Probing with a TP-20

[GoBeavs]

Does anyone have any experience with using a TP-20 with their arm?  I have extra TP-20 tips from our CMM, and I am considering getting a "TP-20 Touch Trigger Adapter Bushing 32931" for my Romer Arm:



For you guys that don't know, a TP-20 uses a magnetic sensor that measures the contact direction when the ruby tip makes contact with a surface.  Then, the software can automatically calculate the point of impact by offsetting the center of ball in exact direction measured at impact.

I know there are ways to use the CAD model to help with offsetting like this, but I just wanted to know if the TP-20 can be used inside of PolyWorks with my Romer Arm.

[PW User]

Hello,

PolyWorks does not take advantage of this added benefit or tip contact sensing.

PolyWorks only uses a software based algorithm based on the CAD surface orientation. the requirement is to have a CAD, align first using measured features matched to nominal ones on the CAD and then, once aligned, use the CAD usrface to figure out which way to compensate.

There are a few new methods for compensation added to V11 but none of them involve using any hardware trick to get the orientation of compensation (other than the first point's tip orientation and the compensation point combinations of for each hardware)

Regards,
Bernard

[GoBeavs]

Thanks.  This was not a show-stopper.  I was more curious because we have extra TP-20's from our CMM.  I might see how Romer uses this adapter.  Maybe I can use Scanworks or something else to probe a pointcloud and then import that into polyworks... just brainstoming outloud really.

[admsteck]

I'm not sure how the Romer handles the TP-20, but we use them on all three of our Faro arms.  We produce stamped and welded sheet metal components for the automotive industry and the use of the touch probe greatly reduces variation on thin parts.  In polyworks I usually only probe features like holes and slots since it is difficult to accurately reconstruct them from scan data.  I have also used it for comparison points but I haven't done full investigation into the compensation.  I think using the direction of travel at impact is more a feature of CMM's as I have never seen that on any portable arms.  Probing a point cloud with a touch probe like the TP-20 would also be a tedious task since it only takes one point at a time.