Use this forum to post pictures of your Quick Cut CNC and the setup you are using!
By hroth
#428
I'm still sealing the MDF pieces and building my enclosure for dust control, but I keep thinking ahead and wondering when in the process there is machine calibration. How do I calibrate the machine so that the machine knows that z=0 is when the endmill is resting on the table surface? Is this a function of the CAM software, CNC software, the control box? Do I have to calibrate every time I change the endmill? Even when calibrated the CAM software could still direct the machine to mill into the table surface, correct?
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By AJ Quick
#429
This is a function of Mach3, that you must setup in order for it to work. It might not be worth setting up without home / limit switches, as you will need to re-calibrate it every once and a while.

But you can set what are called soft limits.

Turn on Machine coordinates, and put your machine in the (0, 0, 0) position. Set all your machine coordinate zeros there. Move your machine to the maximum coordinates. It should be something like (18, 12, 3).

Open your Soft Limits window in Mach3. Set your lows at 0,0,0 and your high at whatever you found as the maximum. Your software will then force the machine to never go beyond those measurements.

Also. I wouldn't set your table surface as Z = 0. You will end up cutting into it unless you also use a sacrificial piece of wood between the table and the part you are cutting. I would set the top of the piece you are cutting, as Z=0, and cut negatively into the material. You will need to set this for each new piece you cut... but it only takes about 10 seconds to move your bit down toward the material, barely touch it (stick a piece of paper between the work and bit) then set your Z=0.
By atmamatt
#433
I agree with AJ on this, never make the actual table surface Z0.0. AJ's solution of setting Z0.0 off top of part and cutting negatively works very well. If you feel the need to speed things up though and are cutting a large number of the same part(s), Z0 on bottom is faster. If you choose to set this up, then I recommend setting Z0.0 as the bottom of the sacrifical material (piece of wood or plastic clamped to the top of the table). Regardless, you want that sacrificial material there.

I do believe I have seen probing add-ons that will automatically set Z0; Renishaw makes one, but those are pricey, I do not know if there is a less expensive one out there.
By atmamatt
#439
actually here's a better idea. A planer guage can be set under the tool. when its just moving under the tool with the slightest bit of friction, set z0.0, remove the guage carefully, and measure it with calipers or micrometers, then set that as your z-offest.

another way using the fowler block or 1-2-3 block uses these steps.

1.with the spindle OFF you slowly jog the spindle down til you're close to the height of the block. DO NOT HAVE THE BLOCK UNDER THE SPINDLE TO BEGIN WITH.

2. With the block clear of the tool, bring the tool down just a lil past the top of the block or close to it as possible.

3. Slowly and very gently press the block and try to slide it under the tool. if it goes under, pull the block away and and slowly move the spindle down a little more (0.010" increments if possible) until the block does not go. If the block initially does not go, slowly raise the spindle up (in 0.010" increments) until the block clears under it.

4. Repeat step 3, but do it in 0.001" increments until the block clears under the tool (you should feel a lil bit of resistance, like it is just touching/rubbing barely).

5.If you feel the need to repeat step 4 to double check, do so now, its honestly a process based on touch and comfort, but its extremely accurate.

6. set z0.0 when comfortable with your settings, and measure the block and plug in the number as your z-offeset.

7. If you're using a 1-2-3 block, you should be set to within 0.001"-0.002". using the fowler block, it may have you raise or lower the the tool a lil to set it off, the important thing is that you DO NOT actually raise/lower the tool while the block is under it. This could cause a crash and damage the tool, the block, the spindle, and could hurt you badly.

the planer guage is the best method, I feel, for ease of use. the other two methods however would give you a more accurate reading on high precision machinery.

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