Interested in Mendel, looking to have some samples made

Hi there,
Like the subject line says, I'm interested in building a Mendel - but sinking that much money into a machine is a bit scary - so I'd really like to see what the machine's capable of first... I'm hoping somebody would be up for printing some parts for me.

My personal interest is in using the machine to print model parts. I know a bit about the results people have gotten from professional-grade machines using Shapeways or print-a-part, and I've seen photos of parts printed with RepRap and related machines... I know the printed parts will require a fair bit of work to make them presentable as model parts, and that a certain grade of detail simply won't be worth trying to reproduce on the machine... But still I think the machine could be useful to me and so I'd like to test that.

I have a model I designed in Blender - probably I'd want to print some part of that - maybe the head or the foot, or one of the working hinges that will be used in the construction of the physical model. I'd really like to try a print of something that's relevant to my work. I believe I could handle the steps necessary to turn a piece of my model into something printable by RepRap (join meshes together if a part is made of multiple meshes, make sure the part has sufficient wall thickness and so on) - but I may need some feedback if I get it wrong.

I understand that taking on this sort of commission is not something one enters into lightly. If you think you might be willing to help me out, please let me know and we can talk about price for the job.

That's a cool robot!
I'd like to point to http://www.thingiverse.com/thing:3130 to show the model printing possibilities.
But what size are you going to build it? I think if you aimed for 15-20 cm height, you would be able to print most, if not all, of the details. I'd print you a part, but my mendel is not up and running at the moment.

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-Nudel
Blog with RepRap Comic

Yeah, the whole robot's going to be 17.5cm high. I've actually scratch built most of the parts already... So really if I get a RepRap it's more for future projects... But the Zaku is the only good model data of my own that I have at this point.

The thing about that anime girl print you linked to is that it includes photos from a version printed with Cupcake and from a version printed with a professional system... The Cupcake-printed parts feature prominent banding in the output (clearest on the leg photos) - par for the course at this point, it seems. I would have to manually smooth that out before using the part. That's harder to do on a detailed surface than on a relatively plain surface, so I figure I'd probably be better off omitting some detail and adding it back on later (using the RP as a basic form only) rather than trying to print all the detail and retain it through the process of smoothing the surface.

Some friends of mine got a Gundam foot printed a couple years back using (IIRC) Shapeways - that output was better than what I've seen from RepRap, of course, but even that had banding (esp. on the near-horizontal slopes - aliased like a line rasterization algorithm) and rough surfaces - there was some raised detail on the sole of the foot, so smoothing out the rough surfaces on the non-raised surfaces would have been difficult: more difficult, probably, than printing the foot without that detail, block-sanding the whole sole, and then adding on styrene plates to add the raised detail...

What happened to your Mendel? Did it stop working or are you still in the initial process of getting it to work the first time?

Yeah, but the one made on the cupcake still looks pretty good, no? And a well calibrated Mendel with a small nozzle can do better than that.

But it would still need a quite lot of clean up I suppose, and there are several ways to achieve that. Some people smooth ABS prints by dunking them in acetone. I like the idea of adding some steel putty and grind the excess off, which I have yet to try. But working up from a base structure is probably a good idea.

Well, I have some extruder reliability issues and need to make a new heat core and such, which I haven't gotten around to. And I need to set up a workbench in the basement as it's a bit on the cold side to work outside in the snow. :p

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-Nudel
Blog with RepRap Comic

Actually, I think the Cupcake-printed parts from that page look kind of crude...

Acetone doesn't sound like a great solution. At least not for parts that are supposed to have well-defined edges. For smooth organic shapes it could be just the thing - chemically melt the surface and let it all re-settle into a smoother arrangement. But I figure it'd be a matter of some time with the part, some sandpaper, and some putty and primer.

Why steel putty? I've never used the stuff, don't know much about it. (Is it just an epoxy putty with metal in it or what?) Used lots of different polyester putties and epoxy putties, though. I love the skill-set I get from this hobby. I can make things. I like that.

RepRap printing is still an art, more than a science. Some people produce AMAZING printed part quality, and some produce 1/2 finished lumps, and everything in between.

With our type of fabrication you are always going to have the ridges, no way around that, but the ridges can be made much smaller, to the point that they are only .1mm each, which is pretty small.

Tetsujin, what part of the world are you in? We might be able to help you find a local person with a printer who can help you out. If you are in the US I can send you a bunch of throw off parts for RepRap that I am not using as examples. USPS flat rate shipping is $5 in the US and $15 international. Just let me know what you need.

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repraplogphase.blogspot.com

spacexula Wrote:
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> RepRap printing is still an art, more than a
> science. Some people produce AMAZING printed part
> quality, and some produce 1/2 finished lumps, and
> everything in between.
>
Part of what I've got to figure out is whether, for me, operating a machine like this is more trouble than it's worth, or if it'd be really useful to me - it's kind of complicated.

> With our type of fabrication you are always going
> to have the ridges, no way around that, but the
> ridges can be made much smaller, to the point that
> they are only .1mm each, which is pretty small.
>
Yeah, I know there's no avoiding the ridges - I'm trying to be realistic about the limitations here. The precision one can get out of the machine has a big impact on how I could use it. I figure that even on a pro machine, there would be some situations where I'd probably be better off adding detail myself instead of including it as part of the print.

Precision in general is an issue I'm very concerned with as I try to work out whether a machine like this is for me. I know there are real limitations to what I can expect, and I can work with that - I just don't know exactly what those limitations are.

For instance - you can change nozzle heads as you see fit, and adjust the feed profile to match... But still, there's some minimum step of the stepper motors, right? Combined with the gear ratio in play (and some mechanical sources of error) there's some best level of precision you can expect from the machine... And I expect that is negotiable as well to some extent, when you build the machine - but again I don't know the details.

> Tetsujin, what part of the world are you in?

Eastern Massachusetts.

> RepRap that I am not using as examples. USPS flat
> rate shipping is $5 in the US and $15
> international. Just let me know what you need.

That's cool. I'd kind of like to do some prints of something of mine just to get a feel for what I can do with the process, but really any kind of sample print would be nice for reference.