Jason Harris at SolidVision told me when I was setting up my SD300 that it might give a false 'replace cutting knife' error around layer 4 or 5 if the build material wasn't stacked tightly at the edge of the build table. It happened to me once in June 2010 the first time I used my SD300 after a long vacation.
A British SD300 user once told me that he tended to build several batches of models near the end of each month. His first build job would usually be sticky and the support material would be hard to remove, but all subsequent jobs would be normal. He worked around the problem by always building the built-in Test Model if he hadn't used the machine that month.
Today I built my first model since 17 December 2011, so my SD300 has been sitting idle for two weeks. I noticed something strange immediately. Normally the SD300 starts by bonding a layer of PVC onto the build table with an even layer of SolGL adhesive, but this time the adhesive was spotty. The adhesive appears here as dark spots underneath the red plastic--it should have been spread under the whole sheet, not just little spots as here.
- The air bubbles in the glue lines had formed while the machine was idle. The bubbles would have cleared themselves within a few layers, but I could have cleared them manually by using the Clean Bubbles function in the SDMove maintenance utility.
- The droplet of SolGL glue was also caused by the air in the glue lines. It could have contaminated the anti-glue pens, but the contamination would have eventually resolved itself.
- A height check error within the first few layers of a job probably indicates there were bubbles in the glue lines, but the problem has already resolved itself by the time it's been detected.