So just like you, I had a well working printer (apparently very rare around this forum) and enough parts to build %80 of another printer. So I got some extruded aluminum and built an H-BOT:

http://www.soliforum.com/topic/5141/hbo … r-or-yahp/

So if I were you, and your SD4 ends up working the way it is supposed to, you could take all of those parts and make your second printer. It more fun upgrading the second printer while you have the first one up and running.

Sweet! I had considered an H-Bot design as well. Interesting that v-slot rails and carriages were also in my list.

And definitely on the having a working printer during the build. One of my conundrums is that I wanted to make absolutely sure I had all the parts to upgrade prepared because once I had the printer torn apart, it would be hell to realize I forgot to print something (or something broke and needed a new print.)

After I tuned my stock printer, and placed polycarbonate panels to enclose it, I found I did not have any of the problems other people were having. Except for moire. But no Z wobble. No missed steps. No clogs. Except one time, that was bad PLA though, not the hotend itself.

So just like you, I had a well working printer (apparently very rare around this forum) and enough parts to build %80 of another printer. So I got some extruded aluminum and built an H-BOT:

http://www.soliforum.com/topic/5141/hbo … r-or-yahp/

So if I were you, and your SD4 ends up working the way it is supposed to, you could take all of those parts and make your second printer. It more fun upgrading the second printer while you have the first one up and running.

For the Z axis, I was envisioning a scissor platform which would ensure the bed was always 100% level. Getting crazy thoughts like DC motors and encoders instead of steppers as well.

Like the Scissor Z axis idea, but consider:

You would need to machine the scissor strut pivot points to exceptionally tight tolerances to maintain a <0.1mm parallel consistency at the build plate.  Also, if the base ends of the scissor are riding on the base of the machine (with rollers, for example), then that base will have to be perfectly flat and rigid as well with no debris strewn about.

Instead of the DC motor with encoder, you could stick with a vertical lead-screw stepper motor setup in the center-back like the current SD, but just lock the scissor end rollers to the base and the bottom of the build plate with precision channel / roller followers and have that act as the stabilizer.  You would theoretically need no other vertical guide rods.

Just my thoughts for now...I do think it's cool!

wardjr wrote:

I found that I could run the line so tight that I needed to beef things up a bit as I could tear the bolts right through the plastic.

In that case, I would be more concerned about those little plastic bits holding the screw. That was my first concern when I looked at it. You might want to make those longer and thicker and just add some length to your line.

Or... what about using eyebolts in a standoff (one in each end) and some fishing line swivels? Then the standoff takes all the pressure from the line instead of your printed plastic. Come to think of it, I just might do that when I replace my carriages. Would work with the belt and existing screws as well.

Lol... see how my mind doesn't quit?

This one solve all of the strength issues it is just difficult to get the bolts under the bearings in.  Notice I said difficult not impossible.  Some day when I have time I will change it.  That was a real quick fix but it works.

I found that I could run the line so tight that I needed to beef things up a bit as I could tear the bolts right through the plastic.

In that case, I would be more concerned about those little plastic bits holding the screw. That was my first concern when I looked at it. You might want to make those longer and thicker and just add some length to your line.

Or... what about using eyebolts in a standoff (one in each end)? Then the standoff takes all the pressure from the line instead of your printed plastic. Perhaps some fishing line swivels (if those are strong enough.)

Come to think of it, I just might do that when I replace my carriages. Would work with the belt and existing screws as well.

Lol... see how my mind doesn't quit?

Why are you winding up the line.

This is what your trying to achieve.

No, I understand for the simple upgrade from the existing belts and is exactly what I will be doing for that.

I am talking about something purpose-built for the spectra line. In that case, you have a threaded rod with both ends on it; one wound the opposite of the other so one unwinds while the other winds. The idea is that the threads keep the line from tangling and also provide a large surface area to grip the line and keep it taut.  Basically a windlass mechanism similar to how a winch works.

P.S. Where did you find that carriage or is it your own design?

This is what your trying to achieve.

Anyway, as I started thinking - I am replacing or modifying nearly everything, even the chassis... why not just build a freaking 3D printer from scratch?

Here is a list of the upgrades already planned (and most parts already sourced for):
1. E3D hot-end replacement
2. New heated build platform and bed mounting system
3. 3mm Z axis upgrade with custom rod (Flex coupling, slop nut, and fixed at the top of the printer.)
4. Linear bearings, pillow blocks, and bearings at every rotating point on the damn thing
5. Temperature controlled heated enclosure
Would love to do the bulldog XL, but can't justify the cost
6. Moving electronics outside of the chassis and rewiring everything with cable management
7. Going to try out the Spectra line upgrade, but fall back to GT2 belts and pulleys if I am not impressed
8. Quiter fans/shrouds
9. Android tablet UI and print server (possibly raspberry pi with touchscreen instead if I can find a cheap HDMI touchscreen)
10. I am not fond of the straightness of the smoothed rods, so the mind has been working on either a whole different set up or replacing them with more precision rods

For the Z axis, I was envisioning a scissor platform which would ensure the bed was always 100% level. Getting crazy thoughts like DC motors and encoders instead of steppers as well.

And of course, dual extruders would be awesome (without losing a bunch of build volume, of course.)

Ok, now I am just talking crazy. Can anyone reason with the voices in my head?

It just seems that with all the printers out there, each one has something about them that is optimal, but none of them have everything that is optimal.