Black V4 Revisit

When I first decided to try Black V4 resin for some Patent model prototyping, Having several cartridges and not having a good option, I decided to give it a go. Nice, my first few prints came out great. I researched it here. I was honestly surprised and disappointed at what I found. It seemed that a number of people were having failures. What had I done differently? I hadn’t even agitated the resin! Luck, skill or what?

A week or so passed and I decided to print some revised models. I agitated the cartridge and used the wiper to stir the resin tank (NOTE: It should be called the resin tray!). I decided to use a raft which is not my style as I have a heck of a time removing them. I increased the supports to 150% and left the size at .80 mm and went for it. Two failures in a row!

The cartridges were both in the same order and the only difference was that the cartridge I agitated failed. I do not understand!

Makes no sense. As I didn’t agitate a black one for a while and a big pile of almost solid black paste had formed on the bite valve impeding it to flow properly. I had to agitate it in order to dissolve it and get correct flow, so it must be something else… M

I’ve found that storing the latest resins in the tank (I agree it should be tray) for more than a day or two can cause issues. I don’t know if it’s the lack of oxygen to the PDMS or if the new resins are slightly attacking the PDMS layer causing things to get sticky.

I started pouring resin from the tank into a separate bottle after printing is done for the day. No need to wipe things out completely but keeping the PDMS mostly clean is a big help.

You can’t pour the resin back into the cartridge (what we would call the tank) because it contaminates the unused resin. But more importantly, if you let the machine fill each time from the cartridge it will read worn out very quickly.

For more than a day or two? Wow, I’ve printed stuff on tanks full of resin after 2 months or more and no issues… Hmmmm

This all depends on the prints. A lot of the prints I do are fairly large with thin walls. They can fail easily.

I’ve noticed that the Black V4 prints seem to be much heavier than others. Since Preform defaults to .80 mm touch points, I’m going to assume that Formlabs believe that an additional level of support is needed. While I am leery of trying again, I will.
Changes in my process:
150% & 1.0 mm supports
Tilt my models to allow more supports. Which will make them even more of a PITA to remove! :unamused:
I’ve also had a problem with the supports on taller vertical surfaces being close enough to the model that they adhere and being difficult to remove. It’s better to have more ‘spots’ than long cylinders to remove.
No raft! Having had a stroke means my left hand isn’t as controllable as I need it to be making raft removal virtually impossible. I have to have help cleaning the platforms.
Since my failures have all occurred near the mid-points of the support or at the touch points, I think/hope that these measures will work.

Of course all of this has to happen after I change the resin tank and cartridge AGAIN! How much are inexpensive CNC mills & lathes? I think that I’ll have space in my new digs. :grinning: BUT an injection molding machine is probably out of the question as my parts are too large for the neat process that Formlabs white paper describes.