How accurate is the Powder estimate…?

Probably seen all the issues printing a nylon 12 GF over the past year and this thread is coming off the current and continuing trouble shooting with Formlabs to make it work.

I’m going to do a detailed “cost breakdown” of this system if you are looking at this system for production running parts… in a later thread but… right now something else drew my attention….

As I run a test print to add to the high cost of Nylon 12 GF and the fact I have had to run at 70% refresh rate (throwing half my material in the trash)… with me doing all this troubleshooting and emptying of the hopper countless times (otherwise I probably wouldn’t have noticed) On this print…

I started with a clean hopper and added one cartridge (6kg) of 70% refreshed nylons 12 GF into the hopper. It of course filled this hopper to the 6kg mark in the hopper.

Notice that Preform has been estimating this print to need 3.89kg of total powder.

Also notice in the photo that the job is not even halfway complete…

Now notice where the hopper level is at

Now folks again it was level with the “6L” mark… as you can see it’s well below what I’d assume the “3L” mark to be at halfway done… (why is everything to do with this machine kg but the hopper…I bring this up below)

Based on our current issues…needing to run production parts above 70% …combined with our well thought out system of contracting manufacturing costs with the machines hourly rate, the labor in post processing, maintenance and the current high refresh needed and cost of materials… we are already on the fence at break even trying to do production with this machine and material…now it’s possibly using double material of what Preform is estimating.

I’m going to let this machine run tonight to be sure (yes I confirmed Preform told me I needed 3.89kg and yes I confirmed I had 6kg and enough for the job…as per the print job pre checklist) but off what we’re seeing it won’t make it over 3/4 of the way through and is shy about 3kg at least (double the estimate)

So folks on top of the high costs and us spending a year trying to make production running this thing a possibility… we may be figuring out that these parts need ”double”…in the material estimate than what’s been given.

Stay tuned… and anyone else calibrated enough to see how far off Preform estimates?

Anyone wanna take a bet if this print job makes it through with the 2kg left over that it says…or even makes it through the print?

Or…am I totally off here as I am a bit confused on why everything Formlabs does with the material is in KG (the bottles, PreForms estimates, the printer dialog) but the Hopper is in Liters… I’m an American not European so someone feel free to correct me if I’m wrong here… :face_with_monocle:

But I just got the the warning and the hopper is empty from “6L” of a 3.89kg estimated print…and its just over halfway through.

I just had to add another cartridge…

So if I am correct…and not losing my mind here and confused on kg versus the Hopper using L… this estimate from PreForm would be for $356.22 of powder for 80 parts in a half chamber but in reality need nearly $712.43 worth of powder at double but I think based off what I am seeing it will need more… So my $4.45 per part material costs may be more like $8.90+…

This whole system with support and getting this thing to run as advertised has been a long year process so sorry its late and I stand corrected if someone can tell me I don’t know the difference between 1kg and 1L… but if I am right this is a deal breaker in production running and/or at least quoting a job correctly.

Please tell me I’m not reading this right

Different materials have different densities that’s why hopper is in Liters.
Kg is weight, Liters is volume

About preform, I assume that it calculates the kg needed based on the volume of the parts.

Maybe because you’re running at 70% instead of 30%, the estimation is off.

So what I am hearing is that “1kg” actually equals “2L”…which would make sense in the PreForm estimate.

What threw me is that the original Fuse 1’s hopper was labeled in “kg” like everything else but with the Fuse 1+ they decided to switch the hopper label to Liters…

Hopefully this is the case and I will confirm by putting 3kg of Nylon 12 GF straight from the jug and into the hopper to see where it actually levels out. According to what I’m told… this 3kg jug should I assume put it a 6L…

That also confused me at the beginning. I also think a kg display inside the hoper makes more sense.
But if the different powders really do have such a different density, i can understand the idea behind it.

unfortunately, i haven’t found any data on the density of formlabs. the data sheet doesn’t list the density here. when i compared the PA12 from formlabs with other materials from other manufacturers, i read several times that the density here often corresponds to 1kg = 2l.
this also explains the message from the fuse at the start of a print job that 9 litres of material should be available. this would then correspond to 4.5 kg, i.e. a complete build space. it is therefore not a random statement, but the fuse indicates to the user that there should be enough powder for a complete build space.

I therefore entered this density directly in my tool for the cost calculation.

However, I notice something else in the pictures:
at what packing density are these prints sliced? and at what model spacing are the objects printed?

we experimented with lower packing densities ourselves and sometimes set the model spacing to 0mm. after we had several parts with increased warpage and consulted formlabs printing experts, we were strongly advised to use the default value of 5mm model spacing and to print the parts at 25-45° angles if possible in order to reduce the chance of warpage.

Based on the pictures, do I think that this is not the case here?

I don’t own a Fuse, but based on my understanding of how SLS works, maybe I can offer some helpful suggestions anyway…

My expectation is that Preform is telling you how much powder you need for your print. But that’s not how much powder you need to execute the print.

The print bed is filled with powder whether or not that powder is being sintered in to the model. So no matter what you print, you consume a full bed’s worth of powder from the hopper. But assuming you’re not just printing a solid block that completely fills the chamber, some percentage of the powder “used” to fill the bed but not actually melted in to the print is recoverable, it’s not actually “lost”. But it still disappears from the hopper.

I don’t think you can use the powder level in the hopper to determine how much powder you have actually consumed with your print. To figure that out using the hopper, you have to recover the unused powder and pour it back in to the hopper before judging.

So what I see is what I think should be expected behavior. Given two objects of the same Z-height but radically different volumes, the same amount of powder goes in to the bed for both prints (or put differently, the same amount of powder is removed from the hopper). The powder that will be recovered for another print isn’t “consumed” but it does get removed from the hopper so it might appear that more powder is being used when in fact that powder just has to take a roundabout route to get back in to the hopper so you can see it.

Guys you can’t have Kg in hopper because it’s volume, not weight. If they had to use Kg in hopper, then there should be a digital scale to show you the kgs inside, not a sticker on the hopper’s wall.

Reason is that each powder has different weight for a specific volume. It’s like filling the hopper with water, and next day filling the hopper with iron.

No that’s not it. For SLS Preform gives you “Fused” and “Total Powder” needed in the chamber to complete the print.

You can read my follow up for the answer. Formlabs switched their hopper from the original Fuse listing Hopper levels in kg to the new Fuse listing Hopper levels in Liters.

It being “Powder” not a liquid at different refresh rates and materials supposedly puts “1kg/2L”.

The entire system handles sifting and refreshing this powder for reuse via “weight” not volume… so it’s trying to determine refresh off that.

Well…The original Fuse and the one we were troubleshooting the past year…was in fact labeled in “kg” in the hopper. They did not decide to switch to Liters in the hopper till launching this new Fuse 1+….So for the past year and all their machines in operation were in fact trying to run kg in the hopper…

Also the Sift fully depends on “weight” and kg for trying to get the refresh rates correct… so maybe that’s the issue we can’t seem to run at their 30-50% refresh and only have success at 70%+….

If you have an empty bottle you can fill it up with water and weight it. (substract the empty’s bottle weight)
For water it’s 1Kg = 1 Litre, so you’ll be able to get the volume in Litres of the bottle.
Your powder is going to be the same in Litres.