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Machined extruder

Posted by JohnHaine 
Machined extruder
July 08, 2012 03:03PM
Folks, I've just joined here and I'm trying to learn about 3d printing, with the object of attaching an extruder head to my Denford CNC milling machine. Obviously I could buy the parts for the extruder head but since I have the mill and a lathe plus loads of material I'd like to have a go at making one by "normal" methods. Has anyone published a design for something like this please, before I start to cobble something together myself?

Thanks, John.
Re: Machined extruder
July 08, 2012 06:07PM
One of the popular Extruder + hot end design. With mechanical drawing and step by step machining instructions =)

For the driving part, I am only aware of those reprap form, which is obviously not optimized for machining and someone who have access to a working. workshop.
I think this one could be simple enough to be machined though: [www.thingiverse.com]

Edited 1 time(s). Last edit at 07/09/2012 08:48AM by sam0737.
Re: Machined extruder
July 08, 2012 06:59PM
I can't recall seeing anyone publishing extruder designs for use on CNC Routers. You might want to think about a design that goes from machine to nozzle insead of the other way around. Everything generally mounts to two horzontal 8mm rod used by typical printers. Some printers use stationary extruders but are mostly not open source.

There also be speed limitations (or harmonics that drive the machine wild) when using a CNC machine. You also need additional power supplies and controllers for the extruder and bed. GCode for your controller might not be a problem but a spare output for the extruder stepper might be an issue.

I'd look into whats involved... In the end your skills might be better served to build a printer. nema 17's belts and pulleys aren't that expensive.
Re: Machined extruder
July 09, 2012 03:50AM
Thanks for the comments Dean. I'm not sure what you mean by "a design that goes from machine to nozzle"? My thinking is to mount the extruder on the side of the mill headstock, and the bed offset on the machine table (by the way mine is a mill not a router) to compensate for the possible loss in working surface. Extra PSUs are not a worry - my drive electronics are home built and have enough capacity as well as either an "A" axis stepper driver or a spindle output control for the extruder.

Yes, I am concerned that the table speed might not be large enough, but the Novamill can be driven quite fast. What sort of axis velocities are used in a conventional reprap please (mm/minute)?

Re: Machined extruder
July 09, 2012 04:18AM
Thorp was doing a very nice machined extruder design quite a while back, he included a number of drawings and ideas in this thread

Re: Machined extruder
July 09, 2012 04:53AM
Feeds of 1200mm/min and moves at 9000mm/min would be typical for a Mendel style machine.

Re: Machined extruder
July 09, 2012 05:27AM
You can easily give it a try on your machine. I'd recommend Slic3r that has a Mach3 output option. So the Gcode would be XYZA and all straights, just let the machine ignor the A moves. The challenge will be in the infil and possibly rapids. Also try long thin parts where the infill is a zigzag of no more then a couple mm. I have examples of this if interested. Adjust the feed rates and see what happens.
Re: Machined extruder
July 09, 2012 11:47AM
You might not find the mill acceptable for longterm use as a 3D printer, nophead pointed out the speeds most printers run at, but there is more to it than that, most CNC machines run with a lot less acceleration than printers, and the bulk of the moves are really short, so even if you can get comparable rapids, I think you'll find it's practically a lot slower than a printer.

I considered doing this to my Mill, but in the end I decided I didn't want to tie the Mill up printing for 5+hors at a time.
Re: Machined extruder
July 09, 2012 11:52AM
Yes, that's a possible problem. In my case also the workshop is getting very cluttered with 2 mills and a lathe, bench space is rapidly disappearing!
Re: Machined extruder
July 09, 2012 03:28PM
What is "Bench Space"???? cool smiley
Re: Machined extruder
July 10, 2012 05:43AM
It's the wooden surface that lies underneath and supports various strata of tools, screws, various other parts, bits of material, odd scraps of paper, and swarf. At least I think it's wood, it's a while since I saw it so may have mis-remembered! winking smiley
Re: Machined extruder
July 10, 2012 07:54AM
Thanx. Haven't seen that in years, is it related to "floor space"? Both seem to have that "space" thing in the name.
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