MMC on slot TP

[Thomas Phillips]

3.7 MR3

I see the bonus for WF and LF but not in TP bonus any help?
TIA

Thomas(not a POLL)

[Jeffrey Lovely]

Report it twice
one direction using wf
and one direction using lf
may have to play with tolerance to update
change it ,change back etc..
3.5 mr2

[rangerboat72]

3.7 MR3

I see the bonus for WF and LF but not in TP bonus any help?
TIA

Thomas(not a POLL)

I also noticed that w/3.7mr2 ? ? ? It gave me bonus tolerance for the DF, but not the LF ? ? ?

I just created a "generic slot" using the variables from the measured slot for location and swapped the length & width. I was hoping that was just a temporary solution until' I upgraded to mr3. But I GUESS NOT ! ! ! Maybe it will work correctly in 4.0 ? ? ?

[Matthew D. Hoedeman]

I have gotten in the habit of using RFS on all my TP dimensions, then using variables to calculate the bonus. I put in a comment just before the dimension stating what the bonus is for the size, then add the bonus to the TP tolerance using the variables.

AND, for a slot, you DO need 2 different TP dimensions since the width bonus will be different from the length bonus. It is a feature of 2 sizes so it needs 2 TP dimensions.

[J Temmen]

The big question is ...are you allowed bonus from length AND width? I generally only use the working part of the slot which is the width.

[Matthew D. Hoedeman]

IF you are allowed MMC, then the length of slot bonus applies to the axis the length of slot is in and the width of slot bonus applies to the axis the width is in. You can't add them together and use them in a combined fashion. That is why any slot really needs 2 TP dimensions.

[T Miller]

I agree with Matt I always use 2 TP dims when doing a slot

[Thomas Phillips]

12 slots TP + composite TP = 24 * 2 TP location = 48 * 30pc cap. study, dang

[kbotta]

DOH! Gravy time....

[Thomas Phillips]

I am all over that-yeah, I just need some cheese to go with all the whine, the report will need to be explained.

[Matthew D. Hoedeman]

TP SHOULD NOT EVER BE USED FOR SPC CALCULATIONS!!!!!
Sorry for yelling, but TP does NOT take into account DIRECTION of deviation so you do NOT know how much variation you really have.
Use this as an example for whom ever wants this TP SPC:
Nominal location = X0 Y0 (just 2, lets keep it simple) with a TP tolerance of 2.0
Part #1 checks X-1.0 Y0 = TP 2.0 (in tolerance)
Part #2 checks X1.0 Y0 = TP 2.0 (in tolerance)
Part #3 checks X0 Y1.0 = TP 2.0 (in tolerance)
Part #4 checks X0 y-1.0 = TP 2.0 (in tolerance)

TP Variation = 0.00mm Pp/Cp is through the roof! It can not be calculated due to no variation. It will show a value of 999999999999+. That's one heck of a great part, based on TP. Ppk/Cpk also can not be calculated because there will be std dev of ZERO.

X axis variation = 2.0mm with a tolerance band width of 2.0mm
Y axis variation = 2.0mm with a tolerance band width of 2.0mm
Pp/Cp will look like garbage due to the variation using the entire tolerance band, no way will this thing pass SPC.

NOW, which one is right? NOT the TP.

[rangerboat72]

Matt, I agree totally...

I have gotten in the habit of using RFS on all my TP dimensions, then using variables to calculate the bonus. I put in a comment just before the dimension stating what the bonus is for the size, then add the bonus to the TP tolerance using the variables.

AND, for a slot, you DO need 2 different TP dimensions since the width bonus will be different from the length bonus. It is a feature of 2 sizes so it needs 2 TP dimensions.

Matt you are right on top of it!

That's exactly the way we've been doing it here for ten years that I know of. I hate it when those DARN DESIGNERS put the diametrical symbol int the feature control frame. Don't they realize they are implying a round tolerance zone for a feature that is actually rectangular (unless it is a rounded slot, but the same zone would apply)...

And I'll have to agree totally with you on the SPC calculations as well.

MATT, YOU THE MAN !