need oversized tap help 5

[stout1]

I produce a part that has a tapped hole and is then plated as the last op. I thought I might be able to get by with using a standard tap since it is a small hole but we are getting plating build up in the hole and the threads are coming in undersized. Does anyone out there have a contact that is experienced in this if I were to give them the plating spec? I would prefer that they be in the US. The thread is an M2X.4. Thanks for the help.

Michael

 

[scastillo]

Is adding a note to plug threaded holes prior to plating not an option?

 

[stout1]

The holes need to be plated for conductivity. Thanks though. It helps to have others look at it that have not been working on it before. Keep the ideas coming.

Michael

 

[MintJulep]

Adjustments to metric tap sizes to accomodate plating thickness are discussed in ASME B1.13M and ASTM A563M.

 

[MotocrossManiac]

I was looking for some information about this a solution to this problem and came across this post were the ASME B1.13M or ASTM A563M.
I have been fighting this problem in one way or another for
sometime. I work with anodized aluminum.

 

[deanc]

How about a rolled thread? Maybe a lower class on a cut thread.

http://www.uscti.com/TapsFinal.pdf

 

[boo1]

Consider cutting the threads slightly oversized so that when they are coated the screw would thread correctly. They do make oversized taps to allow for added material post-processing, they are marked by the Gage Number (H#) and are measured in 0.5 thousandths increments.

 

[MotocrossManiac]

Rolled thread requires a very fussy minor diameter,
I was hoping to find and oversize M6 tap cutting tap and know how much oversize it is.

 

[patdaly]

here you go:

http://www.precisiontwistdrill.com/techhelp/help_pages/pitch_diameter_limits.asp

 

[stout1]

I actually figured it out with some help from our tooling supplier. For my application (M2 X .4) the standard pitch is a D3, so I ordered a D5 and a D7 pitch tolerance taps and sent them off to the plater.

Michael

 

[dimjim]

You might want your tap drill to be larger as well.
That is one small thread!