tolerance
tolerance
(OP)
Hi all,
This is a quick question from an entry level engineer. what is the typical tolerance for a clearance hole shoulder bolt? for example, if I have an M6 screw how much bigger shold the counterbore be for a nice close fit to the shoulder?
This is a quick question from an entry level engineer. what is the typical tolerance for a clearance hole shoulder bolt? for example, if I have an M6 screw how much bigger shold the counterbore be for a nice close fit to the shoulder?





RE: tolerance
Remember that the tighter your tolerance, the more expensive and difficult to assemble the whole thing will be, for a variety of reasons.
As a not-so-entry-level-engineer who was where you are 4 years ago, my advice to you if you're going to be doing any sort of machinery work is to get a copy of "The Machinery Handbook". It'll set you back 75 bucks or so, but I guarantee you that it will pay for itself. EVERYTHING is in there.
RE: tolerance
It's in it's 27th edition right now, so you'll definitely be able to spot it if you see it.
RE: tolerance
Software For Metalworking
http://mrainey.freeservers.com
RE: tolerance
-Reidh
RE: tolerance
While it seems a simple application you either need to do the math or use a table that was driven by the math.
Machineries is a good start, assuming you get to dimension both parts. If one part is dimensioned/toleranced outside of your control then you probably have to do the math.
To find the counterbore diameter you need to take into account:
Is is fixed (mating part has thread in it) or floating (nut & bolt thru holes in both parts) application.
Diameter of the head of the bolt/screw.
Coaxiality of the head of the bolt/screw to the shaft.
Coaxiality of the counterbore to the through hole.
Reidh case has even more to consider.
If you're in the US take a look at Appendix B of ASME Y14.5M-1994 it gives some calculations. There are a couple of websites that do it for you but it would be good practice to work it out yourself a few times.
http://ww
ht
May have been posted before over on GD&T, for instance thread1103-110414: Fixed and Floating Fastener Fit Formulas thread1103-125608: Floating Fastener Formula
KENAT, probably the least qualified checker you'll ever meet...
RE: tolerance
Since you are just starting, learn the difference between "tolerance", "variation", "deviation", "clearance", and "fit", and use the terms properly.
RE: tolerance
ht
RE: tolerance
So I was looking in McMaster, and the M6 screws have a shoulder diameter of either 8 or 10mm. I was asking about clearance for the shoulder. Just to be clear, this is for mating two cylindrical parts (pipe and machined insert) coaxialy with a few shoulder bolts along outside. The clearance I'm concerned with is for pipe and insert (not sure if it's the same for both).
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KENAT, probably the least qualified checker you'll ever meet...
RE: tolerance
What clearance does the application require? Possibly a very close fit, or maybe not.
What are the capabilities of the machine shop. Talk to the shop and give them the reasons for any tolerances you require. Always be able to justify every drawing tolerance from a functional standpoint, avoid drawing block tolerances, and come to an agreement with the shop before hand.
Believe me it took me years to smarten up and get off of my high horse. The engineer needs to partner with the shop; it is not an adversarial role.
Paul Ostand
www.ostand.com
RE: tolerance
I actually started off my engineering career in a manufacturing/tooling company that required it's engineers to start off in the shop. I worked with the tool-makers in the shop for about 6 months, and I think it was very helpful in the reagrd you are talking about.
RE: tolerance
That was a very good policy. I would have avoided some errors years ago, if I had done the same.
Best wishes
Paul Ostand
www.ostand.com