Simplification opportunities

I was just going through the RepRap Cartesian robot build instructions again, this time with an eye for simplification opportunities (I'd rather not have to get anything more printed or do any more work than I have to). Something that caught my eye was the part called "bed clamp bracket," which is a little printed triangle with three holes in it that goes on top of the MDF base board and clamps it on to the printed bracket that supports it from below. I see no reason, structurally or ideologically, why this couldn't be replaced in the design with three large washers. Am I missing something?

Kyle

PS. Now that I may have a real opportunity to get these parts printed, I'm going to be looking for more opportunities for parts like these that can be fabricated by more conventional means while staying true to their original function. The more I look at this, the more I'm convinced that many if not all of these parts could be easily milled if one was willing to go from two directions. Does anyone out there have a milling machine and want to support the cause? I bet Zach would be up to place an order for the RRRF, and I could design the modified parts. "Studding tie bracket" is a perfect example of this, as are the PCB holders.

ah! yes, thats a great idea. once we all have RepRap machines, it will be easier just to print out all the parts, but until then we'll have to come up with workarounds.

what we should probably do is create a page on the wiki that lists a RP part, and then an equivalent part or technique you can use in its place. that would be a good first step.

okay, its up here: [reprap.org]

if someone like to update it with the stuff that joost has done, that would be excellent.

If I can have write access to the wiki (registration is still closed IIRC) I'd love to get started on that.

Kyle

The Darwin design is the way it is because it it designed to be self replicating as much as possible. It is designed to be made by FDM. If you are fabricating it by other means then you would not design it like that at all. The basic requirement is a steady frame to support some rails, motors and bearings.

It doesn't require a milling machine to make a frame. It is much easier to make an open sided box out of precut MDF or plywood. You can get off the shelf plastic or metal brackets to make right angle joins or you can just cut, glue and screw strips of wood in the corners.

Another possibility is I noticed in my local DIY shop you can get square steel tubes and plastic brackets to join them. A lot easier than making a frame from round rods, unless you happen to already have an FDM machine, or a milling machine that is.

It still seems daft to me to start mass producing these things before anybody has shown it to work yet. Once it has been shown to work it will have reproduced itself and within a few days exponential growth will ensure everybody that wants one has one. If lots of people spend money making it and it doesn't work there are going to be a lot of disappointed people.

It reminds me, when I was a kid my dad built a colour television from installments in a magazine called Practical TV. So did lots of other people, kits were produced and sold. The only problem was the design wasn't finished when the first articles were published. It never really worked. One of the first articles was the power supply, but the total power budget was unknown at that time so it turned out to be inadequate. In those days a very costly mistake. The were supposed to be about 8 articles but went on for about 2 1/2 years by which time my mum timed out and bought a colour TV for less than my dad has spent. I think people tried to sue the magazine, there were certainly a lot of very angry readers.

---

[www.hydraraptor.blogspot.com]

I've considered my options, of course. And I'm not even sure I CAN get anything FDM'd, just yet, so this is all very hypothetical. I agree that this design is untested and unproven. BUT the more people there are building and testing this design the more opportunities there will be to find those mistakes before 1.0 and the easier it will be to correct them without making many more people more angry.

I believe I know what I am getting into. I realize that this design has never been proven to work. I realize, as jmarsen would say, that this is still a research project. However, I've also taken a (mostly) objective look at the work that's been done so far and am willing to take that risk, because I believe the design WILL work. I also believe it can benefit from more testing. And if it doesn't work out, I still accept the responsibility for my own actions.

Of course, if my goal was simply to create a 3D printer without regards towards means, I would have many more options. However, I think if I'm trying to create a RepRap proper I should keep it as close to "stock" as possible, so I can help the testing effort. I'm not opposed to replacing individual components with non-RP alternatives because I don't think that will have a visible effect on the testing but I'm trying to follow the actual design as closely as is feasible.

Kyle

Well then what do myself and Joost do with our machines? that is the reason we are open source. I made my Darwin so that when we all find we have the "wrong power supply" then I will change to the one that works and I will replace my parts of my Darwin from parts it has made working on the same goal of being able to print parts. granted when making a machine I have had to make 2 to 3 parts to get it right but i have found that MDF and hardwood will make most of the parts. and I am hoping and willing to share what I have found in making the parts I have made.
Bruce Wattendorf