Empiric 3000 3DP printer

Powder and inkjet printing
rofl
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Joined: Mon Aug 26, 2019 9:13 pm

Re: Empiric 3000 3DP printer

Post by rofl »

It is a ribbon mixer.
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I designed it and 3D printed the hole rotor. I pushed through it a rod of calibrated steel to make it more rigid (it worked as axis) and installed 2RS bearings on both sides.
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Its purpose was to make small batches of powder mixtures. I also made V mixer, which is even more crazy, but I am not sure if I ever going to use it all. This ribbon might do the job for a while. I also learned that I should also consider some sifting device later, but I postponed this one for a while.

I started working with locally sourced plaster (with the base of plaster of paris). I bought three and two of those were quite expensive. One worked really well out-of-the-box with water, but it was hard to justify the price. Second, although expensive, was not working with sprayed water at all. Third one was fair enough called FormX UltraCal 30. It hardened some what with raw water and price was OK for 5kg. I chose this one as first raw material for further improvement.
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I decided to give it a try to improve the flow behavior of powder with hydrophilic fumed silica. As a binder, although I tried powdered sugar, I learned that PVA powder (160 mesh) works way better. Also green parts (or droplets of hardened powder to be honest) with PVA proved to be more rigid and tough when bind with water (compared to powdered sugar). Regarding water, I added SDS to reduce surface tension.
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Exact amounts of all components are still WIP, but I will share these a bit later after some more testing (manual spraying and manual deposition of water over the powder mixture). That is the work done before actual printing.
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dragonator
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Re: Empiric 3000 3DP printer

Post by dragonator »

I was not familiar with ribbon mixers. Neat to know.

Dental plaster supposedly works well without additional binders with water and alcohol. I have also heard Maltodextrine works well instead of sugar. I have not tested any of these myself. I discovered that I really did not enjoy material studies.

Where do you source the PVA powder. Most Dutch suppliers only really sell it solid or dissolved. I have been meaning to try wood with PVA.
rofl
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Joined: Mon Aug 26, 2019 9:13 pm

Re: Empiric 3000 3DP printer

Post by rofl »

Well, anything that starts with dental seems to be pricey. I do not wish to go beyond 10-15€/kg to be honest, yet. Considering that my goal is not plaster, but metals, I just wish to use plaster to understand process parameters as it is less expensive than pricey AISI 316 powder.

I tried maltodextrine, but its particle size is quite large. At the least the one I managed to source in local food store. It is powder however, but particle size is quite large. To be honest, sugar worked even better for me.

Regarding particle size, I would like to go below 100um per particle. Preferred size is around 50um in order to have around 2 particles per layer (i.e. for 100um layer two particles of 50um in ideal scenario).

I sourced my PVA powder from China, Alibaba. However, the smallest I managed to get was 160 mesh. I tried to ball mill it, but also without significant success. I stayed with 160 mesh though. The price of PVA I bough was quite expensive (PVA itself was free as a sample, but because I bought small amount shipping was pricey from China), but did not pay attention to price now, I simply wanted to have some for tests and later I might buy more of it for larger amounts. So far I have several kilos of PVA powder 160mesh. If you could tell me how much you need for your wood tests, I would be able share a bit.

Anyway, with PVA it seems quite good. I am tuning steppers today and some other minor stuff with the printer and I hope to try one already mixed batch of plaster. Binder would be deionized water with a pinch of SDS.

P.S. I have received new HP45 driver yesterday. I do not know, when I have time to solder that all together and test with RPI, but let's hope it will happen in a month or two.
rofl
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Joined: Mon Aug 26, 2019 9:13 pm

Re: Empiric 3000 3DP printer

Post by rofl »

I bit of update.

As it will be difficult to post-process prints after they are printed without de-powdering chamber, I thought I will make one before everything. I used standard plastic box and made some improvements. There is a huge vent hole on the side to connect suction hose. Hole has removeable cover. There is a PMMA screen on top to improve visibility. 20W of LEDs bring more light in to the chamber. Cover and base of the plastic box is connected via GX12 connector. Box has air coupler to connect external air supply that will be used to de-powder prints. Standard syringe was modified and made as a tool.

Next minor modification will made to build piston - to make it constantly heated. I wish to check if that could save post-processing time. If I print while piston (build piston) is heated perhaps I would be able to take printed part actually right away (assumption is that PVA with water would have been cured by the end of the print due to the heat).
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dragonator
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Re: Empiric 3000 3DP printer

Post by dragonator »

A professional looking glovebox. The syringe is a great idea, I have been struggling with mine to handle the air tool while wearing gloves. I am curious to see how visible things remain when you are cleaning thing. My previous attempts the powders blown in the air made looking into the chamber difficult.
maxt
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Joined: Fri Apr 26, 2019 10:38 am

Re: Empiric 3000 3DP printer

Post by maxt »

Hi,
regarding the material binders, I'm pretty sure that the binder is only water, no sugar nothing else added to the powder. Just plain water.

I say this because I've tried a replacement for the freaking expensive 3DS powder. What I used was a locally produced "syntetic ceramics" (AKA plaster :D ), whose granulometry was similar to that of the original powder, and very white.

The binder was the official 3DS clear, which is water and a couple of additions (glycol+surfactant) to make it more easily jettable by the HP print head

I added absolutely nothing to the powder, and the prints where perfect and perfectly solid as well.

I could not continue to use it, unfortunately, only because it badly clogged the vacuum conduits :-( but as far as the printing goes, the binder was just plain water.
rofl
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Joined: Mon Aug 26, 2019 9:13 pm

Re: Empiric 3000 3DP printer

Post by rofl »

Right on track. I have installed additional heating to build piston to (potentially) easy post-processing and reduce wait times before one can dig the part out. This additional heating is targeted towards gypsum and other simple materials that use water-based and other easier binders. During printing I expect to keep temperatures a bit higher (like 60-70C) and be able to dig part sooner instead of waiting hours. Of course my pistons are all metal or PTFE and I might be able to put them into oven preheated to decent temperatures (<200C), but I would like to leave it for more sophisticated binders and materials. I assume I should improve wait times with this pre-heating during printing, but I still do not know, how it will perform.

I used PTFE heating wire that is wrapped around the cylinder. I also built controller for this heater with 24V power supply. It does not have PID controller as I did not want to spend a lot of time on this. It has knob to adjust power output (it simply PWMs it). Empirically I just record, what power keeps decent temperature and I just use that. Since cylinders should be able to go into oven in case it is needed, I was not able to put any electronics or sensors on cylinders, so I use external IR temperature sensor for this purpose. It simply is mounted with magnet (I hope I will not reach too high temperatures) on cylinder and measures temperature quite well. Temperature and current emissivity is displayed on screen.
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travishead147
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Re: Empiric 3000 3DP printer

Post by travishead147 »

The gantry and carriage parts of my 3D printer, the "Empiric 3000," were inspired by the design of the Oasis printer. Since there are many parts available for the HP45 printer that I didn't want to redesign, I kept them similar to Oasis. However, I did make some minor improvements to the coater mechanism to enhance flexibility and provide more adjusting possibilities. Additionally, I incorporated a Transparent wall 3D printer enclosure
to allow for better visibility and monitoring of the printing process.
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