Task of the week

    What I have did

    Group assignment :

  • Studied Shopbot at COEP collage.

  • Test runout, alignment, speeds, feeds, and toolpaths for your machine.

  • Have designed the test pattern in a group.

    Individual assignment :

  • Have tested the runout, alignment, speed, feed and toolpath for the Shopbot machine at COEP collage.

  • Make something big.

  • Have designed the object in Solidworks.

    • Have generate the toolpath in Partwork.

      • Have cut the design part on Shopbot.

        Week 7 :

        This week was about to make something big. This week we have to make something by using plywood on "Shopbot". We have to complete our group as well as our individual assignment. In group assignment we have to find out various parameters of machine kerf, offset, runout conventional, climb rough/finish cuts...etc. We have completed our assignment at COEP (College of Engineering Pune). Because in Vigyan Ashram we don't have the Shopbot machine.

      Week1-1

        Specifications of " Shopbot Wood Router " at COEP : -

        At "COEP" Apeksha Siddharth who is the professor at COEP and also an our "Instructor" for Fabacademey 2020 have given us an introduction about "Shopbot" as well as it's various specifications and how to operate it. She told us about the shopbot machine at COEP is a 2.5 axis which runs on 230 volt supply. It has 8'*4' standard bed size and able to cut wood and plywood. It has guideways in the X, Y-axis and a router is at the z-axis which is capable to spin 12000 rpm. We are using end mill as a cutting tool for this machine.

      Week1-1

        Impotant parameters of Shopbot :

      • Feed Rate :

        It shows that how fast the machine will move the router bit through the material (in this case the plywood of reuired thickness) when we give the cutting pass. It is very important to for getting good quality cut edge.

      • Plunge rate :

        It is the speed at which the router bit is driven down into the material when we start cutting and it will vary depending upon the bit we have used and the material on which we are going to process.

      • Spindle speed :

        It is the speed at which the tool revolve around Y direction. Feed rate and Spindle speed are inter-related. Sometimes it is possible to cut at a faster feed by increasing the spindle rpm. Similarly, if we cut the material at too low feed rate or with too high spindle speed there is a risk of overheating of the router bit and also burning of material get happen.

      • Step over :

        It is the maximum distance in the x/y direction that a cutting tool will engage with uncut material

        After introduction of Miss Apeksha we have discuss various thing related to our group assignment. She has also gave us information related to the softwares, "Partwork" to generate toolpath and "Shopbot-3" for operating machine.

      Week1-1

        First we have cut a rectangular block with 4 slots with different clearance. While loading a plywood sheet on the machine we have to fit it with machine bed with the help of "C-Clamp".

      Week1-1

        Safty come first. Before handling machine we have to consider all safety factors like, To wear shoes, hand gloves, gogal...etc.

      Week1-1

        This is the pattern we have cut for our group assignment.

      Week1-1

        Individual Assignment :

        For my individual assignment I have decided to design a table with Octagonal shape. While designing any object I always prefer to assemble all parts before going for the actual cutting. In various design software, it is a key advantage that we can see any defect during assembly virtually in the software itself. It is a useful feature for eliminating the errors in design and also the wastage of material.

      Week1-1

        In the above image I have shown my first design which is defective. Because, while assembling it in the software, the parts where not get assembled properelly with " Octagonal shape ". So I have change the shape with circular shape.

      Week1-1

        I have also added a dogybone shape slot in my design. I found that doggybone shape is nothing but the fillet at cornors these provides the better and easy fitting of parts with each other

      Week1-1

        For easy operation I have made Subassembely of the main assembely. Which contain the assembely of 2 circular disk at the top and to the bottom and they were get joine by an I-shape link. As I shown in the above image.

      Week1-1

        At last I have assembel the the upper surface with the lags of table .

      Week1-1

        Up to this I have done the work. Due to lockdown in India we were not able to have a lab acess to COEP collage. For cutting the design files of table on the shopbot.


        Modified design of table :

      • In the previous design, there is lack of stability. To provide stability I have redesign the drawing of the table. I have design the lages of table in the such a way that they get pressfit with each other.



      • So this is the new design of the table. That I have design in "Solidworks".


      Week1-1


        New design of table :


      Week1-1





        Steps for generating toolpath for shopbot :

      • Open Partwork software. The following window get open as shown in Img.1. This is the working environment. I want to design a table with racks to place some documents which we required regularly. The upper surface of the table can be use for putting some decorative materials like Flower pot.

      • So I have choose the 12mm plywood sheet to build this table. For that I have select the Width = 2400mm and Hight = 1200mm which is the size of the plywood sheet I am going to use for my work. Also we need to choose the thickness of plywood which is 12mm.

      • Here we also need to select the origin from which the tool will proceed to cut the material. I have selected the bottom-left position as per the position of the plywood sheet mounted on the machine and press OK.

      Week1-1

      • Then select the files which we have to cut. I have saved the part files in the .Dxf format. But we can save the file for shopbot in pdf, stl...etc format.

      Week1-1

      • The designed parts are get open inside the white rectangle. This white rectangle is nothing but the size of the sheet of plywood in software. Arrange all the parts at right hand side in the window as we have selected the origin position at left hand side.

      Week1-1

      • Then first select the inner slots in the design as it is mostly preferable. And click on the join option or press Shift + ctrl. This step is important because as you can see in the image the selected slots which are highlighted in the pink color are not a close vector. And Machine can only process to cut for the close object design. So we have to join these unclose vector before get proceed further.

      Week1-1

      • Here we need to add tabs to each piece, so that parts do not fly out during the machining process. If we not add the tabs, the dislodged parts can potentially damage the other parts of the workpiece, it can also damage the machine or even cause injury.



      Week1-1

      • Go to 2D profile toolpath at the right hand side of the window and do the following settings.

        Cutting depths :

        Cutting parameters :

      • Start depth = 0.0 mm (This is the starting position of the endmill.)

        Here we have select the cut depth 0.5mm more because our plywood has 12mm thickness. If we have select 12mm cut depth then the endmill will not cut through the material. So we have selected 12.5mm cutdepth to get complete cut piece of plywood.

      • Cut depth = 12.5 mm

      • Know click on the tool option. the following window get open. Select Straight 1/4" tool from the list. That means we have selected the endmill with 6.35mm diameter.

        Tool settings :

        Cutting parameters :

      • Pass depth = 0.27 inches

      • Stepover = 0.1 inches

        • Feeds and speed :

      • Spindle Speed = 12000 r.p.m

      • Feed rate = 27 mm/sec

      • Plunge rate = 3.0 mm/sec

        • Change all the above values in the settings and press Apply and click on Ok.

      Week1-1

      • Then press Calculate at the bottom-right side of the window.

        • Week1-1

      • And Save tool path. We can see the changes we have done in the toolpath settings to the right side of the window.

        • Week1-1

      • The message in the window will ask if we want to continue with settings we have done. It will ask that do we have sacrificial layer means the material below the plywood. This will prevent the damage of our endmill. So we have the sacrificial layer below the plywood material, hence I click on OK.

      Week1-1

      • We can see the following toolpath generted for internal profile as shown below.

        • Week1-1

      • Follow the same procedure for the Outer profile.

      Week1-1

      • We can see the generated toolpath of outer profile..

      Week1-1 Week1-1

      • After this process, we can get two file formates. One is .sbp file formate for the machine and another is the .CRV which is the editable file formate. .CRV files can be used and edit all over the world.

        Note : 1) Here we can also use " dogbone " where the legs fit into one another. This will made the stronger and stable design.
        2) Here I also need to add the “finger” (mortise/tenon) at the top of each leg so that they will get fit into the top piece properly.         The mortise and tenon joint is considered to be one of the strongest joints it will allow the easy and strong fitting of the wood parts with one another.



        Machining process :

      • After Unlock of COVID-19 we have get the access to the COEP lab for completion of fabricating work.

      • As toolpath of my workpiece is ready I have given the command to the Shopbot machine to cut the parts. I have taken the plywood sheet of 12mm thickness.



      • These are the separate cut-parts of the table.



      Week1-1

      • This is the final assembly of the table. To get the better support I have cut the two circular plates and have joint them with each other by using Synthetic Adhesive ( Fevicol ).



      • And the table is ready to use...!

      Week1-1

        Download design files :

      Creative Commons License
      Solar Automatic Shredder by Tejswini Chaudhari is licensed under a Creative Commons Attribution-ShareAlike 4.0
      International License