Topic: DIY Economy Bulldog XL extruder! Hopefully...
Disclaimer: Work in progress... has not been tested yet. As soon as upgrade is complete I'll post the final details on how the upgrade went for me for any who want to follow in my footsteps. So you are warned this is potentially a giant waste of money
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/
Some Bulldog XL 1.75mm basic stats:
Length: 80mm (front to back)
Weight: 495g
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
If you can't find anybody willing to bore out your extruder gear to the 6mm shaft size you'd be better off going with the almost identical NEMA 17 pkg but with an 8mm output shaft.
http://www.omc-stepperonline.com/ratio- … p-141.html
The downside is it weighs a bit more. But that's probably ok. I just have a lathe in my shop. But $12 on ebay for a new 8mm ID hobbled gear may be a better choice. It does however most likely mean you are going to need to tweak your extruder design to accommodate the larger extruder gear. So pick your poison.
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:)
