Easy Cnc Conversion Of A Small Mill

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Easy CNC conversion of a small mill
by fred27

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My first Instructable made use of a small CNC milling machine. I've found this machine really useful so I thought I'd document getting it up and running. You may read this Instructable and think "Well, he just bought a few thing on eBay and plugged them together" and you'd be right. This isn't a complicated build of a whole custom designed machine. It's a good way to get up and running quickly and at a reasonable cost. I'll explain why I chose the machine I did and what some other options are. I'll explain the pros and cons of my build.

Read on, and you could be "making chips" in no time...


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Step 1: Other options
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Why not a 3D printer?
I think a lot more people have 3D printers than CNC mills and they're great tools. There's a bit of an overlap with a mill, but they both have their strengths and weaknesses. Comparing a mill to a printer we broadly have:

Pros
Cons

  • You can mill PCBs. This is one of the main reasons for my choice. I was about to go down the laminator / toner transfer method of PCB manufacturing when I discover the milling option.
  • You can mill different materials. Most 3D printers are limited to one or two plastic materials. I can use anything softer than steel - usually wood, acrylic and aluminium in my case.
    • It can be messy. I spend a lot of time vacuuming up sawdust or ground up bits of plastic or metal.
    • Rounded internal corners As you're cutting away material with a milling bit you're limited by the radius of your milling bit when doing internal corners. External corners can be perfectly square and sharp, but not inside.
    There's also differences that can't really be described as a pro or con - just whether they suit what you're doing. With a mill you're subtracting material; with a printer you're adding material. If you want a large block with small cutaways then a mill is the best tool for the job. If you're making a single-piece hollow shape then a printer would be better.
Why not a laser cutter?
Laser cutters are expensive and I haven't seen any simple home builds. They're great for accurately cutting through soft sheet material like wood and plastics but can't do PCBs for instance. Basically they're a also a good tool, but not what I wanted.

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This sounds like it would make a neat little CNC engraver. Especially with Y travel extended to a little bit over 3" from the original of less than 2".
 
Feeling a bit dumb here...lol...how exactly do I go about reading the Instructable? You say "Read on" but I'm not quite sure how. One other question...what is the name or brand of the little machine you converted so I can at least look it up? When I do searches for small mills I don't see that one and it looks perfect for an engraver....and I need one of those! :)

many thanks,

Wayne
 
I plan to convert my Grizzly G0704 to CNC in the future and got curious about the Z axis. Is it necessary to use a ballscrew for the Z? I'm no expert by any stretch of the imagination. But just trying to think logically, I know a ballscrew would probably be better, but the weight of the head and the fact that endmills and such typically are fluted so it pulls the material up, consequently pulling the spindle/head down keeping downward pressure on it. Perhaps I am missing something as far as Z axis backlash is concerned, but it's just something I've been curious about.
 
I plan to convert my Grizzly G0704 to CNC in the future and got curious about the Z axis. Is it necessary to use a ballscrew for the Z? I'm no expert by any stretch of the imagination. But just trying to think logically, I know a ballscrew would probably be better, but the weight of the head and the fact that endmills and such typically are fluted so it pulls the material up, consequently pulling the spindle/head down keeping downward pressure on it. Perhaps I am missing something as far as Z axis backlash is concerned, but it's just something I've been curious about.

It is not necessary to use a ballscrew on the Z axis. Just be aware that staying with the acme lead screw means excessive backlash and increased friction. This means you will need a larger stepper motor to move the head. Maybe a higher output power supply too. Bigger motor and bigger power supply equals more money. If it were me I would go with a ballscrew/ball nut. Might be a wash on cost. Linear Motion Bearing has a good reputation for price, delivery and quality. They sell on eBay.

Tom S.
 
It is not necessary to use a ballscrew on the Z axis. Just be aware that staying with the acme lead screw means excessive backlash and increased friction. This means you will need a larger stepper motor to move the head. Maybe a higher output power supply too. Bigger motor and bigger power supply equals more money. If it were me I would go with a ballscrew/ball nut. Might be a wash on cost. Linear Motion Bearing has a good reputation for price, delivery and quality. They sell on eBay.

Tom S.
Thanks for the input. I see your point.
 
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