I've just listened to an interview with Adrian Bowyer:
Podcast Adrian Bowyer interview

The interviewer asked what are the pitfalls for a builder:
Precis answers: (i) building too quickly (ii) building the whole reprap & then testing it instead of doing test/debug for separate modules.

Next month I start my first Prusa build, so I thought maybe a good point to paraphrase/repeat the interviewers question:


What would you say are the pitfalls for the first time builder?

Alternatively, with hindsight what would you have done differently?

Thanks in advance.

Mike

1. Not asking the community before purchasing something you've never bought before when you're a first-time builder.
2. Assembling everything before learning about improved parts that require disassembling stuff to fit them. For example, you probably want all of these:
2a. [www.thingiverse.com]
2b. [www.thingiverse.com]
2c. [www.thingiverse.com]
2d. [www.thingiverse.com]
2e. [www.thingiverse.com]
2f. [www.thingiverse.com]
2. Getting gouged on shipping when buying from multiple international sellers. Try to buy as much as possible from one source, or else locally.
3. Buying a big beefy power supply in anticipation of using a heated bed in the future; it's not at all necessary if you only print PLA (and you should, since ABS is a PITA).
4. Bought manufactured timing pulleys from the start; printed ones are too imprecise.
5. Realized sooner the critical importance of active cooling for PLA prints.

Edited 2 time(s). Last edit at 10/30/2011 02:46PM by Pointedstick.

The only problem with the above advice is that none of the printed kit suppliers build these, and of course without a printer you can not print your own.

So either find a local friendly existing RepRap user and persuade them to build bits for you, or build a kit and make these a priority to build first and live with what you can buy at least in the first instance.

David

It's also a very PLA centric view. PLA might be easy to print and green but it isn't very useful. It is brittle, creeps and goes soft at 55C.

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[www.hydraraptor.blogspot.com]

> What would you say are the pitfalls for the first
> time builder?

1. Having little or no knowledge of which firmware goes with which hardware, and which hardware goes with which software. That was a big one for me in the begining.

2. Getting parts that don't seem to be listed in any instructions out there. Turns out the instructions are usually outdated.

3. Getting an extruder body, pulleys, or gears, made out of PLA. This can be a problem if stuff gets running too hot (hot end and motors).

4. Using wire that is too thin for the amount of current required.

5. Trying to print without having a level and flat surface.

> Alternatively, with hindsight what would you have
> done differently?

Had I to do it all over again (actually I do it over all the time), real pulleys, real couplings, LM8UU slides everywhere, and of course, the heated bed from the start.

> Thanks in advance.
>
> Mike

As you can see, this is a diverse community with lots of opinions! I'm a big fan of PLA, others not so much. In the end, you'll suffer from analysis paralysis if you try to learn everything before you start, so the best thing to do is dive in and ask for lots of help along the way. LM8UU bearings for all axes and ensuring a level build surface are pretty uncontroversial. Manufactured pulleys and couplings are nice too.

Another thing I'll mention is you might wanna buy 5 or 6 Pololu drivers just to be safe, because you're probably going to end up blowing out one or two of them! I did.

Thanks again for the info.

JCabrer : can you clarify please by 'real pulleys, real couplings' do you mean in ABS or in metal ?

Edited 2 time(s). Last edit at 11/01/2011 04:02PM by 3D2B.

Look at the diversity of opinions in even this one thread. For example, compare and contrast Pointedstick's view that "you don't need to worry about a power supply for a heated bed because you'll only want to print in PLA" (I'm paraphrasing a bit here! ) with others who warn of the downside of printing only in PLA. Printing in PLA definitely seems to be the place to start; whether you need to go to ABS eventually probably depends on exactly what you want to make with your machine. I think that as long as your machine is capable of being upgraded to print in ABS on a heated bed, you won't go too far wrong.

My $0.02 worth (and I'm only a newbie myself - started my build in August; already designing and printing my own "things" in PLA):

1. Choose a machine which is considered to be easy to build and easily upgradeable, and which has a large existing user base. (The Mendel Prusa fits the bill here, but is by no means the only option.)

2. Start simple, and add complexity as you gain experience. E.g. at the moment I am printing only PLA on "blue tape" on an unheated acrylic print bed, but once I am happy with my results with PLA, I expect to add a heated bed and try some ABS for mechanical strength and temperature resistance.

3. Don't get bogged down in "analysis paralysis " - as long as you choose a good "beginner's model" machine which is able to be upgraded (like the Prusa), none of your decisions should lead you down too many dead ends. Once you are able to print your own parts, you can make your own upgrades, either by downloading the files from Thingiverse etc, or even designing your own and sharing with the community.

4. The RepRap forums are an invaluable resource - don't be afraid to ask questions!

Cheers - and good luck!

Edited 1 time(s). Last edit at 10/31/2011 03:16AM by julianh72.

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Follow my Mendel Prusa build here: [julianh72.blogspot.com]

Reprap is like a virus, you catch it then it takes over you.
Nasty microbe, very contagious, huge impact on daily life.
Thats the very first pitfall - reprap itself.

Edited 1 time(s). Last edit at 10/31/2011 08:18AM by NoobMan.

I'm just starting off myself so I've got a lot of time to fall.

One of biggest problems I had was finding the basic information and then the right information for my personal situation.
This book would have helped me a ton if it was around when I got the bug. It came out literally the moment I started ordering parts.

With the build take some time laying out the parts and marking up which nuts, bolts, washers and rods are which.
Two things I noticed about the visual guide;
*If it says it optional or its in the tip section do it. Odds are you'll find it a lot easier or it will save you a lot of time.
*It refers to the rods as being x rod (x being the part of the build its used on, eg bottom rod). Label the rods with both the length and name refereed to in the BoM. Its all to easy to use the wrong rod and have to re-do a section of the build.

Like everything take your time, do your research and never be afraid to ask for advice.

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My Reprap blog

jds-reprap.blogspot.com

1: Don't be cheap. You might get some threaded rod at a very low price - but chances are it is not straight. Same goes for motors, electronics and printed parts. Don't select them by price only. Ask for high res pictures, ask for references if the seller is unknown to you.
2: If you have no experience with soldering consider buying the electronics fully assembled
3: Start with a simple setup, add complexity later (PLA onto painter tape is fine, ABS and heated beds are next after mastering the easier materials)
4: Ask for advice, ask for help. Try your tools on some scrap if you are not used to them
5: Read the Wiki-pages about the components you want to use
6: Have some spare parts e.g.: one extra pololu module is much cheaper when ordered together with other parts than a later replacement because you dont have to buy shipping costs twice - and you save a lot of time and frustration that way.
7: Make sure your parts are compatible. when ordering plastic parts including the extruder, make sure, the hot end you order matches the mouting capabilities of the extruder (if they are from the same seller, this should not be an issue)
Regarding the parts from Thingiverse: My sets include some of those parts, like the extruder, and - as I print on demand - can in fact include all of them, or others. PM me for details on sets if you are interested, as this is not the sales forum.
Greetings
Robert

After keeping an eye on the RepRap project for over a year, I'm finally getting round to making my first Prusa.

I think I have two main questions.

I have access to a workshop rich in vitamins and tools. So I believe I can machine some of the simpler printable parts like the frame vertex while just buying the complex parts. Is it realistic to just order specific parts only? Are there sellers that do that? (I don't know any local rep rappers local to Edinburgh area )

The other is electronics. I have found a odd assortment of old stepper motors of different size and specs, fortunately two are the same so that'll be ideal for the z-axis. To drive them however, I don't know how flexible the recommended electronics and stepper motor drivers are at driving unknown motors.( And they won't fit the standard Prusa motor mounts.) What are the important statistics to know when interfacing a stepper motor? Maybe that'll influence my choice of electronics.

Also, as part of my plan to machine the simple parts, I'm having difficulty finding out the exact dimensions of the printable parts. I have downloaded the .scad files from github and can view them on openscad.

Is it possible to export diagrams with the relevant dimensions?

You can convert the 3D shapes to 2D projections and export them as DXF files. [en.wikibooks.org]

You would then need a tool that can read DXF and make measurements.

Alternatively you can produce STL files and use NetFabb Studio to measure features.

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[www.hydraraptor.blogspot.com]

@nophead Thanks , I've had partial success with your suggestion.

Once I've exported the dxf file of the 2D projection I used LibreCAD to make my measurements, frame-vertex-projection-measured.pdf.

However the 2D projection requires importing an stl file,

 import("/path/filename.stl");

which compiles fine using F5 but generates an error when rendering F6. I checked all the stl files in the latest metric-prusa-lm8uu files, these ones fail:
bar-clamp.stl
pulley.stl
wade.stl
wade-small.stl
carridge.stl
x-end-idler.stl
x-end-motor.stl
y-bushings.stl
z-motor-mount.stl

The common error message produced from rendering all these files is:

CGAL error in CGA_Nef_polyhedron3(): CGAL ERROR: assertion violation!
Expr: pe_prev->is_border() || !internal:lane_constructor::get_plane(pe_prev->facet(),pe_prev->facet()->plane()).is_degenerate()
File: /usr/include/CGAL/Nef_3/polyhedron_3_to_nef_3.h

( = : P without space, not sure why code text is not typeset properly)

I don't know if its a problem with OpenSCAD or with these files? If anyone knows the best place to troubleshoot OpenSCAD, let me know!

@wixi:

I don't know if these comments apply to the specific STL files you are referring to, but I have had some issues with some STL files generated by some applications (including Alibre Design PE) being readable in some applications but not being readable in other applications. This is a known issue with some valid STL files in RepRap host for example: [reprap.org]

When doing a bot of digging, I found that some of the troublesome files used Scientific Notation for the geometry, but some applications can only recognise Conventional Notation (e.g. +1.00000E+002 vs. 100.0). I found a very easy fix: there are tools available that can open an Alibre STL file and re-save as a RepRap Host readable STL file, such as “EasyFIT “ which is available for free here: [www.click-to-fit.com]〈=en (I am sure there are many others.)

EasyFIT can be used for various functions that you might find useful in RepRap, such as nesting multiple parts, re-orienting the parts to align the printed filament fibres with the required material strength, scaling, etc, but it is also handy for just fixing a troublesome file by opening it and re-saving, in which case it simply converts all coordinate geometry to Conventional Notation.

Hope this helps!

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Follow my Mendel Prusa build here: [julianh72.blogspot.com]

Go through the build videos once before doing anything. I know it might be boring but it's helpful. It gives you an idea of how everything is going to be used so you're less likely to forget something. You'll be thankful when you don't have to wait for shipping on that one critical piece holding you back.

I agree with not going cheap the first time you build these. If you ever want to build another for a friend you'll know what you can cut cost on and what you can't. The few bucks you save aren't worth the time or frustration that poor quality parts will give you.

@julianh72
Thanks for the suggestion, I exported the barclamp-stl with EasyFIT but the new copy has the same problem
It seems that rules out notation problems, though I can't be sure.

I think it is a bug in openscad that means it can't always import stl files that it has produced. You don't have to slice the STL files though. You can use the openscad source files and do a 2D projection of the object without exporting it.

Prusa STL files are not that much use anyway because they are tuned for a particular printer (presumably Josef's), so in general the holes will be bigger than intended because most printers print them a little smaller. To print a Prusa you have to use the source files, print a calibration object and tweak the configuration file to get the hole sizes correct. If you want accurate 2D drawings you should set the hole sizes in the configuration to actual sizes. For example an M3 clearance hole should be about 3.3mm but I expect it is a lot bigger in the standard configuration.

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[www.hydraraptor.blogspot.com]

Yes, I've had success with 2D projections in scad files, thanks

I call projection() just after the module object.

module partname(){
   object code blah...
}
projection(cut = true)

Adding transformations like translate() and rotate() can be unpredictable but I get better results when I call them after projection(). It does seem a bit of a hack, IMO it would make more sense to import .scad files before manipulating them.

Would you recommend I add this work-around to the OpenSCAD Wikibook?