Author Topic: DIY CNC Router - The Bootstrap Learning Project  (Read 3938 times)

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Offline The Rusty Gear

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DIY CNC Router - The Bootstrap Learning Project
« on: June 20, 2011, 01:49:19 PM »
I have the extreme privelage of being a member of the local metalworking enthusiast club, and a small group of us have started to build our own CNC routers.  The design is by one of our members, Jim Strong.  He has completed a prototype, and is using this project to teach us all about CNC as we build our routers from a couple of XY tables, and channel iron.  The emphasis is learning about CNC and constructing a unit as inexpensively and simply as possible (total cost well under $1000) We also have the advantage of using his prototype and another CNC machine he has built to machine parts for us – so long as we operate the machine ourselves (there is that learning element again)

The machine I am building will be identical to Jim’s prototype except I will be using a larger XY table for the X and Y axis.  It is a very interesting design and is very versatile and can be modified for many more tasks.  Jim’s goal is to get us a basic 3 axis machine up and running, and then let us loose from there.  The spindle will be a Bosch Palm router which will enable us to machine aluminium.

Below are the humble beginnings of my machine.  Two pieces of 10” channel  iron joined by some 1/8” gusset plates serve as the spine.  We used a mill and reamer to ensure all the holes are precisely lined up and we are using aircraft bolts to ensure a tight fit in the parts.  They just slip right in and there is no movement even without tightening up the nuts.  The insides of the channel iron had to be milled flat so we could use nuts on the back of the bolts.  The large holes on the top and bottom are pass-throughs for the wiring, and the smaller holes are for adjustment of the axis (ie room for expansion)

In the first picture,  you can see part of the Z axis sitting on the table (a disassembled, smaller XY table) and some ballscrews to the left which I may eventually add to the setup (they were $10 at Princess Auto, so I grabbed the last pair)




Here I have set the XY table on the frame and removed the handle – I am currently trying to figure out how I will mount the stepper motors.



Due to space limitations, i've built a small table in the corner of my garage to shoehorn my project into.  I still have to figure out where I will mount all the control electronics.

Tools and Garages

DIY CNC Router - The Bootstrap Learning Project
« on: June 20, 2011, 01:49:19 PM »

Offline The Rusty Gear

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Re: DIY CNC Router - The Bootstrap Learning Project
« Reply #1 on: June 20, 2011, 02:24:37 PM »
In addition to the frame, I have been busy in the last couple of months buying components as well as soldering some circuit boards.  Two weekends ago we tried testing all the components together and ended up with this birds nest of wires.



The steppers were not working, and it took us a week to figure out why.  We were not using shielded cales (like the design called for)  The stepper controllers are putting out 30V and there was a TON of noise.

Time to re-do using shielded cable, and test using the old laptop I plan to use to run the machine (nothing like adding another unknown into the equation!)

First off is the breakout board. Pretty simple, it hooks into the parallel (printer) port of the laptop - The PCB was milled on Jim's machine and I soldered the connectors on.



Next is wiring up the 200W power supply I bought online.



These are both then wired into our home made stepper chopper controllers (a more detailed write-up will follow)  Again, we used Jim's CNC to mill the PCB board and engrave the cover, which we also machined using CNC.  The boards took me about 2 hours each to solder together.



Finally, we hook up the controller to the stepper motor.  It is a NEMA 23, 185 Oz in motor.



Here is the final test setup.  The laptop is using the Freeware Turbo CNC.



I am happy to report that IT'S ALIVE! After fiddling with the configuration settings in Turbo CNC, I was able to get the motor to move using the arrow keys on the laptop!  Very exciting! It means I didn't screw up the controller board, and everything works together! Hooray!

Offline rusty

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Re: DIY CNC Router - The Bootstrap Learning Project
« Reply #2 on: June 20, 2011, 02:46:10 PM »
Very nice write up and idea. Keep us informed!
Tool do job=Good tool

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Offline B

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Re: DIY CNC Router - The Bootstrap Learning Project
« Reply #3 on: June 21, 2011, 04:13:59 PM »
good stuff just above my skill levels

Offline The Rusty Gear

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Re: DIY CNC Router - The Bootstrap Learning Project
« Reply #4 on: June 21, 2011, 05:01:39 PM »
good stuff just above my skill levels

It's above my skill level as well! I have learned so much about electronics, machining, design, programming, etc over the past few months!

There is no way I would have been able to tackle this project if there were not already a prototype built, available with the guidance of it's creator and a group of DIY gurus working with me!

Offline The Rusty Gear

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Re: DIY CNC Router - The Bootstrap Learning Project
« Reply #5 on: July 15, 2011, 11:09:23 AM »
Here is some more detail on the Controller boards.
They heart of the Stepper Motor Bipolar Controller is the Toshiba TB6560AHQ. The chip contains all the logic to input Step and Direction signals from a computer and drive a stepper motor in four wire bipolar mode. The chopper can run up to three amps per winding. It does proper vector current control for full step, half step, quarter step, or eighth step modes. Source power can be up to 35 volts.
We used our prototype CNC machine to mill out the PCB boards, and they came out like this:



A couple of in progress pics



I bought a Hakko soldering station specifically for this project and it certainly make the soldering more pleasurable than I would have thought – though it still took almost 2 hours to wire each board.
Once all the components were soldered, we added the “box”, which consisted of a head sink “wall” for the chip and a top and bottom plate.  The heat sink is drilled and tapped for mounting inside the electronics enclosure and the chip is screwed to the heat sink after thermal paste is applied.

The row of 4 DIP switches closest to the chip are for the different settings for the chip and the row of 6 switches are for hooking up the different resistors to vary the current going to the stepper motors.

All parts machined on the CNC we will be building and cost about $20 each to make.

Offline The Rusty Gear

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Re: DIY CNC Router - The Bootstrap Learning Project
« Reply #6 on: July 15, 2011, 11:17:09 AM »
Here is a picture of the prototype unit. Sorry about the bottom of the pic - I can't get my phone to upload it properly.

You can see it is using a smaller XY table than the one I will be using, but it certainly gets the job done!

The spindle is a variable speed Bosch palm router, which cuts circuit boards and aluminium quite nicely.




Offline B

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Re: DIY CNC Router - The Bootstrap Learning Project
« Reply #7 on: July 15, 2011, 04:56:44 PM »
Looking good
The electronics that are above my head , even wiring motors is just not a concept I get , I may get it if I do it with help but I will not remember enough for me to be comfortable with it.

A lot of guys tell me to get a dc motor off a tread mill with the speed controller to put on my drill press for easy speed changes, problem is I have only an elementary understanding with no real capable application.

I am somewhat versed in master cam and auto cad, I can manual mill and lathe if given the tools and machine. ( not enough to be pro)

Offline The Rusty Gear

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Re: DIY CNC Router - The Bootstrap Learning Project
« Reply #8 on: August 09, 2011, 05:57:25 PM »
As part of the learning curve, our group was given an assignment:

Measure our routers and create the G-code to machine a clamp to hold the router.  After making a hand sketch (and borrowing heavily from the existing design) I drew up the clamp in BobCAD, and then used BobCAD to generate G-Code for the outline of the clamp.

Unfortunately the version of BobCAD I'm using is 2D so the G-Code generated is only good for one pass.  I had to then take this Gcode and put it some depth commands to cut to the entire depth of the piece.

I didn't take any "in progress" pics, but here are the finished clamps, along with a 1" x 1" spacer. 



The four holes on the clamps were also drilledd as part of the CNC program, but the clamps were a solid piece.  I drilled the "bottom" half of the boss for an 8-32 tap, then drilled the top half to clear the tap.  After tapping the bottom half of the hole, I cut the boss in half (approx where the threads start) to create my clamp!  Further work needs to be done to mount the clamps to the spacer block, and then mount the entire assembly to to the Z-Axis. 

Offline Heiny57

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Re: DIY CNC Router - The Bootstrap Learning Project
« Reply #9 on: August 10, 2011, 07:26:21 PM »
 :spincl:   :beerdude:
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Offline rusty

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Re: DIY CNC Router - The Bootstrap Learning Project
« Reply #10 on: August 10, 2011, 07:28:20 PM »
Very nice work I wish I had the room to do something like that.
Tool do job=Good tool

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Offline 79pacecar

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Re: DIY CNC Router - The Bootstrap Learning Project
« Reply #11 on: August 11, 2011, 11:58:44 AM »
As part of the learning curve, our group was given an assignment:

Measure our routers and create the G-code to machine a clamp to hold the router.  After making a hand sketch (and borrowing heavily from the existing design) I drew up the clamp in BobCAD, and then used BobCAD to generate G-Code for the outline of the clamp.

Unfortunately the version of BobCAD I'm using is 2D so the G-Code generated is only good for one pass.  I had to then take this Gcode and put it some depth commands to cut to the entire depth of the piece.

I didn't take any "in progress" pics, but here are the finished clamps, along with a 1" x 1" spacer. 



The four holes on the clamps were also drilledd as part of the CNC program, but the clamps were a solid piece.  I drilled the "bottom" half of the boss for an 8-32 tap, then drilled the top half to clear the tap.  After tapping the bottom half of the hole, I cut the boss in half (approx where the threads start) to create my clamp!  Further work needs to be done to mount the clamps to the spacer block, and then mount the entire assembly to to the Z-Axis.



Nice Work!!!!   

But I am surprised you didn't cast those parts first and then machine them!!! :beerdude:



 
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Offline The Rusty Gear

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Re: DIY CNC Router - The Bootstrap Learning Project
« Reply #12 on: August 11, 2011, 05:06:38 PM »
The reason I didn't cast these was we there was some plate on hand and the challenge was to go from concept to machined part in one sitting/evening.

One of the reasons I was wanting to build this CNC machine was to use it to cut out MDF patterns for the foundry!

Offline rusty

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Re: DIY CNC Router - The Bootstrap Learning Project
« Reply #13 on: August 11, 2011, 06:50:53 PM »
Makes good sense to me. If you don't do  it all the way why try?
Tool do job=Good tool

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payable to 'The United States of America,' for an amount of 'up to, and
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