lavezzitrupos.com is really good, except O.D plug size is always larger than thread major e.g: for .375 -24 UNF - 3B the O.D of plug is Ø.500
Typically, this is true, but you can custom order in most configurations. For example, one I use on a daily basis is a .500-20UNJF-3B and the probing surface is also Ø.500.
EDIT: Ok, so I read through a couple "heated" threads about cylinder probes. I understand reason WHY they are inaccurate, but I think in my situation that doesn't apply. I only use the cylinder probe for checking threads that have a true position that needs an accurate diameter for MMC purposes. Typically at A0B0. I've also used the cylinder probe to check a sheetmetal part off the waterjet with some serious draft angles and large-ish tolerances. It was run on the CMM because the sheer amount of dimensions that needed to be checked.
In my case, the cylinder probe works just fine.
No it doesn't.
You are NOT checking the position of the thread.
Just the minor diameter.
That can be accomplished using a normal probe and the pitch function.
For sheetmetal you can use edge points and control the depth of measurement.
No it doesn't. You are NOT checking the position of the thread. Just the minor diameter. That can be accomplished using a normal probe and the pitch function. For sheetmetal you can use edge points and control the depth of measurement.
In my instance checking the minor diameter location is what's needed. Besides that, the minor diameter is what is controlled for MMC. We can't change the diameter of the tap that's establishing the thread. I can't get an accurate measure of the minor diameter with a normal probe and utilizing the pitch function. It may be close, but will never be accurate.
I could use edge and corner points for sheetmetal parts, and make my program cycle time 2-3 times longer than necessary. Supervisors don't like long cycle times when CNC machines are held up because their parts are waiting to be inspected on our single CMM and I'm taking forever to check a part with ±.030 tolerances off the waterjet.
I'm not telling you how to do your job, please don't tell me how to do mine.
Yeah, the center will stay the same, but if the TP has a MMC callout, you'll need an accurate diameter. I've used cylinder probes to measure TP @ MMC of threads in the past with great results.
FYI - unless the drawing states otherwise, MMC bonus on a thread is derived from the pitch diameter, not the minor diameter.
Someone will have to explain to me how, no matter how you slice it, MMC can be practically applied to threaded holes. Max/Min pitch dia or not, any engineer who applies an MMC to a threaded hole has never used a wrench... just my opinion... not necessarily trying to start an engineering rant... not necessarily.
I, typically, don't use MMC on a thread if it doesn't need it. Most of the time it's a .005 or .010 TP and we don't need it. On the occasion we have a thread that skirts with being out of tolerance, we might apply it then. I was never certain about what diameter of the thread got the bonus, just always went with the minor as it was the only one I could measure. But is the Pitch diameter the one that SHOULD get the bonus?
Also, we have a 2mm shank probe that we use regularly without any issues. However, I prefer to use a regular sphere probe and pitch function. Interesting thread though.
