macona wrote:Extruded aluminum would not work for something like this. If you dont want this thing to ring like a bell it needs to be made from cast iron or possibly polymer concrete. This would be best with gibbed dovetail slides. I wouldnt even use linear rails, there is a pretty good chance of brinelling the rails and trucks from the impact.
Yes, if you have not experience building something like this it will be difficult and will cost a good chunk of money. I would start out with something like a worn out milling machine like a bridgeport. Replace the head with some sort of power hammer and install ball screws on the X and Y axes.
Programming a random tool path may not be too simple. Maybe if you can write something that will create a random point cloud and then turn the X-Y coordinates into code.
metalman wrote:For what you want to do you should first try a pneumatic planishing hammer. Harbor Freight sells a cheap one for about a hundred bucks. http://www.harborfreight.com/pneumatic- ... 94847.html They do about 1000 -2000 hits per minute and have several interchangeable hammer heads for different size impressions. I built one from a cheap air hammer with a modified hammer head and some 1-1/4 pipe for about $30. Then I graduated to a CP sytle hammer once I saw how much better they were. But I still have and use my original home built hammer and a HF plashing hammer plus a couple mechanical hammers too. A boy never has enough toys or hammers...
If that isn't fast enough for you then you can add a CNC X/Y table later. For sheet metal work, normally the metal is held by grippers on the X axis gantry and the hammer is stationary. My big mechanical hammer weighs between two and three thousand pounds and has a 48 inch throat. The X/Y table has to be fairly heavy too to stand up to the pounding that the sheet will receive.
cvoinescu wrote:Someone suggested applying pressure instead of hammering; that may work better and stress the machine less, and that was what I was thinking when I suggested the ShapeOko. It should be capable of applying a few kgf -- not sure whether that's enough, though. Another idea would be to make a contraption that raises the hammer, then lets it drop freely. That way, the machine does not suffer any impact stress; it'd all be between the hammer and the table, and you can pack more punch.
wolvescaptain wrote:Think of raising a little hammer an inch or two and letting it free fall, that's all I need.
wolvescaptain wrote:
Isn't that effectively the same as a CNC? Or does it work differently?
macona wrote:Programming is going to be a pain though to get a random stippling pattern. Each point must be programmed in and they need to be close to each other otherwise it will take forever to complete a sheet.
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