tveltman

http://reprap.org/bin/view/Main/WebHome

I came across this site while surfing the web and I am thinking of building one with my brother (once I get out to California). It seems like a phenomenal way to replace all of those irritating little plastic pieces that seem to break, especially as these cars (and parts) become increasingly difficult to find. I just thought I would pass this along to anyone else who might be interested. I think the total cost to build one is probably around $500, so it isn't an insignificant investment, but as the project progresses, you will find more and more toolheads (like the hot wax extruder which would allow you to make wax pieces for lost-wax casting in aluminum, etc), and the ability to replicate parts in a variety of plastics alone is probably worth the money.

Alternatively, if anyone has already had this amazing idea, and has built one, I would be more than thrilled to get a set of parts made, and of course I'll pay for all the materials.

Good luck keeping the sharks on the road!

danglerb

Extremely neat idea, but I can't think of any part for a 928 it could make due to size and/or temp requirements.

dprantl

http://en.wikipedia.org/wiki/Polycaprolactone

"PCL has been known to become brittle, lose its tensile strength and fall apart after several months so is not suitable for permanent or critical applications"

Dan
'91 928GT S/C 475hp/460lb.ft

tveltman

Well, there are loads of plastic pieces on the interior of the 928. Things like door hardware, latches, even actual switches and *****. Additionally, you can use it to print circuits on ABS plastic, so you could definitely find a use for that. I'm not saying it would be a financial gold mine, but it is one more use for it. Plus being able to turn out wax blanks for metalcasting could be very useful, especially if you went to the trouble of increasing the size of the machine, which is already fairly large.

PCL is not the only material it will extrude, it is just the convenient one for construction and prototyping. It will do ABS and maybe Teflon, though I'm not sure of that. ABS is used in many highly durable roles, such as the pistol frame on the Glock, I believe (feel free to fact-check that but I think that is a true statement)

danglerb

I wonder if the same basic machine would work with some kind of wax for casting metal?

Take a look at the Shark, 3 axis cnc for wood.
http://www.wood-carving-machine-tips...nes.html#rs-p1

UncleMaz

I saw something similar on Leno's garage website. I will try to find the link again. He uses it for very old, hard to find parts. Michael

Edit: http://widgets.nbc.com/o/47f1317f105...a4377d3bfd6c81

danglerb

The dimension printer on the Leno clip looks like the same basic tech as the DIY reprap, just more precise maybe.

tveltman

Precision generally is a result of the leadscrews and the motors. If you have very tight tolerances and your motors are very well-made, then your machine is going to be very precise, on the order of a CNC machine. For most people, that isn't necessary, especially for cast metal parts that would need to be machined anyhow (like a new set of GT heads with cooling mods done )

One of the ways they suggest that you make your first RepStrap (so that you can crank out a RepRap with it) is to use a pre-existing CNC machine, or to use the CNC machine (assuming it works) to machine the parts out of aluminum/steel/unobtanium.

86'928S MeteorGrey

I have a dimension machine in my office. I make ABS parts daily. It cost about 40K. While you could make parts for the 928 with it, the parts will never win a beauty contest unless you sanded them smooth and painted them. I would probably use it to replace a **** of a radio in an old Chevy truck, but that's about it. ABS is fairly strong, but is DEFINITELY not what a glock is made of. A glock is made of an impact modified, glass filled nylon.(Dupont Zytel) My dimension machine will print in .007" layers and will create a part within a 8"x8"x12" envelope. The ABS parts bond permanently with acetone as a cement. There are newer machines that print in Polycarbonate, but the prices for those start at about 80K. I could build a great working prototype for a new part for our sharks, but before I tried to sell anything, it would definitely be built into an injection mold tooling for production.

Lopez

Mike is correct - we have both ABS and polycarbonate rapid prototyping machines here too. I wouldn't use them to create replacement parts either - even our more expensive (over 200k) printer produces parts that would need to be sanded and painted before you put them into a car.

If we're building something that has to last we machine it out of aluminum. And injection molded is way better for plastic parts - we make molds from the plastic printed or laser cut parts if we're doing anything that begins to resemble even a small production batch.

danglerb

That is what I think of as the basic accuracy, but what you end up with depends on the whole apparatus including the software. With a good understanding of the underlying mechanics the software can enhance the basic accuracy, and sloppy software can fubar it.

Mike what do you think about "printing" some intake runners?

86'928S MeteorGrey

This dimension elite machine has an accuracy of about +/- .002 inch on X and Y. Z, however is dependant on the layer thickness. Depending on the part, it will dictate how the part is oriented for printing. Have you already got a 3D model of said intake runners? I can give you a quote....

namasgt

we used a process like that to make an intake, one of our guys designed, for a CBR engine, it came out decent.

danglerb

So far I have only have one D, DESIRE.

I have no idea what its like to work with any modeling software either, but the idea of cooking up some ITB's, modified Euro S, etc. is insanely appealing, especially prior to knowing any of the costs.