fit tolerance for shaft

[TWR2]

Hi

What is the acceptable tolerance of a shaft for a bore that is 1.6242 +000/-.0002.
Shaft diameter being 1.625.

If the bore is 1.624 +000/-.0002 does this make a big difference.

In order to have a forced fit, not pressed, and not sliding right on, how much tolerance should be between the bore and the shaft.

Note- I am not an engineer who can digest the machining book real well so directing me here won't help.

Regards,
TWR2

 

[KENAT]

What is the tolerance on the shaft diameter or is 1.625 the actual measured value?

You say you want a forced fit not pressed. By this do you mean you want enough interference so that it doesn't just slide out but that you can install it by hand, don't need a press to assemble it?

KENAT, probably the least qualified checker you'll ever meet...

 

[TheTick]

This is the kind of lesson used to teach someone how to use Machinery's Handbook. Get the book, or get someone with the book.

 

[TWR2]

KENAT-
1.625 is base dim.

What tolernce would be an acceptable interference fit, forced by pounding. (lightly)
What tolerence would be acceptable press fit.

We are talking about a fit that can be done in the field with a hammer and a jig to cover the shaft while pounding it in.

Thank you
TWR2

 

[CorBlimeyLimey]

More info needed;

Materials of parts involved?
Surface finish?
Surface hardness?
Application of assembled joint?

 

[TWR2]

Hub- ASTM A 27 Grade 60/30
Shaft- probably 1045, at best 4140 finish 63
Hardness- don't know
Function- shaft to wheel.

Typically shaft is welded on back side, one inserted into the bore of the frame. This practice evolved as field people did not have the machinery to actually make a press fit while repairing the parts.
Now new machinery is ordered, using OEM specs for a press fit but the field guys still don't have machinery to make installation.

Regards,
TWR2

 

[byrdj]

could they heat the wheel, thus a press fit would be slip fit for the few minutes to assemble

I recall the amount of increase with heat would be 0.007"XdiameterXdeltaF. so warming the wheel to 370F would negate the 0.001 press fit and provide 0.002" to make it an easy slide fit

 

[TWR2]

Yes, this is an option, though timely due to hub thickness. Have considered opositie and placing shaft in liquid nitrogen.

will .002 be the difference between achieving a slip fit, and a press fit.

Thank you

 

[byrdj]

A RC1 sliding class "intended for accurately locating parts" for 1.6" shaft would be 1/2 to 1 thousands loose.

Unfortuanetly I do not have press fit classes in my notebook, but size to size would require force to assemble.

Most plants have an oven in the lunch/break room, or be careful and even with a rosebud, they make temp sticks, a wax that melts at the labeled temp used to know when 350F is reached with out getting to hot

 

[CorBlimeyLimey]

Can you add a threaded hole in in the end of the shaft. A puller arrangement could then be used for assembly.

If you are welding the shaft to the hub after assy, do you need a press-fit?

 

[Tmoose]

R-and-R-ing light press fits (or even slip fits) in the field is looking for disaster. And, even with keys, inadequate interference (unless locked with heavy axial clamping) with rotating loads will relentlessly bring on fretting that can either lead to wear or seizure, whichever makes the most trouble.

I'd be looking at a tapered locking device. They easily tolerate a few thousandths shaft diameter variation, which would REALLY compromise a straight cylndrical fit design.

http://stearns.rexnord.com/pdf/Installation/951-00.pdf

Most have built in jacking holes, so the "puller" is a couple of bolts. If creating a tapered hole in the wheel hub is a problem there are multi-piece devices including both tapers that have cylindrical ID and OD. The holding strength approaches a heavy shrink fit (solid axle/thick hub). Try that with any field assembly.

 

[TWR2]

Thank you gentlemen for your assistance.
We will hone out bore, freeze shaft.
Existing bore is1.624 +000-.002 Existing shaft is 1.6250 +.0007-0000
will look at what appropriate bore Dia should be for slip fit in field.
Regards

 

[byrdj]

When you say freeze, do you mean liquid Nitrogen at -300F, or just put it in a food freezer -10F

with the food freezer you will only get 0.0005 shrink, which MIGHT be enough to make a normal size to size a tap fit.