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.

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.

Video:

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.

Video:

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...).

Video:
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.

Video:

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.

Video:

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.
Video:
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.

Video:

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.

Video:

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.

Video:


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

Monday, November 14, 2011

My First Model Railroad Ops Session

School and life have been pretty crazy as of late, in case anyone hasn't noticed the precipitous drop in post frequency already.  My roommate decided to offer me a break from my school work this weekend and invited me to her dad's ops session on his HO model railroad layout.  Of course, I'm a big train fan (being active in both the WPRM and WRM museums), but modeling hasn't appealed to me in a long time, since it's pretty hard to beat 12 inches to the foot in detail or realism.  I didn't really know what to expect, but boy was I impressed.

First lets talk about Phil's layout.  The women of his family were kind enough to allow him to go off and build his own man cave, separate from their house; talk about living every man's dream.  This second picture shows about a quarter of the envisioned layout, and something like 90% of what's built so far.  He's targeting 1950' era Union Pacific branch line, which is about ten years early for me (much too many steam engines still running around for my taste, but he did have two token EMD and Fairbanks-Morse diesel switchers in the yards).

The entire layout is DCC controlled, which is an incredibly elegant system which uses modulated AC in the tracks and then individual microcontrollers in each locomotive decoding these command signals.  This means the entire layout can be wired as one electrical block, instead of the traditional system where you electrically isolate every chunk of track that you want to operate on independently using DC.  Each of the operators then have their own throttle keyed to the ID number of their locomotive, so as they issue speed commands, the commands are sent to all the locomotives, but only followed by the one matching the programmed road number.  Add in that the throttles are wireless (915MHz ISM), and it means that you can drive from one end of the layout to the other, while walking around with your train, without having to worry about other operators, beyond them not physically being in your way.

The layout being DCC became important once you put ten guys in the room, because some of the rail yards started getting pretty crazy with two or three operators working them at once.

I have done plenty of hours of actual yard switching, but I had never been to a model ops session before, so what came next I certainly didn't expect.  It turns out there there is a dispatcher in an adjoining room, but in the 1950's wireless radios weren't particularly useful, so Phil actually has hard-line telephone handsets under every station that you can pick up and talk to the dispatcher on (a few of the handsets can be seen in the second picture above).
Furthermore, Phil had timetables printed up for the "scheduled" trains on his layout, following wall clocks running at 4x real time speed.

This meant that as an operator, I was handed a throttle and assigned a locomotive, and keyed the locomotive road number into the throttle to take control of it.  I then answered the ringing telephone under the table and spoke with the dispatcher in the other room, who assigned me to train #22, gave me special instructions for the run (a slow order by the Weber Branch), and authorized me to take the main line following the prescribed timetable.  Once I reached Wanship, I knew that I was going to meet the Westward #21 so I went into the hole and waited the 20 minutes (5 minutes real time) before being passed by it.  I then continued onward to my final destination of Park City.  Of course, this was all complicated by the local switching and extra trains scattered throughout the layout by the dispatcher to keep things interesting, but being a scheduled train meant I didn't need to worry about much more than one flagman who had fallen asleep on the track.

Overall, it was a very fun way to spend a Friday night.  It's going to be one impressive layout when it's completely done; I'd say it'll be able to easily accommodate a good 25 operators simultaneously.  If you have any further questions about the layout itself, I'd venture Phil probably wouldn't mind if you contacted him at Gulley [at] pasco [dot] com.

Monday, October 31, 2011

I Got Interviewed for EEWeb

Hey everyone.  Things have been a little crazy as of late with midterms, and I just took the FE exam this weekend (which was much overrated), so there isn't much in the pipeline other than more SerialCouple testing and maybe some initial work for my senior project.  To keep you entertained in the mean time, EEWeb contacted me this summer and did an interview asking about how I got inspired to be an engineer.  It's an interesting read, so I encourage you to go check it out.

Tuesday, October 25, 2011

SerialCouple Used as Sous-Vide Controller

The testing of the SerialCouple prototypes continue (Part 1, part 2, part 3).  For those not following along, the SerialCouple board is a low cost thermocouple adapter, meant to be used in conjunction with a standard FTDI USB adapter to enable you to monitor and log a single thermocouple channel to a computer using standard serial port monitoring software.  Production boards are still a few months out, but while they're in the works, I've been playing around with different things to do with the SerialCouple.  This demonstration is taking advantage of the extra IO pins afforded on the serial port connector to control a heater as a sous-vide cooker.
Sous-vide is a hip cooking method where you vacuum seal the food and then cook it long and slow in an elevated temperature water bath.  The challenge is that you need fairly precise control of the water temperature for food safety and cooking quality reasons.  By cooking food in this long and slow manner, it is possible to bring the food to a single consistent temperature throughout, which enables you to have a perfectly medium-rare steak ALL the way through the meat, or a soft boiled egg that is perfectly soft ALL the way through.
How I built my sous-vide cooker is by attaching one of my SerialCouple prototypes to a junction box which I built with a solid state relay in it.  This SSR is then used to control a 615W lab hotplate, which heats the pot of water which I'm monitoring with the SerialCouple.  The SerialCouple handles all of the thermostat logic internally, with the SSR connected to the CTS pin of the serial port connector.  With the addition of a >4V battery, this can operate entirely independently of a computer (after using the computer to set the target temperature).
I used a 9V battery clip and a 6x0.1" female header to make the adapter cable, although only the bottom three pins are used, so a smaller socket could have been used.
I had to blue-wire jumper the CTS and RTS lines on my prototypes, since I only bothered routing the transmit and receive on the PCB itself.  In the next batch, I'm going to route all six pins, as well as correct all of the other routing mistakes I've made.

Water Temperature Performance

I played with implementing a PID algorithm on the SerialCouple a little bit, but I eventually came to the conclusion that the simplicity of a basic thermostat (heater on if below set point) algorithm, coupled with a correctly sized heater, have adequate performance for my needs.  In the initial trials, I only used 2 cups of water in the pot to see how well the SerialCouple could maintain a set temperature.  Unfortunately, the hot plate was powerful enough that the transfer delay between the hot plate and the pot caused the system to oscillate, but turning down the power, and later adding more water, significantly improved performance.
The first trial was with various power settings on the hot plate to a set point of 50C for 2 cups of water.  As can be seen in the graph, this tended to oscillate a couple degrees, but not as much at lower power settings.  These graphs were made by tapping the serial connector with a USB adapter and logging the output to a file with PuTTY, then graphing them in MATlab.
The next trial was with 6 cups of water at a temperature set point of 64C.  This was to test soft boiled eggs, which you need to cook for at least 45 minutes.  Since you're cooking eggs (which you can just leave in the shell) in a low temperature bath, the proteins won't over-cook and become unappealing, because they never get hot enough to.  The power settings for this trial was 4/6, like the red line in the previous graph, except for the middle third of the heating up ramp, where I got impatient and turned the hot plate full power (which you can see in the graph as the change in slope on the way up). 
Zooming in on the set point when the water bath reached it, it can be seen that there is minimal oscillation, considering the ADC's resolution.  I'm happy with this level of stability, considering that it's monitoring an unagitated water bath (which tends to have a few quarters of a degree of noise just due to turbulence).  You can clearly see the quarter degree limit in the ADC's resolution in the graph, which is what causes the jaggedness of the lines as it jumps between possible readings.

So how did my overly-complicated soft-boiled eggs turn out?  Amaaaazing!  I just had to crack off a nickle-sized piece of shell, and was able to pour then entire egg out onto a piece of toast.  The yoke was tacky firm, and all of the whites were a consistent creamy consistency; almost a runny pudding or a custard consistency.  If you're a fan of soft-boiled or over-easy eggs, I highly suggest you try cooking them like this.  It is quite outstanding.


As I said, work is progressing slowly on revising the SerialCouple boards for production.  I'm planning on fixing all of the routing errors, and adding the option of a PCB thermocouple jack instead of the screw terminals I'm currently using.  Current expected cost is going to be about $30 (plus an FTDI cable if you don't have one already).  Email me if you're interested in possibly buying one when they become available (sometime around January 2012, I expect) and would like to be kept updated.

Monday, September 26, 2011

Monitoring an Oven with the SerialCouple

Progress on the SerialCouple boards has been coming along.  I think I've identified all of the hardware issues, so now it's just a software problem.  I decided to have some fun with the prototype today and have it monitor my oven while I baked a batch of brownies.  The SerialCouple boards are rated for the entire K type temperature range (-200C to 1350C), so the only limiting factor as to how hot you can measure is the rating of your thermocouple.
My new roommate happened to walk in on me setting all of this up.  That was a rather amusing conversation...  Luckily, she's learning pretty quickly to tolerate my eccentric hobbies, which I appreciate.

I had a little difficulty installing the thermocouple, because some parts of my oven door are grounded, which causes the ADC to issue a fault code, but using a non-metallic sheathed thermocouple, or in my case finding a non-grounded section of the door fixed that.
I generated the graph by having PuTTY log the serial port to a file, then imported it into MATlab and plotted it to a png.  Pretty simple, but I have visions of eventually writing a proper DAQ interface for the SerialCouple, likely in Java.

Looking at the graph, you can see that I added the brownies at the 8 minute mark, checked on them at the 35 minute mark (2100 seconds), and declared them finished and turned off the oven at 38 minutes.  The oven temperature was set to 325F, so it does seem to run a little hot.  When baking, I would typically let the oven pre-soak a little more before adding the brownies, but I was in a rush for some baked chocolate deliciousness today.

Saturday, September 24, 2011

Volunteering in Rio Vista

The Western Railway Museum (not to be confused with the Western Pacific Railroad Museum which I also volunteer at) has track work weekends twice a month, where we go out and do maintenance work on the several miles of track that the museum has in service.  A typical Saturday consists of driving a few miles down the line and replacing every other tie under the track (which I have written about previously) or straighten and repair rail joints.  This was certainly not a typical weekend.

The old Sacramento Northern line that the museum runs on has a number of trestles originally built in 1939, which inevitably need to be maintained.  The project this weekend was to replace the center bent, which has been suffering from being in standing water, so we were to replace it with a shorter bent, and pour a new concrete cap on top of the old foundation to keep the wood from sitting in the water that collects underneath the bridge.  Joel had already staged the new bent to the left of the old one, the concrete frame and forms on a flat car on the bridge, and jacked up the bridge.
First thing to do was to cut out the old bent.  This was done with a sawzall powered from a diesel generator, while the top cap was held in place by the tie crane on the bridge.
 Once the legs were cut out, we lowered the top cap to the ground.
We found a few of the original 1939 date nails in the lumber we were tearing out, so we pounded them into the new bent, for "historical accuracy."  It hurt the engineer in me a little to improperly date-mark the timbers, but I've already got a 39 nail from the last time we replaced ties, so it seemed like the best thing to do with them.  They were in surprisingly good condition for 72 year old nails.
Some of the nuts were so rusted onto the bolts in the old bent, it was twisting the wrought iron bolts that finally broke, not the stuck nuts.

Once we had the old bent out, we cleaned up the old foundation.
We then took the new concrete cage and lifted it into position.
Getting a concrete contractor to come out on a Saturday was going to be an ordeal, so we only framed it all up such that we could have someone come in Monday to pour it for us.
We then used the crane to lift the new bent into position, and bolted it to the 16" stringers to hold it in place until the concrete can be poured.
Once the bent was bolted in place, we took a break for lunch, and then installed the concrete form for the new foundation cap.
Everything went extremely well, which is mostly thanks to all the hard work Joel put in beforehand staging everything.  Since the new bent is a foot and a half higher, hopefully the new lumber won't sit in water and rot out like the old one.

It was a fun day.  I keep trying to get down to Rio Vista more often, since they work every second and forth Saturday, but college keeps getting in the way.  Hopefully I'll have more time this year to work there.  If anyone in the Sacramento area would like to get involved, email me and I can put you in touch with Joel, who is in charge of the track crew work weekends.