How NOT to draw a sheet metal product. AVOID this mistake!

Every time we want to draw a model, we need to take into account how it will be produced. If not, you can end up with a beautiful model that is useless to manufacture the product. We don't want that, don't we?

How would you draw the following sheet metal product?

Simple aluminum can, as an example

I took a simple aluminum can as an example.
How will you draw it?
The two most common ways would be:

• Make a solid drawing and use the shell feature 
• Use the sheet metal complement 

If you don't see the difference between the two options at first sight, don't feel bad, you came to the right post.

 Why should I use the sheet metal complement?

If you really want to manufacture the sheet metal product, you must know that building a solid chunk in Solid Works and throwing some dimensions over it won't give you the expected result.

When manufacturing a sheet metal product, one or more of the following will occur:

1. The sheet of metal will deform, changing its size
2. The thickness of will most likely change
3. The product will consist on multiple sheets of metal

The most important result that we need is the resulting sheet.
Solid works calculates the needed sheet before starting performing all manufacturing processes on it.

As an example..

Look at the following nonsense sheet metal product

Ugly and useless

Unless it is is manufactured by foundry, that is worthless. We need the initial sheet of metal:

The unfolded sheet allows you to produce the product

The unfolded model takes into consideration the change in size by folding and working on the sheet.


To be able to draw your model in those terms, you should think on the manufacturing process.
For example, in the case of the aluminum can, I recommend you to see a video and see, as always, that the model won't be as simple as it seems. It takes multiple manufacturing steps to end up with the aluminum can, and if we consider the little opening metal piece, three parts constitutes the model.


At this point, maybe you just want the model for another reason, like rendering an image for marketing purposes.

The WRONG way of modelling the aluminum can

As stated, if you don't need the model to actually produce the sheet metal product, then, go ahead and build a normal model, with normal operations:

As always, insert images of the aluminum can in each plane. In this case, top and side.

Start drawing half the silhouette

After drawing half of the silhouette, perform a revolution extrusion. Don't forget to draw the axis to reference the revolution feature.

Then, continue with the top view. Insert the image
By the way, you can insert it in Tools, Drawing Tools, Image.

Auxiliary circles are drawn over the image of the top plane

Here, the auxiliary circles will allow you to draw from lateral plane, but still accessing the extreme points of the circle, as references.
The surface is shiny and has many changes in radius. Its troublesome, so don't get frustrated. Make an approximation, as I did, unless you want to cut the can perfectly in half, so you have the real section of that part. Too much of a problem, it doesn't make a functional difference.

Drawing the section to perform the revolution cut

You can draw lines to help you with the depth of the drawn section. That, together with the circles in the top plane, you can make an approximation of the side section

 

 

Result of the metal can after the revolution

 

 

 

 

Make use of the rounding feature in every sharp edge that is rounded. It is a really easy process.

Draw the following sketch using splines. Then use an extruded cut.

Perform an extruded cut from sketch

The model is almost complete
Draw the little piece of metal that allows to open the can and extrude it. (Does it have a name?)

Drawing the nameless piece

Then you should use the shell feature to end the drawing being an empty can and not a piece of metal.
In this particular case, SolidWorks couldn't build the operation for some reason, so I will search more in detail why is this happening.

Apply the polished aluminum appearance and insert an image to the side, and the can will be complete
The hole in the top is optional: is it open or not?

Final result of the sheet metal product

To insert the image, enter en appearance and select the wanted image. Then, adjust the size and position. It is really straight forward.

Inserting and adjusting size and position of the desired image

You can always render the final image if you want!

I will upload the sheet metal procedure to model the can when I have some time.

Regards

How to easily simplify a complex model of a pair of scissors

Sometimes it is possible to simplify a model that needs to be functional but doesn't need to be exactly the same as the actual one.
In this opportunity I choose a simple pair of scissors, which has some complexity in the uneven form of the handle

Final model of the Scissors

When using images to copy the form, it is difficult to draw intermediate sections, because no all sections will be visible from the photographs. That's where approximations come handy.

Inserted images to facilitate drawing from the real scissors

It would have been better if the side photo had a clearer background, but it is not really an issue.
As always, insert both images in paint, and adjust the size so you can save two images with the same relative size. Insert them in SolidWorks:

Create a drawing in a plane>Tools>Drawing Tools>Image

Then position both images, moving them "minus half the size" in each axis, if you want it centered:

Positioning the images relative to the origin

Then, is time to draw.
Create drawings following the limits of the image. Use splines if necessary. It is recommendable to draw each blade separately, so it can be treated as an assembly, and can be moved as in reality. If not, it will be a solid block.

TIP: you can draw one blade, then put it in a folder "Right Blade", suppress it and draw the second one. Then, you can save two different files, which only difference will be that one blade is suppressed in the first, and the other in the second. This allows for a unique file to modify, and the relative position between them will be easy to handle.

Separate in folders and suppress the one you don't want for the moment

 This model can be extruded pretty much from one drawing per blade. Perform different extrusion operations for every area drawn that you need to give volume to. Select the proper lenght for every extrusion.

Following  we see the basic drawing of the model. Use splines to adjust all curves, following the model. Take your time and use all necessary points to obtain a model that reflects reality.If splines get out of control, add more intermediate points or stop the spline and continue with another one from the ending of the first one.
 Simplifying the shape in the other planes, we can make a good approximation with little effort. The real model has organic curves difficult to copy from the picture.

Basic drawing of the model

TIP:Take into account that avoiding to select the holes in the extrusion will save you time. You won't need to perform an extruded cut later.

In the middle of the drawing+extruding part

Simplifying the extrusion of the handles by using a defined distance to extrude, makes the model much more easier. Coping the real form is a really difficult task, which has to be solved in a different way, to eliminate the problem of the photos, which don't show you the middle sections of the scissors.
(A different approach could be, measuring different points and drawing a line that passes through all those points)

As regards the Anti-Slip shape of the handles, it can give some trouble if done incorrectly.
It will obviously be done by a pattern, a pattern guided by the curve of the hole specifically.

Anti-slip feature

For the sake of simplification, we will draw a rectangle and then use the round feature to adjust the shape.
Start by defining a plane to extrude into the scissors. The position will be approximated by eye (how would you measure that?!)

Define a plane to draw the rectangular shape

TIP: don't define the plane from the inside of the handle and then extrude to the outside. Instead, draw the shape from the outside, and extrude it "to the next surface". Using the first method will probably give you model errors. (For example, I got parts painted black which were defined to be red. When drawn properly, this issue disappeared)

Use the second method to perform the extrusion of the antislip

Perform the matrix with the pattern operation. The direction will be the curve that defines the hole. In "operation and faces", select the extrusion and the round feature (you should round it before applying the matrix feature).
It is possible that you will need to use one matrix operation for every direction, to complete the total anti slip bands.

Matrix (pattern) operation to solve the anti slip bands

I didn't enter into detail in some features which are easy to perform and don't need any explanation to be understood (like the center pin, some rounding features, etc)

Now, you should apply the appearance of black and red plastic to give the same look as the original scissors. It usually can be selected from the menu on the right:

Appearance selection

If you want to experiment with the rendering option, try to search for the most realistic look possible.
The problem is if not done correctly, you can end with a shady, too lit or low contrast image like the following.

The rendering itself deserves a complete study to search for the best possible appearance

Comparing the result with the real scissors, we can conclude that it is not always necessary to make a complex modelling (like the one carried out in the post of the "Candy model") which implies to draw inner sections and guiding lines to use the "covering feature".
On the other hand, the color of the scissor and the selected material is not optimal. If you need the reality and the model to be exactly the same, pay special attention to rendering options.

The result is pretty similar to the obtained model

How to draw complex models in Solid Works and not dying in the attempt

If you happen to trust deeply in your SolidWorks skills, I challenge you to replicate the following model by your own method. Solid works complex models gives you the opportunity to be creative and show your modelling knowledge.

Example of a Solid works complex model

It is a seemingly easy candy for the christmas tree.
Well, if you thought that way, I tell you that trying to replicate it without oversimplify if turned out to be quite a challenge. I will show you my way of solving this problem.
Steps to take

1. Insert an image in each plane and draw the contours
2. Draw relevant sections 
3. Draw guide lines
4. Perform both covering features
5. Close the ends of the model
6. Twist by using the flex feature
7. Mirror the model
8. Optional: apply material and render with Photoview 360

1) Insert an image in each plane and draw the contours

Candy's rudimentary plane, made up with photos

As you can see, the model is defined by all non uniform curves (including the center). In these cases, I recommend taking a picture of each view and adjust every image to a rudimentary plane (unless you have the actual plane, obviously)
Save every image in a separate JPEG. Using a single image first makes easier to adjust the size to the same for every image.
This Solid works complex model has a reflective surface, and the table has a similar tone to the candy. That gave me a harder time adjusting lines to the drawing. When possible, avoid that reflective surfaces and maximize contrast between the model and the background.

"Image of croquis" lets you attach images to the 3D drawing

In order to have all planes positioned, use the command "move entities", when the image is selected. Use half the size in X and Y to center the image. You can even put the calculation inside the box in properties to calculate it.

Centering the planes

The result should look similar to the following

All photos in position

2) Draw relevant sections

We will need various sections to make the "Covering command" work. One for the knot, one for the center candy, and one for the twisted envelope.
For the twisted envelope we need to define an inclined plane. I hope this is clear with the following image.

Definen the "Section plane"

If the plane was not inclined, the drawing of the lateral envelope will be out of the actual candy envelope. To define the plane, draw a constructive line that unites most salient point of the envelope, in the bottom plane ("alzado" plane). Then simple use a "Geometry reference", "plane" and define it containing the line and perpendicular to the bottom plane.

Now, draw the following sections of the candy, to use the "covering command" later.

In blue: section lines necessary 

You can later mirror all operations with respect to the center. Do not draw everything two times! 
(although I will use the full candy for the explanations)
Important: to be able to relate the sections with the curves in other planes it is necessary to build point. In this case, which all are curves, we must build the points. I recommend drawing the axis of the sections, and cutting them "to the nearest object":

Draw an axis and cut it with "to the nearest" object (the ellipse in this case)

 Now, that point (between the axis and section) will be selectable for the lines in the other planes, allowing you to link lines with the section, necessary to use the "covering command".

3) Draw guide lines

Then, draw guide lines. You could use the covering command to draw the surface, but without the guide lines, it will be a uniform surface, very different from the actual candy.

Guide lines

 Important: every guide line should be a different drawing. If not, the covering feature can give you errors when building the surfaces.

 The following image shows you how all lines are drawn following the limits of the images provided. Note how blue lines end in the point of the ellipse, point defined by the axis and the ellipse itself. If you didn't draw the axis, you wouldn't be able to select that point, the blue line will end "in the air" and the covering feature will break. Solid works complex models will usually have this type of difficulties.

Splines follow the limits of the drawing, ending with the defined point

4) Perform both covering features

Apply the covering command for the center and the envelope

Violet: guide lines. Blue and yellow: section lines

Similar to the last example

5) Close the ends of the model

To draw the end parts of the envelope, you can make an approximation with the "Dome" feature.
Important: as this dome is non uniform, because of the non uniform base spline, you are forced to click on "non uniform dome" to build it.

Dome feature

Building the dome wasn't a perfect solution. Using a surface that included the guidelines drawn would be more accurate, but for some reason, SolidWorks couldn't build it.

6) Twist by using the flex feature

The following step is to use the "Flex feature" to apply torsion to the envelope.

 

Flex feature

Defining torsion planes

Select "torsion" and move the red plane to the knot. Then select the angle of torsion, which is 15° in this case.

Note: now, from the side, the envelope has been moved from its original plane. A better solution would be to initially draw the section 15° counterclockwise, so when it is twisted, it ends in the correct place and the envelope has that twisted look. The only way to know the angle is by try and failure.

7) Mirror the model

The drawing of our Solid works complex model is almost complete! Finally, apply symmetry to draw the other part of the candy.

Solids for symmetry

The only trick for the symmetry is to use "solids for symmetry", and select the center plane as the reference.

8) Optional: apply material and render you Solid Works Complex Model with Photoview 360

If you want a realistic look, you can use photoview 360 to make the rendered image, but those details for another post.

End result of our Solid works complex model

How we upgraded a rubber extruder machine and gained 30% efficiency

I was hired to overhaul a worn out rubber extruder machine. The company did not want to buy new equipment. The machine was old and therefore spare parts were not available, so I had to design the parts. Consequently, it was a perfect opportunity to upgrade the design.

The infamous, old machine

The machine was near useless at this point; the main bolt had a crack almost to the core, the rubber backed off from the main bolt due to wear, greatly damaging the bearings and the housing was full of deposits... but I decided to try the task as a challenge.

To remove the main bolt, we had to cut it in half with a grinder machine. It was stuck.

Bearings where damaged by the rubber entering into them

The main bolt, before grinding it in half

For extruding rubber it is necessary to heat the bolt and cylinder liner so the rubber is more fluid. It is also a must to cool the excess heath with coolant. You should never use non treated water, because minerals start to deposit and trouble will arise with time. Obviously, this is exactly what happened.

We used citric acid to remove the excess of deposits which would cause difficulties when assembling the machine. Citric acid is inexpensive and not dangerous if used properly.

Using citric acid to remove deposits inside the housing

To seek possible optimization points, I decided to model the machine in Solid Works and then run some simulations. Many parts were not optimized, like the main bolt (which moves the rubber) and the end piece (which acts like a cap).

Before entering in detail with every piece, this is the model of the machine to the present day:

First design for overhauling/upgrading the extruder machine

After running some simulations, I concluded that machines (especially old ones) are not that difficult to improve, because they are usually oversized, and not to mention that wear leads to decrease in the machine productivity. After the upgrades, the machine produces more than 30% more rubber. Money can be saved in materials and energy and efficiency can raise significantly. Also less pieces were off tolerance.

Compare new orange line with the old blue line. The production increased 30%

I will post how did this work follow in future posts.