Thread: MDF CNC kits

Forgot to add the camera is 15mm in diam to give you a size to work by.

Thanks for that

So you don't zero the webcam to the centre of the spindle? It looks offset so I assume it's looking to the side?

Now I have another question. This one relates to setting up the motors in Mach3. Have I worked this out right

Steps per revolution: 200
Step Resolution: 8 micro steps
Screws: M12 thread 1.75 pitch

200x8 = 1600 / 1.75 = 914.28571428571428571428571428571

So I need to put the final number in the "Steps per" box of the Mach 3 Motor Tuning and Setup screen?

Yes the camera is offset but the button script puts the spindle dead centre of the camera crosshair when you press the button. Is a real advantage as you do not have to mount.demount the camera each time. Do the Z axis after this and you are set up and running in very short time.

Yes your calculation is spot on. Mach3 will probably only let you enter the whole number 914 first time. Do the calibration and it will set the steps to decimals. Don't get hung up on the decimal points as 1/914 of a mm is 0.001mm and better than you can measure even with a vernier.

Yes again, the steps go in the motor tuning screen as you say. Don't forget to set the pulse to 2 or higher in the same screen. Xylotex need a 2ms pulse.

Ahhh ok, now I get it. I'll be back with some more questions when I get a camera

I went for broke and entered in the numbers before. I just finished cuting some air (too late to start the router) and did some moves with the MDI screen and everything seemed to move the right distance. I just laid a ruler on the table and eyeballed 20mm movement on the X and Y.

Is the 2ms pulse for the "Step Pulse" or the "Dir Pulse" box? I had zero in both pulse boxes. What does the pulse do?

Now we are getting in the electronic technical side which I refer to as mumbo jumbo.
As best as I understand it is the width or duration of the pulse. It just gives a little more time for the electronics to see the pulse. Obviously 2ms is a very small time so it is not like it is holding anything from happening. If you hop on the zylotex site or maybe in the instructions there is a graphic that shows the signal as a flat top 2ms duration pulse.

Like I said all mumbo jumbo to me and I hope I have not led you astray with my explaination. You set them both to 2 or as high as 5.

Now you have it running you will be wishing away the hours until you can run the machine for real.

When you get serious about calibration I just set a verier on the table and push the jaw with a set move in MDI. Compare the vernier value and you have your calibration done. Some cut a square and measure the job for accuracy but this assumes the cutter is exactly the right diameter.

Just to add to this step duration setting discussion, some more useless info.

The step length when set at zero is 5us. When set at 1 it becomes 6us, set at 3 it is 8us, at 5 it is 10us. etc.

That is micro seconds. A microsecond is a millionth of a second. A millisecond is a thousandth of a second.

Just set it to 2 in Mach if that is what Xylotex recommend.

I use Gecko drives and set mine to 3 as they recommend. But can see no difference if set at zero either.

Greg

I was just giving some thought to workholding on the table and I was wondering what would be a good method.

I'm considering attaching a bit of 300mm wide MDF to the table and getting some of those T tracks from Timecon spaced about 30mm apart (anyone know how wide the T tracks are?)

Cheaper here

http://www.woodworksupplies.com.au/category73_1.htm

Greg

It was raining today so I got a break from fence painting and finally modified the table.

Using 24mm MDF and T-Track from woodworksupplies (Thanks for the tip Greg).

This has increased the usable size of the table to 430mm x 300mm.