Joining the crew, and getting started developing!

Hey! I am new to the crowd, but I very much back the reprap idea (and progress you guys have made) and want to see this move forward, so I decided to stop lurking and finally join the team *woot* :p


The reason I joined is more because I wanted to try to accelerate development as much as possible - I want to see this go places. Now, I dont have the most free time in the world, but I am quite mechanically inclined and have a knack for technical drawing. I have two things that I would like to contribute towards that I think would critically increase the appeal of this project:

Direct metal laser sintering
-and-
Milling heads

After looking extensively into metal laser sintering and pictures from the site, I saw many crucial issues that would warrant the need for more than a minor redesign (it would need to be in an air-tight temperature-controlled atmosphere of an inert gas, for example). While this is possible, we all walk before we crawl, and that seemed a bit daunting to tackle.

But, as far as the milling heads, I have drawn up plans for a rotary multiple tool head. In summary, it draws inspiration from the linear-to-rotary motion in the everyday retractable pen, and mounts multiple chucks (or some similar standard bit holder) around a circular toolhead. The idea behind the multiple chucks is to increase the amount of tools already provided to the bot and allow for more autonomous machining.

Now, I had planned to finish the drawings, transfer them into some kind of CAD program, post them up and judge the response (encouragement, discouragement, ect). If generally positive, I would send in for prototypes, refine (and repeat if necessary), then have them machined (and hopefully use the toolhead to machine more of itself?).

...But I didnt plan far beyond there, as I dont even have a reprap. Lol.


Some of the issues I have ran into stem directly from me not having one to play with: I dont know how toolheads mount to the reprap (my current plan uses four bolts and only needs a slab of something rigid to attach to), and I wouldnt have the slightest idea how to interface it with the reprap.

But, more pertinently, Id need to know where to start. Does this even sound like a good idea? Is there already a similar solution out there? Where should I post dev notes, in a forum thread, or a wiki page?

Any and all general guidance is welcome


-Along with CAD program suggestions, those are welcome too! (I know nothing about CAD programs and need to find a good one to get familiar with, there happens to be quite a few)


This seems like a good crowd here, many thanks in advance!
-Cameron

The multiple tool head thing has been explored quite a bit in the world of CNC in terms of ATC(automatic tool changers) and CNC lathe turrets. Some of the quick change tailstocks they make for lathe's might interest you.

Anyway, I agree that an enclosure filled with inert gas would be the way to go with any sort of metal welding. Strapping a MIG welder to a reprap might be a good way to get the feet wet on this.

Looking forward to seeing what you're up to with the mechanical pen thing you're talking about.

Cheers,
-Johnny

But, more pertinently, Id need to know where to start. Does this even sound like a good idea? Is there already a similar solution out there? Where should I post dev notes, in a forum thread, or a wiki page?

People are welcome to use either; I like to tack stuff up on wiki pages and then do a request for comments in the forum, myself.

I believe toolchangers are quite interesting; I'd suggest you get a machine up and running at some point because otherwise you'll eventually hit a slightly frustrating wall of not being able to realize your ideas in atoms.

-Along with CAD program suggestions, those are welcome too! (I know nothing about CAD programs and need to find a good one to get familiar with, there happens to be quite a few)

That's tricky. Today, freecad looks interesting to me (but I haven't tried it):
[sourceforge.net]
but no there's no real pack leader on this matter. Open source, proprietary, it's all good. (I favor the former.)

Also, be sure to find your local RepRap User Group:
[forums.reprap.org]

---

-Sebastien, RepRap.org library gnome.

---

Remember, you're all RepRap developers (once you've joined the super-secret developer mailing list), and the wiki, RepRap.org, [reprap.org] is for everyone and everything!

Hi Cameron,

... have you some experience or equipment for DMLS?

I'm on the way finishing my venting/exhausting, inert gas is the next step.

With venting working i'll start with cutting, engraving and sintering - plastic- and mineralic/ceramic powders can be fused with air, so i'll start with black granite-spheres of 0.1mm diameter and try to make solid obsidian-parts ... for metall-dust i'll need nitrogen or argon, so this has to wait until the inert-gas-support is running ...

---

Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

I worked for a company that produced heating wires from stainless steel and bronze. Wire work hardens as it's pulled through successive dies and a 20% reduction in cross-sectional area hardens it from soft annealed to spring-hard. If it needs to be further annealed, it's drawn slowly through a furnace in the absence or oxygen. Because the ends of the furnace are open to allow the entry and exit of the wire, the oxygen-free atmosphere is hydrogen, bled into the furnace-pipe that the wire is passing through at a low positive pressure, simply burned off in open air at exit. If an atmospheric feed into a sintering chamber was fed over a flame, could enough oxygen be reacted that there wasn't enough left to react with the fusible media? It would be considerably cheaper and more convenient than buying MIG/TIG gases from industrial suppliers.

JohnnyCooper Wrote:
-------------------------------------------------------
> The multiple tool head thing has been explored
> quite a bit in the world of CNC in terms of
> ATC(automatic tool changers) and CNC lathe
> turrets. Some of the quick change tailstocks they
> make for lathe's might interest you.


Yes actually, while most that ive found are a bit more complex than my idea, the objective is still the same. Definitely gives some ideas to pull from. So I guess now my question is what would prevent us from using some pre-existing plan in a reprap? Would there be any benefit to reinventing the wheel specifically for the reprap?


SebastienBailard Wrote:
-------------------------------------------------------
>That's tricky. Today, freecad looks interesting to me (but I haven't tried it):
>[sourceforge.net]
>but no there's no real pack leader on this matter. Open source, proprietary, it's >all good. (I favor the former.)

>Also, be sure to find your local RepRap User Group:
>[forums.reprap.org]

I prefer an open-source solution to a proprietary one myself. FreeCAD looks pretty mature, looks like FreeCAD it is. Thanks!

And the user groups, I found mine, but it looks (at a glance anyway) like my group doesnt even have a collective reprap between them, let alone anyone with a private one. That, and it doesnt seem very active


VDX Wrote:
-------------------------------------------------------
>Hi Cameron,
>
>... have you some experience or equipment for DMLS?
>
>I'm on the way finishing my venting/exhausting, inert gas is the next step.
>
>With venting working i'll start with cutting, engraving and sintering - plastic-
>and mineralic/ceramic powders can be fused with air, so i'll start with black
>granite-spheres of 0.1mm diameter and try to make solid obsidian-parts ... for
>metall-dust i'll need nitrogen or argon, so this has to wait until the inert-gas-
>support is running ...
>
>Viktor

Lol I have none, just what Ive gleaned of various articles, movies, and forums off the web. Doesnt mean I couldnt learn from the more experienced among us though, how much experience do you have?

And because Im curious now: how have you enclosed your reprap? And can you maintain the temperature in your enclosure as you currently have it set up? Details man, details


murrayd Wrote:
-------------------------------------------------------
>If an atmospheric feed into a sintering chamber was fed over a flame, could
>enough oxygen be reacted that there wasn't enough left to react with the fusible
>media? It would be considerably cheaper and more convenient than buying MIG/TIG
>gases from industrial suppliers.

I would consider that needing further looking into. If designed correctly, that could kill two birds with one stone - maintaining the atmosphere temp and its oxygen content (either directly or through heat sink/pump). I would imagine the degree of oxygen reacted would depend on the fuel though...

Hi Cameron,

... i have a CNC-mill, not a reprap, so it's a complete different battling area

Actually i'm working without any housing or ambient temperature-control - i have and can apply a heated bed, ambient heaters or IR-tubes when needed, but with micromachining and laserspots around 30 microns and 50 Watts optical power i don't need ambient temperature control.

When experimenting with the 5Watt-diodelaser-modules this can change, but this i'll see then ...

My experience with lasers is some cutting/engraving with DIY-CO2-lasercutters and developing applications with comercial lasers (disc-lasers and puls-welding systems).

With 8Watt-diode-lasers limited to 4Watts i built a brazig tools for gold-paste and soldering/fusing wires and glass-fibres.

I'm awaiting the shipment of the 5Watt-diodelasers, then i'll blog some more infos in the forum and the LaserCutter-wiki ...

---

Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

How hot does the bed need to be for Direct metal laser sintering?

Would a simple plastic tent work for an air tight enclosure? Does metal fumes build up if not vented, and if so, could they be removed by electro-static plates? I'd prefer not to "vent" 'cause it might require a lot of gas.

Tony

---

Creating the society of the future
[conceivia.com]

Hi Tony,

... the temperature of the heated bed depends of the material - good experiences with some 5 to 10 degrees below melting point for weak lasers.

Most enclosures arent't airtight - they have the venting/exhausting above the working area and inert gas support per nozzle or cone around the laser spot. You have to vent the fume out of the laser beam, so there should be a constant flow of gas from the nozzle to the vent.

You won't evaporate the metal, so the preferable fusing temprature ist above the melting temp but below the boiling/evaporating temp for DMLS.

For cutting/engraving this is different - here you want to evaporte the material instantly, so you heat as much as you can

---

Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

That's what I thought. To hot for me ;(

Tony

Hi Tony,

... my lasers have enough power to melt the powder at roomtemp, so i haven't applied a heating yet.

Even with the 5Watt-Diodelaser there is enough energy-density for fusing metal powders when moving with some mm/s.

The otimizing with ambient temperatures near the melting point is made mostly for high-speed sintering with a scanning laser, where you want to cure a complete layer in some seconds.

For DIY-DMLS you would drive the laser head in XY like a pen-plotter, so it's much slower (some minutes per layer) than with galvo-scanning (some seconds per layer), but you can fuse without preheat ...

---

Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]