When I lent my services to a collegue who was working on a film about 12 years ago, I was introduced to the world of cnc. I remember watching this huge machining centre milling out a slab of mdf and turning it into a fantastic set of gears. I knew that it would have taken me hours to achieve the same thing with traditional power tools. I decided then that I would invest in a cnc router for my own business Oxenham Design. At that time I could turn on a computer, but even to check email seemed like a crazy set of operations. I persevered and learned every piece of relevant software I could get my hands on. I am now fortunate enough to be using Vectric's ASPIRE software, and Techno cnc routers, which has helped us to create some amazing projects, both in part, or in full. I thought that this blog would be a great place to share "behind the scenes" adventures with the software, materials and equipment we use, as well as the projects we build.

Thursday, 18 April 2013

Modelling a Simple Item


I wasn't able to post this simple tutorial until tonight due to work. This will be a simple tutorial based on a household item. This one will be very simple, and allow you to get a little familiar with some of the tools in Hexagon.

I'm going to create a basic drain plug for a bathtub drain! Simple and fun, and won't eat up a whole day of your time!

I will call the tools by name and show an icon where-ever I can remember too.

So lets get started:

I don't have any particular drain-plug in mind, so we'll invent it as we model, based on any generic plug.

The first step is to create a cylinder with 16 points (or sides) and 2 sections. This should give us enough resolution to do what we need.
Up in selection tab is where we can choose to use the edge selection tool. You'll notice under it are the options for loop, ring and between. Remember these.
If we select one edge on the bottom, then hit the LOOP select option, the software will select all the edges on the bottom of the cylinder. Then if we grab the yellow box on the universal manipulator, we can scale the bottom edge loop in a little. This is going to be the part of the plug that goes into the drain hole.

Next, select a top edge, then 'loop' select the entire ring.

 If we grab the center yellow handle on the manipulator, and hold the CTRL key, we'll extrude those edges outward evenly. Again, this is all visual.
While still holding CTRL, grab the green arrow and move it upwards a little. This will extrude the edges up.
Lets move back to the bottom of the plug, and finish that up. LOOP select all the bottom edges, then using the yellow handle on the manipulator and CTRL, extrude them in a little ways to give the plug some thickness.
While still holding CTRL, extrude the edges upwards with the green arrow on the manipulator.
Again, use the CTRL key and the yellow handle on the manipulator to scale the edges inwards, until a small hole is left open.
Under the VERTEX MODELLING tab, select the CLOSE icon. We'll use this to close off the little hole we just created.
Once we select the CLOSE tool, any open portion of the geometry will be highlighted in white. We just need to click the highlighted hole we want to close. You may have to rotate the model using ALT and the Right Mouse Button (RMB) and rotate it for a better view to get the software to select the right hole. Once the highlighted hole opening turns red and is filled in, we have to end the tool by pressing the VALIDATE button on the right side PROPERTIES palette.
Now lets select the newly closed hole polygon, and holding CTRL, extrude it down a bit. This will give a small nipple that the plug I used for reference has.

Now, lets see how our model looks when we smooth it out:

Under the PROPERTIES bar at the left, there is the number selection for smoothing. I only ever smooth to the number 2 while modelling something, this gives me the look, without bogging the computer down with too many polygons to calculate!
I really like the underside of the plug with the nipple, but the very bottom portion needs some resolution to better define it.
Lets turn our smoothing off for now. Just simply select the #0 under smoothing. This will let us work on the low resolution model. Anytime you can work with the low resolution model, the better and simpler it is.
Let's select 2 edges and press the LOOP selection, you should get what I have above.
 Under the VERTEX MODELLING tab, you'll find the EXTRACT AROUND tool under the EDGE TOOLS fly-out palette. It's the one with 3 lines.
 Now we just have to drag out a new set of edges. Keep the fairly close to the original. This will add resolution to the bottom edge, keeping the corners fairly sharp.
If we select the #2 smoothing again, we can see how sharp the bottom of the plug is after adding the edge loops. Much better. However the edge of the plug that sticks out above it needs some resolution as well. Lets take care of that now.
Put the smoothing back to zero, and loop select my highlighted edge. Then we will do exactly what we just did using the EXTRACT EDGES tool again.
Now we'll have 2 new sets of edges on each side of our originally selected edge loop.
After applying #2 smoothing, the edge looks nice and sharp. The final edge to tackle is the next one out. It's totally rounded, and needs sharpening.
The exact same process as the last two steps is applied again. Now we have some good definition happening!
Let's move back to the top of the plug. Select one of the outside edges, then use LOOP SELECT to highlight the whole edge.
Using CTRL and grabbing the yellow center handle on the manipulator, extrude the edges in to where the little handle on the drain plug would start in real life. About where I have it located now.
Use the green arrow on the manipulator to drag the select ring up a little. This will give us the dome look to the top of the plug.
If we smooth it now, we have that great mushroom dome happening to the top of the plug. Perfect!

The plug that I have has a set of circular ribs around the top for whatever reason. We'll duplicate those as well.
We're going to select one of the highlighted edges above, then beside the loop select feature, is the RING SELECT feature. This will select all the edges on the same loop ring on the model. It should look like the above image. Now we're going to connect all these edges with an edge loop. This will give us some edges for our ribs.
Under the VERTEX MODELLING tab is the CONNECT function. With all the edges above selected, and hitting the CONNECT tool, you'll see the new edge loop added. It adds it right down the center of each edge.
Here's what you should end up with. Now were going to do the same thing a couple more times:

We just keep RING SELECTing  our edges, and CONNECT them with the CONNECT tool. Ive added a total of 5 new loops. You could do as many as you want, or none. This is all visual anyway.

Now we want to select all these new loops to create the ribs. Again, it's faster to select one line of each loop, then hit the LOOP SELECT feature. This will select all the edges we want.

If we select the EXTRACT AROUND tool under the VERTEX MODELLING tab, we can add edge loops on either side of our selected edges.
Now if we pull the center selected loops up a little bit with the green arrow on the manipulator, we will have added our ribs like on the real one.
With a level 2 smoothing, it's really coming along!

Now for the handle part with the hole for the chain loop!

This is a very important step to make sure we're working on this properly! In the upper left corner, make sure your in the WORLD co-ordinate system. Second is to look at the red line i've drawn on the model. This is the center of the model which we'll need to be familiar with to make sure we select the proper edges in the next step! It's easy to identify the center of the model by looking at the bounding box edges around the model.

We want to select the six edges of the whole, leaving the very last edges at the top and bottom unselected. Now if we grab the blue square 'scale' handle, and move it towards the center of the model:
We'll end up flattening it right out. This will become the basis for the right side of the handle that sticks up.
Now let's do the EXACT same thing on the left side of the plug. The square opening looks a little wide for my liking, so lets narrow it in a little.
Select all the flat edges on each side of the plug, then use the blue 'scale' cube on the manipulator. This will puul the edges into the center of the model. Just adjust them a little, to better proportion the handle base.
Lets CLOSE the hole with the CLOSE tool under the VERTEX MODELLING tab at the top.
Don't forget to hit the validate key to close out the tool.
We now have to add some resolution to the newly created polygon that filled the hole. It would be considered one giant N-GON, meaning a polygon with more than 4 edges. This will be very unpredictable when we smooth the model, so we need to fix it now.

We going to now use the FREE TESSELATE tool that's found under the VERTEX MODELLING tab at the top of the screen.
 This tool has a little yellow box that defines where it is positioned. If we hold the shift key, it will snap to the available points on the model. Were going to split the large N-GON we created right down the center. You have to hit the validate key after every section connected.

Now we need to connect the remaining edges to each other. Move from one point to the opposite point, then validate the tool.

Just keep repeating the process to connect all the edges so they look like the above image.
Now we can select all the newly created faces,
And using the green arrow handle and the CTRL key, we can extrude them upwards to create the handle for our drain plug.
We now have to set up our model for the hole in the handle. Lets RING select all of these edges, then connect them with the CONNECT tool we used before. This is found under the VERTEX MODELLING tab at the top.
This connects our selected edges with a new loop right around the middle.
Lets add 2 more edgeloops to define where the top and bottom of the circle will reside. Select the 2 highlighted, then RING select the rest.
With the above edges all selected, we want to connect them with the CONNECT EDGES tool.
This will give us a whole pile of resolution to work with for the hole.

Lets select the 4 polygons on each side of the handle, then delete them. This will leave the opening for the chain hole.

The 4 polygons we deleted on each side might not make a perfect square, effectively leaving us with a rectangle opening. We need to fix this now.

If we select the above edges on each side of the opening,
Using the red axis scale box on the manipulator, drag the edges in a little to square the opening up a little. You could be very anal, and use the input box to apply the exact dimensions, we're going for visual, so as long as it looks fairly square, we're all good.

Now we'll turn the square opening into an octagon that will smooth into a circle when we apply smoothing.

We'll select the 4 outermost points on the left and right openings
We'll use the yellow center scale box on the manipulator to drag the end points inward, to shape our octagon.
If we rotate the model, you'll see that that our opening is all distorted, an easy fix is next!
Select one edge on one side of the opening, and LOOP SELECT the hole.
With the opening edges all selected, drag the blue scale box into the center of the model. This will flatten out all the edges into the same plane. The edges all align planer if you stop dragging at the location of the yellow center scale box on the manipulator. If you drag past the yellow scale box, the edges end up reversing, still being out of plane.
Repeat the same procedure, but on the opposite side.

With all the edges planer, we just need to make sure that all the edges around the opening are selected on BOTH sides.

We're going to let Hexagon connect the hole for us. If we select the BRIDGE tool, under the MODELLING VERTEX tab, the edges of the opening get bridged closed.
Now we want to add some resolution to keep our hole edges sharp, otherwise they'll go soft and look weird! We'll just RING select the inside edges of our hole.
Use the CONNECT tool to add an edgeloop down the center of the hole.
Use the EXTRACT EDGES tool and split off two edges, placing them close to the ends of the hole.
VOILA! We have our finished drain plug!!! Good job!

In fact, lets create the ring using a TORUS primitive from the SECOND LIFE tab, scaled and rotated to fit.

Here's our plug rendered out in another software package. As boring a thing as a drain plug is, it makes you appreciate it a bit more after spending all this time with it!

1 comment:

  1. That was soooo cool !! I'm into radius constrution and it looked liked something I would build in a Tiffany store. Then I saw it was a drain plug. WOW
    Thanks, Cookie