Best way to tolerence machined hole to center of boss?
Best way to tolerence machined hole to center of boss?
(OP)
I have a product that is getting seven new holes added. It's more important that the holes be drilled in the center of their bosses (so the self tappers wont bust out the side) then the holes be positioned to [-A-], [-B-], [-C-].
Should I call each boss a datum tolerenced to A/B/C and then toerence the drilled hole to it's datum (boss)?
Or can by tolerencing each boss to A/B/C and then say their holes must be concentric to them?
Thanks
Should I call each boss a datum tolerenced to A/B/C and then toerence the drilled hole to it's datum (boss)?
Or can by tolerencing each boss to A/B/C and then say their holes must be concentric to them?
Thanks





RE: Best way to tolerence machined hole to center of boss?
RE: Best way to tolerence machined hole to center of boss?
Am I understanding ?
Thanks Again
Joe
RE: Best way to tolerence machined hole to center of boss?
Seems to me your 3rd option would work "Or can by tolerencing each boss to A/B/C and then say their holes must be concentric to them?"
Hard for me to make a suggestion without a picture.
Chris
Systems Analyst, I.S.
SolidWorks 06 4.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 06-21-06)
RE: Best way to tolerence machined hole to center of boss?
Self tap hole diameter +/- tol
Small circle in big circle (for concentric)1.0 to its boss?
Thanks
RE: Best way to tolerence machined hole to center of boss?
RE: Best way to tolerence machined hole to center of boss?
Appreciate all the help.
RE: Best way to tolerence machined hole to center of boss?
Chris
Systems Analyst, I.S.
SolidWorks 06 4.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 06-21-06)
RE: Best way to tolerence machined hole to center of boss?
Sorry
RE: Best way to tolerence machined hole to center of boss?
My customer was upset about the gage cost to measure each to A/B/C. I have a target fixture that would need to be added to. I told them we could check the bosses on the CMM at each die set then use a small MMC template to check each hole during regular production, to save the money.
Now they want me to dimension the print for them.
RE: Best way to tolerence machined hole to center of boss?
RE: Best way to tolerence machined hole to center of boss?
http://i4.tinypic.com/166lm39.jpg
RE: Best way to tolerence machined hole to center of boss?
Chris
Systems Analyst, I.S.
SolidWorks 06 4.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 06-21-06)
RE: Best way to tolerence machined hole to center of boss?
RE: Best way to tolerence machined hole to center of boss?
RE: Best way to tolerence machined hole to center of boss?
It got me thinking though why not name all bosses datum
[-J-]. Has anyone ever seen this used [-J1-], [-J2-],
[-J3-]... [-J7-]. I don't think the bosses could be mistaken for target datums. So then Boss 1 would be positioned to A/B/C and then called [-J1-]. Under that would be the hole size and tolerance, under that would be a feature control frame True Position to [-J1-]. Then have an arrow to each boss calling them [-J2-], [-J3-] etc.
Think that would be OK?
RE: Best way to tolerence machined hole to center of boss?
Do you have a copy of Y14.5?
RE: Best way to tolerence machined hole to center of boss?
I have never seen number and letter designations used for datums and I think it might be confused for datum targets. I think it would work but I'm not sure if it would be as clear as what you want. Also, you would need a seperate FCF for each hole in order to reference each of your psudo-datums.
Maybe if your FCF for the holes positioned them to -J- and had a "SEP REQ" note undernieth, and then your datums would each be -J1-, -J2-, etc...
RE: Best way to tolerence machined hole to center of boss?
RE: Best way to tolerence machined hole to center of boss?
RE: Best way to tolerence machined hole to center of boss?
RE: Best way to tolerence machined hole to center of boss?
http://i10.ebayimg.com/02/i/07/96/07/f1_1_b.JPG
RE: Best way to tolerence machined hole to center of boss?
RE: Best way to tolerence machined hole to center of boss?
http://i4.ebayimg.com/04/i/07/93/f1/03_1_b.JPG
RE: Best way to tolerence machined hole to center of boss?
RE: Best way to tolerence machined hole to center of boss?
Thanks to all.
RE: Best way to tolerence machined hole to center of boss?
Next, to locate each hole coaxial to its boss you need what's called a "repeated datum." Do a section view of the boss and add the multiplier 7X to the view caption or to the section lines in the parent view. Assign a datum to the boss diameter, call it -D-. In the section then call out the hole size with a pt fcf using -A- as your primary datum (assuming -A- is assigned to the perpendicular surface and you want it be your primary datum) and -D- as your secondary. Note that both the hole and the boss are features of size so you can gain bonus tolerances by judiciously using material condition modifers (sometimes needs some soul-searching as to which ones to use). Under the pt fcf for the hole add the note INDIVIDUALLY. To the -D- datum symbol add the note INDIVIDUALLY. The multiplier e.g. 7X is not necessary as it has already been assigned to the section.
Tunalover
RE: Best way to tolerence machined hole to center of boss?