Greetings from Utah!

Hello everyone,

Recently I stumbled across this community and I must say that I am very impressed. I have always been intrigued by rapid prototyping and was looking into the possibility of getting a machine for myself. I came across various groups here and there but nothing really caught my attention and the small spark fire in my brain died down to some embers. Then when I was looking at varoius methods of rapid prototyping I discovered this place.

I am really interested in building one of these machines, but the main thing that concerns me is the precision. I currently have limited access to a Dimension BST rapid prototyping machine that can lay down ABS with a .01" resolution. I would love to be able to build my own machine that could achieve the same precision but at an affordable cost.

Unfortunately I lack the knowledge to deal with the controller side of things. I have a basic understanding of digital electronics and have built a handfull of circuits (I'm pretty handy with a soldering iron). But I don't have the know how or the ability to code the PICs (and if needs be, redesign the project for a higher precision.)

If I could get some assistance in doing so I would happily crank out parts with the completed "precision" RepRap so others could make them. (from the looks of things the current Darwin design is capable of ~.04", I would be very happy with .01") I am only 20 so please forgive me if I sound a bit naive, but I have already been sucessful in building a couple other copmlex projects (built my own multi touch table somewhat similar to Microsoft's Surface from scratch).

Nighthawk,

Current repraps are getting around .1 mm so you aren't too far off. Micro-stepping the motors would get you down to the precision you wanted without too much fiddling--I think, so don't quote me if I'm wrong. Outside of that, things are pretty easy as far as directions go. Buy the parts, put them together, fiddle with it till it prints.

Future versions will be much more accurate so if you must have .01" then you might want to wait a bit. I wouldn't wait but that's me...

Demented

Thanks for the info!

That makes me happy to know that they are able to achieve that type of precision. I talked to the owner of the Dimension BST that I mentioned earlier and it looks like I will be able to print off my own parts at cost so that helps out a bunch. And since I am planning on going with the 400 step motors half stepping looks like it will be able to get me right on top of my accuracy desires. The only thing I really would like to see implemented was a support extruder but that shouldn't be too hard to add on later once the details get worked out.

hey nighthawk,

if precision is what you're looking for, check out these numbers. with the McWire 'Seedling' Repstrap machine, it uses 1/4"-20 threaded rod. that means it has 20 turns per inch. with a 200 step motor running in half-step mode, you get this:

20 * 200 * 2 = 8000 steps / inch = 0.000125" / step

so, the positioning accuracy will be very easy to attain. of course that is the *ideal* accuracy. things like backlash and such will drop that down a bit, but certainly still within the 0.01" range.

the real problem is getting the filament the correct size you want. currently the smallest nozzle size we offer is 0.25mm. last time i played with one of those, it was producing 0.30mm.

Dang, so really any of the current designs (including the Darwin) are capable of the precision but it really all comes down to the tool head.

!Idea!

This project seems exactly like something that belongs over at CNC zone with all the other crazy CNC contraptions. I have noticed that the RepRap project gets brought up every now and then, and there seems to be moderate interest. I wouldn't recommend going over there and trying to directly generate more interest, but perhaps if you were to go over there and request a quote for getting the parts machined that you need (thats what they do for a hobby after all) then you would indirectly generate interest in the subject while getting a source for parts at the same time. They are all CNC hobbyists so it shouldn't be too hard to find someone who can machine super fine nozzles. If you could track down someone with an EDM machine or an industrial laser we would be in great shape.

Here are their guidelines for requesting quotes
[www.cnczone.com]

EDIT: So after digging around the CNCzone site some more it looks like you have been there before. Perhaps now they might have more interest as it is much more complete and accurate.

Edited 1 time(s). Last edit at 12/18/2007 02:43AM by Nighthawk.