CNC Mill v2.5 (2007)
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CNC Mill v2 (2006)
After the first attempt was cleary not going to work, I set about designing a new mill. For a guy who isn't an engineer and had never really "designed" anything mechanical before, this was both challenging and rewarding, as the cliche` goes.
The most noticible difference between v1 and v2 is the material. Instead of using MDF, v2 was made entirely out of steal. I had the luxury of having a contact who had access to a laser table and cheap steel, this was a huge breakthrough for me. Now I didn't have to worry about making mistakes cutting the pieces, I just had to worry about making mistakes drawing them! In retrospect, it's almost as easy to mess up a drawing as it is a physical cut.
My first order of business was to buy a set of stepper motors, a controller, and a power supply. There are ample resources on the web to salvage steppers from printers and make powersupplies from scrap PC parts and etch your own controllers, but for me this was just out of the question. Although I wanted to claim this as "my own" design I also wanted to eliminate as many variables as possible, and still stay within my budget. The last thing I wanted was to troubleshoot a circuit board when something didnt' work, when to be honest, I dont' know squat about circuit boards.
I ended up buying the whole kit from xylotex.com. At the time of purchase he was selling 410oz/in motors for the same price as the 270oz/in, so like most, I thought to myself "bigger must be better". However, after seeing the motors run, I think their speed is a lot slower than I wanted. They do have more torque and would obviously be better for cutting thicker material at slower speeds, I'm not planning to cut anything other than plastic or MDF, so the added torque doesn't do much for me. An expensive mistake though....
With the steppers in hand I started drawing. As a side note: I think it's incredible and amazing that people design things without 3D modeling. If it wern't for the ease of 3D, I can guarantee this project wouldn't have gotten off the ground if I would have had to draw it by hand, or worse yet...with Autocad! That's just my preference though, I have been told first hand by dozens of people that Autocad is the only way to go. My take is that if 3D is the first and only thing you've done, then 2D seems really limited and difficult. But again, that's just my opinion.
This machine actually ran for about a month! I cut a few pieces on it and drew several shapes with a pen mounted the the Z in a makeshift sort of way. The biggest problem was the accuracy and repeatability. I had a few BIG problems with this design.
Acme nuts: The nuts I used were home made from a piece of 1" x 2" x 2" UHMW tapped horizontally. I think that the design lent itself to backlash, and tons of it. Also, UHMW may not have been the best choice, it seems really soft compared to the delron nuts I've seen elsewhere.
X Axis Rail Design: The whole thing here was a mess. I still can't figure out why I didn't flip the rails so they were on their sides instead of mounting them flat to the base plate of the machine. Mounting them flat made spacing really difficult to adjust for because I was dependent on the thickness of certain materials, which I now know varies :)
Details: There were a bunch of little things that I just couldnt' get right, like the bearing mounts, the motor mounts, and the couplers.
All of these things made this machine basically worthless in function. However, the flaws taught me what I did wrong and what I would need to improve in order to get a functional machine.
The most noticible difference between v1 and v2 is the material. Instead of using MDF, v2 was made entirely out of steal. I had the luxury of having a contact who had access to a laser table and cheap steel, this was a huge breakthrough for me. Now I didn't have to worry about making mistakes cutting the pieces, I just had to worry about making mistakes drawing them! In retrospect, it's almost as easy to mess up a drawing as it is a physical cut.
My first order of business was to buy a set of stepper motors, a controller, and a power supply. There are ample resources on the web to salvage steppers from printers and make powersupplies from scrap PC parts and etch your own controllers, but for me this was just out of the question. Although I wanted to claim this as "my own" design I also wanted to eliminate as many variables as possible, and still stay within my budget. The last thing I wanted was to troubleshoot a circuit board when something didnt' work, when to be honest, I dont' know squat about circuit boards.
I ended up buying the whole kit from xylotex.com. At the time of purchase he was selling 410oz/in motors for the same price as the 270oz/in, so like most, I thought to myself "bigger must be better". However, after seeing the motors run, I think their speed is a lot slower than I wanted. They do have more torque and would obviously be better for cutting thicker material at slower speeds, I'm not planning to cut anything other than plastic or MDF, so the added torque doesn't do much for me. An expensive mistake though....
With the steppers in hand I started drawing. As a side note: I think it's incredible and amazing that people design things without 3D modeling. If it wern't for the ease of 3D, I can guarantee this project wouldn't have gotten off the ground if I would have had to draw it by hand, or worse yet...with Autocad! That's just my preference though, I have been told first hand by dozens of people that Autocad is the only way to go. My take is that if 3D is the first and only thing you've done, then 2D seems really limited and difficult. But again, that's just my opinion.
This machine actually ran for about a month! I cut a few pieces on it and drew several shapes with a pen mounted the the Z in a makeshift sort of way. The biggest problem was the accuracy and repeatability. I had a few BIG problems with this design.
Acme nuts: The nuts I used were home made from a piece of 1" x 2" x 2" UHMW tapped horizontally. I think that the design lent itself to backlash, and tons of it. Also, UHMW may not have been the best choice, it seems really soft compared to the delron nuts I've seen elsewhere.
X Axis Rail Design: The whole thing here was a mess. I still can't figure out why I didn't flip the rails so they were on their sides instead of mounting them flat to the base plate of the machine. Mounting them flat made spacing really difficult to adjust for because I was dependent on the thickness of certain materials, which I now know varies :)
Details: There were a bunch of little things that I just couldnt' get right, like the bearing mounts, the motor mounts, and the couplers.
All of these things made this machine basically worthless in function. However, the flaws taught me what I did wrong and what I would need to improve in order to get a functional machine.
CNC Mill v1 (2004)
This was the first solid attempt at building the machine. I chose MDF for the basic frame material as it was relatively inexpensive and easy to get my hands on. To make the cuts I used a standard hand saw, cordless 5-1/4" circular saw, and a square. Dad has a bench top drill press so we used that to make all of the holes. This first one was fully assembled at my parents house, because Dad has better tools and more space than me.
The biggest obstacle to overcome with something like this is keeping everything square. Of course we were only spanning about 34" max at any given point, so it seemed like squareness shouldn't be an issue..... I was wrong, even across 34" it's terribly difficult to stay truly square.
Since I hadn't ordered the stepper motors yet, we ran the X, Y, and Z using drills! However once the axis' reached their ends you could see and feel the strain on the brass "bearings" as it would almost always tear apart one of the seams.
The biggest obstacle to overcome with something like this is keeping everything square. Of course we were only spanning about 34" max at any given point, so it seemed like squareness shouldn't be an issue..... I was wrong, even across 34" it's terribly difficult to stay truly square.
Since I hadn't ordered the stepper motors yet, we ran the X, Y, and Z using drills! However once the axis' reached their ends you could see and feel the strain on the brass "bearings" as it would almost always tear apart one of the seams.
