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Renishaw TP20 modules

Hello,

In my company in TIGO SF machines we use TP20 modules in various configurations. Normally they use low force modules when a 0.5 tip is mounted and a 6way module for all the rest. The TP20 machines as compared to TIGO machines with X1C head are way...way less repeatable/accurate.

I read in the specs that 6way are generally less precise than standard force modules and also more expensive. I would like to replace 2 probes specifically 1 with 6way that is in star formation (length of probes out of specs with 40 mm vertically and 1 tip at 30 mm horizontally) and a low force module that is in star formation with 0.5mm tips left right and a pointing (x+) 2x40 mm tip. I know both probes are out of specs but replacing them with standard force modules does not seem to improve the results by a lot (at least some preliminary testing).

So i would like more experienced user to let me know if using low force modules in star configs is a good idea (out of specs according to renishaw), how can I mount a 0.5mm in a star probe if a low force module is needed and finally what are your opinions of 6way probes for none special applications needing measures in Z-

Thanks in advance!
  • If you don't need Z-, then don't get a 6-way. I have a 6-way but I need to get underneath the part. I have one medium force module, several standard, and two low force.
  • 6 way probes are the only ones that are designed to be "pulled" to get a reading. All other forces are only meant to be "pushed."

    With that said I would not recommend changing your 6 way star probe, made to take a Z minus reading to a standard force one.

    I have a probe that is basically an "L" for measuring in Z minus, on a 6 way TP20. We used a 50mm carbon fiber extension, to a 5 way star, and then a 2x20. It calibrates and measures just fine.

    Maybe your build is too heavy for the 6 way. Try taking the 40mm off, and see how the 30mm does just by itself. (if I read your description right, sounds like that was two tips on one probe.)
  • The thing is that the rack with the 6ways and in general the whole build of the probes is how I found them. We have many programs, validated since many years ago that work like this and any change for example going from 40mm to 30mm would require work not worth having. I know for a fact that we don't measure in Z- by pulling so 6way modules are not needed and for me it was a mistake done many many years ago by the person that build the rack.

    The issue now is that I seem to be unable to get good results with a 0.5 tip if not used in a low force module, while having a low force module in conjunction with a star formation is a no go per renishaw.
  • IMHO touchspeed is just as relevant in this discussion, as the modules themselves.
    Any probes under 1mm should have a significantly reduced touchspeed implemented (and calibrated whilst set to to the slower touchspeed), any time it is used.
  • IMHO touchspeed is just as relevant in this discussion, as the modules themselves.
    Any probes under 1mm should have a significantly reduced touchspeed implemented (and calibrated whilst set to to the slower touchspeed), any time it is used.


    That's true, I am using 1mm/s for 0.5mm tips while 3mm/s for anything bigger. Sometimes I go up to 5mm/s for 2mm+ tips but this is very rare. In any case, my problem still is there. I went from star configs to single 0.5mm tip with low force module and dropped my standar deviation to half. Still not perfect because I still use a 6way module to form the primary datum and I think this is what is holding this validation back atm.