DIY CNC machine for steel?

[Sven]

You can also opt for building in epoxy concrete (often called epoxy granite).
And yes, you can use a chinese spindle but the bearings have to be ok.

A guy close to me built an epoxy concrete machine with a chinese spindle (I think 2200 watts but up to 18000 rpm) and can easily mill steel, to about 200s of a mm.
He used old servos but you can get simmilar results with closed loop steppers.

Have a look over here in a dutch thread (maybe use google translate):
http://cnczone.nl/viewtopic.php?f=8&t=8410&hilit=epoxy&start=406

Here it is
Here it is in action, steel 12000rpm, 4500mm/min feed, 15mm doc, 0.5mm, at long life settings:


He says he can also do 20000rpm en 9500mm/min but that is no good for tool life.

[lukeleb2010]

Thank you both for your responses.

After further research, I agree that the easiest way forward for me is to buy a small, cheap manual mill and convert it to a cnc machine.

I found this on Ebay:

http://www.ebay.co.uk/itm/Proxxon-MF...YAAOSwHjNV-BT2

And here's a conversion:

https://www.youtube.com/watch?v=iVYIXzO6UtI

Couple of questions:

Firstly, does this look like a rig that could cut steel to any degree of success?

Secondly, I know that manual mill can have quite larger backlashs. Will this be an issue in a CNC conversion and how can it be overcome?

Many thanks,

Luke Blades

[Davek0974]

Here is picture of a mill, it's a Bridgeport - the most common mill ever made i think, I have one just like it. It's 1100kg of solid cast iron and has a proper 2Hp motor on it.

It is capable of milling steel, but will only take relatively light cuts due in most part to it's versatile nature - the head can swivel, rotate and tilt, these are great features but make it weaker when it comes to real milling.

Steel needs lower speeds and more power, yes it can be done with high speeds but you can expect short cutter life and you will only be scratching away the metal.



That being said, I am building a gantry style CNC machine and fully hope to be able to do fine milling in aluminium but nothing tougher, i am looking at cutters of around 2 - 5mm diameter.

I really would look closely at what you need to achieve but steel milling is going to be a tough nut to crack.

Conversions can be done, plenty of Bridgeports have been CNC'd - ball screws are a must and a good machine as a foundation is a big help as lot of them have had a hard life.