- #1
_Bd_
- 109
- 0
Hi,
I've been reading about stacking up tolerances. It's the first time in working with them. I understand the gist of it and I've seen a few simple examples however when I move onto my project I keep getting lost as I don't know what and where do they stack and if I should just add them up or Add them up and divide by two? (some of them are holes)
Here is the gist of it:
A flat PCB (a sheet looking thing with no components) slides into an aluminum block that has a datum feature on the side. the PCB is supposed to stop at that daturm. That datum is on Block A (Black).
Once the PCB is up against the stopper, Block B (grey) then drops on top of the PCB with some dowel pins.
The PCB mechanical drawing has those two holes as datum features with a tolerance of .003" (.075mm)
The thing is, Block B (grey) is mounted onto a big fiber-glass sheet (Let's calle it Block C).
Block A and Block B are mounted on the same sheet, and are assembled using screws.
My main question is:
- Would the tolerance analysis be done on Block C since that's where the alignment between block A and block B are done? or is it done on block A or block C or some sort of combination? and where does the PCB come into play?
I've been reading about stacking up tolerances. It's the first time in working with them. I understand the gist of it and I've seen a few simple examples however when I move onto my project I keep getting lost as I don't know what and where do they stack and if I should just add them up or Add them up and divide by two? (some of them are holes)
Here is the gist of it:
A flat PCB (a sheet looking thing with no components) slides into an aluminum block that has a datum feature on the side. the PCB is supposed to stop at that daturm. That datum is on Block A (Black).
Once the PCB is up against the stopper, Block B (grey) then drops on top of the PCB with some dowel pins.
The PCB mechanical drawing has those two holes as datum features with a tolerance of .003" (.075mm)
The thing is, Block B (grey) is mounted onto a big fiber-glass sheet (Let's calle it Block C).
Block A and Block B are mounted on the same sheet, and are assembled using screws.
My main question is:
- Would the tolerance analysis be done on Block C since that's where the alignment between block A and block B are done? or is it done on block A or block C or some sort of combination? and where does the PCB come into play?