I ended up not replacing the extruder, and simply added laser cut MDF spacers around the gearbox.  Which meant that this upgrade required no changes for the carriage.  Since there isn't enough room for the cooling fan on the back, and on top would no longer work once you had the gear box covered in MDF I simply neatly bored out the fan mounting holes, and used a small zip tie to attach it around the MDF spacers once they were installed.  I think it looks fantastic! And I get amazing prints especially with .3mm layer heights.  I think the .1mm layer height would be more impressive, but the .5mm nozzle, at least my DIY bored out version seems to allow for some weird things to go on, and it gives it a very rough look.  I think if I switched back to the smaller bore size it would look way better.  But I am so happy with this upgrade, and print quality that I think I am finally done upgrading my doodle.

However there is a new ghost in the machine that has appeared.  While the small banding on the .1 mm resolution print on the right has been there, the larger sporadic banding issues have not been present.  I am thinking this is partially due to that fact that my hot end is not a snug fit in my mk5 extruder.  And now that I have worked out my other issues like atrocious banding, etc... the other ugly details that were previously hidden are coming out.  Not surprising. 

I am planning on doing an extruder redesign, or at the very least a reprint of the mk5 or perhaps mk4...

But I will have to save those for another day.  I have a brand-new laser cutter I am performing brain surgery on so  I can rid myself of the atrocious Chinese software that came with the machine. It uses a hardware USB security dongle (paranoid of pirating much?) And the driver board that it came with is encoded, so it only works with that specific garbage software... Fortunately nothing a $15 Arduino Mega 2560 and GRBL derivative won't fix:)

And to add  to that I have a filastruder in the mail, a filawinder to build, and a 3D printer I am designing from the ground up. 

Rough life no?

Anyhow I'll post more pics of prints after I reprint the extruder.

Took me about 2.5 hours in total, mostly because I took my sweet time in insuring I centered my extruder gear on my lathe so that with my dial gauge (resolution down to the 0.001") that the needle didn't budge more then 0.00025".  In other words for this case I had pretty much effectively zero runout. This insured my new 6mm bore would be as near concentric as possible to the outside diameter of the gear. 

Also I should have foresaw the need to purchase the appropriate wire connectors etc... fortunately I had some on hand. But this particular motor does not come with them.

Firmware code I changed to invert extruder axis in config.h:

to

Conclusion:

One of the most pleasant upgrades i've ever done. Was really straight forward, and didn't require much fussing. Having a lathe helped immensely make this simple for me.  But I am sure there are more creative solutions around not being able to find a geared stepper with a 5mm output shaft.  Also FYI the geared steppers have a gear hobbled directly onto the stepper motor shaft.  So don't think you can slap the gear box on any old stepper. 

One of my favorite benefits of this upgrade besides getting rid of moire effect is that I can crank my tensioner-arm sprain down as hard as I want.  With the increased torque from the 5:1 gearing I have 5x the torque.  I think even with the 1/32 driver torque reduction torque will be far beyond adequate.  More tension arm pressure means far less prone to stripping filament...

I'll post pictures of some prints shortly

just found this
http://www.thingiverse.com/thing:261460

So the Bulldog XL is one torquey awesome high resolution extruder that I hear gives you fantastic print quality. However weighing in at $150 USD it's quite the expensive upgrade.  So here is my solution for a diy version that will cost about $40 - $60 depending on your setup, and tool availability.  The nice thing is this will allow those with the printerboard MB to increase there extruder resolution for less moire effect, and some other good things. But mostly I am excited to make my prints look that much more pretty:)

Essentially the bulldog xl is a geared down stepper (I believe NEMA 17 package) with an all metal extruder. Read Adrian's nicely detailed review for more info about it: http://www.soliforum.com/topic/4594/rep … idoodle-3/

After my M5 z-rod upgrade made it much more apparent to me after getting rid of the majority of my banding issues, that I had what I would later be informed is referred to as the moire effect. Sort of gives prints a grainy/ripply effect on the side walls.  I went on a search to eliminate this and was told I ought to upgrade to a 1/32 stepper driver if I could, and I can since I have a sanguino MB.  So $6 USD order to china for a 1/32 pololou driver clone I thought I would be moire effect free...

Then Adrian in his wisdom informed me that while I would probably see great improvement I may encounter other problems with the inherent decrease in torque that comes with increased micro stepping, and that while doubling my resolution I still may need more resolution to really ice my cake of print perfection.

Obviously this was not acceptable... So I immediately scoured the internet for a solution for a geared extruder, first thought was to make a printed version utilizing stock SD parts, then Ian Johnson turned me on to the idea of just getting a geared down NEMA 14 stepper like was on the original solidoodle. 

Anyhow end point was that i found this!

http://www.omc-stepperonline.com/ratio- … p-140.html

It's a Nema 17 pkg with a 6mm dia. output shaft, and it's total length from front to back is 80mm. Weighing in at 380 grams we really have some opportunity to actually make a lighter extruder package if we can keep accessories below 115 g.  But just being equal is fine with me as well. 

That 80 mm would include your front extruder assembly as long as you can keep it from sticking out past the output shaft which is reasonable given the shaft length, and that most of the extruder variants I have seen around here do not extend out past the motor shaft.

You will have to find a solution for either a new 6mm ID extruder gear (stock is 5mm) or bore it out to 6mm, probably will need access to a lathe or bribe a local machine shop to take care of it for you. Also you will need to provide spacers to mount your extruder assembly to since the gear box is round. But other then those challenges you should be able to go with a stock carriage.  As long as you move active cooling to the side of the extruder instead of the back like it is with the Solidoodle 2 and 3.  I will be ditching my aluminum heat sink all together, and just use the stock 40 mm fan on an extruder variant I am working on.

Anyhow I will post more pictures and progress as parts come in. But i'm very encouraged that this will be a relatively painless upgrade that has run me so far $40 including shipping.  Plus i'll have an extra stepper lying around after I am done.  Extra steppers are always a good thing:)