PDA

View Full Version : Convert CNC router to 3D printer?



jeffmorris
12-06-2012, 06:41 AM
I have a Magnum Phoenix GS CNC router. I replaced its outdated electronics with PBX-RF RF Isolated CNC Breakout Board and three MondoStep 7.8A drivers. I use Mach3 software to control the machine. What do I have to buy to convert my CNC router to 3D printer? I think I have to buy:

3D printer head > Which one is best?
Stepper motor for 3D printer head
Stepper motor driver
Heated bed

How do I configure Mach3 software for 3D printer?
I have Cut2D V1.5 software. Do I need different program to convert 3D models into code for Mach3 software?

BloomingtonMike
12-13-2012, 12:00 AM
I am new to this too and doing the same only on a CastCNC Joe's CNC machine I built.

Here is what I bought:
1. extruder with a stepper motor and a heater cartridge
2. hot end on the extruder (my QU-BD MBE extruder had these first two items already but I am not sure how good this extruder is)
3. Heated bed - I bought QUBD's
4. 4th axis to control the stepper - Sure there are cheaper ways (like a pololu 4988) but I am using a 2nd G540 purchased from dan mach
5. a way to control temeratures of hot end and a heated bed if you use one - I am using Nuri's boards - GnexlabStore (http://store.gnexlab.com/) - I bought a gecs2tc1 (thermocoupler) and a gecs2ts1 (thermister) as the heated bed is thermister and the heater cartridges will be thermocoupler monitored
6. power supply for the hot end and heated bed and maybe a fan on the extruder - I am using a 30amp 12V Dc $30 shipped on ebay power supply
New 12V DC 30A 360W Regulated Switching Power Supply for LED Strip Light | eBay (http://www.ebay.com/itm/180852147612?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649)
7. K type thermocoupler long enough to get to your controller from youer hot end
8. Way to attach extruder setup to your Z

Nuri's site has info on slicing with a plugin for Mach. I want to try that.

Not sure cut2d does anything with stl files - prob need aspire for that.

More to come as I learn more

3dstuffmaker
12-13-2012, 02:11 AM
Hi jeffmorris,
It is my opinion you can buy Stepper motor for 3D printer head to convert your CNC router to 3D printer.

Best Regards
David Paul
3D Printers for sale,3D Rapid Prototyping Technology,3D Printing Machine -3Dstuffmaker (http://www.3dstuffmaker.com)

Dean448
12-13-2012, 08:23 PM
Mach3 is used to convert GCode to machine motion. When used for 3D printing it works the same way it would driving your machine for cutting wood.
Printers require 4 channels. X, Y, Z and then E. E drives the extruder stepper. An extruder works the same as any axis. You tell the machine to travel one inch and it Mach3 sends the correct amount of steps. You tell the stepper to feed 100mm of filiment into the extruder and 100mm gets fed into the extruder. So Mach3 tells you how much material you used by driving the E or A axis in a relative way.

One step back is the slicer program. It takes a three D mesh model and cuts it up into layers equal to the thickness of the filiment coming out of the extruder. Could be around 0.33mm. So every plane is a 2D GCode map, all in straight line segments. No arcs moves are used in home slicers. The code can get very large but Mach3 had no problem loading large files.

One step back is the 3D modeler program used to design the part. The output is STL or OBJ. These models consist of a bunch of triangles.

Mach3 doesn't require any modifications. You just need the slicer program to convert any E to A. Then block a bunch of M codes that aren't used by Mach3. There may be other minor changes depending on the slicer used.

Both the extuder and headed bed remain at the same temperature while printing. I use an ebay temperature controller to hold the extruder at 255 degrees for ABS. I just use a power supply to hold the bed at about 110 degrees.

So Mach3 doesn't really have to control temperature You simply power up the two heaters and let Mach3 only control the 4 axis of motion.

I've been using this simply approach for some time and it works.

Fastest1
12-17-2012, 09:25 AM
I run a Gnexlab board that takes care of the temperature control of the extruder and or bed. As Dean said, manipulating the GCode for an E or A command is about all that is different. Not to say I have been really successful in printing but all of my issues have been extruder meltdown or clogging related. When I get over my lazy spell I am going to fix my extruder and build a remotely driven feeder with a hot end design similar to Arcol's, maybe even using a cpu water cooler. I dont want any PEEK or PTFE in the barrel at all.

Dean448
12-18-2012, 03:21 AM
Getting the extruder correctly designed is by far the hardest part of building a printer. Most take there chances with purchased extruders with mixed results.
I'm using an all metal design that uses PTFE. The trick to using a PTFE liner is to fully support it in all directions. At first I tried brass but the filiment kept sticking. There are a lot of theories/claims as to the best way to build an extruder. Do a lot of research and don't just go with what seems to be popular.

Fastest1
12-18-2012, 11:39 AM
Dean I dont get the PTFE need. That is the 1 aspect that gives me fits. The PEEK too for that matter. I do think the PEEK could be excluded as there are better or more rigid techniques for merely holding an extruder tip. The PTFE even if captured could melt and if it does, doesnt it always cause a major clog? (in my experiences it has but I have a tendency to lean towards the more is better approach at the cost of tools, too much heat in my case). Do you know where the filament is sticking? And could it be heat related? I have got an Arcol on the way (why I just dont build my own, still puzzles me). I see Bradley C. Fudge using what appears to be a cpu water cooler just above the hot zone with claimed good results. There is plenty of evolution quickly. I think the results still will improve as the printed structural parts are replaced with more solid metal parts. We will see, I am sure I wont be leading the technology wave LOL.

Dean448
12-18-2012, 09:37 PM
I don't know what extruder you are working with but I would agree that many have issues with PTFE when its used as a dual purpose: lubricate and provide structure for the extruder in some way.

I'm using PTFE as a liner only and constantly run at 255 which is plenty hot for ABS. I have gone above that but I don't see any reason to. PTFE can take the tempeature but it will soften. My point is that if it is captured on all sides with a rigid support material like metal then it can't go anywhere even if get hot enought to deform.

Heres my theory on cooling. you need to get real hot in the heating chamber so you can stay hot enough out at the nozzle tip. The down tube is where cooling is important. The filiment coming down the tube is like a ram. Idealy you want the filiment to be hard just above the heating chamber/nozzle so it can push with enough force to expel material out a .4 hole. If the material goes liquid high up in the tube then it pushes is all directions potentially increasing drag on the walls ultimately reducing PSI where it counts at the tip of the nozzle.

So you need to cool just above the heating chamber which you already knew.
Some extruder designs actully insulate in this section which is wrong. I'm sure there are a bunch of good ways do this this but water would be a bit extreem.

My down tube is made up of a PTFE liner then thin steel jacket (like a break line) then I put a steel wool like ball around the jacket just to try to pull the heat out more. Others use fins that work well also. The only issue with cooling this tube down too much is that you might cool the hot chamber as well.

I've never purchased a complete extruder so I can't really recommend one. I'm into making the extruder with some off the shelf compoents like nozzel, down tube and liner. Let me know if you are looking to build or buy.

Fastest1
12-19-2012, 07:41 AM
My first extruder was a Steve's from a H1 I had built. Then a few pieces from an Mk7 hot end and now more of a mix of a few idea. The Arcols that I am about to try follows many of the traits you refer to. Small heat chamber seperated by a small steel tube, no ptfe or peek. I am going to attach it to a remote filament extruder most likely using the same drive I have, just modded to use a push to fit tubing fitting.

Dean448
12-19-2012, 10:19 AM
I just pulled up V3 and V4 of this arcols. I didn't look at the cad files in v3 but it appears that the end heating chamber and nozzle are somehow connected using PTFE which won't work after time. I may be wrong and he is using some other material to connect the two. It also appears he is using wood, which should never be used in the lower end.

V4 however looks much better. Its all steel and notice the lack of outter support rod that are used to hold the lower end to the upper end when using PTFE or PEEK. And after time don't work.

This V4 does use PTFE as a liner as I described and he is using a healthy aluminum heat sink to prevent high heat from getting up in to the extruder body.

I'm not sure if this is for 3mm or 1.75mm filiment. I only use 3mm with a typical wades gear driven shaft. I would expect that it would also work for 1.75 when you direct drive off a stepper motor.

The concept looks good. When using PTFE and make sure that its tight to the inner walls of the tube, pushed solidly against the back side of the nozzle V and is pushed tight against something at the top. If you don't hold it at the top the entire liner will be pushed up the tube and material will back around the liner at the nozzle end resulting in a mess.

This is a solid lower end but unless he is selling these parts you need to build them. He also gives you no information how to design the upper end. Do you have that covered?

Fastest1
12-19-2012, 10:56 AM
I am getting the V4 and am going to modify it a small amount in the mount area to accept a PTF fitting for the incoming filament. I have a few feeders still working but dont like the plastic to stepper interface as it gets wobbly when warm, probably redo the sides in aluminum. Also I want to use bipolar 23's (feeder only) that I can run thru my G540. Plus I have a few around.

Dean448
12-19-2012, 04:42 PM
on the upper end I tried abs printed bodies to hold the stepper and other components with no luck. It worked for a while then started skipping teeth when the stepper backed off due to body distortion. Now I'm only using abs for the stepper gear (because the stepper gets hot), PLA for the large gear because I had a bunch printed and pretty much the rest in steel.

The strength and reliability of steel can't be beat at these tempeatures and forces. However to fabricate in steel you need to invest in a metal cutting band saw and MIG welder.

Well good luck, let us know how it turns out.

Fastest1
12-19-2012, 08:50 PM
Well I do have a few mills and lathes around the garage.

That was my experience to with the skipping teeth. I would end up wedging a piece of metal between the stepper and the mount. At 1 point I screwed a small piece of angle sheet metal to the mount and the stepper to eliminate the movement/warping when warm. I will just cut my own gears or order them. Or eliminate them entirely and just hob a piece of alum or steel and put it on the stepper spindle. Oh yeah I hate to say it, got the bandsaw, mig, tig, and a few other things lost in the depths.