Engineers/drafters, need help with a print.
 

Below is a cut from a print (it's just a steel tube). But I cannot remember what the symbols "250<" on each end of the length are in reference to. Any ideas? My CAD guy is out and I'm trying to rush a quote through. Thanks
http://forums.pelicanparts.com/uploa...1176148609.jpg

It may be a surface finish callout. If so, it's pretty rough. It doesn't appear to be a geometric tolerance callout.

I also thought surface finish, but that doesn't make sense in the application.

A surface finish call-out would nomally look more like a check mark with a closed top on the bottom 'v' or a circle drawn in the bottom 'v' for an unmachined surface.
The V shown usually indicates a countersink on a hole, but on the ends of the tube? I would normally call that a chamfer, besides I can't figure what the 250 would mean?

Never seen such a symbol. You will probnably need to ask the customer to be very clear on what he wants.

Yep, but I wanted to double check that I wouldn't look completely incompetent for asking:D

surface quality.

basically, it needs to be cut to fit within the +/- tolerance listed

Length and angularity tolerances are listed separately.

I would guess '250' indicates this tube is connected on each end to another piece labeled as '250' on another drawing.

I also think I could make this piece with a hacksaw in my garage ..... :D

78,000 parts a year on this one, 570,000 on another length. The garage hacksaw gets tiresome at those EAU's:D

Or maybe not .......

250 is the finish in micro inches. 250 is pretty rough, like a phonograph record. Is it mating to a soft metal gasket?

Nope, it's actually just the center tube to an office chair.

But that isn't the standard symbol for surface finish!
If the correct symbol was being used one leg of the 'V' would be longer than the other.

As far as I know, a 'V' with equal sides is only used for a countersink in a hole call-out, or to specify a field weld as part of a welding call-out. Neither of these seem to be applicable in this application.

I suppose the only way you'll know for sure, as others have said, is to call up the supplier and ask him exactly what he means.

Lendaddy, I am 100% sure that is a finish mark. The larger the number, the rougher the surface can be. A 16 finish would pretty much require grinding to achieve while a 32 is typically a machined finish, 250 is pretty rough in comparison, but you might want to look it up in machinists handbook to be sure your cutting operation is good enough. (we seldom use finish mark numerical call outs where I work, so my memory of how "rough" a 250 finish can be is hazy).

For reference, that ground plate we made for you had a 16 or better finish on the large surfaces and a 32 or better finish on the machined cam track surfaces.

If you still need to know more, I will look in a machinist's handbook when I am back at work tomorrow morning.

Thanks Tim and everyone else, I'm going to get the scoop from my customer tomorrow.

We use surface finishes pretty regularly at our shop, so I'm with Tim on thinking this has to be a surface finish. A 250 turned finish would made with something like a 0.040" to 0.080" feed which is pretty fast. If they spec something that rough, it's usually because they want it made fast (ie cheap) or it's mating to a soft surface that they want to deform for a better seal.

This actually makes sense as they are currently being cut on a "Modern" which is a lathe style cutoff.

Here is a link to chart showing some various surface finishes that can be obtained with various processes. 250, while kind of crude, may be dicey depending on your tube shearing/cutting equipment, so it might be worth cutting a sample with your equipment to make sure it is acceptable. (I am a worry wart when it comes to making parts to other companies prints and getting burned down the road due to innapropriate or un-neccesarily tight tolerances)

http://icrank.com/cgi-bin/pageman/pageout.cgi?path=/data/surface_finish.htm&t=2

David, what do you do for a living?.....It seems like you and I often have similar responses to various mechanical/machining questions. ;)

I design custom automated machinery and we have a machine, shop, fab shop and controls department where I work. http://www.radcoindustries.com/