Month: March 2018

Cutting Edge Science

~ joelshaw@sbcglobal.net ~ 2 Comments

One of my first tool purchases when I graduated from college was an air compressor. I wanted one my whole life, and I finally had the means to purchase one. It worked great for years, but along with usage and age came problems. The check valve in the tank leaked after a few years, several years later the unloading valve stuck so it couldn’t restart under pressure, the centrifugal starting switch flew apart at some point… but I always managed to bring it back to life. Its efficiency dropped over time, and eventually it would not build over 90 psi.

This compressor was 20 years old and designed for disposal rather than repair. I had already had picked up a large commercial compressor, so the logical course of action was to scrap the old unit. Destined for the scrap pile or not, I just had to know what failed. I took the compressor apart and discovered that the reed valves had cracked.

If you are not familiar with reed valves, they are pieces of sheet metal that seal against a hole in one direction and let compressed air pass in the other. During operation, pistons reciprocate in a cylinder compressing air and forcing it past the reed valves and into a tank. The compressed air is then restricted from returning from the tank by reed valves. In my particular compressor, this happens about 60 times every second in each of 3 cylinders!

I had already decided that compressors are considered disposable these days, that this particular one had dutifully served me for years, and that I needed to let it pass on to the great scrap pile in the sky. However, I was curious how much a replacement reed valve would cost if I naively decided to fix it. After some searching, I found the correct valve for my model number was available for only $2.37. WAS is the key term… it had been on backorder since 2005. Did I want to scrap my compressor for lack of a $2.37 sheet metal part that was once available? Obviously not. I decided to make a reed valve.

I did some research and found some hardened spring steel shim stock (strong sheet metal) that I thought would make an acceptable reed valve, ordered the shim stock, and tried to find a way to cut out the part. What is the most obvious way to cut thin sheets of metal? Snips?

Snips are my my preferred tools when I want to be intellectually humbled. I can think about the shape I need to cut, ponder best way to attack the sheet metal, be patient and deliberate… but the tin snips always do what they want. Not what I want. Convincing snips to cut a shape is like convincing cats to go somewhere that they don’t want to go. In the end you are cut, scratched, scraped, bleeding, confused, demoralized, and have only accomplished what your adversary wanted all along.

I put down my snips, picked up the internet, and decided to use SCIENCE to manufacture the reed valves. I found that it is fairly simple to electrochemically etch a complex shape from sheet metal without the plastic deformation and warping typical of other methods..

I am not going to go into the detailed science behind the project, but all that is needed is a DC power supply (12V battery or charger), some salt water, some alligator clips, some spray paint, a sacrificial piece of metal, and the sheet metal workpiece. Send me a comment if you want more details or suggestions for your own project.

The basic steps are:

  • Lightly sand, clean, and paint both sides of the sheet metal workpiece (the paint will act as an electrical insulator).
  • Scribe the desired shape onto one side of the workpiece. Make sure to scribe through the paint so that metal is exposed.
  • Use alligator clips to attach the workpiece to the positive terminal of the power supply.
  • Use alligator clips to attach to a sacrificial piece of metal to the negative terminal on the power supply.
  • Place the workpiece and sacrificial piece in a plastic container filled with salt water. Make sure the workpiece and sacrificial piece do not touch each other.
  • Watch the workpiece bubble for about 45 minutes.
  • Remove the workpiece from the salt water and rinse thoroughly.

For this particular experiment, I used the used the old reed valves as a template and traced each lobe onto the workpiece with a scribe. The final results are pictured at the beginning of this post. It was little effort while things were set up, so I made two parts. Now I can fix my compressor again 20 years from now when parts are over 30 years on backorder.

Any advice I can give for the next DIYer that wants to cut sheet metal?

  • Bend the attachment point for the alligator clips on both the workpiece and sacrificial piece so that they are not under the salt water. I discovered that the alligator clips were much more prone to electrochemical etching than the workpiece.
  • I don’t know if the bubbles coming off of the workpiece were caustic or not.  I held my breath for the 45 minute duration just in case.
  • If you want to etch a design onto a piece of metal rather than etching through the metal, the DC Power supply can be replaced with an AC power supply. This will visibly etch the surface, but it will not cut through the part.

UPDATE: I am more surprised than happy to report that the compressor works as well as ever with its new reed valves! I am adding a reminder on my calendar to update this post in 20 years. Stick around, and we will see if the custom reed valves last as long as the factory part did.

It Takes Two

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I live in an odd house. I have alluded to that fact in a previous post, but I would like to elaborate and eventually get to an explanation of the title.

Ever wanted a pantry that had a window with a view? My pantry had a  window with a view… of the back of a wall. I spent years of indecision regarding the best use of this area. It seemed like a shame to sheet rock over it. I thought about printing out a scenic picture to place behind it, but the glass was cracked and I couldn’t get to its outside for repairs. I thought about building a refrigeration unit and having cooled storage for the summer when the house gets hot, but that quickly became cost prohibitive. A secret cubby hole? Opening it up to the other room? A big fish tank? I finally decided to remove the window and put in some shelves.

Removing a window must be simple, I thought. There were some screws that looked like they held the window in place. I planned to remove the screws, slide the assembly out, make some shelves, and have have the whole thing together in time for dinner. I thought.

Over the following days, I realized that IT TAKES TWO people to build a house. One person to hold up the pantry window, and the other to build the house around it.

I removed all of the screws I could find, and the frame would wiggle but not slide out. I started piecing away, sawing, and chiseling the window frame from the inside. There were 50% odds they installed the assembly from the inside and I might be lucky. Nope. Oh well, I lost that gamble.

I know the window was installed (100% odds) and it had to go in from either the inside (50% odds) or outside (50% odds). Therefore, it was obviously installed from the outside. I painfully contorted myself to piece away, saw, and chisel the outside of the window frame from the inside. I removed enough material that it should have come free, but it didn’t budge. Apparently, 50% odds +  50% odds doesn’t always add up to 100%. The game was rigged.

I finally got ignorant with hammers, saws, crowbars, and broken glass. Apparently the builder framed the house, installed the window outside of the house’s frame, added some more 2x4s for spacing, then bricked the house. This left the window frame mounted inside of the structure and behind the bricks that are now embedded inside of the wall.. This might be common practice, but it is news to me. Please don’t tell my wife, but it might sometimes be minutely advisable in some extremely rare situations to hire someone who knows what they are doing.

Window out! Now to address the shelves. This is where I discovered that the two guys who built my house were so good that they didn’t need to use a straight edge or square. Building the shelf housing and shelves was like a geometry lesson: it took rhomboids, kites, obtuse trapezoids, and parallelograms… most of the quadrilaterals but oddly no squares or rectangles.

Needless to say, it is done now. It might not be the best solution, but sometimes any solution is better than no solution. AND, sometimes a solution now is better than a better solution down the road.

My advice from this little project?

Sometimes it is best to go ahead with some idea rather than waiting for the best idea.

Sometimes it might be remotely conceivable that occasionally there might be a rare situation when there is some small chance that it could possibly (but probably not) be worth consulting someone who knows what they are doing. I can’t be sure about that, though. It would be best to consult a professional.

Boats and Beer, a PSA

~ joelshaw@sbcglobal.net ~ 1 Comment

Have you ever heard of Shipwright’s Disease? Though I don’t have a ship (or even a boat) it is something that I have been plagued with my entire life, and I personally consider Shipwright’s Addiction to be more appropriate. I was made aware of the affliction years ago, and I am seeing its effects more and more as I grow older. In lieu of an actual definition, it was explained to me this way:

  • You have a boat with a light bulb that needs changing.
  • You remove the light bulb to discover some corrosion.
  • You figure that if the light bulb is corroded, the rest of the wiring might have issues.
  • To remove the wiring, it is necessary to remove some of the paneling.
  • While the paneling is off, you decided to go ahead and replace it.
  • The new panels make the carpeting look old, so you decide to go ahead and replace that.
  • You realize that you can’t have a boat with new panels and new carpet but an old engine, so you decide to rebuild the engine.
  • If you are already taking apart the engine, why not make a little more power.
  • If you are going to make a little more power, why not make a LOT more power.
  • The inside of this boat with new carpet, paneling, and a more powerful motor is great, but it just doesn’t match that old faded gelcoat on the outside.
  • AND, it goes on. I am sure you get the point.

 

So I explained the boat half of the title. How does it relate to beer? Most recently, Shipwright’s Addiction has surfaced through my whim to brew beer. I decided it would be fun to drink a beer that I made myself, so I wisely bought only the most basic brewing kit… pretty much some buckets, some malt extract, and some yeast.

That’s when things started to go pear shaped.

I didn’t want to heat up the kitchen too much while brewing, so I found a propane burner on Craigslist that came with a mash tun for brewing all grain.

In order to utilize the mash tun, I needed a better way to cool the wort. My Craigslist purchase of a wort chiller came with some more brewing “stuff”. The volume of beer I need to brew to justify the equipment required a way to dispense a larger volume of beer. I went to Craigslist and purchased a kegerator. The kegerator wouldn’t fit the size of keg I had acquired, so I built a bigger kegerater. My bigger kegerator had empty space, so I needed to  more kegs… and CO2 bottles… and a CO2 filling station… and it kept going. It is really not my fault. Craigslist is obviously to blame.

In the end, things went from two buckets, some malt extract, and some yeast to almost everything shown in these pictures, and more. I even had to obtain an extra tool box and make shelves to hold all of the beer paraphernalia.

While I typically try to make  my posts helpful for the DIYer, this one isn’t. It isn’t even about boats or beer. It is a Public Service Announcement for those related to DIYers.

If your loved one is afflicted with Shipwright’s Disease, you can’t fight it. You can’t stop it. The best you can do is to keep them away from hobbies and sources of enjoyment, limit their internet usage and access to Craigslist, and give me all of their stuff when it becomes too much to bear.

Hot Paint On a Cool Chair

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After one of my frequent plunges to the depths of the the internet, I returned with a neat idea. It began with the plan to update an outdated couch that my friend (now wife) gave me from her church. While it ended with no changes to that couch, the plunge down that particular rabbit hole yielded a fun project:

  • Started searching for appropriate fabrics to reupholster the couch.
  • Found out that I can have custom fabric printed with my face on it!!!
  • I didn’t want to wait for custom fabric, so I researched the types of ink that they used.
  • Found out fabric paint exists.
  • Decided the fabric paint is too expensive for the size of project I wanted to do.
  • Found something called Textile Medium that changes acrylic paint into fabric paint.
  • Calculated the number of little acrylic paint containers needed for the size of my project and got frustrated.
  • Discovered Latex paint is acrylic paint.
  • Lost interest in the couch and decided I wanted a wing back chair with flames.
  • Purchased a wing back chair (my mom actually got it from Goodwill).
  • Purchased Latex Paint and Textile Medium.
  • “Commissioned” my mother and beautiful wife to paint the chair (my artistic talents are somewhat lacking).
  • Enjoyed my Flaming Chair!!!

I was kind of surprised with how well the chair turned out, so I want to quickly post some things I learned. It might help the next person with some project, but it will definitely help me remember when I will get back to that couch someday.

  1. I am not sure the Textile Medium is necessary. We used it on parts of the chair but not other parts. Next time, I probably won’t mess with it.
  2. The fabric should be lightly sanded with fine grit sandpaper before painting and between coats to improve pliability and adherence.
  3. Latex paint from the hardware store seems to work fine.
  4. Plan on multiple coats.
  5. Plan on it taking a LONG time to dry.
  6. Let it dry between coats as much as your patience will allow.
  7. The final surface of this project is not what I would call “plush” or “soft”. It is not advisable to scrape newborns against the painted fabric surface.
  8. Sanding at the end might offer a softer feel, but it also might dull the colors and require another thin coat to bring them back. Some experimentation is in order.
  9. Due to the non-plush texture of the final product, I am looking at alternate options for my Flaming Underwear project.

As always, please comment if you have any ideas or suggestions. I am always anxious to learn from the experience and ideas of others.

A Cool Trick for Working On AC Systems

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Last week was Mechanic Week for me. I knew I was going to put a new clutch in my wife’s little car, but I was also provided the surprise opportunity to replace the locked up AC compressor on Red Truck. With about 200k miles, I am kind of proud that it made it this long.

Everything is really easy to get to and the truck has high mileage, so I decided to do it right: new compressor, flush everything, new dryer, new orifice tube, pull vacuum for an hour, etc. With everything out in the open, I figured I might as well. I was able to replace the compressor and dryer in about 30 minutes. Then I got the orifice tube.

If you are not familiar with AC systems, the orifice tube is a small nozzle that allows the freon to expand from liquid to gas. Cooled gaseous freon subsequently goes through a heat exchanger to cool the car. The orifice tube is a small 1-piece device that simply slides into the high side freon tube before the evaporator. The orifice tube has an integral tang at the top for easy removal. Pull on the integral tang, and the whole device slides out of the freon tube. It would make sense to place that tang near the opening of said freon tube. Ford thought otherwise (shown to the right).

It turns out that needle nose pliers can be modified to reach the tang of the orifice tube. Modified needle nose pliers are very good for un-integral-ing the integral tang from the 1-piece orifice tube, leaving nothing to grab. Luckily, Al Gore loaned me his internet so that I could find a solution.

This seems to be a fairly common problem. I found that the “old guys” get a long wood screw, wrap tape around it as a guide, screw it into the top of the orifice tube, and yank on it with unmodified pliers and all of their might. Despite Ford’s best efforts, I had it out in minutes. Does this mean I am now an “old guy”?

While I am talking about Ford A/C systems, I would like to complain about something else they did. Some engineer somewhere decided to use a rubber ball instead of a shrader valve on their high side service ports. It might have saved a penny at some point, but I’ve never met one that didn’t leak. I’ve also met very few high side couplings that will reliably press the rubber ball enough to get a consistent reading. Why, Ford? Why?

Pulling all of this together, I wish someone would take Ford’s high side service port design and shove it up the engineer’s orifice tube. Also, try using a wood screw and some tape to remove your orifice tube if you (or it) are in a bind.

 

Needless to say, the gallant steed is all back together and on the road. Hopefully the AC system in Red Truck will keep together for another 200k miles.