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3. Computer Aided design

  • This week was CAD week, I worked on desinging the part of the demonstrator that will allow water to drain from the tanks simulating the sluice gates.

Sluices

The Purpose of Sluice Gates in the mekong delta are:

A. To store fresh water

B. To keep out salt water

Thair are 1000s of sluices constructed in the Mekong basin at a variaty of scales, larger gates across the Mekong River itself and main tributries and then smaller ones in the ajoining irrigation channels. Sluices help irrigate the land with fresh water even in the dry season from November to May. The use of sluices is integral to the irragation of the Mekong.

CAD Model

Below is quick recap of my project in the broadest sense possible! I’ve highlited the ‘Sluices’ which is what ill be tackling this week.

This was my initial sketch of the sluice gate system, whilst this resembles a sluice gate in no way shape or form it should work well in the modelled version. Here a simple rack and pinion connected to a stepper motor which will raise and lower a plug (Which is the gate) in the bottom of the tank. I may well still actually create a gate but in terms of simplicity and demonstrating the principle a plug will suffice for now.

I will be modelling this in Fusion 360

Initial Sketch

This is a quick sketch of raising/lowering mechanism. This will be clamped around the wall of the container.

Dimensioning The Bracket

Using the McMaster-Carr Component library included with fusion 360 I located a suitable rack, pinion and NEMA 17 stepper motor. As seen below this allows very easy incoropation of parts into your design

I will use a bracket to keep the rack up agaisnt the pinion gear, whilst not being that complicated this did requuire some sketching to determine the correct dimensions of the bracket, to avoid the gear either a. jamming being stuck unable to move or b. for the rack to fall out!.

One thing i had to determine the depth of the torugh to contian the rack was to measure the combined height of the gear and rack when the where overlapping such as when they would be working

With a couple of iterations I mamged to have a good idea of what i needed to do in my CAD design.

Drawing The Bracket

  • The first step was to draw the base plate a 49mm square and then add the 4 3.5mmm mounting holes for the NEMA17 motor. This Was done by ‘create sketch’ and then ‘extruding’ the square to 6mm. then Drawing another sketch extruding negatively to cut thorugh the plate. Then using the rectangular pattern tool to repeat this pattern 4 times aroind the perimter of the plate.

  • The next step was to create the inlayed section for the motor, this was a 22mm in diameter and cut to 3mm in depth. using the same method as decribed before

  • The next step was to drill the 5mm hole for the motor Shaft through the plate.

  • Then I started with the trough, due to the screw holes overlapping with where a continuous trough would be, I opted to make 3 troughs for the rack to sit it, although it could have been done by just drilling through the front face i thought this may comprismise the strength of the bracket so opted for this method.

Once Extrudued I used the ‘rectangular pattern’ feature to repeat 3 times.

  • Finally filleted the corners of the plate and the supporting brackets using ‘fillet’ to a 2mm Radius for the plate and 1mm radius for the supporting brackets.

Assembling

  • I Then imported the stepper motor, rack and pinion and construced a ‘rigid’ joint between the motor and the plate. Then I added the ‘fasteners’ 4 M3 drilled broach hex screws.

  • Then I made a motion joint (‘revolute’) for the pinion on the shaft of the motor. I seltected the axis at which is was free to rortate round and then snapped it to the center point of the motor shaft, and then applied and offset of 16.25mm to allign it with the trough.

  • I repeated the previous step but for the rack, this time the joint type was ‘slider’ and i snapped this to the vertical axis of the trough.

  • Then a motion link was created between the rack and pinion, here the relationship between the motion of one component to the other is set.

Plug

  • Here I made a plug and added a 12mm OD 2mm O-ring

Animation

GIMP

In order lighten my sketches I used (GIMP) to alter the contrast and saturation on my pictures

Mass Image Compressor

Addtionally i’ve been using (Mass Image Compressor) As a handy tool to batch compress picutes for my site.