Tag Archives: Laser Cutting

Pretty on the outside and ugly on the inside prototype

By | | , , , , , , , , , , , , , ,
Leave a comment

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.

Looking for success in failed laser cut jobs.

By | | , ,
2 Comments

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

By | | , , ,
Leave a comment

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.

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

By | | , ,
11 Comments

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.