Going from 3mm to 1.75mm

If I have a printer that takes 3mm filament, is it simple to convert it to one that takes 1.75mm by just replacing the J head? The reason I ask is that Replikeo advertise a kit at $250 with 3mm and at $350 with 1.75mm, but on ebay you can see 1.75mm J heads for $10 or less (example: [www.ebay.com]). I appreciate that the really cheap extruders will be low quality, but this seems like a big price difference between the two Replikeo versions, so I am wondering if I am missing something. Replikeo also sell a 1.75mm J head as a separate component for $39, which makes it even more confusing.

And one last question: the main difference between 3mm and 1.75mm is that 3mm needs a more powerful motor to drive it through the extruder - is this right?

Thanks for any words of wisdom!

Differences - hotend, extruder body, and supplied filament.

also that link is not real jhead, its nothing like a jhead, its a peice of china crap

Its actuly more of a e3d hot end clone... not a jhead in any way shape or form.

If you want a jhead get a jhead from [www.hotends.com]
or if you really want a e3d get a real one from [e3d-online.com]

Dont wast your money, hair, sanity and reals of filament on that china clone.

You also need to change your extruder block and your hot end to go from 3mm to 1.75

Also check your local supplers of filament. here for eg 1.75 is sold by the meter, so its really 3 * the price of 3mm also sold by the meter.

Edited 2 time(s). Last edit at 05/20/2015 11:57PM by Dust.

Sorry Dust, I bought a similar hotend for $20.00 and it works like a dream. I'm printing at 70mm/sec. Very happy.