research paper and zcorp printer

Hello all, i have few of things i'd like some help on from the community.

Firstly, at uni we have 2 zcorp printers which i'd like to try printing off mendel parts with. At present they're set for just plaster and a water based fixing agent but there is a type of resin that i could try with, but i'm not sure about its structural integrity. Now, if i can get a full mendel up and running from the zcorp, i can print several sets each week. I'll be testing it extensively first, and our lab guy is very good, but I don't know what the outcome will be yet.

Has anyone attempted using a 3d powder printer? What were the results with plaster and epoxy? Was there something else that worked better?

In terms of tesing, being an engineer I'd like to take the weakest bit and see what it can take but i don't know which bit. Is there an FEA for the mendel that anyone's done than we can use as a starting point? (As a total aside but related to the FEA, has anyone thought of doing a structural optimisation of the pieces to try and reduce build volume?) Is there a piece that is highly prone to failure on the mendel?

Finally, by the end of the year I need to have written a research paper. I have a lecturer who's very interested in this as a project but i need to find some way to tie it to civil engineering. It could be maybe looking into modular design or emergency housing applications, as in including a printer so you don't have to have all the door handles and light sockets etc. Its really quite broad but it needs to be research, and in civil, not mechanical engineering. I'll likely be doing the lit review mid-year and the final paper at the end, so the results will be a while coming. Ideas are welcomed please!

Thanks, Andy.

For the zcorp powder printer, the plastic and epoxy parts that come out them
are not very strong. I suppose you could try doing a UV cure on them, but I
doubt that they would be able to handle the shear stress forces in a reprap.
It would also be extremely expensive to create the parts that way. I think
you could buy a whole reprap kit cheaper than the zcorp resin.

For FEA, I don't know if anyone has done that or not. I know that build
strength repeatability on mine varies with room temperature and humidity
(I'm in SE USA where humidity is always an issue). For me the strength
variations seem to be all over the place, so I just skip FEA and makes
thing twice as thick/big as they need to be to handle stress they will
see.

Tying it in to civil engineering might be a tough task. What immediately
springs to mind is making a plastic model of a topo map - with actual
hills and valleys instead of just lines. I suppose you could print out
plastic chunks shaped like gravel. Maybe make hardhats or survey stakes.

Printing buildings would be considered civil engineering, right?

printing buildings

Hmm, well UV is an option but yeah it does get pretty expensive. thankfully i'm only paying for the materials, its at uni so there's no mark-up. we do have a few other things there, including a laser cutter, so i could just revert to that i guess. at least it can reliably be made under ideal conditions. i'm going to be testing it in the next week or so. it'd be nice if i could get it to work as i could print off a few dozen sets a week to send out to people, which will make the masses happy. i'll only be able to do it for a limited time though, things get busy after the first month of uni. but yeah, cost is a big factor, i'm setting an upper limit at around $300 for a full set and i need to prove the concept before i can sell it at all. but redesigning the pieces for the zcorp would take time that i don't have. some (like pulleys) will have to be otherwise they'll be too thin.

i guess an easier question than FEA would be: what pieces have broken the most?

the civil bit: both good ideas. print the tools to work with, print the building, print the fittings. things like door handles and taps and hooks and whatnot can be printed. i just need to figure out what of that is immediately useful. emergency housing and modular design is something i've been interested in for a while, i could find some way to tie it into that maybe...

I talked with our architect students that use a zcorp powder printer and for more solid output they undersize the print and oversize holes, coat the output with 2 ton epoxy, hang it to dry overnight, and then file off the excess drip marks. It sounds messy and expensive, but it might be an option for you. I'm not so sure how that would work for the pully teeth, but it could definitely strengthen up the sheaves.

Someone else will have to answer the question of "what pieces have broken the most", none of my parts have broken, but I made them all extra thick/solid. The extra time to print overdesigned parts versus the time to take the machine apart and replace a broken part makes the overdesign a better option. Essentially
engineering theory got trumped by reality. Most of the reprap parts are overdesigned for that reason.

Tying reprap into emergency housing may be difficult. When I think of emergency housing I think quick and cheap. Reprap is neither of those for most common things. Yes it can make a door handle, but for cost of material and power, you
can purchase a metal door handle cheaper - and in the time it takes to print a door handle (4 or 5 hours) most people could have gone to a store and back several times.
The argument to that is that if you were on site in an emergency then maybe
you wouldn't have access to a store - the counter to that is, if things are that
bad you probably don't have access to power to run a reprap either.
Although, a reprapped door handle definitely has a more geeky cool feel to it
than a purchased one.

Keep trying to come up with a way to tie them together though.

I thought of something that may be civil engineering, emergency housing, and reprap related - or maybe not.

Water valves/manifolds for 55 gallon drum emergency/low tech water supplies.
The majority of the 55 gallon type water supplies that I have seen have
a metal outdoor faucet welded into the side of them with a hose pipe
connected to them for bathing, washing, and I guess drinking water.
The $15 (USD) metal faucet could be replaced with a reprap made plastic
ball valve, a reprap plastic hole insert, two neoprene washers, a reprapped
securing nut, and some waterproof sealant. You would still need to a drill
a hole in the side of the barrel, but that's cheaper than welding - and a
large punch and sledgehammer would work in a pinch to make the hole.

Another option would be to join multiple barrels together and have a
reprapped manifold that fed multiple hoses to multiple places (I'm thinking
along the lines of a tent city arrangement). The last manifold I put in was
several years ago, it was brass, cost around $150 (USD) and my thought then
was "why isn't this thing made out of plastic, it would be cheaper."

criswilson10, that's better than my idea, which was 'design a PourStrap which can cut up 4'x8' plywood panels'.

I've noted it as a "RepRap Without Borders" idea:
[objects.reprap.org]
If Andy does not end up working on it. Do you think it is viable? Timewise, when you need those water valves for emergency deployment, you need crates of them now. Or you have a rural community that prints them out every few days, as they build infrastructure - it's more 'developing nation', and if we look at it that way, it may be a very important tool for people.

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Andy, I'd suggest making the negatives of the Mendel parts - large (multipart) blocks with voids in the shape of mendel parts, and then filling those with Epoxy-Granite, poured urethane plasic resin, etc:
[objects.reprap.org]

I think you'd have to waterproof the plaster mold with a barrier agent.

No one has done this yet, so you may run into a nightmare of fussiness regarding materials, fit, precision, and so on, and be cursing me for suggesting it.

Ask these guys if it would work or how to really do it ("Oh, just use a reinforced plaster rather than USG Modeling Plaster 1"):
[open3dp.me.washington.edu]

And please make a note on the wiki and in this thread telling us what they said. (gah! I still need to mailing-listify this forum software and open up the project to the world that way.)

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-Sebastien, RepRap.org library gnome.

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Remember, you're all RepRap developers (once you've joined the super-secret developer mailing list), and the wiki, RepRap.org, [reprap.org] is for everyone and everything!

Is it doable yes - look in a plumbing store for PEX fittings. Lots of
simple plastic connectors
Is it cheaper than a metal outdoor spigot/faucet, yes.
Is it cheaper than a PEX spigot - I'm not sure, but I'm willing to bet it is.

Hi guys,

Well despite my inability to write anything at all, I have in fact been running around at uni trying to get a few things done.

First, I have printed of a test piece and will have a play with it this afternoon. Thus far its just been given an epoxy coating, which should be strong enough. When i pulled it out of the printer I tried flexing it a little and it didn't budge, which is promising. So hopefully I can skip mccwire and go straight to mendel! The only minor details is that it'll cost about $350 for a full set of parts...

Attached is an image of the extruder connector, A tower from a previous project with the same printer, and a function ball joint that had already been printed.

As for a research topic, after some deliberation it looks like trying to design mechanical components for emergency situations is unviable for numerous reasons. remote areas however do present a possibility. I also found this article the other day. d-shape The guy in it is actually trying to work with some people attached to the uni mentioned at the end of the article, and I'll try and get involved in it, but I'm not sure how much use I'll be.

I need to do more reading into it and talk it over with supervisor.

Anywhoo, when I get a chance I'll upload some finished photos.