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Questions tagged [tolerance]

The tag has no usage guidance.

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0answers
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Tolerancing considerations for temperature rated mechanical assemblies

I am currently designing a mechanical tensile testing setup to operate at different temperatures (-20 to 100 C) in a wet environment. I plan on machining two sets, one from stainless and one from PMMA....
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1answer
26 views

What are functional and manufacturing datums

Can somebody please explain what is ment by functional datum and manufacturing datum, with respect to dimentioning and tolerancing.
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1answer
34 views

Typical tolerances for valve lift using a camshaft?

I am working on a linear actuator for a valve. Wondering if anyone out there can point me towards the tolerances that are used for valve lift in a typical internal combustion engine using a camshaft?...
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0answers
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Measuring 30-50 ppm strain, how balance wheatstone bridge?

I'm working on a project where I measure 40 ppm strain with resolution of 4 ppm. So far my approach is use a simple wheatstone bridge with a JFET, using 2 strain gauges (120 ohm, GF 2) in the left ...
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1answer
11 views

H6 tolerance shaft manufacturing

I’m a electrical engineer but an amateur in mechanics. I’ve been checking some tools and machines in the market for small works which would allow me to manufacture small but precise pieces, such as a ...
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2answers
191 views

Interference fit in acrylic/plexiglass (PMMA)

I'm trying to fit a shaft into a hole in an acrylic piece that is 5mm thick to cause an interference fit. The shaft has a max. diameter of ⌀5mm and a min. diameter of ⌀4.988mm. I have access to a ...
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1answer
58 views

How to provide concentricity tolerance in assembly?

I have a part(let's name it as supporting plate) which is gonna be welded on two parallel sides of a rectangular channel. The supporting plate has holes drilled at its end, the two supporting plates ...
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1answer
38 views

Tolerance of pin in Scissors

I'm currently designing scissors, and I have to describe the tolerance and fits of the parts. What kind of tolerance must be used for the pin holding the two blades together, though allowing for ...
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2answers
156 views

Help with mechanical drawing?

I'm not a mechanical engineer and am not used to looking at mechanical drawings. I'm trying to understand what these tolerance features mean. There is a positional tolerance feature, which ...
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1answer
78 views

Tolerance on bolt major diameters

What are the tolerance specs on the major diameter of imperial bolts? Specifically, a 1/4-20 imperial bolt has a major diameter of 0.25in, but what is the tolerance on that dimension. I (and ...
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1answer
213 views

Bushing and Shaft Alignment

I"m working on a design and having difficulty calculating possible misalignment. I have a shaft (diameter D, tolerance t) that is running through two bushings. The two bushings are separated by a ...
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1answer
98 views

How thick of an oxide might form on a cast zinc part?

I'm looking into possible failures of a cast zinc part. I'm wondering if the Zinc-oxide that develops after a time would have a thickness great enough to cause dimensional tolerancing issues? ...
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1answer
209 views

What does the accuracy and precision values for a pipette mean?

Is the accuracy interval the tolerance for the instrument? Does the precision interval indicate a single standard deviation? And more importantly, does the precision assume a perfect operator (so the ...
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2answers
2k views

How to find press fit/ slip fit for non standard size parts?

I am looking for calculator or chart for slip fit and press fit for non standard size parts. For example, I have oversized dowel pin 10mm +0.03/+0.01 diameter. I need to create a slip fit hole for ...
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1answer
365 views

What is the difference between incremental and cumulative error?

In a description for ballscrews on a CNC, I saw two types of error listed: Incremental error: < 0.0006"/ft Cumulative error: < 0.0008" at 35" What are these types of error measuring? What is ...
6
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1answer
158 views

Specification of hole design tolerance

Suppose the fit for a rod and a hole in a gear is supposed to be free running and the fit is 3mm H9/d9. For the specification of the hole for the manufacturing of the gear, is "3mm H9" already ...
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1answer
60 views

Placing machine visions targets with high accuracy

My company is working on a machine vision application. One of our requirements is that the camera peer through a frame (like a picture frame - see here ), where the top and bottom border are etched ...
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2answers
413 views

How to specify and tolerance a “sharp” point?

I need to have an electrical probe machined; but I am unsure how to specify my requirements. I am an electrical engineer with only moderate mechanical knowledge. The probe will be machined from 0....
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2answers
249 views

Assist for vertically telescoping support?

Two questions. Has anyone had experience in retrofitting consumer (locally-available) square aluminum tube as telescoping structural support? Ergo; with 0.125" wall thickness square tube at an ...
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1answer
49 views

How to rebuild and lubricate worn plastic parts?

I'm hoping to rebuild a joystick (sidewinder strategic commander), though the parts inside it are a bit too wobbly because they have been worn beyond tolerances. Due to this wobbling on one (rotation) ...
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2answers
115 views

Typical flatness of Portland cement

Does anyone have a feel for the flatness of Portland Cement when poured in a standard/typical way? Say, for example, that I wanted to pour a cement "cube" (20"x 18"x 19.25") in a mold. How flat would ...
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6answers
7k views

Distance sensors with accuracy of 1 mm?

I am making a device for measurements. I would like to measure the distance within accuracy of 1 mm. Range could be 2 cm to 15 cm . I looked at Proximity Sensors but the readings displayed by these ...
12
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3answers
2k views

Measuring longer distances with high accuracy

I am involved right now in the fabrication of steel structures on the order of 5-50 feet long. Presently, we measure these structures with garden variety commercial tape measures. Most of the time, we ...
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2answers
2k views

What are the longitudal tolerances of thread on metric nuts and bolts?

It's not exactly my area of expertize and I've spent a couple hours ears deep in norms, and I'm not really sure if what I found is correct (the figure I found was to the order of 1$\mu$m). When using ...
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3answers
3k views

How does measurement uncertainty combine with tolerances?

Given a tolerance within which your workpiece should be manufactured, say some length should be $10\pm1$mm. If you determine that your uncertainty in measuring this length is $0.2$mm (at 95%). How ...