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JavaDog
11-08-2004, 10:13 AM
Just a quick question. Can a well made CNC machine using servos and a good router, but built from MDF, handle milling Alum?

See, I was thinking of ordering high-quality parts (Servos, Gecko drivers, Ballscrews and Linear Rails) for my machine, but saving some initial cost by building it out of MDF. I have a few reasons for this:

1) MDF is easy to work.
2) MDF is cheap enough that I can tinker with the design.
3) If the MDF machine can cut Alum, I can use it to remake the machine from Alum once my design is final.

So, any thoughts?

keithorr
11-08-2004, 02:19 PM
Maybe,
My machine was bought. Made of tubular steel frame for stand and aluminum plate and extrusions for the machine itself. I usually use it for contouring graphite for glass molds. As sturdy as it is, it's still a challenge to get good work in aluminum. No match for a proper mill.

JavaDog
11-08-2004, 02:21 PM
As sturdy as it is, it's still a challenge to get good work in aluminum. No match for a proper mill.

Is that more of the Servos/Steppers and/or drive system problem or a construction problem though??

keithorr
11-09-2004, 01:43 PM
The machine is too light. The position accuracy or motive power is not a problem, but vibration is. If I mill aluminum plate with an appropriate 1/4" end mill, I can get pretty good cuts. I can't hog anything and the swirl marks in finish cuts is more than you would get with a good mill. The router bearings aren't up to the job, and the 12" Z axis isn't rigid enough when extended. I have to use a tall fixture block to raise the workpiece so the Z axis is only hanging down a couple of inches. The uprights are of 1" aluminum plate, the crossmember is 6" square tube. The base plate is 1/2" aluminum plate with 5/8" plate rabbited on edge and screwed to the base to form T-slots. The ballscrews are rolled.

I cut dry just to keep the machine clean. I could probably get better results with proper coolant. I don't think you would want to use coolant with an MDF machine.

Hobbiest
11-09-2004, 09:16 PM
Many of the members here have milled aluminum with their MDF machines. Balsaman is the only one that I can think of off hand. Good luck.

JRoque
11-10-2004, 11:31 AM
Hi. This is no claim to fame but I did most of my hard aluminum alloy cuts on a machine that was held together with a couple of 2x4s. I noticed that using the right cutting tool for aluminum, slow feedrate and, yes, WD40 meant that there was little load put on the frame. Now that I switched to 8020 extrusions, I'm cutting the same alloys at a much faster rate and the edges come out much smoother.

Not to knock off MDF but when I cut it, I get tons of a fine 'talc' that gets everywhere including the screws, rails, lungs, etc. Check the 8020 forum (http://www.cnczone.com/forums/forumdisplay.php?f=228) out and post your frame requirements - maybe they can help you as they did with me.

Later,
JR

JavaDog
11-10-2004, 01:01 PM
I don't have a problem keeping the speed down to save some money initially. Once I start selling some parts, I can always upgrade the machine.

So MDF will work if:
1) Keep the ipms down.
2) Use some sort of cutting fluid!
3) Use the right bits (and keep them sharp!).

JRoque
11-10-2004, 02:05 PM
I'd say so. See the video here (http://www.cnczone.com/forums/showpost.php?p=43130&postcount=19) when I cut my router's base. I used a plain PVC clamp I got from the hardware store to hold the router while cutting the real holder. Because the whole setup it was so flimsy and my then router was only 1/2 HP, I did that cut very slowly. But, it worked.

Regards,
Julio