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DESIGN AND FABRICATION OF SELF CLEANING BLACKBOARD DUSTER A PROJECT REPORT

Submitted to Mr. B.V.S.N. REDDY (Assistant Professor, Mechanical department)

Submitted by:

Vipul Mathur (1130507) Subham Rattan (1130529) Virendra Pratap Singh Rathore (1130498) Amit (1130490) Rajan Vishwakarma (1130591) Siddhartha Ganguly (1130497)

INDEX: 1. 2. 3.

4. 5.

Abstract Introduction Fabrication3.1 Timeline 3.2 Brief Outline 3.3 Components 3.4 Fabrication process CAD Modeling Results and End Note

ABSTRACT: In the traditional blackboard eraser chalk architecture the traditional blackboard chalk dust is a common problem. It is generally known that eraser for cleaning the blackboard in schools and colleges become saturated with chalk dust and have to be cleaned. In the past, this has usually been done by clapping the eraser together. This phenomenon produces a great deal of dust that is rather objectionable both from the standpoint of health and cleanliness. The objective of this project is minimize the lecturer’s effort. Our idea aims for lightening the burden and trouble during cleaning for lecturers. It is also healthful for teachers because when cleaning of blackboard is done by hand, it may cause hygiene problem. The duster will run manually as well as automatically. We began the project by first attempting to come up with an original idea to fit the problem. After coming up the idea, we followed the usual design process to finalize our project.

INTRODUCTION: Since our childhood the day we entered school first thing we have seen are blackboards. They laid the basic foundations of our knowledge from the basic ABC’s to what we learn even today. India being a country emphasizing on education since ages. But the chalks we use on blackboards or the markers on whiteboards need to be erased if next thing is to be taught. This black or whiteboard erasing method is a tedious job. So to reduce a little bit time and energy of the teachers who shall raise the next generation we have tried to design the automatic blackboard erasing mechanism. The concept of automated blackboard cleaner in terms of technicality is not new or innovative. But it seems a marketable idea if the design has new features. As a student, the blackboard is something we see very often in our classroom. We realize that most times, it takes lecture time away from the teachers to erase the board. We believe this valuable time and energy could be put to better use. Our initial target was to have the design the entire manual part and then modify it to automatic. Furthermore the design was intended to use for LHCs and Smart classrooms, it would be best to keep the noise level down so it would not distract the class. Therefore another goal was to have the design be quiet, if not virtually silent. The design was supposed to erase the board within minimum seconds and also with minimal application of effort. As with the traditional chalkboard design, the teachers may face hygiene and dust problems making this the reason for selection of this project. Now-a-days white/black boards are widely used in almost educational institute though smart classrooms are there as option. About 70-80% educational institute in India uses white/black board as the writing medium in their class rooms. They are large in size, for that reason it is very time consuming process to eraser the writing from the board with strokes of duster. If a class is going for an hour then about 10-12% time become waste because of cleaning the board with duster. Considering this the automatic system can solve this problems. The automatic design will shorten the times as well as effort. Our design has horizontal movements of dusting arrangement that will erase the board within a few seconds. And it has an advantage to remove the automation part so that it can be operated in manual way too and the whole design, manual as well as automated, can be established at a very low cost. So, “The Automatic Board Duster” is a spectacular replacement of traditional duster and it can be

suggested to use this to reduce the effort of the board user as well as to introduce the classroom with an automation system. We can see several similar patent designs of our project but our some special modifications will make it stand apart. Our project can be operated manually as well as automatic unlike others. Including the minimum application of funds and moreover, our project’s simple design make it best at architecture at students’ level.

FABRICATION: 1.) SCHEDULED TIMELINE: For the fabrication of the design in this project, a systematic approach was utilized by the group to plan out the entire process. We formulated a timeline to act as a preliminary guide for the work to be done. It shows the weeks as per the academic calendar and the respective activities alongside it. The timeline for the manual operation of the cleaner is as follows: WEEK DATE

WORK TO BE COMPLETED

09

18/09/2016 to 25/09/2016

a) Procurement of blackboard b) Basic material requirement calculation c) Finding the optimum material for project

10

26/09/2016 to 02/10/2016

a) Accumulation of materials (can continue up to subsequent weeks) b) Finalizing the mechanism

11-12 03/10/2016 to 16/10/2016

a) Drafting the design b) Checking its feasibility

13

a) Initial stages of fabrication of manual design

17/10/2016 to 23/10/2016

14

24/10/2016 to 30/10/2016

15

31/10/2016 to 06/11/2016

a) Sessional–2 and Diwali a) Fabrication continues b) Deciding the mechanism for self- cleaning of duster

In the execution of the fabrication process, we have strived our best to adhere to the aforementioned timeline. But, in the actual process, it was still subjected to some deviations.

2.) BRIEF OUTLINE: For the manual operation of the blackboard, we have considered the use of a travelling mechanism for a slider which would support the transversally placed duster. This mechanism would allow for easy and smooth motion when operated by any user. Initially, we considered the following for the travelling mechanism: a.) Wheel and rails, e.g. Railway wheel contacts b.) Sliders, e.g. almirah drawers c.) Ball bearing type slider and rails, e.g. modular kitchen drawers d.) Meshing gears Out of these, we have decided to opt for the ball bearing type slider and rail mechanism as it has rolling contact between the rails and the steel balls which reduce the friction considerably. Also, they are relatively economical and readily available in kurukshetra markets. For the automatic operation, we have decided to utilize a cable drive for the actuation of the duster. This mechanism would use pulleys, cables and a cable clamp. If this doesn’t suit our needs, we have thought of making use of a rack and pinion type arrangement. Both the designs would be powered by an electric AC motor.

3.) COMPONENTS: The various components used in the fabrication in this mechanism particularly for its manual operation are as follows: a.) Blackboard: This component is the base of the mechanism which would be rubbed to erase the markings of the chalk. It has one side of plain blackboard whilst the other is a whiteboard  SPECIFICATIONS: Length- 3Feet; Height- 2Feet

b.) Plywood: Practically, the blackboard is fastened on the wall and as we are simply fabricating model. We need something which would play the role of wall and this purpose is taken up by the plywood. So, the various other components would be fastened on the plywood. The use of plywood will also make the set-up easily portable.  SPECIFICATIONS: Length- 4Feet; Height- 3Feet; Thickness- 6mm; Material- Layered Wood c.) Guideways & Slider: This is a three layered unit in which the first or base layer is guideways which can be viewed as a long rectangular path way with wall on its sides. The top edge of the wall is bended inwards to constrain the slider motion in longitudinal direction only. It is entirely made of Stainless Steel.  SPECIFICATIONS: Length- 900 mm; Width- 35 mm; Depth-13 mm; Sectional Thickness- 2 mm

The second layer is the retainer which is exactly the same in shape to the first layer with slight reduction in width and height and very short length compared to the guideways. The slight reduction in width and height is for easy fit into the guideways. The retainer is segmented into 4 parts, each having 3 cuts on both the edges. There is oil lubrication in between these surfaces to facilitate easy sliding. The side walls of the retainer and guideways are not in direct contact. There are small bearing ball in between them. The sidewall of second

layer has been provided with circular holes throughout its length. The bearing balls are kept in these holes trapped by sidewalls of the guideway from one side and third layer from other side. So, ball rolls in between second and third layer.  SPECIFICATIONS: Length- 108 mm; Width- 35 mm; Depth-10 mm; Sectional Thickness- 1 mm

The retainer combined with the second layer forms the slider part. The shape of third layer is the same but inverted i.e. it is open at the bottom not at the top. The width is slightly smaller and height is slightly bigger in size as compared to the second layer. The length is the same as that of second layer. The third layer has been fixed to the second layer by welding.  SPECIFICATIONS: Length- 104 mm; Width- 26 mm; Depth-10 mm; Sectional Thickness- 2 mm

The

entire

assembly

is

as

shown

in

the

following

figure:

d.) Duster: This includes a wooden plank with carpet wool glued on one of the surface. The carpet wool will actually rub the blackboard. The carpet wool has been selected among different available materials like cotton, carpet wool,

scrub etc. The following image shows the assembled plank and duster along with spring in between.  SPECIFICATIONS (Plank only): Length: 480 mm; Depth: 5 mm; Width: 70 mm

Section view of duster assembly:

Duster material:

4.) FABRICATION PROCESS: 1. The blackboard has been centrally fixed on the plywood with nut-bolt arrangement at the four corners; for this four holes has been drilled through both the blackboard and the plywood. 2. The guideways has been bolted to the plywood immediate to top and bottom edge of board. Two stoppers have been fixed at the ends of the guideways to restrict the slider movement out of the guideways. 3. The guideways can also be bolted directly to the board but that would simply be a hindrance in the effective utilization of the board space and also the thickness of the carpet wool will have to be more than the thickness of the guideways as a result of which the weight of the sliding part would increase unnecessarily. 4. The heads of the two nuts have been welded to the third layer of the two guideways and slider unit. This has been done to facilitate the fastening of the duster to the slider. 5. The contact normal force between board and the carpet wool can be varied by varying the degree of tightness of the bolt on the duster. 6. A clamping device equipped with spring has also been used in the middle of plank so that a uniform normal force can be generated between board and plank throughout the length.

7. A handle is also there at the middle of duster to move it along the guideways manually. The following image shows the assembled components. The duster is not yet affixed to the board as it is currently under work.

CAD Modelling: The manual operation of the blackboard was modeled through SolidWorks application software wherein each component was made separately and then assembled in the assembly mode by applying suitable mates. The resultant assembly is as shown in the following figure:

Magnified sectional view of sliders and plank assembly (the ball bearings are between the retainer)

With the help of motion study adviser, an animated result of the working of blackboard is made which shows the cleaning operation in a timeframe of 10 seconds.

RESULTS SO FAR: The manual operation of the blackboard was realized in this semester using the approach explained. Also, a CAD model has also been made which illustrates the working of the blackboard. In the coming weeks, the project would be carried forward to facilitate automation in blackboard’s operation. NOTE: Our project is still under progress and will be continued in the next semester....