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need help getting started with a CNC MillStrap

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need help getting started with a CNC MillStrap
June 27, 2011 07:28PM
I have a Sieg X2 miniMIll retrofitted with stepper motors and a usb controller making it a CNC machine. I would like some information for starting out on making an extruder that can be reversibly attached to the machine and how to control it.

I have run into problems adapting extruders I've seen here to something that would fit on the mill. First, I'd like to check my knowledge of extruders, which is that they use rollers turned by a stepper motor to push a strand of ABS into a hot(105C) metal tube with a small hole at the end. The Buckrap Hot End Bow extruder (http://reprap.org/wiki/Buckrap_Hot_End_Bow) looks the most promising, is there a way that I could feed the material to be extruded in from the side then have a rod stick straight up inline with the extruding nozzle so it can be fitted in a collet and allowed to rotate? Does the material have to be isolated from the hot metal in the extruder before hitting the nozzle or can it touch the inside? Can I make my own nozzle by hollowing out a screw and using a tiny (0.017") drill bit to make a hole in the end? My controller board (sold by probotix at [probotix.com]) can control an extra stepper motor, will this suffice for controlling it from my PC? How do I control the temperature of the extruder?

Once I can figure these out I should have everything I would need for building a MillStrap. Also, my mill only has 9 inches vertical travel without anything in it, so a long extruder would limit this range even more.
Re: need help getting started with a CNC MillStrap
June 28, 2011 08:19AM
The simplest way to get your machine going would be to reuse the stepper drives you have and switch out the breakout board in your setup with Arduino & ramps pcb.

Because your machine has more X travel then Y, or X axis travel, you could mount your extruder on the side of the spindle box without losing any Z travel.
Re: need help getting started with a CNC MillStrap
June 28, 2011 11:14AM
I don't want to put to many holes in my CNC machine for mounting the extruder on it, but I'm already used to losing 2-3 inches z travel from the length of millbits. It looks pretty easy to just have two controller boards set up and switch which one the motors are plugged into, but I still need a little information about the extruder.
VDX
Re: need help getting started with a CNC MillStrap
June 28, 2011 01:22PM
... i repstrapped my Isel-CNC-mill with Gen3 electronics and extruder - atached are some images.

Today i added the heated bed with an Aluminium sheet coated with PET tape, so next days i'll do some optimizing for printing with ABS ...


Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org]
Call for the project "garbage-free seas" - [reprap.org]
Attachments:
open | download - CNC-Fraese-Extruder-Externer-TempController.jpg (240.5 KB)
open | download - CNC-Fraese-Extruder-Detail.jpg (180.7 KB)
VDX
Re: need help getting started with a CNC MillStrap
July 06, 2011 02:43AM
... actually i'm changing the controller from Gen3 (which is outdated) to RAMPS with Arduino Mega 2560 and Teacup firmware ...


Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org]
Call for the project "garbage-free seas" - [reprap.org]
Re: need help getting started with a CNC MillStrap
July 06, 2011 10:13AM
yeah, so I've done a lot of research and it looks like I can just buy a main board and extruder controller and I'll be done.
I got an old molding machine 1 1/4 dia extruder form scrap for $25.00
Welded a stand/desk under it.
Wired it with pyrometers to control heat.
Bought strand chopper for $300.00.
Set up old home oven to dry material.
Run strands out into a bucket of water.
Water should be about 80-100 deg.
I have not used cooling pump on water.
strands went in water about 1-2".
I but a bracket in water with a pulley for strands to go around and under water.
Then need rubber like roller and knurled metal roller vary speed to pull strand up out of water.
A 12 volt lawnmower (1-10 amps) starter could be used to turn rollers with O ring belts.
May take more that 1.
Need a DC voltage variable to control speed.
A cheap powerstat (Autoformer).

It would run 2 strands at 20 lbs/hr.

ABS must be dried to remove moisture. 2-4 hrs at 180 deg.
Moisture = bubbles.
Also do not oveheat material. Find out what heat is required for your material.
Disclamer:
Do not hold me for your ability or inability to do this safely.
Study to show yourself approved.
Ask questions for safety.
Email me and I can sent schetches.
old gray 71
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