Interesting gift to family!

For Christmas this year, “Santa Claus” brought the family an interesting gift/project.  It’s a 3D Printer Kit!  Made by a company in Czech Republic, Prusa Printers, the kit is a fairly complex collection of parts made simple through excellent assembly instructions, extremely well organized kitted parts (each chapter has its own bag/box of parts), and very high quality components.

About a week after Christmas, the four of us gathered in my Workshop and began to assemble it.  With Kate reading instructions, Clare and I assembling parts and providing more than two hands to support sub-assemblies as they were joined, and Kerry queuing up the next batch of parts/tools, the assembly progressed without any major glitches until…

Voila!

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Surprisingly, the printer looked the same as the manufacturer’s when we were all done!

Of course, having a ‘thing’ look like a printer is different than one that works like a printer, we tried our first print:

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First try at printing! Note that ‘Self test was OK’! That was a relief!

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Equivalent of “Hello World” on a Prusa printer!

OK!  Great stuff!  But now, we had to know how to do our own stuff.  So pulling up a chair to my ‘CAD Workstation’, I designed a challenging first test for the printer.

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First custom print! Very ‘sophisticated’ 1 cubic centimeter!

Well, ok, maybe this wasn’t all that ‘challenging’, but it did allow me to learn the ‘process’ of going from ‘concept’ to actual ‘thing’ we could hold!

Ok, how about something useful?

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Second custom printing, this time a little more complex and significantly more useful!

Ah, this is more like it!  Gears that fit together and fit on a motor that I could use to drive the gear!

But, it was quite clear that I couldn’t keep this thing on my desk and if it was going to ‘live’ in the workshop, it had to be protected from dust and provide a means to vent the fumes out of the building if I was printing with something like ABS plastic.  So, here is the progression to add an enclosure (based on a design found on Thingiverse!).

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Realizing I needed an enclosure in the dusty workshop (and something to redirect fumes if necessary), I went with inexpensive Ikea end tables as an easy enclosure.

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Enclosure all built using 2 tables stacked with various 3D printed hardware holding it together and plexiglas panels to keep the dust out and fumes in (panels still have protective coatings).

 

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Getting ready to permanently mount the printer in the enclosure.

Finally, having a more ‘established’ location, with some help from a friend, I learned of a 3D Print server that runs on a low cost Raspberry Pi computer AND it also supports a webcam so that you can not only remotely control the printer, but also observe the progress!

 

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Running for a long time unattended, I added a camera so I could check on progress remotely. Base is 3D printed on this printer, of course!

Finally, able to run long jobs unattended, I could make something big and useful (What it is will be disclosed in a later posting)

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In the enclosure, after a 30 hour print job!

I think this tool is going to be VERY useful!

 

 

 

 

 

Construction of the back for Kate’s Chair

I received a question about how the back of Kate’s Chair was constructed.  I decided that I’d post the ‘secret’ method that I used  ;-)

I used a single piece of wood to make both rails and selected the section to maximize the grain continuity between the two sides. You can see the center line following the center of the grain pattern.

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Hunk of Cherry used to make side rails for back of chair.

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Close up of grain pattern.

 

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The section sliced and laminated.

The section has been sliced into multiple thin layers, glued back together, and pressed into a vacuum bag against a form shaping the piece into the curve for the back.  The diagonal lines were used to keep the pieces in order in case they were dropped before gluing.  This is a trick from the old punched card days :-)

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Side rails sliced into two rails and being fitted to head and bottom boards.

Note the extra slice on the side, this will be used as a guide to make the inside support form.  Also note the curve of the tailboard marked on the wooden block.

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Sides with Tenons, ready for gluing back frame.

Using Domino floating tenons made this job a lot easier!

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Assembled form for back support.

The support followed the curve of the rails, with the horizontal curves changing slightly from top to bottom to give lumbar support.

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The form filled with expanding foam.

I used a stiff formulation of expanding foam to provide solid support for the fiberglass shaping.

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Filled form shaved to level surface.

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Needed a few repairs to fill some gaps.

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Form covered with heat shrink covering.

This covering is used on model aircraft.  It is stuck to the surface with an hot iron and then shrunk to fit tightly.

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Form, all ready for fiberglass!

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Fiberglass all cured.

Note the curved clamp on the top.  This was done to squeeze the fiberglass to a uniformly flat flange that will be used to attach to the rabbet in the back frame.

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Back support removed from form.

Unfortunately, even though I used an epoxy release agent on the form, the material still stuck to the back support enough that it tore away from the form when the cured fiberglass was pulled away.  It’s not a huge problem, I can easily put another cover on the form should I make another chair.

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Fiberglass back support attached to the Back frame.

Note that I used tee nuts attached to the fiberglass ‘flange’.  They had to be trimmed to flatten the outside to get them to fit within the rabbet but this also prevented the nuts from spinning when the screws were tightened after upholstering the back support.

That’s pretty much it!  I did bring the pieces to a professional upholstery shop, I know my limitations!

Take care!

 

 

 

Clare wanted a Hallway Entrance bench for her new apartment…

She saw this in an online store:

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and wondered if I could make it for her.  I came close.  Here’s what I made:

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Of course, being real wood, I couldn’t resist matching the grain everywhere I could…

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Especially around the drawer box and decided to try a new (for me) joinery technique using dovetail splines…

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I’ll have more photos showing construction steps at a later date.

Replacing CNC Router Project

I’ve been using my CNC router pretty steadily since I first made it about 2 1/2 years ago and while it’s been quite useful and productive, the old DIY version has a few ‘idiosyncrasies’ that I wanted to address.  The more severe of these issues were:

  • With the main Y and Z tracks formed by two parallel pipes held in place with common 2X lumber, the spacing of the pipes would vary fairly largely as the humidity changed.  When expanding, the pipes would push the bearing wheels outward making the tracking tight, but the worst effect was after the wood shrunk again, the tracking would then be loose and have to be re-aligned before I could use the tool.
  • The Z axis, sandwiched between the Y Gantry plates ended up making the Z truck relatively narrow and, as a result, the router motor wasn’t held as rigidly in the X direction as I would have liked.  The effect of this were holes that weren’t round, inaccurate tracking on curves, and a system that was too ‘sloppy’ to try to mill aluminum – something I’d really like to try.

I didn’t see an easy way to modify what I had, since these problems were fundamental to the DIY implementation.  So, looking around, I found a router made by Carbide 3D that looked like it would meet my needs and further discovered that the mechanism (the part I really needed to replace) was available in kit form from Sparkfun!

This new mechanism is about 2/3s the size of the Old router (16×16 vs 24×24), but I never routed anything ranging larger than 15″ on the old one.  Hence the new one, being much more solid, promising faster travel speeds, AND not requiring realignment every time I want to use it, seems much more valuable to me.

I decided that this project needed to be done in three phases:

  1. Replace the old CNC router with new mechanicals, reusing the motors, electronics, and base from the old system.  I’d have to add another motor to the mix since the new system uses two motors for Y Axis.
  2. Replace the old base with a new base constructed out of T-Slot aluminum extrusions so that I would have a robust structure to which I could hold down soft metal parts for routing.  I’ll mount this on a cabinet that I can wheel around as conveniently as the current CNC router base.
  3. Finally, to achieve the full capability to route soft metals, replace the electronics with a faster processor, high voltage power supply, and more powerful drivers.

The first step, then, was to strip the old CNC router of it’s mechanicals, but, before I did, I needed to do two things:

  1. Flatten the base of the old router so that the new mechanicals would have a flat base to rest on.  The older bed had high spots as high as 1/32″ due to cupping of the slats I had installed.  Originally these had been trimmed to +/- 0.005″ over the entire bed.
  2. Make an adapter to mount the Bosch Colt router motor in the new system.  The new kit included an adapter for a Dewalt DW611 compact router, but the DW611 router is slightly smaller than the Bosch. I really like the Bosch motor and have invested in a number of expensive chucks primarily for CNC routing.

So, using the Old Router to plane its bed:

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Old CNC router planing its work surface to flat.

I’ve got a new flat surface and, taking a nice solid piece of hard Maple, I machined an adapter for the Bosch router.  I can buy an aluminum one, but these are shipped from China and I didn’t want to wait for weeks to get one.  This one will serve nicely until I decide to upgrade to aluminum…

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Old CNC Router working on its last job. Making the mounting adapter for the NEW ROUTER!

By the way, the chunk of Maple was glued to a 1/4″ thick MDF waste board using CA glue and then the waste board was sanded off on my thickness sander.  Easy hold down technique!

I then stripped off the old gantry and removed the stepper motors.  WOW! What a job THAT was!  I had used Loctite Green on all the mounting nuts and set screws and it was a chore to free these up!

Building the kit was easy and in no time I had a new mechanism mounted on the old base!

 

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New CNC Router mounted on old stand

Here’s a closer view.  The router had just finished its first job, a test pattern I used to test and trim the old router.  This first pass on this new router actually came out better than the LAST pass on the old router!  Yippee!

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New CNC Router finished first job with excellent results!

This new router uses a different drive mechanism than the old one.  The old one used conventional Acme screws driven by the stepper motors.  This new one uses GT2 treaded belts and the motor has a matching treaded pulley that literally pulls the assembly along the stationary belt.  The belt is very strong, but has a coarser pitch than the Acme screws I used so that the steppers need to be micro-stepped about 4 times for each step of the previous system.  This will give me faster travel (something I need to mill aluminum) but, until I replace the electronics, a slightly coarser finish.  Oh well, something to look forward to…

 

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Drive system for new CNC Router, Y axis shown.

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New Router X & Z axis drives.

Finally, I can use the same folding setup from the previous router to fold up the system for storage:

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New CNC Router folded up to put away.

I’ll be using this version for a while until I’m sure I’ve gotten it completely stable and then move on to the next phase of the project.

 

 

 

 

 

 

Hacking a toaster oven into a reflow solder station!

As I’ve moved into smaller and smaller electronic devices in my projects (and gotten older) I find that I can no longer reliably solder some of the components to the printed circuit board by hand.  I discovered that others had used toaster ovens for reflow soldering (Wikipedia link) where the printed circuit board solder pads are lightly covered with a solder paste, the surface mount components are placed on top of the paste, and the whole circuit board is heated in a sequence to solder all the components at once.

The sequence is supposed to look something like this (from Kester EP256 datasheet):

 

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Here is what I was able to get with this oven:

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Here is the profile I’ve gotten with a bit of tweaking.

Close enough!  It takes a bit longer to reach target temperatures than the professional equipment, but mine uses FAR less power, and, what the heck, why do I care if it takes 5 minutes instead of 4 minutes to solder as many circuit boards as I have to do?

Here’s what the oven looks like:

 

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Front of the oven. Controls are timer, mode (I use convection mode), and temperature (max’d out).

To convert, I had to take off the cover and rewire the controls.  I disconnected the silly neon lamp on the front of the oven and used its wires to power my controller and then cut the main power line feeding the thermostat and branched off both sides to the solid state relay I use to control the heating element in a more sophisticated way.

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Inside of the oven control section. Note the use of high temperature wire and porcelain wire nuts.

Even though I have an embedded computer controlling the heater, I decided to leave the original timer and thermostat in place to provide a layer of safety to this tool (even though it won’t be left unattended – unless I have to go to the bathroom, the UPS man is delivering something, etc etc etc).

To monitor the temperature accurately, I installed a stainless steel probe K type Thermocouple.

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Inside of the oven with the shelves removed. You can see the stainless steel thermocouple that monitors the temperature right at the tray holding the workpieces.

Here is how it is mounted from the back.  I was fortunate that this particular oven had the extended back (to provide room for the probe) AND had a little bumper installed exactly where I wanted to put the probe!  I just removed the bumper and ended up with a pilot hole to drill for the probe!

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View from the back. Note how the oven extends outward, providing room and a pilot hole for the probe.

The new controller was built from an Arduino type processor called ‘Moteino‘.  It is a very small circuit board and usually has an onboard radio for wireless applications, but, in this case, I didn’t need the radio.  It’s very easy to program this module, very small footprint, and, short of making my own PCB, about as low cost as I could get!  Of course, now that I have a reflow oven, I might be able to make my own board…

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Mounted the new controls on the side. Shown is the new controller and solid state relay, which switches power to the heating element, mounted on a thick piece of aluminum to absorb any heat it generates.

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Close up of the controller. The red circuit board is the ‘smarts’ of the device while the circuit to the right converts the thermocouple signal to an accurate digital value used by the controller.

The red and green lights in the upper right are used for status.  The red light’s intensity is proportional to the current temperature in the oven.  The green light flashes based on which phase the sequence is in. And BOTH lights flash demandingly when I need to open the oven door to accelerate the cool down.

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Here it is, all buttoned up and ready to solder circuit boards!

 

 

 

 

 

 

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