, so I could coordinate with our team on that.
Hi Gideon
I recently just bought the printer. Grey material is all they have. Nothing else. I had request for the dental sg resin but it is not avaiable in my country. It is not approved by our fda yet.
Grey resin is all I got for the time being.
Yes, I cured it with dental curing light but not much change.
Orientation might be critical where the layer steps could be influencing the size of the hole. The calipers you are using look like the ones I have and typically calipers don’t make accurate inside measurements especially with small round interior measures. An interior micrometer would be much better for that since the points are round.
For the most part my printer has been really accurate and consistent with sizes. I was able to print some threaded parts with a 28pitch internal and external. These threaded parts have been in the field for 8 months now and still holding their shape and working fine. The only issue I had is i had to chase the threads a little to make sure they were clean from any support points.
One other thing to check is you should have a fairly high poly count for round surfaces that are critical. Large poly flats will ruin your accuracy. When I export models I use a low break angle such as 6 degrees, skip details below .012"
