Printable diagonals I'd like to discuss experimental diagonals for the darwin design. The current 10 diagonals that are needed involve quite a lot of steel, weight and assembly time (as was just pointed out by hydraraptor here: [blog.reprap.org] ) Together with a square frame, the brackets would only need to resist a pulling force. If we could (mostly) print these diagonals, this would result in a higher proportion of printable parts and lower material costs (in you use bulk industrial plastic, an not a prototyping service). There are 3 sketches I've made with decreasing amount of non-printable parts needed. The first one will probably work, but the gain is perhaps not as big either. [attachment 951 Diagonals1.png] V2 reduces the need for two more bolts, two nuts and four washers. It could have multiple places where it can lock together (more holes that the pins fit in). [attachment 954 Diagonals2.png] Because it's made of two parts it will fit in the print volume... easily even, when printed diagonally as well. What do you guys think? https://reprap.org/forum/read.php?14,14915,14915#msg-14915 Sat, 13 Jun 2026 05:52:27 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?14,14915,15827#msg-15827 Re: Printable diagonals https://reprap.org/forum/read.php?14,14915,15827#msg-15827 www.westcoastnetting.com] . The only advantages to this over the threaded rod I can see is weight and possibly it might be easier for people to get metric eye bolts at the big box stores rather than trying to find metric threaded rod longer than 10 cm.]]> ronanwarrior Mechanics Sun, 17 Aug 2008 00:15:08 -0400 https://reprap.org/forum/read.php?14,14915,14968#msg-14968 Re: Printable diagonals https://reprap.org/forum/read.php?14,14915,14968#msg-14968 -------------------------------------------------------
> pe cord (Dyneema) doesn't stretch
>
> From [en.wikipedia.org] (but a
> brief googling will get you a more reliable
> reference!)
>
> Under tensile load, UHMWPE will deform continually
> as long as the stress is present - an effect
> called creep.
>
> So you might not want it as a continuous load
> bearer... though it isn't like a reprap is going
> to put it under serious strain 24/7 ;)


Perhaps not serious strain, but definitely 24/7. This is a constant load application, because it remains taut even when the RepRap isn't in use. A cord that has a tendency to go slack may not be the best solution...]]> Kyle Corbitt Mechanics Sun, 27 Jul 2008 21:05:17 -0400 https://reprap.org/forum/read.php?14,14915,14966#msg-14966 Re: Printable diagonals https://reprap.org/forum/read.php?14,14915,14966#msg-14966 -------------------------------------------------------
> If the diagonal being pulled does not stretch then
> the other one will not be able to compress even if
> it is weak in compression.
>
> The M8 studding is weaker in compression because
> it can bow under moderate force but to do that the
> opposite one would have to stretch which requires
> massive force.

That makes sense... Thanks! :)]]> Andromodon Mechanics Sun, 27 Jul 2008 20:45:57 -0400 https://reprap.org/forum/read.php?14,14915,14962#msg-14962 Re: Printable diagonals https://reprap.org/forum/read.php?14,14915,14962#msg-14962
[forums.reprap.org]]]> Andromodon Mechanics Sun, 27 Jul 2008 18:24:35 -0400 https://reprap.org/forum/read.php?14,14915,14960#msg-14960 Re: Printable diagonals https://reprap.org/forum/read.php?14,14915,14960#msg-14960
The M8 studding is weaker in compression because it can bow under moderate force but to do that the opposite one would have to stretch which requires massive force.]]> nophead Mechanics Sun, 27 Jul 2008 17:12:45 -0400 https://reprap.org/forum/read.php?14,14915,14959#msg-14959 Re: Printable diagonals https://reprap.org/forum/read.php?14,14915,14959#msg-14959
Why, again, do we only care about pulling forces here? As two opposite faces of a square move to make a parallelogram, one diagonal expands (pulling force) and one contracts (compression). So, it seems that if we are going to talk about pulling forces, we could equally (and symmetrically) talk about compression forces.

Granted, if we agree to always tighten the diagonals such that there is always a pulling force, we could focus on things that can withstand only that force. We could also agree to always put a little more diagonal in than the frame is comfortable with, causing there to aways be compressional forces instead.

I don't know.. Our basic assumption on this topic seemed arbitrary. Feel free to set me right. I am no mechanical engineer. :)

Have a great day!]]> Andromodon Mechanics Sun, 27 Jul 2008 17:00:09 -0400 https://reprap.org/forum/read.php?14,14915,14947#msg-14947 Re: Printable diagonals https://reprap.org/forum/read.php?14,14915,14947#msg-14947
Quote

pe cord (Dyneema) doesn't stretch

From [en.wikipedia.org] (but a brief googling will get you a more reliable reference!)

Quote

Under tensile load, UHMWPE will deform continually as long as the stress is present - an effect called creep.

So you might not want it as a continuous load bearer... though it isn't like a reprap is going to put it under serious strain 24/7 ;)]]> Ru Mechanics Sun, 27 Jul 2008 05:28:32 -0400 https://reprap.org/forum/read.php?14,14915,14945#msg-14945 Re: Printable diagonals https://reprap.org/forum/read.php?14,14915,14945#msg-14945 [www.dsm.com]

It withstand 15times the force steelwire would and even 40% more than aramid.

I think, that would be my first choice so far ;)

'sid]]> sid Mechanics Sun, 27 Jul 2008 02:16:18 -0400 https://reprap.org/forum/read.php?14,14915,14940#msg-14940 Re: Printable diagonals https://reprap.org/forum/read.php?14,14915,14940#msg-14940 nophead Mechanics Sat, 26 Jul 2008 20:20:51 -0400 https://reprap.org/forum/read.php?14,14915,14939#msg-14939 Re: Printable diagonals https://reprap.org/forum/read.php?14,14915,14939#msg-14939
It's fairly cheap, $3.95 for 50 ft, with 300lbs load capacity:
[www.rei.com]]]> Gene Hacker Mechanics Sat, 26 Jul 2008 20:15:00 -0400 https://reprap.org/forum/read.php?14,14915,14936#msg-14936 Re: Printable diagonals https://reprap.org/forum/read.php?14,14915,14936#msg-14936
The only other use of the M8 studding is the z-axis. My experiment with four tiny steppers failed with M8. Perhaps we could replace all the M8 with M4 and kill two or three birds with one stone. Cheaper, lighter, even smaller brackets, still only one type of studding. We would probably have to move the motors to the top as Forrest pointed out so the studding is always in extension, but that would have the benefit of increasing the z-travel.

Replacing the MDF bed with a composite laminate would also make it lighter, but a bit more exotic. 3MM HDPE laminated with AL is very flat, strong and light.]]> nophead Mechanics Sat, 26 Jul 2008 18:19:09 -0400 https://reprap.org/forum/read.php?14,14915,14934#msg-14934 Re: Printable diagonals https://reprap.org/forum/read.php?14,14915,14934#msg-14934
Then again, it is quite a heavy machine now. I can barely carry it to demo it.]]> ErikDeBruijn Mechanics Sat, 26 Jul 2008 16:08:48 -0400 https://reprap.org/forum/read.php?14,14915,14932#msg-14932 Re: Printable diagonals https://reprap.org/forum/read.php?14,14915,14932#msg-14932 Yes I will endeavor to try things out for people, remember HydraRaptor only has a build area about 130 by 140mm.

The studding bars are only about ]]> nophead Mechanics Sat, 26 Jul 2008 15:49:54 -0400 https://reprap.org/forum/read.php?14,14915,14931#msg-14931 Re: Printable diagonals https://reprap.org/forum/read.php?14,14915,14931#msg-14931
Ru,
Now that Nophead has shown that the filament can span bridges, it should be possible to make a large zip tie. Would someone like to design one?]]> Enrique Mechanics Sat, 26 Jul 2008 15:32:07 -0400 https://reprap.org/forum/read.php?14,14915,14927#msg-14927 Re: Printable diagonals https://reprap.org/forum/read.php?14,14915,14927#msg-14927
If we have some ideas I'll post a summary on Builders.reprap.org for sure. Hopefully I can post it with something tried out by hydraraptor :)
With the ridges, you can use 3 sides of the beam at different offsets (resulting in different tensions). Using a single bolt to have an adjustable tension would also work.

Making compound parts that could be replacements for the structural parts of a RepRap is important, but I chose to discuss this first, since it is an easy start and to get some experience with it. I think we could print other (modular) structural parts with ribs for extra strength as well, but we have to design those first and they will impact the Darwin 1.0 design to a greater degree. I think for Mendel it would be a nice achievement to replace much more of the structural steel.]]> ErikDeBruijn Mechanics Sat, 26 Jul 2008 12:17:11 -0400 https://reprap.org/forum/read.php?14,14915,14926#msg-14926 Re: Printable diagonals https://reprap.org/forum/read.php?14,14915,14926#msg-14926 -------------------------------------------------------
> I like the Idea!
> I think the design should be interchangeable with
> steel rods
> -Leav

This is slightly off topic, but you just reminded me of an idea i had a while back:
It would be good to develop some kind of 3d object file that could be customisable by the user with various different options:

e.g. the extruder could support several different motors with the mounting holes in different places, which could be chosen in software before printing.

It's probably not worth getting into this yet though as there are a lot more important things to do.]]> greenarrow Mechanics Sat, 26 Jul 2008 12:06:42 -0400 https://reprap.org/forum/read.php?14,14915,14923#msg-14923 Re: Printable diagonals https://reprap.org/forum/read.php?14,14915,14923#msg-14923
Quote

looking back, I really don't see a problem about using a couple more bolts.

Very true ;)]]> Ru Mechanics Sat, 26 Jul 2008 11:48:10 -0400 https://reprap.org/forum/read.php?14,14915,14922#msg-14922 Re: Printable diagonals https://reprap.org/forum/read.php?14,14915,14922#msg-14922
they are much easier to get and much much cheaper than a rod.]]> Leav Mechanics Sat, 26 Jul 2008 11:25:50 -0400 https://reprap.org/forum/read.php?14,14915,14920#msg-14920 Re: Printable diagonals https://reprap.org/forum/read.php?14,14915,14920#msg-14920
Quote

Not sure how you would tighten this. perhaps V1 is a better option after all

I think adjustable tension is probably the killer here... I'm assuming you want fairly fine control over this so you can true up your darwin frame. The V3 doesn't really have this facility at all, and I'd be concerned that the V2's adjustabaility would be just too coarse.

I guess you'd need to ask someone who's set up a darwin already, really ;)

Personally, I'm visualing something like a zip tie: [en.wikipedia.org] I'm rather assuming that we can't make something quite like a proper zip tie fastener, but it would be a terribly useful item to be able to make.

Each crossbeam part (for they would be identical, ideally) would have a partially serrated surface with teeth angled back towards the tie points. Two opposing beam parts places serrated sides together woudld bite. They'd be solid bars rather than flexible strips to make the whole thing a little more rigid.

The tricky bit then is the bit that holds them together. You want something firm enough that the beam can take a decent amount of tension without springing apart, yet you still want to be able to tighten the bits easily.

Something which can clamp the two crossbeams together should work... a C shaped clamp that slides on from the side, with a simple pin or clip to hold it shut would probably do, given that most of the force will be tension in the crossbeam. The clamp just needs to be able to stop a comparatively smaller lateral force from pushing the two beams apart.

So. Uh. I'm not going to try and ascii art this one. Does anyone feel I should try and make a proper diagram?]]> Ru Mechanics Sat, 26 Jul 2008 11:09:33 -0400 https://reprap.org/forum/read.php?14,14915,14919#msg-14919 Re: Printable diagonals https://reprap.org/forum/read.php?14,14915,14919#msg-14919
The whole subject of how you print parts to make a larger whole is one that needs a lot of discussion and thought.]]> Forrest Higgs Mechanics Sat, 26 Jul 2008 10:38:05 -0400 https://reprap.org/forum/read.php?14,14915,14918#msg-14918 Re: Printable diagonals https://reprap.org/forum/read.php?14,14915,14918#msg-14918
This is just the general concept of using a groove really.
I'm sure that this particular setup can be improved greatly but the groove is key.

Not sure how you would tighten this. perhaps V1 is a better option after all :)

-Leav]]> Leav Mechanics Sat, 26 Jul 2008 10:08:13 -0400 https://reprap.org/forum/read.php?14,14915,14917#msg-14917 Re: Printable diagonals https://reprap.org/forum/read.php?14,14915,14917#msg-14917 Of course there are many variations possible. This was a concept to get the discussion started. The utterly cool thing is that Chris (hydraraptor) could print an STL we design to test the concept and to improve his RepRap.]]> ErikDeBruijn Mechanics Sat, 26 Jul 2008 08:50:27 -0400 https://reprap.org/forum/read.php?14,14915,14916#msg-14916 Re: Printable diagonals https://reprap.org/forum/read.php?14,14915,14916#msg-14916 I think the design should be interchangeable with steel rods, so that people using a printing service can easily use steel rods instead of paying $1000 for a rod. :)

I have an Idea for V3, but it won't translate into words well so I'll post a pic when I reboot into windows later and start up SolidWorks.

-Leav]]> Leav Mechanics Sat, 26 Jul 2008 08:46:44 -0400 https://reprap.org/forum/read.php?14,14915,14915#msg-14915 Printable diagonals https://reprap.org/forum/read.php?14,14915,14915#msg-14915 blog.reprap.org] )

Together with a square frame, the brackets would only need to resist a pulling force. If we could (mostly) print these diagonals, this would result in a higher proportion of printable parts and lower material costs (in you use bulk industrial plastic, an not a prototyping service). There are 3 sketches I've made with decreasing amount of non-printable parts needed.

The first one will probably work, but the gain is perhaps not as big either.
[attachment 951 Diagonals1.png]

V2 reduces the need for two more bolts, two nuts and four washers. It could have multiple places where it can lock together (more holes that the pins fit in).

[attachment 954 Diagonals2.png]

Because it's made of two parts it will fit in the print volume... easily even, when printed diagonally as well.

What do you guys think?]]> ErikDeBruijn Mechanics Sat, 26 Jul 2008 07:28:09 -0400