Assignment 7:Computer-controlled

Computer-controlled Cutting

This week assignment is to make something Big!!!

I planned to make something useful for our lab. After getting inspired from yamnitsky desk i decided to make press fit table.

Design

This week we have to make something big using CNC machine. I used Solid Works to make 2D design of the press fit table.Before making the actual table i decided to make the scaled down model of the table. After this i will scale it to the actual dimension using parametric approach.

Below find the layout which i made on my notebook before making it in SolidWorks. The main concern during the design was to provide good mechanical strength.

The material used for prototyping is cardboard of 7.6 mm thickness. I used laser cutting machine to make scale down model.

The design are having five parts.

Part 1

This part is to provide hold the table. The length of this part will depend upon the table size. This part also has two slots of width equal to thickness of material. These slots are used to hold the part2.

Part 2

Again this part is also used to provide support to the table against gravity. Its length will depend upon wodth of the table.

Part 3

This part is to provide mechanical strength to table in length direction. It has three slot of 8mm X 7mm each.

Part 4

This part is to provide mechanical strength to table in width direction. It has four slots, inner ones having size of 12mm x 7mm and the size for outer slots are 8mm X 7mm.

Part 5

This part is the top of the table having four slots at corners.

Here is the assembled table.

Downloads

part1.SLDPRT part2.SLDPRT part3.SLDPRT part4.SLDPRT part5.SLDPRT

part1.dxf part2.dxf part3.dxf part4.dxf part5.dxf

Stool!!!

Design

I also planned to make a press fit stool for my lab. In this there are two parts.

Part 1

This part is to support the plate of the stool. The rough sketch for this part is shown below. The designs are made according to the discussion with local instructor.

Problems faced during the stool design!!!

Initially the width of the slot in the design was according to thickness of material. Then i relaized two parts will meet at 90 degree for this size of slot.

Now the requirement is the meeting angle should be 60 degree. For this some caluclations was done as shown in figure. From this calculation it is proved that the width of the slot should be greater than thickness of material.

Below find the snapshot of the drawing in Free CAD 0.16.

Material=Cardboard (thickness=7.6mm)

Material=Plywood (thickness=5mm)

Downloads

Design for Lamp Shade

The lamp shade is designed using Onshape.In the first picture the rib of the lamp is shown.

Tolerance of the slots.

After working on test piece i got some experience how to decide the width of the slots. The slot width decided by me is equal to (thickness of material -0.2 mm). I used this directly because plywood is very uneven,so tolerance test might or might not given the best idea about tolerance.