Bolts and nuts are industrial fasteners. They are daily consumable items in engineering
industries. Bolt is a piece of metal rod, whose one end is unsettled and the other end is threaded.
Nut is the item, which rolls on these threads. Bolt and nuts can be sold independently in the
market. Therefore, manufacturers follow a standard in manufacturing bolts and nuts so that there
is uniformity of the product in the market.
The objective for this lab was to manufacture a hex thick nut by using basic tools used in
manufacturing shops. The tolerancing and dimensioning of the nut was according to the standard
table of Hex Thick Slotted Nuts.
The design approach was plan driven, the design process was understood in terms of discrete
sequence of stages.
Theory and Calculations
The following dimensions and tolerances were selected from the Standard table of Hex thick
Basic major diameter = 3/8
F: max = 0.562, min=0.551, basic =9/16
G: max =0.650, min = 0.628
H: max = 0.415, min=0.398, basic=13/32
Tools & Equipment: Hacksaw, files, vise, Vernier caliper, micrometer, blue dye, scribe,
protractor, punch, drill press, thread gage, tap and die set, tapping oil.
1. A stock of 0.75 inches diameter was used. From the standard table of hex thick nuts, we
selected a basic major diameter of 3/8 for our nut. The dimension was suitable since it
would require less work producing the finished product while using basic workshop
2. The stock was held firmly using a bench vice and the nut was cut out using a hacksaw.
The cut was based on the calculation below:
a. H max * 125% = 0.518
b. H max * 150% = 0.6225
Once cut from the stock the nut was shaved using a double cut file to obtain the
dimensions specified in the standard table. Further smoothening was done using a mill.
The workpiece obtained at this stage looked as shown below:
3. One surface of the nut was painted and left to dry.
4. A center square was then used to obtain the center line. And the center was marked using
a scriber then made visible using a center punch.
5. On the surface of the nut, we used a compass to draw lines in the directions of 60, 120,
180, 240, 300 and 360 degrees so that we got 6 angles.
6. We then calculate F by using the following formula 𝐹 =
so that we find F which is
from the center to the top and we marked it on the nut.
7. We used two pieces of wood to hold the nut on vise to avoid damaging it.
8. We connected all the line on the surface of the nut and then we used the double cut file to
cut each side of the nut to shape as nut. The nut looked as shown below:
9. We then placed the nut in a drilling machine. And we made a hole through at the center
of the nut.
10. We then held the nut on a vice and using a tap and die set we made internal threads on the
nut. The process involved to round once and go back for half round.
Discussion of the results and corrections
The final product we obtained from the experiment above is as shown below:
By analyzing the dimensions and appearance of our nut, we found it to be not exactly what
we expected. The hole drilled was not at the center of the nut. The dimension F was also not
consistent throughout the nut. The thickness was also not the same throughout the profile of
the nut. However, we managed to obtain good threads. The unexpected result could have
been brought up by:
1. Poor alignment of the nut when drilling. By not putting the nut in the correct alignment it
caused the center to be missed by the drill bit in the drilling machine
2. Another source of error was the ineffective use of the available equipment, this resulted
in the varying side dimensions of the nut.
My working hour is $10
My group and I spent 7 hours to have the product complete.
The material cost $10
So, The product cost in manufacturing:
($10*7) + $10 = $80
The product will cost out of manufacturing:
80*3 = $240
We managed to use simple workshop tools to make a sample nut. We learnt how to use a tap and
die set to make internal threads. We also learnt the important parameters used in making a nut as
well as other basic skills such as using wood to prevent damaging a workpiece on the vice. To
improve on the accuracy of making a nut, we encourage using accurate machines to make the nut
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