For example, none of the 300 series would be capable of heat treat, and are not magnetic unless they are well work hardened. Stainless has many qualities, depending on the alloy in question. I had options in selecting the grade, but that's unusual. Stainless alone is not a good enough reference, although I used to build tooling for a company that specified stainless simply as CRES. As you've already noticed, if you specify the class, all the critical features are addressed by the schedule, so you need not provide any further information. Leaving the designation open, without a class fit, is asking for threads that run from too loose to an interference fit. I would suggest you specify your threads as fractions, not decimals-and should include a class fit, such as ¼-28 UNF 2A (A designates an external thread, B designates an internal thread). I've seen that done, even on a professional level. That way you don't provide conflicting dimensions. If you must dimension each end, plus the center, one of the dimensions should be noted as a reference dimension, such as the length of one end, or perhaps the center, if it's not critical. Be careful of double dimensioning parts, too. A quick glance should tell the builder what material size is needed. It's usually a good idea to provide an OAL (over all length) on parts, so preparing rough stock isn't a challenge. I'm used to hand generated drawings, obviously showing my age. Yes, I realize that ACAD may make this suggestion difficult. All of these would be displayed in the title block to eliminate the need to tolerance each dimension. Fractional dimensions would be either ± 1/32", or 1/64", depending on the nature of the part, and engineering requirements. 010", and three place decimals perhaps ±. Two place decimals, for example, might be ±. Typically, when I was actively machining, the number of displays was a sign of tolerance. I don't want my drawings to look like they were done by the doofus I am.ĭon't display dimensions in four places unless you have a tight tolerance, which would be restricted to that particular dimension. I wonder if it is too late to register for classes at Chatt State this semester. I wonder what my chances are of finding it without going thru all those boxes. I've got 50 boxes of books here and in one of them is my old drafting textbook. Since this part slides in a bushing, should I designate fit (loose sliding fit)ĭo I show that as a fit/finish mark, or an actual dimension.Īnd should the shaft be undersize, or the bushing it slides in oversize. Should I designate surface finish for the unthreaded portion. 2425 min for class 2A.Īnd for the 2D AutoCad drawing shouldn't I designate threaded length. If I am reading Machinery's Handbook correctly, I stopped by to see the guy today and ask him what gradeĪnd about a few parts that don't even have a material specīut he wasn't there today. I don't know the grade of stainless steel. I have no idea what the tolerances would/should be.
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