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CNC router

UKworkshop.co.uk

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Anonymous

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Just wondering if anyone else has built themselves a CNC router table? I completed this one around 1 year ago, and still haven't put it to good use! As you can see, I use it for all kinds of projects, not just in wood.

 
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Anonymous

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Looks pretty decent Kong. A few members have considered it over the past year-or-so but I don't think any got off the ground.

What do you use to contol it HPGL?

Also, the motors look like large steppers in the photo but can't see how you engaged the drive (linear rack?). Can you tell me more about it? open forum or pm is fine
 

Neil

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Tony":wou7ygzp said:
open forum or pm is fine
Open forum please!! :D
Even though I am completely incapable of making something like this, I'm still really interested to hear all about it.
Sorry I was lost for words earlier, Kong - it really it a fantastic-looking piece of engineering.

Cheers,
Neil
 

radicalwood

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Hi Kong.

Looks like a good piece of engineering, you taking orders for routed patterns with that system ? there must be a market out there for it. What is the max size you can do.

All the best

Neil
 
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Anonymous

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:oops: Wow, nice reponse everyone, thanks!

Tony, and anyone else wanting to build one - I have the complete build fom start to finnish photgraphed, and I am more than happy to share all the details with you. I gotta admit, thee is some money involved, but if you can understand the principals of how it works, thee is no reason why you can't build a "budget" machine.

The drive system is leadscrew. You can't see them, since the main screw to drive the gantry (main bridge if you like) is below the table. I have a photo to explain:



The motors are servo motors - DC motors with an encoder (similar to the holey disc inside your mouse) which lets the motor controller know how far the motor has moved.
The whole system is programmed via g-code (think 3d graph-paper) and run by a standard PC.
I gotta admit, I built this using "everyday" tools - table saw, drill press, etc. so it should be perfectly within the limits of most of us here.

radicalwood - I will try to send you a PM.
 
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Anonymous

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Hi Kong

This is my specialist area as you may have seen from my profile and so I would be very interested to hear more about the specs of the system. Could you let me have details of motors + controllers and encoder resolutions you used etc.

With dc servo motors and controllers + and lead screws + linear bearings and slides, you must have made a significant outlay for the system.
However, I know of a few people who have asked me build one for them and if you are interested in making them for other poeple, then let me know and I will pass on details.
 

wizer

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i'd love to see the whole build process and some more info about it in use.
 
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Anonymous

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Crikey look at that, I never thought to look at your profile, but I have now!

I bought a lot of stuff from the USA. Geckodrives (www.geckodrive.com) supply the servo motor drives, which drive 24v 8A servo motors with 256 PPR encoders (sorry guys, PPR - pulses per revolution - as the motor turns, it sends a pulse to the motor driver to say, "I have moved" so 256 ppr gives 256 pulses per 1 revolution of the motor). Using quadrature encoders brings the PPR to 256x4=1024. I used a 1:1.5 reduction on the motors for a top speed of around 4200mm/min with a torque of 540 oz/in torque.
I used 4mm pitch trapezoidal leadscrews with anti-backlash nuts, giving a theoretical resolution of.........something like 0.002mm. Of course in practice this thing only gets 0.2mm accuracy, but part of the reason is flex in the router spindle and those gantry sides are only 1/2" aluminium plate.

I guess I have never thought of building them, but to be honest, it would be a nice. Perhaps we could discuss this off list?
 

Chris Knight

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Kong,

That is quite a machine - fantastic piece of work! It could be great for someone wanting to make complicated joints or numerous small pieces I imagine (thinking of woodwork rather than metalwork here)

It's a bit like a Woodrat on steroids! I guess that makes you King Rat - if not King Kong!
 
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Anonymous

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Lol, here is what it is good at - carved sign in under 6 minutes.
The piece of oak upto the pencil line is 450mmx150mm. The lettering is carved variable depth with a regular 60 degree cutter.





Of course there was some programming invloved, around 10 mins to draw the lettering and tell the computer the size of the stock. Not too long though eh!
 
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Anonymous

Guest
At the risk of insulting everyone, here is how it works.
There are a pair of steel rails at the bottom of the machine, on these rails run big bearings (sliding bearings). The main bridge sits on these bearings so can run freely the length of the base. If you add a fixed screw to the base, with the nut attatched to the bearings, when the screw turns, the nut moves, taking the whole bridge assembly with it up and down the rails.
Now then, across the top of the bridge there are another two rails, with big bearings, and another screw to move the router along. So you see, by controling the two screws rotation, we can move the router left-right and back-forth - just like a graph, we have an x-y axis.
Of course we need height control for the router, so another set of rails/bearings/screw is added vertically, and it slides on the bridge. This holds the spindle itslef, and is known as the z-axis.
Through the miracles of modern technology, I can take a 3d drawing done in a 3d CAD program, and have the computer break it down into plotted points like a regular graph - x1, y2 etc. The computer now turns the screws to move the spindle to that location. Once it is there, it gets the next location and moves the router to there, and so on.

This is the best photo I have to explain it. You can see the three pairs of rails, and two screws (z-axis screw was not in place at the time). On the end of each screw is a motor, controlled by the computer.



Clear now I hope!
 
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Anonymous

Guest
:shock: I'd love to have one of those. It has a huge potential.

Have you made any other more elaborate projects besides those letters?

Pedro.
 
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Anonymous

Guest
The machine probably cost around £4000 with all the software. If oyu compare that to the commercial machines available, it is a very cheap machine.
Yeah, I have made plenty with it, it will cut/carve whatever you can draw. One of my favourite pieces is an MDF/hardboard radiator cover.

 
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Anonymous

Guest
No, it is all biscuit jointed MDF rails/stiles with hardboard panels. The total length is around 7 foot. If you look closer, you will notice a bit of engraving done on the MDF in the centre.
 
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