To Lap Or Not To Lap. 1

[mechantaeus]

Hi :

I have a component ( a typre of crosshead that reciprocates in guides. The whole assembly is lapped, now I want to do away with the lapping, just assemble , oil and let the whole assembly wear in during operation. Anybody with a similar situation?
Please help.

Thank you.
-mechantaeus.

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Work Hard and Work Smart.

 

[alexit]

We eliminated the lap in a fit when our new machinery was capable of holding the required tolerance and finish.

You have two reasons to lap, fit and finish. If the fit must be 14-17 micron loose, you better hold 0-1 on the rod and 0+2 on the bore...Lapping also changes the surface finish, so as fine as machinable and you are most of the time 2x roughness compared to a good lap surface.

 

[dykpa]

Have you concidered 'Non embedding lapping media' I had a problem with some valve gear once (I actually made and scrapped 4 sets - about 6 months work) untill I came accross this stuff . I now use Ajax scouring powder (usual disclaimer) and refine it by letting it sediment in water but you will want to get the comercial stuff which I cannot afford. You apply it, run the product in and then give it a good blast out with parrafin (kerosin) before you re lubricate it. Hope this helps