Setting this discussion up to gather up and brainstorm ideas.
LIST OF EQUIPMENT AND MATERIALS UNDER CONSIDERATION:
Materials to be Used:
Some design considerations:
Everyone feel free to inject any comments. This is your chance to provide input on what features go into the DIYDrones CNC Machine!
Current Bed Size:
Currently we're thinking the bed size will be 18x24 inches.
Insights from bGatti:
Some observations I can offer from experience:
1. Inexpensive skate bearing are not well sealed, and will likely stick if exposed to wood dust.
2. The most vibration on my machine is twist across the gantry - so make the gantry height ~twice the height of the lower extremity (from the table).
3. Parallel ports are increasingly harder to find - especially on laptops.
4. It doesn't take a lot of power to move a cnc machine - you will probably want to turn down the power to avoid breaking bits / bending the spindle shaft anyway - so don't specify a motor system which is stronger than your specified spindle. Anything which can be cut quickly on a strong machine, can be cut slowly on a lesser machine. $1000 is a lesser machine.
5. I have a wooden bed; I'd love an aluminum bed, but with $1000 to spend, the wooden bed isn't my biggest challenge. (It's gantry twist and probably runout for PCB Boards).
6. 3D printers want speed more than brute rigidity - most blogs on the subject of hybrids concede this point - which said - there are many parts which can be made slowly - but some parts call for a flying buttress - which does depend on a certain rate of speed.
LIST OF EQUIPMENT UNDER CONSIDERATION:
can you move / copy the blog in here somewhere?
Not that I know how. But feel free to cut and paste anything here from the blog that you want.
Functional Specification (WIP)
Ok so I'll go back in the original blog post and gather what we already discussed/settled on as desired functional spec so we can have it in a consolidated list:
- Cost: around 1000 USD
- Can mill aluminum
- Work cube:18''x24''
- Ease of assembly
- Gantry and dove-tail x axis setup
- Probing/measuring functionality
Future modular upgrades:
- Trunnion table (5th axis)
- Automatic tool changer
- Waterproof enclosure
- Cooling system
- Possibly swap the spindle for a 3D-printing extruder?
Tell me if I miss anything.
Good, we'll brainstorm here, and I'll add another discussion where I'm going to list all the agreed upon specifications.
How about a weight limit? I don't think I want to have a machine that's more than 20-30 lbs.
Yikes! What if we use aluminium for the base plate? Is it going to be strong enough and strong enough?
I'd really like it to be able to fit on a desk. I like the 18x25 or so dimension. Anything larger will be too heavy, and I think beyond the scope. We're talking about a hobby use, with some small part production, right?
Why not use a piece of honeycomb with steel face sheets? This will give us light weight and great rigidity with only a minimal increase in cost.
let's not limit it yet.... the "table" alone could be quite heavy as we want it with no flex.
interesting blog about building one cnc http://www.liming.org/cnc/index.html
This one seems to have a wooden base board. That would cut down the weight significantly.
Also, I find 24x48 will be a little too big. How about a nice 24x24? Or design it in some way that the platform can be expanded. Probably we need the gantry width to be predefined, say 24", and allow for the length to be expandable.