Thursday, December 29, 2011

Tutorial on Cutting With a Radial Arm Saw

We're getting into the big guns now.  The radial arm saw is best suited for cross cuts, as I explain in yet another exciting video.


I'll go into more depth as far as different blades and cuts in the table saw post this weekend.  The 16 minutes of me droning on about drill bits just didn't tickle my style, so it'll be pictures and diagrams in addition to the video.

Monday, December 26, 2011

Tutorial on Using a Drill Press

I'm quickly running out of both wood working tools and winter break, so enjoy these while they last, and I'll be back to my more typical hobbies once school starts again in January.


Saturday, December 24, 2011

Using a Radi Plane to Cut Curved Edges

The Radi Plane is a clever little hand tool for cutting simple curved edges on your work piece.  This could also be done with a router, but when you're working on small projects where you only need to do a couple edges, this is much faster and easier.


Typically, you would be using better quality wood than I am ($2 2x4s), so you wouldn't be hitting knots and having as much trouble as I am in the video.

Friday, December 23, 2011

Tutorial on Cutting With a Scroll Saw

After showing you how to use the band saw yesterday, I figured it would be a good follow on to show you how to use the scroll saw, which is the smaller cousin of the band saw.  The scroll saw is meant for much lighter cutting, but has the advantage of being able to cut incredibly sharp corners, so you can do all kinds of detailing (or scrollwork, which makes sense...).

In the video, I also show you a basic project I did even when I was little, which was cutting out jig saw puzzles.  All you do is take a thin piece of 1/4" wood and cut it into interlocking pieces, and bam; jig saw puzzle.  Hours of fun.
Once you've done this and are looking for more involved inspiration, I was tipped off to one user on YouTube who uploads some interesting videos of him doing more some impressive work.

Thursday, December 22, 2011

Tutorial on Cutting With a Band Saw

Another quick little skill-building video tutorial today; this one is on the basics of cutting with a band saw.  I know that most of my readership is more interested in my electronics, and those projects will return when I get back in Davis in January, so just hang tight and enjoy this month off while I spend some quality time with my dad's wood shop.


It has become easier and easier to get access to this type of equipment through hacker spaces and facilities like the Tech Shop, but if you are looking to put together your own serious wood shop, we wasted a lot of time and money before we finally bought all DeWalt tools.  Ours is 20 years old, but I expect little less from the current model.

I've already gotten some comments asking for information on how to actually change the blade in the saw, so enjoy a bonus second tutorial just about how to change the blades.


The band saw tracking I mentioned in this second video works on the principle of a crowned pulley.  Woodgears has a good introduction to crowned pulleys, as does Make Magazine in issue 22 pp 158-160.

 Finally, here is a close-up of the band saw and guide blocks themselves.  The blade will ideally not be touching any of the three of them (so if it is, adjust the guides and/or the blade's tracking), but inevitably will touch them as you feed stock into the saw.

Wednesday, December 21, 2011

Tutorial on Sweating Copper Joints

Yesterday I showed you how to cut copper tubing using a tubing cutter.  Once you have your tubing cut to length, you're going to need to somehow connect it to the fittings how you want.  The traditional way to do this is by sweating the joint, which is the plumbing term for soldering.

The tools you'll need are:
  • A propane torch.  If you're only doing small joints for crafts you might be able to get away with smaller crafting torches, but if you're trying to joint long lengths of tubing, appreciate that all that copper acts like a heat sink while you're trying to sweat the joint.
  • A flint sparker or other torch-lighting mechanism, if your torch doesn't happen to have a self-ignition system.
  • Steel wool.  This is used for cleaning up the surface of aged copper tubing and removing oxide to ensure a good joint.
  • Plumber's flux and brush.  This is important, because without flux the solder will just roll off the copper and not suck into it like it needs to.
The one thing to note in the video is that I interchangeably call the joining alloy solder or lead.  Technically it is 40% lead and 60% tin, so I misspoke in the video.

This is all explained in the video, but the steps to sweating a joint are:
  • Clean all surfaces to be joined with steel wool until shiny.
  • Apply flux to ensure good connection between the copper and solder.
  • Join the fittings and apply heat to the whole connection.
  • Touch solder to a single point on the joint, and enjoy seeing it magically suck in to make a solid joint.
    • Be careful while applying solder that you don't apply too little solder, but once you apply enough, the excess will drip from the bottom of the joint.  Try not to burn yourself.
 This is the finished joint.  Notice how the solder readily sticks to the surface of the copper.  If your solder just beads up and runs off, you need to clean the surface again and apply more flux.
Since I'm using this for crafting and not actual serious plumbing, I also take the time to hit the joint with a wire wheel to clean off the excess burnt flux once I finish.  It cleans off very easily.

Tuesday, December 20, 2011

Tutorial on Cutting Copper Tubing

Being able to cut copper tubing can be useful around the house, but I also find the various sizes of copper tubing to be useful crafting supplies, so while I don't tend to do much work putting together gas lines, I still do this quite a bit.


The process is rather straightforward.  Using a tubing/conduit cutter, place the tubing between the cutting blade and the two rollers and tighten the cutter until the blade is just touching the tubing.  Then simply spin the cutter around the tubing, tighten the cutter approximately an eighth to a quarter of a turn, and spin it again.  Eventually you will cut all the way through the tubing and it will separate.  Once you finish cutting the tubing, use the deburring triangle on the back of the tool to smooth the newly cut openings.

Sunday, December 18, 2011

Toy Waterworks Project

To continue the series of toys from my childhood, this was one of our summertime favorites.

The concept is quite simple; given an adapter from a standard garden hose to 3/4" slip fit PVC pipe and an assortment of pipe fittings and lengths, you build your own water park in your back yard.   PVC also comes in threaded sections and fittings, but as small children, it was much easier to assemble and disassemble sections when they were just press fit, and half the fun was trying to keep all the sections stuck together as you built higher and higher towers.  We spent hours putting together and taking apart these pipes and generally just making a wet mess of ourselves.

The only part that you need which is a little unusual is the hose-to-3/4" slip fitting, which you will rarely find as one piece.  What you can find is female slip fitting to male hose thread, and female-to-female hose thread fittings.  This set is pretty free-form, so you can grow it or shrink it as much as you and your children feel inclined.  The prices I quote are from Orchard Supply Hardware, but most hardware stores will have these parts in their plumbing section.
  • 3/4" slip to male hose thread - $1.89
  • Female-to-female hose thread - $2.89
  • 27' (3x9') of 3/4" schedule 40 PVC pipe cut into 2-4 foot lengths - $5.97
    • You can also buy pre-cut sections if you don't have a pipe cutter, but they will be more expensive and a pipe cutter is something you'll find useful.
  • 3x plastic flushhead sprinkler heads and risers - $2.94
  • Reducing tees and/or reducing ells from 3/4" to 1/2" NPT to screw sprinklers into - $2.07
  • 12-15 assorted tees, ells, caps, three-ways in 3/4" slip fitting to connect the pieces of pipe - $5
  • A hot summer day - priceless.
 In case you have never cut PVC before, it is very simple if you have the right toolVideo:

Unfortunately, I can't find any pictures of us playing with ours when we were little, and it is much too cold for me to go outside and stage a dramatic reenactment, but hopefully you get the idea.

I would suggest you buy the bulk 10' sections, but it is possible to buy pre-cut shorter pieces.

 These reducing fittings are to screw into the risers which connect to the sprinkler heads.  You can have fun with just the reducing fittings themselves as a bubbler; the pipes won't tend to stay together if you have all the ends capped in sprinklers.
 This is shown with a brass sprinkler head, but you'll find the much cheaper plastic heads in the same place.

Thursday, December 8, 2011

Numitron Display Tube Tutorial

Anyone following my electronics projects from the beginning has probably already picked up on my love of vintage displays.  I've done several projects with old vacuum fluorescent displays and nixie tubes, but Christmas came early for me today in the post.

I just got a package from Russia today with half a dozen IV-9 numitron tubes in it, which are a different display tube from the same era.  How numitron tubes work is that it has eight tiny incandescent filaments arranged in the typical seven-segment plus decimal point configuration, and you simply pass current through the filaments you want lit up, and they literally light up exactly like a light bulb.  They are still pretty easy to get online; you can get the IV-9 tubes I'm using for less than $3 a piece on eBay.


This filament display has a huge advantage over VFDs or nixie tubes.  VFDs take 40-60V and has the complexity of a heated cathode; nixie tubes require a heart stopping >120V, and both types require rather specialized driver ICs because of these high voltages.  Numitron tubes, on the other hand, only need 2-3V, so I was able to use jellybean constant-current linear LED drivers out of my junk box.

As a proof of concept, I plugged a numitron tube into a breadboard over an Allegro A6278 LED driver, but any constant-current driver will work, or even just some resistors and transistors.  I hooked this up to an ATTiny2313 AVR and wrote a simple piece of code that cycled through all the digits 0-9.

Finding information on the IV-9 tubes is a little challenging if you don't happen to be able to read Russian, but about the only critical piece of information you need out of the datasheet is the filament current and the pinout, which are relatively easy to find; the filament current is still labeled mA, and the pinout diagram is relatively straight-forward once you realize the pins are numbered clockwise looking from the bottom of the tube.  These filaments are specified for 17-22 mA.

Like always, now that I have the proof of concept running, I'm working on a larger project, so look forward to that in the future.

Saturday, December 3, 2011

Two Phone Intercom Toy

I like the idea of writing a series on the home-brew toys that I grew up on (and actually still play with some now).  My childhood was one filled with days of playing with packing material and old electronics rubbish that comes from growing up as the child of a chemist turned EE in the Silicon Valley.

One of these toys that I played with was a rudimentary intercom, build from a pair of analog telephones, a 9V battery, and a single resistor (and optionally some LEDs).  My pictures and videos show the battery and resistor loose and just clipped on, but it would be very easy to build a more robust toy with a standard plastic gang box and a dual phone jack module from ACE or Home Depot.


The intercom lacks most features; it can only handle two phones (or more, but all must be off-hook and in series) and unless you can find some real pulse-dial phones, you can't even ring the other phone (If you're lucky, pulse dialing will in fact ring the other phone).  Even still, it is a very impressive version of the classic two cans and a piece of string toy.  Run the cables between children's bedrooms, or up a tree house, or anything else you can come up with.
The principle of operation is very simple.  Phones operate over a single pair of wires, which carry both sides of a conversation at once.  The microphones rely on a bias-current flowing through them to pick up sound, which is why you can't just plug two phones together and hear each other.  By splicing in a 9V battery and a 300 ohm resistor, you can crudely insert 5mA of current, which is enough to at least hear each other.  Conveniently, when either phone is hung up, they go into a much higher DC resistance state, meaning that this loop current being drawn from the 9V battery is stopped when it's not in use.

As shown in the video, if you also put an LED in-line with the phones, it will light up when both phones are picked up.  An obvious extension to this system would be to install an LED in both phones, so that the users can tell when the other phone is picked up.

Of course, in this day and age. if you wanted to put together a more sophisticated system, with multiple phones, ring service with extension numbers, spanning more than your house, etc, it would be entirely possible.  On eBay you can get several Polycom or Grandstream SIP VoIP phones for less than $100, then plug them into the internet anywhere and your kids can call their friends as much as they like.  I've shown how to do this in the past.

Friday, December 2, 2011

Two Player Chinese Checkers Board

For anyone who doesn't happen to have a subscription to Make Magazine, let me say that their latest issue (#28) is quite good.  The theme is "Toys and Games," and after reading through it there are more than one projects I think I'm going to do something with.

The first such project which I have gotten a chance to build is the two-person Chinese Checkers board.  Traditional Chinese Checkers is a six-person board, but that comes with a short-fall; four or six people playing and strategy is usurped by chaos; two players playing and the wide expanse of board allows much confrontation to be avoided.  On pages 56-57, Charles Platt gives plans for this two-player configuration [PDF warning].  I liked the look of his board in black ABS, so while I was in Sacramento for the FE exam, I stopped by my nearest TAP Plastic and picked up a piece of 8"x16.75" single-side textured ABS.  I think the cost of it came to something like $12.

Of course, in the article, he explains how to drill the hexagonal matrix of holes by hand using a drill press, but trying to drill 61 holes by hand and get them to all line up just right seems like a tedious task to me.  Luckily, since I am a mechanical engineer at a world-class university (and paying quite a bit more than expected for the pleasure), I figured I would utilize the facilities provided to me for such personal projects.

As a student of the mechanical and aerospace engineering department at UC Davis, I am allowed access to the Engineering Fabrication Laboratory, which gives me access to 6 CNC end mills, plus as many lathes, and various other useful equipment such as drill presses, fully equipped welding bays, a sheet metal brake, wire EDM, the list goes on.

It was these CNC mills of interest here.  They're outfitted with MillPWR CNC controllers, which means that you can program drill patterns quite easily through the attached control panel (and save said patterns to floppy disk).  I figured out what the file format is for the hole patterns, and then wrote the code needed for the tedious task of these 61 holes.
Now drilling the entire board is simply a matter of telling the mill exactly where the bottom left corner of the ABS plastic is, and then successively telling it to move to the next hole position and manually drilling the hole.  You can automate the entire drilling process, but it is often faster to control the drill speed manually than to have the mill operate on its own.

Look forward for other projects from this issue, or shout out in the comments if you've done anything from it yet as well.  I'll hopefully have some more time for such next quarter.  If you don't yet have a subscription to Make, I'd highly urge you to; it may be only a quarterly issue, but they are always of high quality.

Appendix A:  MillPWR code