Designing a Mini2440 Faceplate for Chameleon 1
11/09/2009 08:23 Filed in: C.A.D. | Mechanical Engineering
Synopsis: ESawdust has had several requests to create a Chameleon 1 faceplate for the FriendlyARM Mini2440 ARM9 development board that’s suitable for running embedded Linux, Windows CE and other embedded OS’s. This article describes the processes we go through to layout a faceplate and create cutouts for shapes we need to allow connectors to protrude through the face. By the end of the article you’ll see a completed prototype faceplate for the Mini2440 and how we got there.
The article is broken down into sections including measurement, layout, prototyping and finally, there’s a video tutorial on how to create a complex cutout shape, a DB9 cutout, using a consumer grade C.A.D. package, ViaCAD (Windows and Mac versions.)
ESawdust follower, @BusError (Michel), maintainer of the embedded Linux distro for the Mini2440, put me in touch with Charlie Springer of Industrial ARMWorks who was kind enough to supply us with a Mini2440 and FriendlyARM displays to start sizing up.
The Mini2440
In case you’re not familiar with the board, this is a top-down shot of the Mini2440. I put a physical ruler nearby so I could calibrate photos. I have a virtual caliper in the image also which is showing the board to be around 3.94” square.
Measuring
The first order of business is to determine the orientation of the board and identify the side that makes the most sense to expose via the faceplate. In the case of the Mini2440, the side with power, audio, RJ45, USB, RS232 was the obvious choice.
I measured the board with physical calipers and got a 3.94” square board. Also, using the screen caliper software, I calibrated the virtual calipers to the photos I took of the connector edge. I then began measuring all the typical dimensions such as:
1) Offset of the left side of each of the major connectors (except DB9) to determine the relative position of the connecter from the left side of the board. Here’s an example of measuring (virtual calipers) from the board left edge to the left edge of the mag jack.
While measuring the key dimensions, I take down all the numbers in a spreadsheet (shown later) for eventual faceplate placement calculations.
Layout
The overall Chameleon 1 faceplate is a pretty simple shape on bounds. The baseplate on which the board is mounted is 4.9” wide and the enclosure lid and faceplate are example 5” wide so the lid fits snugly around the baseplate. You can see an example of the Mini2440 resting on 1/4” standoffs on the baseplate of the Chameleon 1.
Based on the width of the board and the width of the baseplate, assuming the board is centered on the base plate I can easily compute the “easements” or margin between the board sides and the side of the baseplate. (4.9” - 3.94&rdquo
/ 2.
The baseplate is 0.4” tall. The standoffs add another 1/4” and the PCB is about 0.063” thick, so that is the base offset for the height of all the connectors on the faceplate.
So, the two main layout tasks are:
1) template of the board hole patterns to drill on the baseplate so the board perfectly lines up with the faceplate cutouts we’ll do in the next step.
2) faceplate connector cutouts so the cutouts are exactly the right height and right offset when the board is mounted according to the spec.
It’s convenient, when possible, to have the board connectors protrude slightly from the faceplate rather than be very recessed. It helps make the faceplate fit feel solid and positive. Fortunately, with the Mini2440, they did a good job of extending the connectors past the edge of the board so we can line the board’s mounting holes up pretty close to the edge of the baseplate and get a nice fit for the faceplate.
Using a CAD package called ViaCAD, I designed for mounting the Mini2440 on the baseplate of the Chameleon 1. Here’s a scaled down image of the template for the base plate mounting for the Mini2440:
The template is made to cut out and overlay over the Chameleon 1 base and has the center-punch markings in the middle of each mounting hole which you need to easily center-punch the mounting holes for a perfect fit.
The faceplate template is a lot more challenging than the baseplate.
I start with a blank faceplate design, again done in ViaCAD, save it as a new faceplate and remove all the dimensions from the drawing (planning later to prototype with it, so using a laser cutter, for example, I don’t want anything except the cutouts as lines on the design.
Here’s the blank faceplate design I start with:
Using all the connector height, width, and offset measurements I mentioned earlier, I create a spreadsheet that helps to easily identify the X / Y offsets of the various connectors as they map to the 5” x 2” faceplate. The spreadsheet accounts for the width of the board, the margins on the side of the baseplate, the baseplate height, PCB thickness, standoff height, and full width of the faceplate.
Here’s a quick example of a working spreadsheet I use to start laying out the connector cutouts on the faceplate:
This serves as a pretty accurate but not final guide to initially placing connector cutouts on the faceplate.
Most of the cutouts are pretty simple - holes and squares. Love those. The harder cutouts are for odd shaped connectors like DB9. So, one of the things I had to create was a DB9 cutout for the Mini2440. Later on in this article I developed a video tutorial on how to create a DB9 cutout from scratch using a CAD package. Once I have the DB9 cutout, I can add it to the faceplate design.
Using the spreadsheet computations and DB9 cutout, I can complete the Mini2440 faceplate design which looks like this (image is not 100% scaled):
Prototyping
Before submitting a design like this to have manufactured at a sheet metal fabricator or laser cutter for a lexan version of it, we like to prototype it by using cardstock or some type of heavy paper. This lets us see exactly how everything’s lining up and tweak any positions or sizes if needed.
So, the beautiful thing about using CAD programs is you can print a design at scale and use that scale pattern to test and prototype.
Using an 8 1/2” x 11” piece of black card stock, I cut out an oversize boundary around the printed faceplate design and tape it to the card stock.
Using an Exacto, I cut the holes out of the design along with all the connector cutouts. The last thing is to cut the faceplate boundary out of the card stock from the template and remove the white plate off the cardstock.
Next the Mini2440 can be mounted on the baseplate. Using the baseplate template, I line it up with the physical baseplate of the Chameleon 1 and tape it in place directly on the baseplate. This will guide the next step, creating the center-punched holes for mounting the board.
The baseplate template in place, I center punch the holes for the board. It’s best to cut a short, thin piece of wood (0.35”-0.4&rdquo over which the baseplate can straddle so the center-punching doesn’t bend the baseplate. It supports it so you can easily drill it later, too.
Next, flip it over and using a sharp awl or nail, tap a small center-punch dent into the base plate precisely where the template center holes are (there’s a small dot in the center of the mounting hole.) The center punch will keep the drill bit from skating when you drill out the holes. This is really important to make sure the faceplate lines up perfectly in a later step.
With the 4 mounting holes center-punched, you can see the small indents in the baseplate where you drill:
Next, simply drill out the center punched holes with a drill press or hand drill.
I used a hand drill. 3/32” bit for 4-40 holes works well. Keep the wood block underneath the baseplate during drilling to catch the drill when it breaks through.
With the mounting holes drilled, I can add 1/4” standoffs and the 4-40 screws to attach the Mini2440 to the baseplate:
Using the black faceplate prototype I cutout a few steps back, I can literally screw it onto a Chameleon 1 and start checking it out. From a distance it looks remarkably like a real faceplate. On my first prototype, the DB9 cutout came in too high and too small for the hex studs, so I learned right away what I had to do, trimmed the cardstock and rechecked the fit.
Here’s the prototype faceplate on a Chameleon 1 taken in a light studio to help see what the production version might look like:
We’ll be creating a large cutout in the top of the lid for the Friendly ARM LCD display, but for those who use the board standalone without the display, a Chameleon 1 basic + a production version of this faceplate is all that’s needed to have a sweet lid for the Mini2440.
For those of you interested in how to create complex shapes for faceplate cutouts, you can watch the video below where I do a tutorial on creating a DB9 cutout with a CAD tool.
Tutorial for Creating a DB9 Cutout
One of the key skills you need to create your own faceplates is to be comfortable with a CAD tool. In our case, for the production units, our designs go into SolidWorks because our Chameleon 1 manufacturer, Advantage Manufacturing (Colorado Springs, CO), has the technology to take the SolidWorks CAD models directly into sheet metal CAM files needed to punch it all out to spec in industrial volumes.
However, if we’re making a few faceplates and can’t justify punching several hundred that are required to make going through sheet metal manufacturing, we can have the faceplate laser cut on Lexan in a number of colors like dark smoked or even sold black. This is a very cost effective useful way to make custom, professional looking faceplates for Chameleon 1 enclosures.
Fortunately, the kinds of functions and features needed to create complex cutouts on a faceplate can be easily achieved with a consumer level CAD package. We use ViaCAD for these.
The video tutorial below takes you through making a complex cutout shape like a DB9 using ViaCAD and this is the design I’ve used for making the Mini2440 faceplate’s DB9 cutout:
Wrap up
We have a few more things to wrap up this week on the design including getting a lid cutout for the FriendlyARM touch display. Our next steps are to get a Lexan version of the faceplate made and do our final adjustments. We’ll probably first offer the faceplate in a smoked Lexan and see how sales go before committing the faceplate to sheet metal. Will update the blog and site when the Mini2440 faceplate is available for sale.
If you have a popular development board for which you’d like to see a new Chameleon 1 faceplate, contact us and we’ll see what we can do to help you out.
Landon Cox
www.ESawdust.com
The article is broken down into sections including measurement, layout, prototyping and finally, there’s a video tutorial on how to create a complex cutout shape, a DB9 cutout, using a consumer grade C.A.D. package, ViaCAD (Windows and Mac versions.)
ESawdust follower, @BusError (Michel), maintainer of the embedded Linux distro for the Mini2440, put me in touch with Charlie Springer of Industrial ARMWorks who was kind enough to supply us with a Mini2440 and FriendlyARM displays to start sizing up.
The Mini2440
In case you’re not familiar with the board, this is a top-down shot of the Mini2440. I put a physical ruler nearby so I could calibrate photos. I have a virtual caliper in the image also which is showing the board to be around 3.94” square.
Measuring
The first order of business is to determine the orientation of the board and identify the side that makes the most sense to expose via the faceplate. In the case of the Mini2440, the side with power, audio, RJ45, USB, RS232 was the obvious choice.
I measured the board with physical calipers and got a 3.94” square board. Also, using the screen caliper software, I calibrated the virtual calipers to the photos I took of the connector edge. I then began measuring all the typical dimensions such as:
1) Offset of the left side of each of the major connectors (except DB9) to determine the relative position of the connecter from the left side of the board. Here’s an example of measuring (virtual calipers) from the board left edge to the left edge of the mag jack.
While measuring the key dimensions, I take down all the numbers in a spreadsheet (shown later) for eventual faceplate placement calculations.
Layout
The overall Chameleon 1 faceplate is a pretty simple shape on bounds. The baseplate on which the board is mounted is 4.9” wide and the enclosure lid and faceplate are example 5” wide so the lid fits snugly around the baseplate. You can see an example of the Mini2440 resting on 1/4” standoffs on the baseplate of the Chameleon 1.
Based on the width of the board and the width of the baseplate, assuming the board is centered on the base plate I can easily compute the “easements” or margin between the board sides and the side of the baseplate. (4.9” - 3.94&rdquo
/ 2. The baseplate is 0.4” tall. The standoffs add another 1/4” and the PCB is about 0.063” thick, so that is the base offset for the height of all the connectors on the faceplate.
So, the two main layout tasks are:
1) template of the board hole patterns to drill on the baseplate so the board perfectly lines up with the faceplate cutouts we’ll do in the next step.
2) faceplate connector cutouts so the cutouts are exactly the right height and right offset when the board is mounted according to the spec.
It’s convenient, when possible, to have the board connectors protrude slightly from the faceplate rather than be very recessed. It helps make the faceplate fit feel solid and positive. Fortunately, with the Mini2440, they did a good job of extending the connectors past the edge of the board so we can line the board’s mounting holes up pretty close to the edge of the baseplate and get a nice fit for the faceplate.
Using a CAD package called ViaCAD, I designed for mounting the Mini2440 on the baseplate of the Chameleon 1. Here’s a scaled down image of the template for the base plate mounting for the Mini2440:
The template is made to cut out and overlay over the Chameleon 1 base and has the center-punch markings in the middle of each mounting hole which you need to easily center-punch the mounting holes for a perfect fit.
The faceplate template is a lot more challenging than the baseplate.
I start with a blank faceplate design, again done in ViaCAD, save it as a new faceplate and remove all the dimensions from the drawing (planning later to prototype with it, so using a laser cutter, for example, I don’t want anything except the cutouts as lines on the design.
Here’s the blank faceplate design I start with:
Using all the connector height, width, and offset measurements I mentioned earlier, I create a spreadsheet that helps to easily identify the X / Y offsets of the various connectors as they map to the 5” x 2” faceplate. The spreadsheet accounts for the width of the board, the margins on the side of the baseplate, the baseplate height, PCB thickness, standoff height, and full width of the faceplate.
Here’s a quick example of a working spreadsheet I use to start laying out the connector cutouts on the faceplate:
This serves as a pretty accurate but not final guide to initially placing connector cutouts on the faceplate.
Most of the cutouts are pretty simple - holes and squares. Love those. The harder cutouts are for odd shaped connectors like DB9. So, one of the things I had to create was a DB9 cutout for the Mini2440. Later on in this article I developed a video tutorial on how to create a DB9 cutout from scratch using a CAD package. Once I have the DB9 cutout, I can add it to the faceplate design.
Using the spreadsheet computations and DB9 cutout, I can complete the Mini2440 faceplate design which looks like this (image is not 100% scaled):
Prototyping
Before submitting a design like this to have manufactured at a sheet metal fabricator or laser cutter for a lexan version of it, we like to prototype it by using cardstock or some type of heavy paper. This lets us see exactly how everything’s lining up and tweak any positions or sizes if needed.
So, the beautiful thing about using CAD programs is you can print a design at scale and use that scale pattern to test and prototype.
Using an 8 1/2” x 11” piece of black card stock, I cut out an oversize boundary around the printed faceplate design and tape it to the card stock.
Using an Exacto, I cut the holes out of the design along with all the connector cutouts. The last thing is to cut the faceplate boundary out of the card stock from the template and remove the white plate off the cardstock.
Next the Mini2440 can be mounted on the baseplate. Using the baseplate template, I line it up with the physical baseplate of the Chameleon 1 and tape it in place directly on the baseplate. This will guide the next step, creating the center-punched holes for mounting the board.
The baseplate template in place, I center punch the holes for the board. It’s best to cut a short, thin piece of wood (0.35”-0.4&rdquo
over which the baseplate can straddle so the center-punching doesn’t bend the baseplate. It supports it so you can easily drill it later, too.Next, flip it over and using a sharp awl or nail, tap a small center-punch dent into the base plate precisely where the template center holes are (there’s a small dot in the center of the mounting hole.) The center punch will keep the drill bit from skating when you drill out the holes. This is really important to make sure the faceplate lines up perfectly in a later step.
With the 4 mounting holes center-punched, you can see the small indents in the baseplate where you drill:
Next, simply drill out the center punched holes with a drill press or hand drill.
I used a hand drill. 3/32” bit for 4-40 holes works well. Keep the wood block underneath the baseplate during drilling to catch the drill when it breaks through.
With the mounting holes drilled, I can add 1/4” standoffs and the 4-40 screws to attach the Mini2440 to the baseplate:
Using the black faceplate prototype I cutout a few steps back, I can literally screw it onto a Chameleon 1 and start checking it out. From a distance it looks remarkably like a real faceplate. On my first prototype, the DB9 cutout came in too high and too small for the hex studs, so I learned right away what I had to do, trimmed the cardstock and rechecked the fit.
Here’s the prototype faceplate on a Chameleon 1 taken in a light studio to help see what the production version might look like:
We’ll be creating a large cutout in the top of the lid for the Friendly ARM LCD display, but for those who use the board standalone without the display, a Chameleon 1 basic + a production version of this faceplate is all that’s needed to have a sweet lid for the Mini2440.
For those of you interested in how to create complex shapes for faceplate cutouts, you can watch the video below where I do a tutorial on creating a DB9 cutout with a CAD tool.
Tutorial for Creating a DB9 Cutout
One of the key skills you need to create your own faceplates is to be comfortable with a CAD tool. In our case, for the production units, our designs go into SolidWorks because our Chameleon 1 manufacturer, Advantage Manufacturing (Colorado Springs, CO), has the technology to take the SolidWorks CAD models directly into sheet metal CAM files needed to punch it all out to spec in industrial volumes.
However, if we’re making a few faceplates and can’t justify punching several hundred that are required to make going through sheet metal manufacturing, we can have the faceplate laser cut on Lexan in a number of colors like dark smoked or even sold black. This is a very cost effective useful way to make custom, professional looking faceplates for Chameleon 1 enclosures.
Fortunately, the kinds of functions and features needed to create complex cutouts on a faceplate can be easily achieved with a consumer level CAD package. We use ViaCAD for these.
The video tutorial below takes you through making a complex cutout shape like a DB9 using ViaCAD and this is the design I’ve used for making the Mini2440 faceplate’s DB9 cutout:
Make a DB-9 Cutout with ViaCAD from Landon Cox on Vimeo.
Wrap up
We have a few more things to wrap up this week on the design including getting a lid cutout for the FriendlyARM touch display. Our next steps are to get a Lexan version of the faceplate made and do our final adjustments. We’ll probably first offer the faceplate in a smoked Lexan and see how sales go before committing the faceplate to sheet metal. Will update the blog and site when the Mini2440 faceplate is available for sale.
If you have a popular development board for which you’d like to see a new Chameleon 1 faceplate, contact us and we’ll see what we can do to help you out.
Landon Cox
www.ESawdust.com
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