Tool Change Calibration Methods

      From fully automated to eyeball-and-caliper manual adjustment, there's more than one way to get tools dialed in. January 19, 2012

Question
I have a Beisse Rover 30 arriving next week to replace my beloved Shopbot.
On the Shopbot, I was able to make a touch off pad and write code to auto measure tool length. Does anyone know if it possible on the NC1000 controller to retrofit a tool length touch off pad and write a subroutine using the "JP - conditional jump based on PLC bit"? If so, does anyone know of a reasonably priced aftermarket touch pad? I canít seem to find on in the US under $500.

Forum Responses
(CNC Forum)
From contributor J:
At the place I work they have a rover and I almost had to laugh when they had to change a bit and get it zeroed. They use a caliper and eye ball it then they use a piece of MDF to run a test cut. It makes my Shopbot look like it is in the next century compared to that. Like you said a touch plate is so much nicer.



From contributor X:
I'm sure Biesse has an automatic tool diameter and length probe or touch pad. I know they even have laser tool recognition on their glass/stone division machines, light years ahead of a touch pad, as it even measures profile tool length and diameters and inserts the data automatically.

The thing to ask yourself is, what is the time that it takes you from the moment you decide to change the tool to the moment your cutting again with the new bit? Both methods, already mentioned, are time wasting methods of setting up a tool. Not to mention your tool touch off is only measuring your tool length and not the diameter which may have been reduced due to sharpening.

Instead of setting up one tool setup 5 tools of the same kind while the machine is running parts and when you need to change, you just grab a fresh tool and insert it into your tool holder or spindle. A good height gauge is crucial for this method. I suggest you ask Biesse, I'm sure they have something as simple as a touch pad and more.



From contributor M:
You have to tell us more about this automatic too gauging! I owned a Multicam for years with automatic tool touch off. It was fantastic, simple, accurate, and really inexpensive. I ran an Omnitech too, same thing. It is not just the time, but the accuracy and the certainty as well that are great features. Imagine my surprise when the Holz-Her I am using now did not have this feature.

I have wondered lately just why it is that I have never seen an optical tool sensor that at least judges length and diameter, now I understand that what I have been envisioning in my mindís eye already exists? Seems to me it does not need to be too much more complex than a bar code scanner.

I generally can change one tool in about three minutes manually, length and diameter plus entering the information into the controller. My Multicam touched off all six tools in just over three minutes and the Omnitech did all eight in fewer than three. On the machine I use now I need to measure the tool length manually with a stand, and the diameter with a dial caliper or a special three flute gauge.



From contributor W:
We install the bit in a tool holder and measure it with a tape measure (accurate to less than 1mm). We route a 100mm X 10mm deep test square into a piece of MDF and measure it with digital calipers. Adjust length and diameter in the controller and it might require two minutes.

We install replacement tools before and after work, or during lunch. We have a few extra tool holders so the fresh bit is already in the tool holder when we perform the change. Even if we had auto "touch off," we would still measure a (test) part to confirm bit diameter.



From the original questioner:
It seems everyone has their own way of measuring their tools. I just know that on my current machine when I change a bit, I (or more importantly the operator who is not as careful as me as the owner) do not have to measure the bit at all. No test run. Itís very accurate and repeatable every time.


From contributor B:
I cut melamine all day long and for my application, bit diameter has never been an issue. The manufactureís specs are always within my tolerance. I have however seen too many spoil boards wasted by cutting too deep (usually slip of a digit). Cutting as little as possible through the material saves vacuum as well. I have also wasted parts of a sheet because we did not cut deep enough and the guys did not notice until after unloading. It only has to happen once every two months to cover the cost of implementing an auto system.


From contributor O:
I have a Rover C6 5 axis with a touch pad. It takes seconds to measure a tool with an automatic one touch button feature. Came with the machine last year, also comes with an HSK calibrate tool to set the height of the touch pad. The touch pad is a good feature. I deal with a company that sharpens my tools and gives the re-sharpened diameter so there is no guess work. I also have a Heian two head two table flat matrix table machine. I have a presetter and know the dimension from the head to the table with the head down. I do a quick calculation and never touch off a tool - just change my G54 work offset for my material height.



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