Machining experts please advice.

Fjamming · 10-17-2007, 01:28 PM

When working with aluminum, is it possible to receive a product that has a 1/8th inch variance? Is that acceptable? How does aluminum arrive? Blocks? I don't know how you receive and work with aluminum, but I received a product recently that's out of spec by 1/8 of an inch. They were rings that was suppose to be at 5/8th inch thick, but came in at 1/2 inch. The vendor told me when they received the raw material, sometimes there's a variance. The item was CNC machined and I thought it's suppose to be very precise. 1/8th of an inch sounds ridiculous. Am I wrong?

Thanks.

Briman42487 · 10-17-2007, 01:59 PM

what is it? if they used a good raw material and a cnc, it should be perfect. chances are they either had a bad batch of materials or something was wrong in the computer.

Fjamming · 10-17-2007, 02:02 PM

Suppose to be "highest quality aircraft grade aluminum available".

mikey · 10-17-2007, 02:06 PM

Was it a finished product or raw material.

A CNC is only as good as the program, might be that they have 'loose' tolerances.

Fjamming · 10-17-2007, 02:07 PM

It's beadlock rings. I imagine they had to use raw materials and machine it to the rings I wanted.

mikey · 10-17-2007, 02:13 PM

Quote:

Fjamming previously said:

It's beadlock rings. I imagine they had to use raw materials and machine it to the rings I wanted.

I see, I thought maybe you had received some raw material you wanted to machine.

Which dimension is out of spec on the ring?

Fjamming · 10-17-2007, 02:14 PM

Quote:

mikey previously said:

I see, I thought maybe you had received some raw material you wanted to machine.

Which dimension is out of spec on the ring?

They were suppose to be 5/8th inch thick, but came at 1/2 inch.

I added additional content to the original post to make it more clear. Added text in italics.

NCFJ · 10-17-2007, 02:17 PM

1/8" is not acceptable. The whole premise that the raw material was off is not a valid claim. The CNC machining process is based on cutting a specific piece from raw material no matter how big the raw material is. Obviously you cant cut a 5" piece from 4" of raw material, but you can cut a 5" piece from a 6",7",20".30" you get the idea. I would not accept a piece that I was paying machining cost on to be 1/8" out. Heck, you can stamp bead lock rings out to better tolerances than 1/8"

Briman42487 · 10-17-2007, 02:18 PM

so its a 1/2" the whole way around. someone just entered the wrong numbers.

Fjamming · 10-17-2007, 02:19 PM

Quote:

Briman42487 previously said:

so its a 1/2" the whole way around. someone just entered the wrong numbers.

Briman, it's 1/8th inch thinner then it should be. Not sure if they entered the wrong numbers or just trying to save some money.