7
votes
Accepted
Difference between min/max clearance and min/max tolerance and relation between them
The minimum clearance occurs when the largest possible shaft meets the smallest possible hole. That would be in this case a shaft of $50.02 mm$ in a hole of $50.00 mm$. The difference between the two ...
- 1,943
7
votes
Why/when do we use a transition fit?
A transition fit actually makes the end product more consistent than the clearance fit. In transition fit clearance (if occurring) is less compared to the clearance fit. Also, if interference occurs, ...
- 134
5
votes
Distance sensors with accuracy of 1 mm?
Was looking for other distance solutions, and came across this question.
A sensor that I've found works well is the Sharp GP2Y0E02B (digital version) (newer version is the GP2Y0E03). Configuring it ...
- 181
4
votes
Explain tolerances in technical drawing
It says the flats shall be within 0.100 units of radial dimension positioned with reference to 'A'.
i.e. if you were to make the rim which is a perfect circle, then mill the flats at the three ...
- 1,078
4
votes
How to choose tolerance size?
I think you need to understand what a "tolerance" means in an assembly items. My token view is, a tolerance is the permissible deviation of a part from its ideal design dimension. ...
- 8,232
3
votes
What is an acceptable tolerance for a non-engineering dimension
There are general tolerances, often defined for different industries.
You cannot expect that a surgical instrument is designed with the same general tolerances as a drilling rig.
If you have found a ...
- 884
3
votes
Conventions regarding sliding and press-fit tolerances for shafts and bearings
Shafts and bearings usually use interference or transition fits - they shouldn't slide and for installation you should use force - some kind of press or clamping tool would be best, eventually if such ...
- 305
3
votes
When tolerances are mentioned without +/-, should they be considered as a span?
If it says +/- 1% then it means from -1% to +1%. in everyery standard i have ever seen.
+/- is simply shorthand for writing a symmetric bound one can also make unsymmetric bounds like 0 to 1% or ...
- 3,684
3
votes
Accepted
Do drawing dimensions have to start from datum?
If the request is coming from whoever will be machining or inspecting the part, I would side with them. They know what they need to see to make sure the part ultimately meets the print.
Also, since ...
- 2,357
3
votes
Accepted
What does a divide symbol on a drawing mean?
The "division sign" is a form of obelus that in Scandinavia sometimes meant subtraction, not division, and in many European countries (e.g. Russia, Poland, Italy) it is used in engineering ...
- 469
2
votes
Runnung a motor continuously
Assuming the limitation is power/heat buildup...
The power dissipated in the motor winding is a square function... if you decrease the voltage by 50% (and therefore the current) you have decreased the ...
- 31
2
votes
Accepted
Choice of Datum Features and Number of Datum Features
Typically in my experience, your 3 orthogonal edges of the rectangular blank are your first 3 datums. Your dowel hole would be the first machined feature and since it locates the rest of the features, ...
- 2,357
2
votes
What is an acceptable tolerance for a non-engineering dimension
If you use ASME Y14.5, typical implied tolerances are +/-:
1/64 for fractional dimensions
0.01 for dimensions to 2 decimal places
0.005 for dimensions to 3 decimal places
0.0005 for dimensions to 4 ...
- 2,357
2
votes
How to provide concentricity tolerance in assembly?
As you have not placed constraints on the project implementation, consider that most welding requires a jig of some form to maintain alignment of parts. The use of the generality "most" also refers to ...
- 7,307
2
votes
How to choose tolerance size?
This is a very difficult answer to answer within a single post but I'll give it a try.
Tolerances, Cost and Machine capability
The very first thing you need to remember is that tolerances are ...
- 24.3k
2
votes
Conventions regarding sliding and press-fit tolerances for shafts and bearings
Typically you want an interference fit on a bearing ID since the shaft is usually the element that's rotating and whatever the bearing OD goes into will have a looser fit. If your shaft is rotating ...
- 2,357
2
votes
What are the Exact Rules for Significant Figures, Precision, and Uncertainty?
To begin with, in the title to your question are you confusing precision with accuracy?
Accuracy is how close or far off a given set of measurements (observations or readings) are to their true value,...
- 9,752
2
votes
What should be the hole diameter (tolerance) at a given fixed diameter of the shaft?
For steel the difference is 0.0002"-0.0003". If the hole is undersized or shaft is oversized by this amount it is a press/interference fit. If the hole is oversized or the shaft is ...
- 5,629
2
votes
How to interpret general tolerances (e.g., ISO 2768)
In general your idea behind tolerance are ok, but for the part you've drawn it's already way more complicated then you would think.
For example, you have a tolerance on the left hole diameter of +/- 0....
- 884
1
vote
how do you define tolerances for moving parts so that they work properly?
You basically need experience with real things in your hands. It depends on material and surface finish as well. You to do things like drill and ream holes of different tolerances see how pins fit ...
- 5,629
1
vote
Tolerance value as part of formula
Accepting the units on the individual terms, we are left with the following approaches:
$\Delta f/f_o = -0.00340 \pm 0.006$ ppm / $^o$C$^2$
$\Delta f/f_o = -0.00340 \pm 0.006$ (ppm / $^o$C$^2$)
$\...
- 2,991
1
vote
How to choose tolerance size?
3rd edition Marks HandBook circa 1923 is what I use. When the local library re-opens, check out the modern versions in the reference section.
- 11
1
vote
How to choose tolerance size?
There are standards. But that's really putting the cart before the horse.
Imagine you're designing ..anything. By default the tolerance is whatever you can expect from the fabrication process if ...
Drew♦
- 2,141
1
vote
Specifying GD&T feature when not expecting the fabricator to measure it
To my experience yes, this Cover Your Ass usage is a relatively common, especially when you are outsourcing the machining and assembly.
Actually, I've had an bad experience, at a company where I ...
- 24.3k
1
vote
Coplanarity Profile Callout Confusion
I think you need something inline with this:
Note that the datum A is identified by using an indicator under the callout.
A-B could equally be used with the same meaning if you identify the two ...
1
vote
Coplanarity Profile Callout Confusion
This is fine, but not typical for cylindrical faces.
The Profile GD&T symbol describes a 3D tolerance zone around the face, and as such is typically used for complex surfaces where other symbols ...
- 7,771
1
vote
Accepted
Mechanical tolerances on a CNC machine
It's going to be an uphill battle from that point on. While you can get every part of the machine and the process to tighter tolerances, their errors may compound to the sort of tolerance of 0.025; ...
- 6,115
1
vote
Accepted
Tolerance of pin in Scissors
Just looked at my kitchen scissors; clearance approximately of +.001"/+.003".
- 612
1
vote
What are functional and manufacturing datums
In simplest terms, Functional Datums should have something to do with a part. E.g. a mating surface or a centerline of the bearing surface of a rotating shaft.
A Manufacturing Datum is a feature ...
- 1,578
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