Issue with Diameter of Holes

We are currently having an issue related to hole sizes, for our picket panels. The commercial tolerance for the OD of the picket ( 1/2 inch round pipe) is +15000 and - 30000.

We have experinced that when we change the hole size by even 2000 the pickets dont fit well , either too tight or loose. Is there a way to determine an optimum hole size for a material with such wide tolerances. Should we use some statistical tool to determine the mean of a sample of the pickets and use that as our hole size???

Would appreciate your thoughts on thsi issue.

We are currently having an issue related to hole sizes, for our picket panels. The commercial tolerance for the OD of the picket ( 1/2 inch round pipe) is +15000 and - 30000.

We have experinced that when we change the hole size by even 2000 the pickets dont fit well , either too tight or loose. Is there a way to determine an optimum hole size for a material with such wide tolerances. Should we use some statistical tool to determine the mean of a sample of the pickets and use that as our hole size???

Would appreciate your thoughts on thsi issue.

Dear Sai:

Can you correct the tolerance please? Seem to be mising a decimal point (or units).

How do you define "too tight"? Too tight to assemble?

Place the "pickets" in a bind, so that they are "sprung" against the holes to supply a countering torque.

Upset some material into the hole to close the gap.

Pin the pickets, so they cannot fall out.

Cap the "receivers" of the pickets, so they cannot fall out... [picket] ... perhaps formed metal with holes stamped for the pickets.

Just some ideas.

David A. Smith

I think Sai is meaning to say 15 thousandths when he writes 15000 ("fifteen thousand"). It may be a problem with English. If that is correct his tolerances below would be +.015/-.030 for the .5 diameter pipe. When he refers to the hole diameter it is .002, I think.

"N:dlzc D:aol T:com (dlzc)" wrote in message news:APV7f.99499$lq6.61909@fed1read01...

Dear ms:

That is very good.

Sai, pipe tolerance is very sloppy, and unless you can control your supplier, you likely cannot get better. If the pipes were PVC, Harvel makes a very consistent product that is uniform in OD (outside diameter) and ID as well. I don't have any experience with any metal *pipe* manufacturers (fittings yes, pipe no).

Have you considered tubing? This is typically +/-0.005 or better on OD, and available in different wall thicknesses, materials, and methods of manufacture (Drawn Over Mandrell, Welded or Seamless, and so on).

David A. Smith

What is the tolerances on the round pipe? Do you know? Your holes need to be a few 0.001's larger on the min side.

supply a countering

Get a couple of socket weld fittings and measure the bore that they have for connecting to pipe. If I remember correctly, the socket is 0.860" +/- 0.005" (0.855/0.865") diameter for 1/2" pipe that has an outside diameter of 0.840". Remember also that pipe is not perfectly round in all cases and that may affect certain lengths of pipe from fitting properly. You should test the pipe fit with that of the socket weld fitting before attempting to make the actual assembly.

Hope that helps, Jim Y