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Sunday, December 18, 2016

Making a Beautiful and Functional Magnetic Knife Storage System

Our family has long used magnets to hang our knives. The problem has been that the existing knife holders were too short to hold all our knives and were not very good looking. I researched the topic and found that one could combine a nice piece of hardwood with rare earth magnets to make something beautiful that would solve the problem. I started with an $11 piece of Maple from Home Depot. The next step was to cut it to size and bevel its outer edges with my table router. The final woodworking act was to use the table router to carve a half-inch-wide channel down the center. At first, I took some bad advice that I had found online and left a 1/8" gap between the surface and the magnet but later found that to have any useful attraction, I would need to re-route that gap to be 1/16". This was the resulting piece (After being polyurathaned):


The next step was to add the magnets.  I acquired 100 1/2"x1/2"x1/8" powerful rare-earth magnets for around $50 on ebay:

They were very difficult to separate from one another and by the end of the day, my right thumb was feeling quite numb but with some time and work, the magnets filled the channel cut by the router.  Part of the effort was aligning the magnets so that they stuck to each other.  If they were aligned properly, there was a danger that they would collide to violently.  These magnets are so powerful that they can collide with each other destructively, leaving expensive magnet shards.  I lost a couple in this manner but was thankfully left with enough to finish this project.

The result was as good as I had hoped for:

 The only thing remaining is to cover those counter-sunk screw holes with little wood disks.  Other than that, I am happy with the outcome.

Tuesday, March 1, 2016

Upgrading Old Kitchen Bar Stools with a CNC Router

Several years ago, we bought a bunch of bar stools from Ikea for our kitchen.  They were around $8 a piece and are so perfectly sized for our needs that we have not seen anything better at any cost.

$8 Ikea bar stool to be upgraded
 The only shortcoming to these stools are their wood seats.  With time and motion, the screw holes in the wood become looser and the screws fall out.  The other problem is that the wood seats are divided into 4 wedges that allow food and spilled liquids to seep into and accumulate in the trenches in between them.

Of course, at $8 a piece, it would be smarter to just replace the stools -- and I certainly would have done this -- but this model of stool went the route of so many things Ikea: it was discontinued.

So I decided to set out to not only fix these ailing stools but to give them an upgrade, thanks to my over sized Shapeoko CNC Router and to some new materials that I was able to acquire inexpensively on eBay.

To my mind, the ideal material for the replacement seat would be something lustrous like marble or granite but those are too challenging to cut on my machine and far too expensive to acquire so I settled on the next best thing: Dupont Corian.  It is beautiful stone-like surface that is easily milled.  What's more, cheap leftover pieces can be found on eBay with free shipping, despite their high weight, thanks to the USPS, who will ship anything that fits into a Priority Mail box.

I paid $40 for 6 pieces, each of them much better looking than the stools' existing wood seats and all of them big enough to do the job.  The only tricky part would be to cut them to be circular and to precisely drill the screw holes so that they perfectly match the positions of the existing screw holes on the stools' supporting steel plate.

So I broke out my trusty caliper and measured all screw hole positions and the ideal screw hole diameter.  I jotted everything down in my usual barely-legible chicken scratch before putting it into CamBam, my CAD/CAM 2.5D software of choice.

One faulty measurement forced me to re-cut my holes.  Fortunately, all I needed to do was to rotate my piece and try it again.  Excess holes in the bottom of the seat will not be visible.  In the end, my CNC Router managed to get the hole positions right and it did a great job of cutting the circular profile out of the 1/2" Corian plate.

Now that I have the files for the cuts, I can now repeat this procedure with my remaining Corian plates so that all my stools can have the same upgrade.  The only thing that I need to do to improve this seat top is to round or bevel the top lip -- something done easily enought with a trim router.

Much better!

Sunday, January 31, 2016

Fixing One 3D Printer so I Can Finish Another

While I have a perfectly good, highly modified Revolution XL 3D printer, I became interested in delta printers and decided a while back to build a Kossel Mini.  I sourced my own parts and recycled many parts from my first (long dead) RepRap Mendel.  Missing a few key parts and having been distracted by other more pressing projects, I let the incomplete build sit around for a long while until I could no longer let it gather dust and so I got back to it and moved it along.

Kossel Mini in progress
I had printed all the Kossel Mini's printed part using my RXL printer and I needed a couple more parts to break the logjam.  The problem was that my RXL no longer worked.  The hotend no longer heated and I was printerless.  A quick continuity test confirmed that my heater cartridge no longer was able to function.  Fortunately, I had a replacement on hand.  So I took apart my Micron3DP hotend:

The old dead heating block was covered with years of melted plastic and seemed overdue for a replacement.  I cut and stripped the wires on both sides and used butt connectors to attach the new heater block:

After the reassembly of the newly revitalized hotend, I took the RXL for a test drive and printed a couple of Bauhaus chess pieces for a friend with a growing set.  The end to this story is a happy one.

Thursday, July 30, 2015

Add a 3D scanner to a 3D printer to make... Wait for it -- a 3D copier!

I have not made too many efforts to hide my enthusiasm for what I feel is the culmination of inexpensive hardware, cheap or free software combined with what must be an unprecedented social upheaval in creativity.  One such project that caught my eye was a KickStarter project, cleverly engineered by Uriah Liggett from  At its heart, it is a compact 3D scanner server.  Here was his pitch:

I was sold.  I had a $30 Raspberry Pi computer and a $30 Raspberry Pi camera, so I supported his KS campaign to the tune of $150, knowing that it would take a bit of labor and discovery to make it happen.  The trick about it was that the entire frame of the 3D scanner would need to be 3D printed.  Since I happened to have a 3D printer, I was able to print the parts -- usually before bed -- for pennies.  After a few months (and less than 30 days overdue -- which is fantastic by KS standards), I was sent the remaining hardware and was pointed to the software.  I couldn't wait to get started.  Upon coming home from work, my wife immediately took note of the chaotic dinner table and the glazed look in my eyes and was both insightful and kind enough to realize that I was in a frenzy.  She owned the kids for that night and the next.  This was what I had after day 1:

 The instructions were perfect and by day 2, the structure was done.  By day 3 I had it working:

Here is how it works:  You place an object to be scanned on the turntable.  You then access the scanner on the network from its web-based interface (I can do it from a tablet in another room!).  You then have to define various variables like laser visibility thresholds, etc.  When you finally tell it to scan, it draws laser lines over the object and takes photos of it with its camera.  Its Raspberry Pi computer then analyses those lines and infers the shape of the object.  Here it is imaging a figurine:

Here it is in action:


I'm only a couple of days in but I am tweaking the variables and getting some results with my scans:

I'm not there yet, but getting there.

Of course, the grand goal is to be able to say "So terrible that your chess set is missing a rook.  How about letting me make a copy of your other rook?"

Wednesday, December 31, 2014

Milling & 3D Printing Your Own Drone From Scratch

Being an obsessive maker of machines that make things was what eventually pushed me to make my homemade hexacopter drone.   As I detailed in an earlier blog post, I used my Shapeoko CNC router to cut many of the parts I needed from Dibond.

I did not really like the motor mounts that were cut so I decided to look at what the world of 3D-printed motor mounts held for me when I came upon this brilliant parametric design by pwnas on Thingiverse:

I printed six of them in black PLA plastic.  Between what I could make myself with the CNC router and the 3D printer, I had all the frame and landing gear parts that I needed except for motor boom arms.  I bought 6 Aluminum booms from Hobby King for less than a dollar each.  With all the frame parts in hand, I then acquired the following electronic and other components:

  • HKPilot flight controller
  • Flight controller power module
  • GPS module
  • 9-channel radio transmitter/receiver
  • 6 motors
  • 6 electronic speed controllers
  • 6 carbon fiber propellers
Of course I also needed to make use of screws and nylon standoffs.  In the end, I was very happy with the results:

Upside down

It needs just a little more tweaking before it will be ready for its maiden voyage.  I can't wait to see what I'll be able to do with flying heavy lifter!

Friday, December 26, 2014

Hexacopter drone assembled: Almost there!

I'm just about there.  I assembled the the home CNC machined frame and landing gear.  I wired all the electronics including the 6 motors, electronic speed controlers, ARDUpilot flight controller, GPS and radio receiver.  I'm having trouble binding my transmitter to my receiver but assuming I can get over this hump, I should have this bad boy in the air by tomorrow!

More shortly...

Sunday, December 21, 2014

Scrambling to finish my drone before the holidays

I started building my drone a while ago.  I cut many of its parts with my home-made Shapeoko derivative CNC router.  I was flying high for a while as work piled up and I decided to put it aside.  I now pick it up.  I am a little ashamed that it took me so long to get my soldering iron heated up but I reached that crisis point today, with the hope that I will be launching my hexacopter drone on its inaugural flight on this holiday week.  This is one of its 6 arms complete with carbon fiber propeller:

Each arm had 9 connections to be soldered.  I made it a day and got the rest done:

I now need to get this heavy lifter in the air.  I know a bit about Arduino and less about ARDUPilot but I am psyched that I may successfully launch my first homemade drone in the coming days.