Hole Size Tolerence

Well, you haven't said anything about temperatures, nor about the materials the shaft and the stuff forming the hole are made from. If the latter were rhubarb-and-ginger marmalade, then anything would do. Do you want an interference fit, a tight fit, a good running fit, a rattly loose fit or a pi@@ fit?. You need to be much more specific in your application before anyone here can give a concise answer.

Hi,

For Case 1,

I am not sure.

The shaft need to rotate. Is that running fit, transition fit or loose fit?

Confused.

For Case 2,

Press fit.

Thank You

Consult manaul and standards for force fit and journal bearings

Machinerys handbook, IMechE Handbook, Zeus book and many many more sources have this info and how to call it out.

Hi,

Material: aluminium...room temperature

Hi,

For this design. There is no need for lubrication, or bearings.

Simple design to lift object to an angle using plate attach to a shaft like a door.Appreciate your answers.

Thanks

Sounds like its lose!

Loose.

"Lose" sounds like an acceptable answer to me.

You forgot the "r".

RRRRRRR!

So, it sounds like you are making a lifting device and the rotating and non-rotating information is confusing. If indeed just for lifting an object, size the holes for clearance only - 1mm oversize is normal.

Depending on the speed of the rotation you may need a bearing as you could end up with gauling and seizing of the aluminum.

As others have stated you need to present the problem in terms of what the machine is supposed to do and in what environment, loads, speed, etc.

Hi,

My superior wants me to keep simple & less the cost.

So he does not allow to use bearing.

No speed required.

Just need to lift object about 500g about 45 degree .

Thanks

You should be asking these questions to your superior. Since he is the expert on simple and cheap.

How can ask you guidance in how to do a proper job if your hands are tied?

A bronze sleeve bearing is pretty inexspensive.

A pi@@ fit would do, then. Cheerio!

Bearing manufacturers websites such as NTN, Timken will have fits and their uses for holes and shafts listed.

It also depends on desired finish. For example, if you call out a total size variance of .001" on a shaft with a 125 finish, your size tolerance will be eaten up by your finish tolerance and you won't leave much wiggle room for the machinist.

Bottom-line, the Design Engineer should spec desired Material, Hardness, and Fit Class and the Detailer should be able to look up the fit class on standard, and readily available, tables in order to apply the proper drawing designations for both fit and finish.

This is basic design/drafting principle application and if you are unsure of how to proceed, you should be being mentored by someone within your organization - or at a minimum, your final drawing should be being check/reviewed by a knowing professional.

Due to the probability of machine/component failure, or failure to perform as intended, if an improper tolerance is applied - an engineering forum is the LAST place you should be coming to seeking that type of information; we don't have enough information about the design or the application to be able to answer your inquiry with any certainty.

Plus, design/drafting/checking are typically functions that are monetarily billable.

Your superior should not have hired simple and cheap subordinates.

Was that a CH or a RCH. You may have to ask a ginger.

For an Aluminum shaft, I would recommend a big black one. An RCH is way too tight and should only be used for a hardened steel shaft.

At a radiological instrument maker, in the Bronx, we also used BCH (it was a high precision shop).

Hi,

Can I know what is c-hair?

You're too young.

It's also impossible to send an AP a personal message.

Haha, this made me spit my coffee!

1 c-hair = 8 dytes more or less. It depends on the color.

I'm getting strange looks reading this and laughing. This is great for my Monday morning.

You forgot to explain the different color variations.

So you need a precise answer to an non-precise question, and you came to an engineering site full of people who only give precise answers....vewy clever....so the press fit should be tapered, and the rotating shaft should have 1mm (per inch of stock diameter) clearance....

Case 1: plus tolerance.

Case 2: minus tolerance.

Refer Machinery handbook-USA

A few pointers.

Machinery's Handbook will give you a very complete education in the section about shaft fits and tolerances - note that the tolerance for a particular kind of fit depends on the shaft diameter.

Get this document: ASME-Y14.5 - Dimensioning and Tolerancing. There you will find the proper specification syntax for your fab drawings.

PIC Design catalog already offers shaft-bearing and shaft-fixture sets in your size range so your engineering work is already done. PIC will also cut features for you, like flats, grooves or threads.

I wonder how you got this, or any, job.

Engineering, Manufacturing Tolerance Limits Fits Charts ...

HOLD ON ONE SECOND HERE!

We have no idea what type of aluminum it is. What if it's the new aluminum that Ford is using in the new 2015 F150? High-strength, military grade, aluminum-alloy

Also, it depends on how high the weight is lifted. It could be as small as a few pico meters or larger distances like kilometers!

We need more FACTS!

Have you asked the fabricator ? If yes, what was the answer ?

Sorry to sound unhelpful, but isn't there a line to be drawn here. You know the intended function of the parts, the person machining this stuff should have some idea about how to specify.