Spline and gear datums

[[Ja...]]

Hi,

I`m quit new to splines and gears so I have some issues with my programs.

Could someone help me?

1. I have part with internal splines (Datum A) and external gears. And I measured external gears against Datum A, because this is logically for me that they need to be concentric to each other. But there is no information on drawing that I need to use Datum A for external gears. So my managers tells me to measure external gears to them selves. I don`t want to agree with them, but I need some support. Long time ago one gear expert also told me that in this type of example I need to use spline axis for external gears.

2. I have a part with internal splines and datums what I have are circle (datum A) and plane (datum B) But the drawing don`t say anything about what datums to use. Should I measure splines against them selves of against datum AB?

Is there any standard which would describe this topic? 

 

Any information or opinion is appreciated 🙂

[[Ro...]]

Hi,
standards for splines are existing, yes.
E.g DIN 5480, ISO 4156 or ANSI B92.1. But I don´t think that you´ll find an answer inside.

However, the drawing is "the master".
The designer of the part has to know what he designs 😉
I agree with you at no. 1.
Is also logical to me but at the end the drawing or the managers have to decide.

For 2. this sounds strange to me, the drawing has to define datumns.

[[Ja...]]

Please sign in to view this quote.

Thank you,

I have read those standards, but couldn't find anything...

For 2. I`m using datum AB, because these are the only datums on dwg. I got programs from another production site and they used splines for reference, in my opinion it is not the correct way...

[[Ch...]]

The datums should be identified for the spline and gear on the drawing , a lot of Engineers do overlook this. One way to find it is : does the gear or spline have a runout requirement to a datum? If so consider that the main datum u.o.s., this should be measured as a cylinder if it is a diameter. Other times the datum might only be referenced in roll check requirements as a datum axis. If you are unable to find any datum references, I would contact Eng/Design. Beyond that, if your drawing for example only has 2 datums on it, -A- surface and -B- diameter, I would probably go with A|B in this case.

To check a gear to 'itself' or to a spline (P.D.) is challenging but can be done... I would not advise it unless it is clearly required.

 

Good luck.