SuperMill
Newzed
Posts: 2,503
I have received a lot of nice comments about the boards I have made on my SuperMill, so I thought I would take some time and tell you how SuperMill evolved. First, the basic mill is a Proxxon MF70. Here is the link:
http://www.productiveworkspace.com/detail.aspx?ID=93
The price is $290.00 plus UPS. You will note it has three handwheels. These wheels are very difficult to remove, but the little crank handles on each wheel comes off quite easily, so that’s what I did. Now you need an adapter to fit over each wheel to receive the stepper motor. The adapter needs four set screws to hold it tightly to the wheel, and it needs a 1 inch dia. extension about an inch long with a .250 hole for the stepper motor shaft. The shaft is held in place by two setscrews. All my adapters were made by Russell Ferguson at russellferguson@msn.com. I’m sure he still has all the drawings. If you have machine shop capability, or have a friend who does then you can make them yourself.
The stepper motors I used are STP-MTR-23055 at
http://web1.automationdirect.com/adc/Shopping/Catalog/Motion_Control/Stepper_Systems/Motors_-z-_Cables/STP-MTR-23055
They do a very good job and have the power to run the mill axes. You will need a controller for each stepper. I used the IB463 from Intelligent Motion Systems at
http://www.imshome.com/ib_46x.html
I use them in the half-step mode, which gives me excellent accuracy. If you can build your own controller then you can save some money.
On the X drive, I considered mounting the stepper direct to the X table but decided against it. My stepper slides on a sheet of polished galvanized steel which I keep lubricated with white lithium grease from a spray can. A picture of the X drive is attached.
I have also attached a picture of the Z drive. Rather than mount the stepper to the drill motor frame, I simply clamped it in place with two pieces of 1/8" aluminum and two long ¼-20 bolts.
There is a bit of strain on the Z stepper when it is moving the drill motor up. The drill motor is quite heavy so I slowed the stepper down to about half-speed by increasing the delay between pulses to the controller. Works very well.
The Y axis is another story. My workbench was not deep enough to permit mounting the stepper directly in front of the Y table so I moved it over to the side and used a timing belt between the shaft of the Y table adapter and the shaft of the stepper. Here are the Small Parts, Inc. part nos:
Belt – TB6-150-01
30 tooth wheel – TBPN-30/D-01 ‘goes on Y table shaft
15 tooth wheel – TBPN-15/D-01 ‘goes on stepper shaft
This gives a 2:1 reduction which I needed because of the old Gecko controller I was using. If you do not want the reduction just use a 30-tooth wheel on both shafts. The attached picture of my Y drive should show how I have it arranged. There is room for improvement here.
I started out using a BS2E to control all the steppers, but then I switched to the Propeller Demo board, which gave me a tremendous increase in accuracy because of the larger numbers the Prop can handle. If you are smarter than I am, you can probably make a true CNC machine out of this. I don’t know CNC, so the Prop gets its etching and drilling instructions from a DAT list which I have to laboriously compile. However, it works for me so I’m happy.
SuperMill has already paid for itself. So many times I need a small board for a project. I lay out the board, compile the DAT list, load it into Propeller, and in about an hour I have my board – etched drilled, trimmed and deburred.
Sid
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Yesterday is history, tomorrow is a mystery, and today is a gift.
That is why they call it the present.
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Newzed@aol.com
Comments
Thanks for the tour Sid. That is some inspirational work.
I was adding the numbers in my head.
Can I ask what you paid for the IB463's. If I understand correctly you bought three of those.
Is is sold under a different name? Not much for retailers on Google.
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- - - PLJack - - -
Perfection in design is not achieved when there is nothing left to add.
It is achieved when there is nothing left to take away.
ALovisek@aol.com.
Sid
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Yesterday is history, tomorrow is a mystery, and today is a gift.
That is why they call it the present.
Don't have VGA?
Newzed@aol.com
·
program and show you how to compile the DAT files that the propeller uses.
Sid
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Yesterday is history, tomorrow is a mystery, and today is a gift.
That is why they call it the present.
Don't have VGA?
Newzed@aol.com
·
Thanks for the machine write-up on SuperMill. I had seen reference to it in a couple of threads but was not sure what it was.
Question: Most homemade, stepper-controlled CNC machines that I have seen use a PC to interpret G-Code and send signals from the parallel port to control the steppers. You appear to not be using G-Code or a PC for control. Why?
Will you explain in more detail how this increased the accuracy of the machine?
Also, I would really enjoy understanding how you go about generating the data that controls SuperMill. I have seen reference to it before. It would be great if you could include it or link to it here.
You have done a fine job of finding unconventional solutions to technical challenges. The results I have seen in previous threads (You will post or link to some of those as well, I hope!) speak for themselves. Nicely done!
- Sparks
I don't use G-ccode because I cannoit generate it, and even if I could, I don't really understand it.· I am using a Prop Demo board to control the mill, which as far as the mill is concerned, is a PC.
Will you explain in more detail how this increased the accuracy of the machine?
I went through a lot of math to determine that it took 5156 pulses from the BS2e to travel 100 mils.· If I wanted to travel·less than 100·mils, I had to use the */ operator, which is close but not exact and led to a cumulative error.· With the Prop, I can specify exactly how many pulses I want to travel for a given distance.· N t only that, but using a dial indicator, I could determine exactly how many pulses it took to travel 100 mils, and I could adjust the number of pulses 1 or 2 at a time to get exactly what I wanted.· It's really a bit more complicated than that but that is the general idea.
Also, I would really enjoy understanding how you go about generating the data that controls SuperMill. I have seen reference to it before. It would be great if you could include it or link to it here.
Sparks, I think I will write a separate post on how I compile the DAT list.· Thank you for your interest - you should build one.
Sid
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Yesterday is history, tomorrow is a mystery, and today is a gift.
That is why they call it the present.
Don't have VGA?
Newzed@aol.com
·
Thank you for the additional information. If I understood your answer to my accuracy question, some resolution was being lost buy only being able to use 16-bit values with the BS2 versus 32-bit values with the Propeller.
As for building my own CNC machine someday… I surely would like to do that! Sadly I am bogged down in more necessary projects at the moment. Perhaps I can make one as a winter project.
- Sparks