Next round revisions, and the hot end saga!

Hello friends,

Since that Yin-Yang print, we discovered and addressed the following round of improvements in the chassis. Also, (happily telling you that) this gives the IndiaBot design a definite edge over its parent designs (Wallace/Printrbot) for our conditions (read price sensitivity, and suitability to the ‘jugaad’ make-do minds :P):

The power of Z! Well, ideally, the printer should be a “connect and print” experience. But (with my two years of experience living with the Makerbot cupcake) practically, all things will go wrong – the extruder will ooze out too much plastic and trip over itself and lose steps, or you’ll realize after starting the print that you want to lower Z a bit so your raft is squished flat, and it won’t warp or (put your experience here)… and the easily accessible Z belt in Makerbot is truly God-sent! Just grab it, and pull it right or left to lower or raise the extruder, and save your print!

Now, its hard to imagine how life is ever possible without this, so, IndiaBot features an accessible Z belt:

The accessible Z belt

Second, why on earth two Z stepper motors?! I’m sure we can do better with the price we save here! So again, we have a single stepper motor for the Z. I was actually feeling I’m missing some point here, till we made it with a single Z motor, and saw it work, and much more elegantly at that! (reduced wobble due to removing imperfectly printed stepper-screw coupling – again subjective, but lower chances of error)

Also, we added a horizontal frame feature, which gave the final required stability to Z movement (no apparent wobble), thereby making the final structure look like this:

Chassis - front

(Please don’t mind the cluttered smudgy look – its a prototype, we don’t want to worry about looks yet 😛 )

The hot end

Some pains with the extruder have been going on since early days, making us learn the hard way:

Long melt zone - bad hot-end

This was a design we made using a thermocouple, some nicrome wire, and a long brass bolt. Now, though it extruded for a while (visible in the front), it failed soon – the whole filament melted along the length, and plastic started melting at the entry itself, so it would no longer do the ‘plunger’ effect – molten plastic simply ‘folded’ on top of itself right at the entry point (visible on the tip of plastic filament).

Sanity prevailed, and we confessed we got into too much too soon. So we patiently read through the reprap hot end wiki, and adopted a concoction from there, and success was ours to keep 😛

Hot end - extruding happily!

Thanks open source!

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