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Building a CNC router - Complete guide

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Anonymous

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Well, here we go. There is a LOT of info here, some you will understand, some you wont. If anyone is serious about building one of these machines, you should do some background research first, and visit a few websites about the subject. A lot of money is involved, so this is not for the faint hearted!

I have explained how the motion works, a fixed nut, caused to move by the turning of a screw. The motor which turns the screw is controlled by the computer. Obviously the machine needs some nice bearings to run on, and I picked up some lengths of 40mm diameter linear bearing for a song. Used, but good condition. brand new you are looking at £2500 for these alone. Here I have stretchered two linear bearing rails about 2' apart, and bolted a couple bits of 1/2" ali plate between them to form he base.

The next stage is to build up the gantry sides, and add two more linear rails across the base, to form the y-axis. You will notice the linear bearings have been added to the base (x-axis) rails, so the gantry assembly is free to slide back and forth along it'slength.

Excuse the rust, it was a humid August when I started building, so I partly built the machine outside!
All of the aluminium came from the scrap-yard, and was cut on the tablesaw using a negative rake blade for aluminium. All the bolt holes were drilled then tapped, and the connectora are regular socket-headed cap screws.
Next job was to build the z-axis. This is the part which will control the height of the router itself. It rides on smaller linear bearings (25mm) and only moves around 8". Since I took the time to draw out this whole machine in Turbocad first, I knew the exact size it needed to be, and the exact location of each and every hole I needed to drill. Here is the mock-up iof the z-axis.

Once the machine was moved to the shed, the z-axis was fitted onto the y-axis linear bearings, and I began to add the motion parts for the router to move on.

Oh, excuse the mess! That blue dye is marking-blue. It gives a clearer line on aluminium if you use a scriber to mark your holes. As you can see, the z-axis can move left-right, and the whole gantry can move back and forth. No up-down motion yet, that is next.

Here you see the z-axis linear rails in place, and a little bearing at the bottom. The leadscrew will eventually ride in this bearing to control he motion of the router up-down.

Coffe break!
 
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Anonymous

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Ok, you saw the little square blocks on the z-axis slides, well they are the carriages which will hold the router itself. Yup, homemade, but if you don't have a lathe for metal turning, you can pay around £40 for one block!!
This project really does benefit from thee use of a lathe, and it may work out cheaper to buy on for the project, then sell it on once you are done.

So, this thing needs some screws to control movement of the axis, and a method to attatch the nuts to each axis. For the x-axis (base of machine) I bolted on a long length of ali underneath the base rails, and mounted the nut to this assembly. It looks a bit bodged, but it works great.

For the y-axis, the screw is in place, and attatches to the z-axis assembly behind the z bearing rails. It is in the photo below, and you cam also see the z-axis screw in place, along with the router mounting plate, which the nut is bolted to. If you can see that when each screw is turned, it will create a different movement of the router since the screws are fixed in place, and the nutswill move, causing whatever they are bolted to to move.


Next job, motors to turn the screws! This was relatively easy, since the screws are held in place by bearings, all I needed to do was attatch a pulley onto each screw, then attatch the motors via a timing belt. here are some shots of the motors mounted.
http://www.btinternet.com/~jasonrsmith/uber_router/motor_side.jpg[/img

[img]http://www.btinternet.com/~jasonrsmith/uber_router/zaxis_top.jpg

Ok then, I had gotten the motors on, I wanted to test it out, but first i needed some electronic wizardry to interface the computer to those motors. I used "geckodrives" which are driven from the PC parallel port to control the motors. I got the mall wired up into a nice metal box, et voila

Yep, the less said about that the better! Most of it is 5v signal connections believe it or not, and is not dangerous at all. There are only 3 wires in from the big 24v 30A power supply to the gecko drives, and 3 wires out to the motors themselves. the rest is used for various PC control stuff. If you work through it logically, the wiring is easy. Looking at it all at once like that though, it looks impossible.
Unfortunately how to control the beast is way beyond the scope of this howto, but I used Mach2 software from artofcnc.ca so that is a good place to go and look around.

Next up was a temporary table-top, just a piece of ply. Now the machine was working, I bolted on an old crappy router, and used it to cut the router maounts for the Makita RF1101 (US model) router I was planning on using. The cuts are 1mm deep per pass, and it took around 20mins to cut these two mounts.

And here is the router mounted


Whats next.....A table top. Originally, I went for a wooden top, but this had too much sag. For £300, I bought some 20mm thick aluminium extrusion which is designed for this exact use. It is t-slotted, so can be used for clamping to, too! Firstly though, I ran some support pieces of angle-ali across the base, jsut to be sure I could get the maximium stiffness possible.


Well that's about it really, there are a load of details missing, what type of bearings, screws, and so on, but TBH, anyone p[reparing to build one of these machines should have the patience to get out there and find this info out. If you have a ,imited budget, you will go for cheaper bearings/screws, and if you havemoney to burn, you will go for a different type. So, you see, you can use any old iron for this, but the more you are prepared to spend, the better a machine you will have. Faster, more accurate, etc.
There are bound to be a load of questons now, so fire away!
 

Newbie_Neil

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Hi Kong

I was impressed before, but now I am speechless.

A tremendous piece of work.

Cheers
Neil

PS Where did you get the aluminium extrusion from?
 

dedee

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Kong,

way over my head but nonetheless fascinating.

Is there anything beyond the capabilities of this groups members?

Andy
 

Neil

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Fantastic stuff, Kong - thank you for going to all that trouble.

I'm a bit overawed at the complexity & the cost, but there are still useful aspects I can take from this for my pathetically unambitious projects :oops:

I must admit I'm tempted to commission you to CNC-mill some alu pieces for my Neil-Leigh (geddit?) FMT clone :D

Cheers,
Neil
 
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Anonymous

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Neil, yep, very complex and very expensive. But if you understand the principles, there is no reason you cannot build a machine from MDF! Obviously there are alternatives to linear bearings, I have seen people use bearing-guided drawer runners of all things! It can be done on the cheap (say £500) but you do get what you pay for in the end. As for parts, just yell! info@cnccraft.co.uk
 

Gill

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Wow! This is beyond both my means and my skills but it's wonderful to look at how a home made CNC machine was constructed.

We definitely need a drool icon :) .

Gill
 

ProShop

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As I said in an earlier post I saw a couple of these machines at WoodMex last year and was very impressed at A: what could do, and B: the quality of the finished product. And now seeing how to make one I'm even more impressed.

"Proper Job" :D
 

woodshavings

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Hi Kong,

That was very interesting - what a superb project! :mrgreen:

I bet you were pleased to get those linear bearings at a good price!

I have a project (much, much simpler than yours!) that requires linear bearings. The only source I have found is RS Components and they are a fortune!!

Thanks for taking the time and trouble to post - very much appreciated.

John
 
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Anonymous

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Thanks for the nice comments guys (and gals) :oops:

Woodshavings, depending on your project (I am thinking sliding table?) you could opt for the non-supported type of bearings, like I used on the z-axis. Still expensive, but if you go for something like 25mm diameter bar, the stiffness is excellent and the cost is reasonable. You could also try ebay.com (US site) for some linear bearing bargains.
 

woodshavings

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kong":2993rn6j said:
depending on your project (I am thinking sliding table?)
Its not a sliding table !" I'm planning a router table with the router tracking north/south with a fixed rear fence. In this way I can combine the fence of the router with the mitre saw station. I need a pair of linear bearings for the router guide which I am intending to position with a lead screw. (manually driven, not cc !)

John
 

miles_hot

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how do I remove all the ***report to moderator*** stuff from Kong's posts? Obviously others saw the pictures etc however they don't seem to be accessible now as I can't guess what the missing bits are!

Many thanks

Miles
 

wizer

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There would be no point, all the pics links are now broken/gone

For future reference, if you click the 'Quote' button and then Preview Post, you will see the pics.
 

miles_hot

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wizer":2kybmqfn said:
There would be no point, all the pics links are now broken/gone

For future reference, if you click the 'Quote' button and then Preview Post, you will see the pics.
nice tip - thanks for that. Shame that the pics have gone and Kong seems to have gone the same way...
 
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