Misterg
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- 1,822
- Location
- North Wales
I’d never particularly wanted, or seen the need for a CNC machine, but the cheap, ubiquitous table top routers (“3018”, etc.) that have appeared on Amazon, Ebay and Youtube over the last few years sparked my interest – can you really get a working CNC machine for £150 ??
And so it begins…
After doing a bit of research on this type of machine (Youtube videos mainly), I came to the conclusion that while they may function as described, they were pretty compromised when it came to machining anything useful. I briefly considered buying one to ‘upgrade’ but realised that pretty much everything about them would need to be replaced for me to be happy with it.
My thoughts turned to building my own as an interesting project in its own right. I did a rough costing and it was clear that a homebuilt one would be much more expensive than Amazon, Ebay or Aliexpress’ offerings. The cost involved put me off the project – I didn’t want a CNC enough to spash out the best part of £1000 on nice, new bits, but the bug had bitten by then.
I then found out that a cheap Arduino could be used as a CNC controller and a bit of late night, alcohol assisted browsing of Aliexpress, Banggood and Amazon, and I had somehow ordered the cheapest spindle I could find, a pair of cheap Chinese linear rails, a ballscrew, a stepper motor and driver.
I should say that this project is a perfect example of how not to go about building a CNC – It's something I drifted into and was not well defined. When I first started it, the intention was to be able to do some 3D relief carving in wood, but as it progressed, I realised that I really would like to machine aluminium, even if slowly.
It may appear that there was a grand plan, but the truth is that the design evolved on the fly to suit whatever I could get hold of cheaply. The project grew legs and started running when an unused pair of 450mm long THK 15mm linear rails & bearings popped up on ebay and I managed to buy them for less than £40.
I started with the spindle and built the Z axis to suit it - The splindle was one of the cheap, 500W ER11 DC spindle motors that's all over ebay, amazon, etc. At the time I didn't know better, but DO NOT do the same (I will explain why in due course).
The main body of the Z axis was made from a length of aluminium 'U' section extrusion with a few stiffeners bolted across it. As expected the back of it wasn't flat, so I hacked out the middle with a woodwork router and then levelled the rest using abrasive paper on a flat plate (I have a 25mm thick glass plate that I use as my flatness reference).
The Z axis guides are 300mm long 12mm THK rails (more NOS from ebay). I now know that they aren't ideal as they aren't preloaded and don't have side seals (but they were cheaper than Chinese ones).
I'd arranged the rail centres such that 123 blocks were a convenient size to set the rails parallel.
The stepper motor mount (slotted for belt tension adjustment) was machined out on my mini-lathe:
To try and keep things as compact as possible, I needed to recess the Z axis leadscrew into the Z/X axis adapter. Instead of trying to machine it out, I made the adapter plate out of a couple of layers of aluminium tooling plate. The front plate was marked out and drilled with the rear plate screwed and dowelled to it. After drilling, a section was sawn out of the middle of the front plate to create a channel for the Z axis leadscrew.
The original idea was to machine the seat for the ballscrew nut with the plate assembled, but I couldn't fit them in my lathe. Instead, each part was machined separately in a fairly precarious setup using a boring bar held off centre in the 4 jaw chuck.
I was pleased with the way they fitted together
I managed to get it in the lathe to skim across the ballscrew nut seat with a milling cutter
Some welding in the next part, I promise
And so it begins…
After doing a bit of research on this type of machine (Youtube videos mainly), I came to the conclusion that while they may function as described, they were pretty compromised when it came to machining anything useful. I briefly considered buying one to ‘upgrade’ but realised that pretty much everything about them would need to be replaced for me to be happy with it.
My thoughts turned to building my own as an interesting project in its own right. I did a rough costing and it was clear that a homebuilt one would be much more expensive than Amazon, Ebay or Aliexpress’ offerings. The cost involved put me off the project – I didn’t want a CNC enough to spash out the best part of £1000 on nice, new bits, but the bug had bitten by then.
I then found out that a cheap Arduino could be used as a CNC controller and a bit of late night, alcohol assisted browsing of Aliexpress, Banggood and Amazon, and I had somehow ordered the cheapest spindle I could find, a pair of cheap Chinese linear rails, a ballscrew, a stepper motor and driver.
I should say that this project is a perfect example of how not to go about building a CNC – It's something I drifted into and was not well defined. When I first started it, the intention was to be able to do some 3D relief carving in wood, but as it progressed, I realised that I really would like to machine aluminium, even if slowly.
It may appear that there was a grand plan, but the truth is that the design evolved on the fly to suit whatever I could get hold of cheaply. The project grew legs and started running when an unused pair of 450mm long THK 15mm linear rails & bearings popped up on ebay and I managed to buy them for less than £40.
I started with the spindle and built the Z axis to suit it - The splindle was one of the cheap, 500W ER11 DC spindle motors that's all over ebay, amazon, etc. At the time I didn't know better, but DO NOT do the same (I will explain why in due course).
The main body of the Z axis was made from a length of aluminium 'U' section extrusion with a few stiffeners bolted across it. As expected the back of it wasn't flat, so I hacked out the middle with a woodwork router and then levelled the rest using abrasive paper on a flat plate (I have a 25mm thick glass plate that I use as my flatness reference).
The Z axis guides are 300mm long 12mm THK rails (more NOS from ebay). I now know that they aren't ideal as they aren't preloaded and don't have side seals (but they were cheaper than Chinese ones).
I'd arranged the rail centres such that 123 blocks were a convenient size to set the rails parallel.
The stepper motor mount (slotted for belt tension adjustment) was machined out on my mini-lathe:
To try and keep things as compact as possible, I needed to recess the Z axis leadscrew into the Z/X axis adapter. Instead of trying to machine it out, I made the adapter plate out of a couple of layers of aluminium tooling plate. The front plate was marked out and drilled with the rear plate screwed and dowelled to it. After drilling, a section was sawn out of the middle of the front plate to create a channel for the Z axis leadscrew.
The original idea was to machine the seat for the ballscrew nut with the plate assembled, but I couldn't fit them in my lathe. Instead, each part was machined separately in a fairly precarious setup using a boring bar held off centre in the 4 jaw chuck.
I was pleased with the way they fitted together
I managed to get it in the lathe to skim across the ballscrew nut seat with a milling cutter
Some welding in the next part, I promise
)
well either way loving that machine work, very good and certainly interesting ...perhaps the two mr.g should get together I wonder what you would come up with between you !
