[The Blight]

I started thinking about making a big milling machine a long time ago, and one of the materials I thought about using was reinforced concrete. This is the material I have ended up wanting to use because it's cheap, and I don't want to spend a lot of time figuring out how to work with other materials. I also thought about making it from cast iron or welded steel. One of those ideas was to get some old train rails, or something similar and just weld a base and machine it afterwards. Getting the machines to do that would not be an easy task, so I dropped it.

You can sand concrete to achieve flat surfaces after it has cured and "stopped" creeping. Concrete will always move around a little, but after a couple months it's reduced to so little that other factors in the machine play a bigger part in it. So I will cast inserts into the concrete. These will be welded to the rebar inside the frame for extra support. To give the concrete some more tensile strength, I will use threaded rods to post-tension it.

There are two designs that I have been thinking about. I'm not yet done with the 2nd one, so I will only post a picture of the first.



Travels are:
X: 800mm
Y: 350mm
Z: 450mm

The base of this design weights 500kg, and the table weights 100kg. With rails, motors and everything else, it should be around 750-800kg.

I have kind of dropped this design because of something I got from a friend of mine today (PS. if you are reading this, then thanks a billion! I owe you a beer!).




These rails are 1200mm long, and the trucks are 200mm long. They are heavily preloaded, and they are from a high end VMC (Mazak). AS you can see in the last picture, they are pretty big. Because theres only one truck on each rail, I will be making something more like a moving gantry machine. Because the trucks are so heavily preloaded, and they are as long as they are, I bet that they will be enough for this machine. I hope to have a picture up of the new design in a couple weeks.

[samco]

Neat -

You should look at this thread

http://elektronikforumet.com/forum/v...er=asc&start=0

sam

[The Blight]

I have read through that thread quite a few times. Was my no.1 source of inspiration for choosing concrete.

Forgot to mention that by long term, I mean up to 5 years. I don't have anywhere to place the machine for now.. but I can still share my ideas.

[hesham morsy]

hi Blight

ask in yor country for Non shrink concrete or Non-shrink grout the cost will be nearby ordinary concrete

look for 2 more truck on ebay


Bamberg Design

http://www.mech.utah.edu/~bamberg/re...mberg-PhD.html
http://www.mech.utah.edu/~bamberg/re...e%20Design.pdf



Building and Open Source CNC Milling Machine
http://opensourcecnc.blogspot.com/

[The Blight]

Will ask for that.

I have tried looking for more trucks, but it's kind of hard as it's not a standard rail type. Could not find it on the THK website either.

Had a look at the pdf and website. Looks nice.

That last link I have seen before, and it's the biggest source of inspiraton for the new design.