Hello,
I'm a new user and I learned a lot from this forum in the past two months but mostly I saw many people making their own cnc machines which made me think it's possible.
So I'm interested in building my own cnc machine.
Maybe you can help me with a few questions I have.
First, the specifications:
-it will have about 50cm x 30cm x 20cm of useful area (20in x 12in x 8in)
-it will be used for making model parts and maybe pcb's. In model parts, I'm interested in cutting wood plates (balsa especially) in 2d and also making small metal pieces (not more than 3in). Ideally I would like to be able to make components for model engines, which would imply the ability to cut aluminum and even soft steel.
-the speed doesn't matter, especially for cutting metal i.e. it's ok if it takes a long time to make a small part
-the construction should be lightweight
-last but not least, the cost should be low
So, I started to think about this machine. I found a formula to calculate the spindle power needed - this link is an Excel file in French:
http://wapics.free.fr/outil/puisbroche.xls
To summarize:
Power=K*Q
where Q is the volume cut in a minute (in cube mm)
and K is coefficient between 0.017 for aluminum and 0.11 for hard steel.
If we take
-the linear speed to be 120mm/min (2mm/sec)
-the cutting depth to be 1mm
-the tool width to be 5mm
than we have Q=600mm3/min and
Power=10w for aluminum
Power=66w for steel
That is the useful power, but the efficiency is only 65% to 85% therefore 100-150w of power should be enough.
I thought I could use for spindle:
-either a Dremel type drill with power ~100w and 5000-20000 rot/min
-or a manual drilling machine with power ~500w and 300-3000 rot/min
The first one can hold a tool (end mill ?) of 1-5mm diameter, and the second one, 3-10mm.
Which one should I use?
I like the first one better as it's lighter, but can it do the job ?
That's it for now - more questions to come
I would really appreciate any tips and suggestions you have.