Category Archives: Cases / Enclosures

Pretty on the outside and ugly on the inside prototype

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So I’ve been busy doing a bunch of computer maintenance and looking into other things I’ve neglected while building the roaster so it’s been a bit slow.  I decided I wanted to start gluing corners together and drilling some holes to see how the case goes together so I can eventually get back to fixing the issues with the roast controller case.  Over the past several weeks I soldered together all of the boards, made wiring harnesses and figured out a bunch of “oops” moves I had made designing things when I got rushed for time.

Turns out I was not able to get stand offs locally in the sizes I had wanted so the heights are all screwed up where I placed holes on the outside surfaces.  I also forgot to specifically allocate power for the exhaust fan in the original design BUT I did have “Spare” pins allocated. The fan I ordered also was not the right size for the hole template I had used (Inside fan dimension vs outside screw / case dimension)… neither of them were actually labeled right the way every other fan I have is sized.

So with everything screwed or harnessed in place this is what I have for the Arduino…

The Arduino wired for Coffee Roaster control

It is a MEGA2560 mounted on a Crib for Arduino.  On top is an Ethernet Shield w/ microSD slot.  Then I used a variety of crimped headers to connect to some of the pins on the MEGA and on the ethernet shield.  I have twenty five lines in the bundle going to the Arduino.  I had some spare 10 strand cables from a project at Halloween and no 25 strand cables to use so I used one of those cable wraps to keep the all together after connecting DB25 to one end and header pins to the other.  Once the lid for the crib for Arduino is in place it then connects to the back of the enclosure.

Wiring Harness connecting to the back of the controller enclosure

As you may notice the sockets I was using for connecting the power out are the type that snap in.  The majority of these will not snap into most laser cut plastic sheets and instead are designed for aluminum cases.  The plug to the right on the other hand screws in.  These work great with a variety of thicker locations.  The fan was originally going to be on the inside with a wire cover on the outside but with the wrong size fan hole in use I had the wrong cover to fit the fans that I had that would fit the hole.

For the DB25 connectors it turned out good that I had decided to use a cut out pattern  that had the holes on the side for the anchoring hex nuts rather than just having them cut out so that I could mount them to the socket and anchor the connector.  Since the stand offs were too short they don’t allow me to anchor the PCBs to the bottom plate.  Instead I had to screw them to the back plate using normal screws and with the burnt circles on the laser cut work I had to use some washers too to keep it sturdy.  This is what the back plate looks like.

Rear Panel of controller

This panel includes – One non-filtered switched 15Amp Power Entry module, 2 snap in 15 amp convenience plugs, 1 5VDC fan, 2 DB-25.  The left one is the main guts for the LCD, TRIAC control, potentiometers, thermocouple, and a variety of other sensors.  The right includes all the non-essential stuff for backlighting all the buttons on the button pad and a few other things including spare wiring.  You cna see just a screw on the right since it was relatively intact and so it won’t block the DB25 plug being used.  The right DB25 has washers and screws in place.  These are primarily used to attached the PCB in place attached to the back side.

Next up is the inside view of the electronics area:

Rear View of the Back Panel

Rear view of the back panel.  I need to shrink up the crimp connectors around the wire  (they shrink like heat shrink tubing but is actually much firmer).  Also the connector on the right side (the switched power entry module) should have the screws more securely fastened with nuts and washers but this is mainly just a test to ensure it all fits together and then allow me to focus on some programming for a while to see if I can get more working and develop menus etc.  The clear acrylic bar is used to anchor the corners better.  I need to change the locations of the screws since I could not find screws the size I wanted without spending way too much for large quantities of them on the internet and having them shipped to me etc.  The thermocouple board on the right had the same issue with the stand offs so it is just floating loose in there right now.  I need to find somewhere to get the Omron thermocouple sockets where I dont need to order them by the 1000s since it looks like Ryan McLaughlin has stopped selling things on his site when they (used to) have problems getting the newer MAXIM thermocouple chip.  They’re all over the place now but he hasn’t restarted his store up so I don’t know the deal there.

Here is the view down into the enclosure from above:

Top view into enclosure

With the cover on:

Front panel installed on enclosure

Front panel running

Front Panel Running

When I send it back out again for a new case I hope to have a different board to install that will be switching the smaller breakout boards being designed onto the circuit board as well as add a power supply and possibly having an arduino board mated on top of the circuit board perhaps to bring more of the electronics inside.  I might want to try to get a Digilent board perhaps to try converting to it as a transition between Arduino and PIC32 before I completely switch to a dedicated PIC32.

I’ve also been looking at possibly creating a dedicated PC application to communicate with it directly via USB and over ethernet.  I am toying around with the “QT/QML” language but havent gotten too far with it.  I may just go back to Processing though.

RoastGeek Button Pad v 1.0

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This weekend the final resistor I was waiting for arrived.  As a result I was able to solder the button pad board together and mount all the buttons.  I placed the board on my infrared preheater, applied some solder paste using the syringe dispenser on each of the pads, and then using a pair of Weitus tweezers started placing 0603 resistors from the piece cut from a reel.  I then turned the heater on and let it sit for a bit before turning it up a few more times until I got close to the temperatures I needed.

RoastGeek Button Pad v1.0 on Infrared Pre-Heater with SMD resistors placed.

Without a stencil it’s pretty hard not to goop too much solder paste onto the pads.  In most cases I had a suitable amount but a few it got a bit too much.  For most of the cases I had too much I removed some while it was still liquid-like from the preheater softening the paste.  I used the tweezers with a tiny bit of paper towel to wipe some away on the worst spots.  Solder paste is essentially  a mixture of a type of flux with a fine dust of the solder.  When the temperature gets high enough the flux material starts to liquify and the solder particles flow with the wet flux-like material towards the meeting point of the pads and the item being soldered.  As you apply a final amount of heat the solder particles melt and the flux-like material starts to evaporate/burn up.  To do this I used a hot air rework station to heat up the area near the resistors.  It has a pretty gentle flow that I can adjust with a knob so I didn’t have any issue of the resistors blowing away.  This tends to be a common problem using a hot air rework tool to solder SMD parts.  Once they were all in place I turned down and then a bit later fully off the heaters and allowed it too cool down.

0603 Surface Mount Resistor soldered to the board with an infrared preheater and a hot air rework tool.

Once the surface mount resistors were in place I tested each pad on each side of every resistor and confirmed that the correct resistance was measured.  This was to confirm that I didn’t have any “over gooping” resulting in the resistor being jumped by solder underneath of it.  Everything checked out ok so I continued on to mounting the buttons and header pin connections by hand with a standard iron.

RoastGeek Button Pad v1.0 with buttons, caps, and headers mounted

At this stage I tested the board with an Arduino sketch and was able to measure each button as expected.  This board has a much more accurate number compared to the last board.  Each button previously would measure a number that ranged 3-4 from the highest to lowest reading.  This one is dead on for almost every single button except for 2 of them that vary by 1.

I then mounted the board to the back side of the control panel.  I discovered that the standoffs I am using are about 1-1.5mm too tall so I will need to either grind them down or find a different set of stand offs.  I’m thinking of getting some Nylon or ABS ones that have a self-retaining clip for the circuit board side and a threaded end for accepting a screw from the front panel.  I also need to begin wiring up some wiring harnesses to go between the LEDs and potentiometer over to the new board.

I’ll add a picture of the mounted board  here once that takes place.

Looking for success in failed laser cut jobs.

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So having looked at a lot of failures on my project I began looking for places where I could extract some value. First success, the buttons!

YAY! Buttons fit!

Then checking out the engraved converted to outline fonts turned out quite well.

The engraved areas looked pretty good.

Then I tried filling it in with paint…

Infilling the text

More infilling

Finally a look at what the panel looks like with the cover paper removed and the LEDs installed.

Infilled panel with LEDs installed

Now the waiting begins… laser cutting a case – Part 3 of 3

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As mentioned previously my Ponoko order arrived.

So people tend not to show off their screw ups.  The purpose of my building this site was to share with friends, family, and the internet at large what exactly it takes to create a coffee roaster controller.  The money, the heartaches, and well…. the good… the bad… and the ugly.

Unfortunately, today I give you… the ugly.

The Ugly

You don’t usually get to see what goes wrong with laser cutting jobs but considering how many times the curves overlapped each other I’m surprised it isn’t worse.

Surprised it isn't worse!

Most of what’s wrong with the job is obviously what happened on the bottom where the acrylic came in contact with whatever Ponoko cuts on top of.  It seems that some sections obviously burned and melted/cratered portions of the acrylic.

Some areas are brittle.

In a few places the plastic is brittle but only from the bottom side but that last one looked ok on top but there wasn’t enough to count on it not breaking later.  In some areas pieces burned back into one another!

Some areas burned back into one another

Many of the bad spots would not be an issue for a small one off project that gets covered with some sort of screw or bolt.  Others that appear on the surface would be a huge deal.  A few places I apparently removed too much line near a curve and didn’t fill in the straight line so I need to dremel off some stray plastic.

Oops! Apparently I deleted too many straight lines!

Outside of the too many circles and that stray plastic I did not make the spacing correct on the hole that keeps the fan and heat potentiometers from spinning even though I measured it with a micrometer.  It was VERY close but still off by a small bit.

Close... no cigar

I could totally fix it with the dremel for now but will fix it properly for the next run.  Also it appears that I calculated a reduction in the length of the inner bottom plate wrong.

Sometimes you forget you already subtracted the length off the total.

I had taken the outside measurements and subtracted the thickness of the acrylic twice when I had subtracted the rear once already and then subtracted the front and rear later.  Finally I calculated it into a measurement adding it back twice instead of the one extra time.  As a result it is too short front to back.

For these parts I will be testing the process of infilling the engravings for the test to see how they come out for very narrow and wider text.  I will also (when the tools arrive) test the drilling and countersinking with a few various plastic bits before trying them out on the final plastic pieces.

Roaster Controller layout from design files sent for laser cutting.

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After sending files to Ponoko and then finding out they were screwed up so the make job is messed up I had to go back and do a lot more work on cleaning up the files.  Since a bunch of the electronic parts are here already I figured I’d take some measurements and drop things in place on a copy of the display panel and color it in.

This is roughly what it will look like if it ever gets made.

 

As of 6/3/2012 this is an approximation of what the control panel would look like if it ever gets through the make process without problems in the design file.

Now the waiting begins… laser cutting a case – Part 2 of 3

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So last night I received an email from a Ponoko staff member mentioning that I should be prepared that my laser cutting job is not going to be pretty.  After looking at the objects he mentioned being messed up I’m realizing it’s going to be pretty ugly all over.

Almost every place that there happens to be a circle there are between 10 and 20 duplicates.  The staff guessed that the layout had been imported from another program before getting finished in the layout software I used.  Their guess is that conversion added all the extra elements.

The good news is that I can systematically go through and delete elements until there are none left and then undo the deletion on time to get a single object back.  Due to being in a rush to meet the deadline for the voucher giveaway I didn’t test for dupes / double lines as well as I should have and missed all the circles and a couple spots on some of the vector text because I was more focused on all the connections of the various pieces touching each other.

The good news is the making cost is going to be 1/10th to 1/20th the original cost at this rate!  The bad news is I’m going to have to wait another two weeks probably….

So why did this happen?  Originally this was designed for a CNC process against a piece of metal.  When I converted to trying to make this using Ponoko’s laser cutting service it needed adjustments when I imported the data file.  My assumption is fr a CNC machine this would start in one location, mill around the edge of the circle and then drop .1 mm I guess.  It would then mill around the edge again and drop again and again and again until it made it all the way through the material.  The software used that process and generated a dxf file with those paths in it.  When it came into the software I had to use to finalize it for use @ Ponoko many of the shapes I replaced.  I didn’t replace the circles and one area of vector text.

At this rate it might be worth upgrading to the Prime account this month to submit the replacement file to get fast turn around and lower per minute costs on the laser for the prototype.  Then when I get it back and review the results I can make some adjustments and remake or finish the remaining parts and another project quickly and get it all done in the same month cheaper.

After several hours of deleting duplicate circles I’ve chopped 1/2 of the making cost off.  I’ve still got a bunch more work ahead of me but it’s getting to a point where I will likely want to go through the full “pre-flight” check in illustrator trying to delete pieces one at a time and then search for random anchors and duplicate curves.  From everything I’ve seen all of the dupes are curves while the straight lines are fine.

 

Now the waiting begins… laser cutting a case – Part 1 of 3

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So I’ll be the first to admit I have no idea what I’m doing.  Assuming I benefit from a miracle I will eventually be in possession of a laser cut case and it will actually look acceptable.

Ponoko had a spend at least $50 and get a $50 voucher promotion.  I’ve spent days moving lines around and changing colors and thickness and deleting stray bits out of it until I couldnt see straight.  Tonight I finished a 31 x 15 sized panel.  For giggles I put two cases on one panel since it seemed to be the most efficient way of dealing with this.  On one panel I used vector engraving for the labels.  On the other I used vector engraving with a raster fill for fancier looking fonts.  I’m curious how both look and intend to try to fill them with paint to see if they look ok with the various sizes represented.

I’ve thrown together paper models trying to confirm spacing and suitable sizes/dimension and had wanted to try to create a model using some paper coated foam board but I ran out of time.  The promotion ended tonight and I was running out of hours and decided to just give up and hope all my calculations and re-calculations and CAD drawings and everything else I’ve tried were correct.  The order only covers part of the case and I still need to generate a left side panel in addition to the right side one.  The front, bottom, top, and rear are all covered already.  I have a second project I was going to include in the excess space but I figure I should wait for the first order to come in and see how it turned out.  If anything is horribly wrong I’ll try to get it made again using the voucher but otherwise I’ll just continue on if it came out ok.

First laser cut job sent to Ponoko

The top left is the raster filled engraved layout.  The next one to the right is the non filled one.  Next, the bottom piece.  The two items on the bottom right are “inserts” for the LCD area.  I sized them out for the 7 inch touch screen with the two panels able to be “popped in” to the opening to hold a 4×20 New Haven Display mounted into the piece.

Supposedly if you make a rectangle at say 50mm and then make a second rectangle somewhere else at 50.2mm this .2mm is referred to as “kerf” or something.  This sizing allows you to friction hold a plastic piece in an opening….  I figured I’d try it out to see how well that works/doesnt.

Continuing to the left on the bottom there is a cut rear piece on the bottom with a slotted front plate above it to allow air to be pulled through to the fan opening cut into the rear.  Next are two right side pieces.  One has a position cut out for a termocouple connection and then the other does not have one.  Finally on the far left bottom is a second rear with no cut outs and a front panel with the slots cut into it.

Once I decide if I totally botched this I will either redo the job or continue with the right side plate and any adjustments for other sides that I think I need.  Then I will find some acrylic square “rod” to glue into the corners.  Some of the positions will be drilled for mounting the top/bottom/rear and the others will just be glued.  I intend to be able to unscrew the bottom, rear, and/or top while the other edges will be glued in place.  I just went this route since I wasn’t sure on the screws I’d end up using and wanted to see how well things turned out before I would go back and laser cut any of the pieces with more holes in them or whatever else I want to do to it.

 

Adventures in Custom Cases

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The more I look at my project and the fact that it TECHNICALLY does in fact roast coffee now… and the more I think about it the more I feel I need to work on a better project enclosure for my project.  While the Radio Shack case is fine I have concerns with the layout I had to use for the in-progress prototype plain taking up too much space.  I feel like I need to move on to building something that is (at least on the outside) more permanent.

When I look at the schematics and all the wiring involved I keep seeing situations where I need to shrink it all down onto a custom made board.  The more I think about a board (as rendered a few weeks ago in a previous post) I realize I need a box that it will go in figured out.  Once I know the box shape the better I can layout a board since I will finally have “internal dimensions” to try to squeeze it all into.  How to build a case, however, is not entirely easy.

Sure there are blogs all over about people building cases for their projects but most of them assume a standard rectangular box.  The sides all interlock together and you anchor it with some slots cut into the box and a set of bolts/nuts for each corner/side/whatever.  Outside of those sort of cases there are very few options as a DIY case unless you have welding capabilities or other more advanced tools at home like a mini-CNC or something like that.

There are plenty of sites that offer to fabricate stuff for you.  Ponoko tends to one of the more popular ones.  There are also other more “professional” ones that allow much more advanced cases to be built.  These sites include those such as Protocase and Front Panel Express.  Both of those offer free software that you can use to design a case.  Protocase offered a pretty interesting tool that actually creates a 3D case made from various metals and are quite impressive.  The issue is they are also VERY impressively expensive.  The deal is, however, that they do offer “console” type cases that are customizable quite a bit and will allow you to see a complete all around view of the case.  The problem is that you cannot do anything with the file they give you other than to send it in and buy it from them.

Front Panel Express offered a much more open proprietary tool.  This tool you can export the completed panel to a DXF file which can be imported into many other software packages, including those used on the suggested list for Ponoko.  While they don’t really want you to use their software to build a panel at another vendor, of course, it DOES actually work out.

Another issue with the Front Panel Express is that it only allow you to design one panel at a time.  Each side Left/Right/Rear, Front, and Back in addition to your Top control area needs to be built separately.  They make a lot of their panels out of aluminum or steel and have quite a lot of capability to build most anything you want.

The issue?  The following:

At the cheapest this seems to run around $65 for only this panel.  You can save a bunch of money by drilling your own holes for the countersunk screws and the round holes and instead just having them marked using an engraving to help center your drill bit.  I’m not against paying $65 for it BUT I feel that I need something cheap so I can confirm the layout REALLY is good even if I’ve rendered it in 3D.  I need to mount everything in the holes and confirm that yes it DOES fit properly and there are no heat issues or anything else to make me need to move anything.

Enter Ponoko.  When I import the DXF into Google Sketchup it does all sorts of weird things with the text and a few other things depending on the design.  When I try to raise/lower the material it does some odd things as well because of some of the lines etc.  What works better?  I dug out CorelDraw and found I could tweak the Front Panel Express file in there quite well, export it, and load it into Ponoko’s system.  It appears to look ok in there and allows you to use wood, cardboard, plastic, and a variety of other items.

I took the outside dimensions of the FPE designed panel as well as the other measurements from some of the cut outs and dropped them into a few shapes in Google Sketchup.  I then rotated the “rough” panel up 30 degrees since that seemed like a good amount and then attempted to measure the size of the effective foot print.  I then threw together a small 1 inch base and then raised the top edge up the two sides up 30 degrees as well.  I then slid them together and came up with this rough case package.

Using the exported DXF for Ponoko in Acrylic after modifying a few items to make it compatible to Ponoko the front panel ended up around $15.  At this time I haven’t purchased it since I need to make sure all the measurements are correct.  Additionally I need to add the sides now that I’ve gotten measurements confirmed in Sketchup to a layout.  I’m expecting the entire thing to run around $45 at Ponoko for the initial testing versions.

The version in the rendering of course isnt entirely right.  The LCD is actually slid up a little bit and the buttons go up as well.  Each button ACTUALLY is supposed to be rounded on one of the sides and the two round holes on the left and right are for the potentiometers that should have an LED above them.  The top needs an LED and there needs to be screw holes in a variety of places as well as some engraving to label things.

At this time I intend to figure out the distances to the LCD edges and adjust the base width as needed when I find the ACTUAL dimensions of the LCD panel that will be used with a mount designed to secure it.  I will then come up with a back panel and then start having this made.  I will have plastic panels made by Ponoko and when I’m certain that I am pleased with the dimensions/shape and fit I will have FPE build an anodized aluminum case for whatever it costs.

Due to the 30 degree angle and the fact I did not want to use tabs to lock it together I wanted to be sure of my decades old “trig” knowledge when calculating triangles.  The Sketchup Layout works well to see if the dimensions look good.  As long as it all fits together a Ponoko build will let me see a physical model for final confirmation and showing it off before I get a permanent case made.

Anyway I’m thinking for the buttons I’m going to use some MultiMec 1V16 white buttons for the directions, The middle button is currently planned as the 1T type buttons for an “OK/Select”.  I’m don’t think I can get them pre-labeled though so I might have to switch to a different button or do without labeling.  Then the two at the top that are round would be for some sort of Escape/Cancel and perhaps a dedicated stop/end/cool/whatever.  I need to confirm out which buttons to use so I can get whatever I need labeled well enough.

In the position of the potentiometers I might switch them out for rotary encoders to help setup things a different way.  Where the LCD is I will start with a panel that will fit in place of the full sized LCD using a smaller 4 line LCD until I start building the PIC32 system into it.  Once I get to that stage I need to mount the LCD panel onto a backer that screws in place.

If I could scrape together enough cash I’d get some sort of mini CNC machine and perhaps etch some buttons with ESC / OK / COOL or something like that as well as arrows and then infill them with some black.  Totally way involved for a few buttons but would probably look pretty impressive.  If I could make my own panels that would certainly negate the need for another vendor making the final panels.  Too bad those machines are so spendy.

I had ordered some motor controllers from a company in China back at the very beginning of the month.  They shipped from the seller after some Chinese holiday or something.  Apparently they went to some company that handles shipping things to the US or something before it went to their post office.  It left China about a week ago and arrived in the international mail portion of some facility in Los Angeles a few days ago.  It appears today it made it to the REGULAR Los Angeles post office sort facility.  It should probably arrive in one of the Northern California sort facilities tomorrow and MAY make it my local post office.  As I’ve come to expect anything coming from China seems to require a signature 9 times out of 10 so I will probably need to go to the post office on Monday to sign for it.  So we’re around 20 days from when it was ordered.  I’m trying to see if I can control the fan motors differently in some way that would make it more stable and give me a few options for actually building my own roaster later on using much larger blower fans and some other motors for opening/closing vents.