$300 Castable Wax Cartridge came with no slit, short shelf life

I just received my $300 liter of castable wax. I installed it into the printer with a new LT tank and when I went to print the first time the printer stalled on “Filling Tank”. I looked into the machine and no resin had dispensed. Upon pulling the new resin cartridge out of the printer I discovered that the rubber dispensing plug on the bottom of the machine- the one that normally has the slit cut in it for the resin to exit - was scored but NOT cut. The scoring is very light and didn’t go all the way through.

To add insult to injury, I know that these cartridges have a one year lifespan and mine was marked with a manufacture date almost three months ago. I don’t know if I will be able to use a whole liter of this resin in a year but I’m pretty sure that I won’t be able to use it in nine months. Kind of disappointed that FormLabs sold me a $300 bottle of resin that was a quarter of the way through its lifespan, and that I had to do surgery on the expensive cartridge with an Exacto blade to even get it working.

Did I do wrong by cutting the slit? We’re in a hurry to get a print to our casting house for a large order and I don’t have time to send this cartridge back and wait for another one.

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generally, you can just PINCH the nipple hard and it should split on its own.

If not, then you try to cut it by squeezing the nipple will what cut there is spreads… and then touch the center of the bottom of the groove with just the point of the xacto blade… this should cause it to split.

But even then- if you have hand cut the nipple DO NOT TRUST THE CARTRIDGE to hold the resin in without leaking.

Formlabs would tell you not to use the cartridge, but that they will send you a replacement… but that you might use the RESIN in the cartridge if in a hurry by switching the machine to open mode where you hand fill the tank.

its a pain, i know, but in a hurry when you can’t wait for the replacement to arrive- it works,


As written by @Sculptingman : I would not put a cartridge in that needed the valve to be cut for it to open.

However, about half of the cartridges I receive have a valve that is kinda hard to open by hand and to make sure I have no issue in the printer I always pinch them by hand to guarantee the they’ll open once in the printer. Up until not I have not had to use any tools, the pinching was enough.

In recent firmware update, I think Formlabs also has changed the way the printer pinches the valve. I now often hear the arm going back and forth several times before staying in the “pinched” position. This I think is to mimic the way a human would repeatedly pinch the valve to get it to open.

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Similar problem here:

I had a Castable Wax Cartridge with a valve that would not open.
Formlabs Support provided me with a procedure to open it - basically squeezing the valve until it opens (which it eventually did).

Toady, 5 prints later, I took the cartridge out of it’s box:

It turns out you can’t print Castable Wax in Open Mode, the printer returns an error message.
My quick fix was to empty the cartridge and print in standard mode with an empty cartridge. This works of course only if your print volume is small enough.

I can only emphasize @Sculptingman’s and @JohnHue’s advice: Do not trust a defective valve!

Formlabs sent me a replacement castable resin cartridge-

When I took it out of the box- the cartridge was already leaking inside the sealed baggie- from the valve.

Could it be that castable has a problem with the valve material?

I’m noticing that the Castable resin is much thinner than the Grey I normally print with. Maybe that has something to do with it?

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These silicone bite valves are somewhat self-healing. Gently pinching it about a dozen times (upside down, cap close :slight_smile:) will cause it to reopen. Castable is one of our thinner resins, so it is easier for it to leak than a more viscous resin like grey. For this reason, I’d generally avoid using an xact-o blade, as it’s possible to cut open the slit larger than required for normal dispensing.

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Hi Craig, thanks for the response.

I wish I’d have taken a picture, but the silicone bite valve wasn’t cut at all, so I’m certain it didn’t self-heal. There was a very light score mark on the valve that I used as a guide but once I cut down into the silicone there was zero evidence of a prior cut. It looks like the machine that did the scoring/cutting just completely missed this one.

For what it’s worth, I did exercise the valve several times in an attempt to open it up but there wasn’t any cut whatsoever to the material at all.

We’re on a rather strict deadline and had to get a prototype printed for the customer or I would have just waited for a replacement cartridge from Form. I’m checking the printer for any leaks and so far I haven’t seen a single drop. I did slightly under-cut the opening by a millimeter or two so hopefully there won’t be any leaks.

Yeah, the castable wax is much thinner so I can see the risk of leaks. However, the prints, especially at .025, are magnificent. I had to fiddle with the orientation a few times but once I got it dialed in it looks great. Even under a 40x microscope. Serious props to your chemistry department. I can’t wait to see what the final piece looks like.

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It sounds like you did the right thing—I’m glad you like the resin!

Thanks! Still a little disappointed that my $300 got me a container of resin that was already through 1/4 of its lifespan, though. The cartridge even had dust on it. :frowning:

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