CNC Nightmaring

[Shotgun]

I don't want to step on @rabler's post. That's a good conversation going on over there. But, having stepped into the "CNC conversion of an old CNC machine" world, I have a few other ideas that I'd like to bang around.

3d printer. Laser cutter. CNC plasma cutter.
All of these are essentially the same machine with a different head and base plate. You have a <1-head> that is moves around via a <2-gantry> under the control of <3-software driven motors> with a <4-baseplate> to protect the machine.
1- the head swaps out
2 - the gantry/mill are all the same
3 - the software differs based on the gcode (but is mostly the same)
4 - the baseplate could be switched out like the fixture plate that I got with my mill

What I'm proposing is building an adapter to mount various heads into the BP spindle.
A print head is less than $20 (maybe more for 'good' ones?). A properly sized sheet of MDF would serve as the base?
Laser head prices spread from $50 to $300. A polished sheet of .050 stainless or aluminum would probably suffice as a base?
The plasma cutter is the biggest unknown as to price, but it would require some sort of water tray to keep the plasma spray off the mill ways. The CNC BP's came with a coolant system, so running that through a tray seems like a reasonable solution.

Before the point is made, I'll admit that this is not an optimal, professional solution for any one of these technologies. But, in a hobby shop, with limited space to hold my unlimited dreams. . . can we call it a reasonable compromise? It would seem to require storing a few plates and some tooling heads, vs large boxes that each may get used once per year. The benefit is that I would be able to print a part, swap the print head for an endmill to clean up some critical features, then swap in a laser head to engrave a logo, all without ever having to re-indicated the position of the part.

 

[Lex_Peacekeeper]

A print head is less than $20 (maybe more for 'good' ones?). A properly sized sheet of MDF would serve as the base?
Laser head prices spread from $50 to $300. A polished sheet of .050 stainless or aluminum would probably suffice as a base?

so you dont want to use MDF for a print bed, the print will rip out bits of the mdf, most cheaper 3D printers have a very thin metal plate with a coating on it to lit the print get some grip
on the laser, it would be better to use 1/2 to 1 inch of honey comb aluminum as a base as full on contact can still dmg aluminum when at cutting str

 

[DavidR8]

I have all three CNCs' you are thinking about.
A 3D printer needs a heated bed with a either a glass of spring steel build plate.
A laser cutter needs to have a honeycomb bed if you're considering cutting. If you're engraving then a honeycomb bed is not needed.
FWIW laser engraving only works on anodized aluminum where the laser burns off the anodizing. I have engraved stainless by precoating the metal with zinc galvanizing.

 

[JimDawson]

You don't want a plasma cutter anywhere around a machine tool. The fine 'dust' created by plasma cutting would get into everything. I don't want one in the same building as my machine tools.

 

[Shotgun]

The lasers, at least some of them, come with a compressed air port to blow out the kerf (I guess that would still be the appropriate term).
Is this also something that should be banned from the vicinity of machine tools? Or is it light enough to not matter?

 

[DavidR8]

The lasers, at least some of them, come with a compressed air port to blow out the kerf (I guess that would still be the appropriate term).
Is this also something that should be banned from the vicinity of machine tools? Or is it light enough to not matter?

It’s not significant enough to be any consideration.
The air is to put out flames believe it or not.
Really helps make a clean cut, I’ve never found it useful when engraving.

 

[rabler]

I don't want to step on @rabler's post. That's a good conversation going on over there. But, having stepped into the "CNC conversion of an old CNC machine" world, I have a few other ideas that I'd like to bang around.

I'm sure there's plenty of room on HM for multiple conversations. There are a lot of different approaches to this, I think it's good to see the pluses and minuses of all the variations.

I think the one constraint/issue I question with the all-in-one approach is that there are significantly different mechanics between a floating cutting head (plasma, laser, waterjet, etc) and a mill/lathe type mechanical cutting tool. Adapting cutting heads between the floating variety is one thing, but the rigidity required in mechanical cutting produces a fairly constrained work envelope that strikes me as too limited to be useful for general purpose laser/plasma/etc cutting. So even if you could deal with the abrasive issues that @JimDawson discussed, I don't see a large milling machine being a practical format to support a plasma cutter. That said I think you could make it work if you wanted to, you already said you're not trying for a professional solution so I may be belaboring the issue. "Reasonable compromise" is up to you.

 

[Shotgun]

Yeah, with the new information, I'm thinking the plasma cutter was a bridge too far.

But, could you speak more to the "constrained work envelope"? I agree, I'm not going to be able to throw a 4x8 sheet of 3/4" plywood on there and come out with cool cabinet doors. But, I was always thinking of it as a replacement for one of the desktop sized cutters/printers. It would be WAY overkill for making some of those 3d printed lathe toolholder racks. But, OTOH, if it is already there and adaptable?

 

[Boswell]

I have all three, Laser Engraver/Cutter, CNC Metal cutting Mill, 3D-printer. Here are some of my observations on the key differences that you will need to address as you build a mulit-tool

1. Laser Engraver/cutter
   1. Works best in a sealed environment so that any harmful gasses from cutting are exhausted to the outside.
   2. As stated above also needs a very low volume of air to help reduce fire and it also removes smoke in the air around the laser that reduces the effectiveness of the laser
   3. Needs a LIGHT Tight work environment. Can't stress this enough. Laser cutters are powerful enough to blind you before you know you have been in the path. You can solve this with personal goggles but much safer to have a light tight enclosure. Even better is Both.
2. 3D Printer
   1. Temperature management is everything. Small enclosed or simi-enclosed print area makes it much easier to control the temperature. Even stray air currents at the wrong time could adversely affect a print.
   2. Also mentioned above. printing platform is heated and and many (mine included) has a special and somewhat fragile surface that allows for good adhesion of the initial layer and release when complete.
3. Metal Mill
   1. Probably not much I can say here that everyone does not know about

Good luck if you move forward with this, looking forward to the build.

 

[rabler]

But, could you speak more to the "constrained work envelope"?

Well, my knee mill has about 24" of x travel, 9" of Y travel, and maybe 14 inches of Z. But if you start adding plates and stuff, you loose some of that. That's plenty of room for 3D printing. But for material cutting 36" x 24" is a small area. Basically with a mill you spend a lot of space to get rigidity. If you are constrained in your total shop space, it seems to me you could maybe make a 3' x 4' table that allowed plasma and laser cutting, and yet was still something that could be collapsed for storage, or even moved outside temporarily when you wanted to use it.

I guess it comes down to questioning whether the compromises in function are worth the space savings. I have a larger shop so it just hard for me to envision those compromises as being worthwhile, but for a small shop it may be quite useful.