Design tables for generic parts.

[tap90291]

I am trying to put together a table driven part to locate a group of holes based on the simple overall length of the part. The rules first and last holes must be between 50 and 100 mm from each end. All other holes must be evenly spaced at 100 mm between holes. How do I get this to work? I.e. if oal=737mm number of holes would be 8. First hole 68.5mm from end, next hole 100 @ 6 spaces followed by one last hole 68.5 from other end. I have numerous parts to make with the overall lenght between 500 and 1500mm long and they may only change by 1 or 2mm. I think we are close but no cigar yet.

Thanks in advance for any help

TAP

 

[PDCBitman]

Is there a good reason for using a table-driven pattern? This would be much easier with a Linear Pattern by the use of formulas.

 

[lucason]

I take it the part is being driven by a design table?

If so simple formulas can be applied to the corresponding cells in the design table.

First of all there are a few values we know about...
MnimumHoleDistFromEnd=50mm
HolePitch=100mm

Next there are dimensions that need to be driven by the design table.....
OverallLength
HoleQty
ActualHoleDistFromEnd

I hope I have interpreted your requirements correctly and the above is clearly explained - if not let me know and i will try again.

Regards

L

And finally there is one element we need to calculate to use in our formula....
PitchQty

Now the PitchQty can be calculated in a user reference cell in the design table and the formula would read =ROUNDDOWN((OverallLength-(MnimumHoleDistFromEnd*2))/HolePitch,0) You will need to substitute the names I have used with the cell references

And the Driven Dimension formulas would read
OverallLength = Your Choice
HoleQty =PitchQty+1
ActualHoleDistFromEnd =(OverallLength-(HolePitch*PitchQty))/2
Again you will need to substitute the names I have used with the cell references

 

[PDCBitman]

If I understand this correctly, the number of holes should be 7, not 8.

A simple linear pattern with the folowing two equations works:

"NOH@PAT_HOLE" = INT("OAL@SK_BODY" / "SP@PAT_HOLE" )

"DIST@SK_HOLE1" = ("OAL@SK_BODY" - "SP@PAT_HOLE" * NOH@PAT_HOLE" - 1))/2

When changing the OAL@SK_BODY everything updates.

OAL is the overall length of the part (737)
SP is the spacing between the holes (100)

NOH is the total number of holes (calculated 7)
DIST is the distance to the first hole (calculated 68.5)