"Use Thickness" and how to use it?

[stkenitz]

I am measuring a part that has .003" material left on the top (orange surface in photo) for grinding stock.

The points you see going around the threads I am trying to measure the T-Value of to see how much more we need to EDM off of them.

So in the point feature window, should I set my T value to THEO or ACTL to account for the grind stock? The threads are tapered at a 45° angle, so I am assuming the T-Value should also be .0021 and not .0030?

[KIRBSTER269]

Um, no 2 threads are the same. so taking T- values on the thread won't repeat, for one time you might be on the peak of the thread, while another you'll be in the valley. not sure what you're trying to accomplish here.


correction, unless of course the threads were created by a die, is this a casting? I'm doubting this, but will ask the same.

[Tinyfxds]

We use T values all the time on our parts to check how much stock is left on shutoff surfaces. If my z zero was on the top surface, I would adjust that in my alignment and run the program as is. This would adjust the position of the points accordingly. I've never checked threads before using the T-value but I would think it would work the same.

[KIRBSTER269]

If you read what I stated above, it won't work, unless the threads are formed Identical, I took example pictures showing on my plate all threads are 1/4- 20. Taking a stand and put a black mark on one tighten to the plate, highlighted it cause not very clear and moved it one hole over as you see the threads don't line up the same, this is why it won't work. threads are not clocked exactly the same.

IMG_0767.JPGIMG_0768.JPG


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[stkenitz]

This is a part where we are EDMing/burning the threads, not a cast or injected part. The threads are large.

So...I will try to explain as best as I can. The threads should theoretically be in the exact same spot from part to part, because the electrode, pickup, etc. are constant. It is all fixtured and oriented the same, the thread start/end location is the same.

So, I am taking a vector point at a given Z height, every 22.5°. The top flat has .003" left for grinding, and the threads are pitched at 45°. So...theoretically if we moved the part up the .003", the surface would only change by .0021" if you trig it out. (Z vs the 45°).

I'm sorry if that doesn't help much...I can try and draw something up or take some more snapshots.

[KIRBSTER269]

Ok, no problem, From the very beginning manual alignment and DCC alignment, your initial plane, to level and Z origin, click on that plane and before moving the points around, change the Z value to .003. Then move your points where you want them to hit on your imaginary part, according to your CAD. Do this for both alignments. This way it would account for the extra material.

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[KIRBSTER269]

sorry that should be .003 my bad

[stkenitz]

That makes sense. Should it be -.003" Since the actual Z0 is .003" below the current material surface? Sorry. I have had so many intricate and unusual parts in the last few weeks...my brain is fried.

However we already measured the part, re-burned...re-CMM'd and laser scanned. Turned out good. I just wanted to double check that the .0021" T was correct.

[KIRBSTER269]

you said it had extra material. If your CAD model is the right size, and your part has extra material, then that surface would be higher so plus .003