Catapults

I think I cope with stress by designing and building weaponized toys.  The ping pong ball guns and now the catapult.  I can remember the stress I was under when I made the trebuchet and the rubber band Gatling gun. The intent of the catapult design was for science.  The design was to allow to figure out the best angle of trajectory, where the rubber band should be placed, and the length of arm.  

I probably oversized the catapult.  The length of the catapult is 24” and the plans need to be printed on 11x17 paper.  I don’t regret the size; it works well.  I might come back and make a desk top version.

The saw tooth design is so the dowels can be moved to change the angle of trajectory, where the rubber band is placed.  It also allows for the arm to easily be replaced.  Over the process of making it, I realized the location of the rubber band was not important but how many rubber bands. 

My kids assembled most of the catapults.  The oldest choose not to participate.  The younger two glued and screwed most of the pieces and cut the dowels to length.  They installed the hooks and placed the location of the dowel stops.  I actually think that I was able to teach the middle child some tricks. 

Here are the mechanical advantage lessons that I think I taught him.  If he remembers them that is a different story. 

• Wedges to split glued parts that are not supposed to be glued.  We used a chisel to separate a clamping joint that got stuck together with squeeze out
• Lever arms, we used a screwdriver to put in the multiple hooks required for the project
• Blade pinch, he learned what happens as you pinch a blade when trying to cut material. 
• What happens when… The catapult has several different options that can change trajectory and tension.  He was able to figure out that different angles caused the marshmallow to fly differently.  He was also excited when I added a second rubber band and told him I doubled his power. 

Overall, the project went well.  They are a little bigger than I thought they would be. They launch marshmallows and ping pong balls about 40 feet.  The kids had fun.

Bedroom Furniture: Nightstand

This was a quarantine project.  I had purchased the lumber for the project just before the shelter in place order had been issued.  This is what I would consider fine furniture, which is out of my comfort zone.  I had determined that this bedroom furniture was going to try out more traditional joinery.  This would be mortise and tenons and dove tails.

I worked with my wife on the design and material selection.  We like the simple clean design, so we went with a mission style look.  There were aspects of the aesthetics that were not decided until we started putting the parts together.  My wife liked the red-brown tone, so we went with cherry wood.  Which I am grateful for, because walnut would have been expensive.  Some of the design features I wanted to incorporate a couple of things.  The first was putting in a USB outlet. The second was open/slatted sides. 

The USB outlet was simple, but I made it complicated.  I did not want a cord hanging down the back of the cabinet.  I hollowed out the back of one of the legs and then put in a piece that was cutout in the middle to house the cord.  After the sides were put together, I dilled into the hollowed-out section to pull the cord through.  I realized before drilling that my tenons went through the hollowed-out section, so I needed to rethink where my holes where located.  Installation was harder than I wanted, but easier than expected.  I took string and put it in one hole and with a vacuum and sucked it out the other end.  Then I used the string to pull through the wiring for the USB charging port.  The wires are connected back together and then connections are put together using heat shrink tubes. 

The slatted walls were done by grooving the rails and then putting slats in the groove.  It really was not very difficult, and I simplified a lot of the details.  There are small pieces that needed to be put in the spaces between the slats.  I cut out the curves on the scroll saw so there was a top and bottom to the parts and they were unique to each pair.  I my try to use the router and a template for the next time.

There was a fair amount of learning from this project because this is not a type of woodworking that I do.  Here are some of the key insights:

• The legs have dimension.  When cutting all my rails I cut them to the width and depth of the nightstand.  I am grateful I figured out the mistake before gluing it all together. It allowed me to practice forming my tenons again.
• Rough lumber is not as scary as I thought it would be.  I could only get rough lumber and I have never worked with it.  There are some things that I have had to take into consideration.  The first is surfacing it then putting a straight edge on it.  It is not as difficult as a thought it would be.  It is not like the stuff I got from work a few years back. 
• Tenons don’t need to be supper long.  I made them one inch long.  They were going into 1 ½” legs.  I should have made them 5/8” long.  The tenons were not that difficult; it was the mortises.  They were a pain to clean out.  I will also make them wider than 5/16” next time.  The rails are ¾”+ thick.
• Epoxy: I don’t know.  It is the first-time using epoxy and it does fill in gaps.  It was a little messy and there was a fair amount of waste.  I have to say the joints are strong.
• Dove tails are easier to cut on a scroll saw.  I cut a couple of test ones out by hand.  I learned quickly that a cheap coping saw is no good for cutting out waste.  It was a pain and the blade moved everywhere.  It was easy to set the angle and cut on a scroll saw.  It is probably the same on a bandsaw.  Now if I just put the pins and tails on the correct part. 
• Rulers and tape measures become scales.  I have known this for some time, but it really came out in this build.  I needed to keep with in my constraints of height, width and depth.  Thickness of the boards was when all the saw marks were removed with a planer.  Groove thickness was based on what looked good.  Parts changed as things were put together.  The measuring devices were used more for consistency purposes rather than getting to a specific measurement.  That being said, I still depend heavily on my tape measure.
• Good joinery makes the assembly a lot easier.  The nightstands came out square and I did not have to worry about making sure all the parts were at the same spacing because all of that was planned for in the joinery.

Overall I am pleased with the look and design.  My wife choose the hardware and it looks better than the ones I was looking at.  Now onto the computer table.

The past 60 days

I really don’t know how long it has been since we have been under “shelter in place” orders but 60 days sounds like a good round number.  I typically do not post these entries to the public on my blog but I feel the need to share my feelings. 

It has been interesting watching my social media feed.  I liked seeing all the fun things that people were doing.  Honestly it also sometimes made me feel jealous that I may not been included, or it was impossible for me to do.  Now, these types posts have gone and replaced with memes and spiritual/uplifting messages.  These messages are nice/funny/uplifting, but I cannot connect with them as I could with people and pictures.  It is lonely on social media these days.

I consider my self one of the fortunate ones.  I am still employed.  My family and I are healthy. However, I have, as a new manager, to make decisions that affect others.  I have had to let talented employees go, cut hours and have seen revenue streams dry up.  I have friends and family lose employment and health.  It is not fair.

I took my family across the country away from friends and family at the beginning of the year in hopes to start something better.  We were here long enough to start to make acquaintances and building friendships to have the doors slammed shut and connections fade.  We wave to our neighbors and to people we see. I have plenty of people around me but no one to talk to.

We had plans to do so much with the kids.  We are grateful that we were able to make it to DC once before the shutdown.  Parks and trails are closed.  There are so many things that we want to do that we crossed off the calendar.  The kids are bored and feel they need to occupy the time with screens.  I want to go places, but places are closed.

When the news started that we might shut down, I planned out some projects to fill any extra time that I might have during this time of uncertainty.  These included a couple of nightstands with traditional joinery, the projects with the kids, and some home improvement projects.  Many are almost completed, and I am running out of the things that I planned to do.  There is nothing to do anymore.

I am hearing that things are opening with conditions attached.  Slowly, and some quickly, states are starting to go back to a new normal.  Information is confusing and often contradictory.  We are trying to do what is asked.  These times are uncertain and confusing.

I am using technology to connect, have meetings.  Face to face social interaction has been replaced with face to screen.  My company is starting to invest in better AV equipment to cut down on travel expenses.  We are connected in several different platforms. It just is not the same as discussing a problem in a room, face to face.  I see and hear others but do not feel and connect with others.

If you have read this and are concerned, don’t be.  I am fine.  Things are different and they will be for some time.  We will get through this.

Ping Pong Ball Guns

In this time of quarantine and isolation, it has been hard to keep the kids entertained, busy and learning.  I have been trying to teach the scientific process and working though problems to a solution.  I am an engineer by career and degree, so these attributes are important to me.  I saw a plan to make a rubber band gun in a magazine.  I didn’t think it would be too hard to create experiments that would entertain the kids and allow them to look at data to come up with a solution.  This project was not as easy as I thought it would be.  Here are some of the highlights that I learned.

Setup:  I created a board with 11/32” holes spaced at ¾” from the centerline.  I was able to get 10 sets of holes.  I drilled 7/36” holes on the centerline and spaced them 1” apart.  I drilled 3/16” holes in a clothes pin 1” apart and put in 3/16” dowels.  Created spacers in 3/16” thick material.  Sorry, I did not take pictures of the test board.

Experiment 1

What height should the rubber band be placed to have optimal distance?  We set the rubber band holder and the clothes pin distances as constant and raised the clothes pin by 3/16” spacers. (This was the thickness of scrap I had. 1/8” would also work.)  My youngest helps with this part.  We had a sample size of 6 at each height.  The neat thing about this experiment was there was definite height that was the optimal height.

Experiment 2

What should the space between the pins that hold the rubber band be?  We set the height at the optimal height from the last experiment.  Unfortunately, we could not set the clothes pin distance constant.  As the pins get closer together the potential energy of the stretched rubber band is decreased.  Yes, I did consider this and had a solution, but I did not do it.  To compensate we moved the clothes pin back after we moved the rubber band pins in three times.  This did muddy the results.  There was a couple of spaces that did create very consistent results.  I did a sample set of 10 on this experiment because the middle child, who likes science, was helping me.  That was not a good idea because he had about the same attention span of the younger child.  Should have kept at 6 samples.

Experiment 3

How far back should the clothes pin be?  The rubber band pins and clothes pin height remained constant.  We were not too concerned with distance and consistency on this experiment.  We just wanted to see what distance the clothes pin could hold the rubber band without misfiring. 

Results

So, with all the data and observations, we determined the best dimensions for a rubber band gun.  I took some clip art and blew up the back section to trace patterns.  The kids and I traced and cut out the guns.  Attached the cross piece to hold the rubber band and the clothes pin.  The kids were excited and the wife not so much.  The oldest decided the ping pong balls were not that impressive so he has tried shooting other things. 

Here are some of my observations on this process.  Some are design related and others scientific.

• Bernoulli's principle – It was actually pretty cool to see this in action on the height of the clothes pin experiment.  Depending on the height of the rubber band it would put a top or bottom spin on the ball.  Top spin would make the ball just drop.  The bottom spin would cause the ball to float.  It made sense the optimal height was just below half the diameter the ball.
• Eight-inch rubber bands degrade quickly.  It only takes 5-10 stretches of a rubber band before it stretches over 8”.  We did account for this and change the rubber band for each experiment.  Where this proved to be difficult was experiment 2.  The distance that gave the most reliable results was when the rubber band stayed in place on the pins.  When the rubber band did not have the tension to keep it in place the results were not as consistent.  This was because we would have to put the rubber band after each shot.  A little high gave the ball more top spin and a little low and we would have more bottom spin.  On the guns we ended up wrapping the rubber band around each pin once to hold it in place
• Ergonomics and gun holding is a pain to figure out.  The trigger finger is not the index finger but the thumb.  That makes it difficult to hold.  It was a lot of cutting.  Cardboard only helps so much because it is only 1/8” thick. 
• Angling the clothes pin does not help a lot.  It actually could create a problem if angled too much; the rubber band might not fire.
• Clothes pins are cheap and break easily.  This could be because I made them not well supported and replaceable. 
• These guns are super inaccurate and unreliable, but fun and sort of safe to shoot. (doesn’t leave as big of a mark as the rubber band gatling gun; not speaking from experience)

It was a lot of work just for a two-piece wood project.  Worth it for the kids and glad they had fun.  Sorry no plans for this one.  It is better to make your own on this one.

Tools in Review

With the move across the country and a new job, I have had to purchase some tools that I have lost access to or just left behind. Here are some highlights.

A new lawn mower

I decided to ditch the gas lawn mower and left it in California.  I have heard good things about the Greenworks system and that is what I went with.  I have the lawnmower, edger and blower that work all on the same battery.  I have not been disappointed.  To be fair I have not mowed my entire lot in one go.  The single battery is able to cut the entire front yard.  I don't have grass in the back so not sure if it will do both.  To put things in perspective, I have a half acre of land.  This is the first time that I have had a self propelled mover.  It is nice to say my youngest had fun "pushing" it by himself.  Now he just needs to learn how to turn.




New Planer
I went with the home  brand standard of the DeWalt DW735.  It is a good planer and had access to one at my previous job.  I had always thought I would get the Shelix head to go with it.  But then there was a realization.  The new head would cost about $500.  New blades are $55 each and they are sharpened on both sides.  If I would replace them every year (this is a guess), It would take me 10 years to pay for the Shelix head.  By that time I may want to upgrade or go a different route.  While the Shelix is a good cutter head, I don't see the need to drop the money on one right now.  This may change now that I have to buy my lumber in the rough not surfaced two sides.  The biggest issue, and it is big, is that it does not hook up to a standard shop vac hose.  I am not sure what the connection is but I am taping the hose on right now.



New Cordless Tools
I broke down and got new DeWalt drill, diver and circular saw.  My old drill was no it's last legs and needed to be replaced.  Not much to say with the systems that I purchased.  The drills are smaller and easily used by my kids.  They helped me repair the fence.  The circular saw is a game changer.  Needed to cut a 2x4 stud to length and I didn't need to go to the chop saw.  I will say that the saw is a battery drainer.  I have two 2 amp batteries and it will drawing the batteries cutting down sheet stock.
New Hand Tools
This was the reason that I went to the Woodworking Show.  I picked up a hand saw and marking gauge at Lee Valley.  I am looking to do more traditional joinery on some furniture that I am making and these are kind of important in the laying out consistent marks.  I also picked up a square and marking ruler at Wood Peckers.  I know that these are square and it is amazing on how far off my other marking tools are.

The Woodworking Show

The nice thing about moving back east is there are the Woodworking Shows back here.  They stopped doing them on the west coast several years ago.  I have to say, it is an expensive not worth it show.  They advertised Kreg, Erlex and other vendors there. I was hoping to go to get some deals on some tools I needed for upcoming projects.  Well it was mostly resellers, so the deals were not there.  The entire show was something that I walked in an hour.  I had a nice chat with the Grex vendor about sprayers.  Purchased a couple of tools from Lee Valley and Wood Peckers. Probably will not go again. 

That being said I am interested in going to some of the larger shows, but that will require a little more planning and travel.  

New Dust Collection

Last year I bought a shop vac and dust deputy from Home Depot.  I was pleased how they worked but did not like the amount of room it took up.  I came across a video on YouTube that had this design for it.  The link can be found here. This is not my design, but I did make some changes to the original design.  One thing was that I had a different vacuum.  When I went to shop for the parts, I found that the 2 ½” PVC coupling was not snug in the foot attachment holder.  I did not think this was going to be a big problem at the time.  As I was putting it together, the legs were too loose to pull around the shop to various tools.

The fix to this was to make a table out of 2 ½” PVC.  It is amazing how sturdy this is.  It is also difficult to remove pieces that were not cut to the correct dimension.  Overall, it came together in a few hours and works well. 

On the subject of using this as a vacuum, I find the system lacking.  I lose too much suction in the system to use effectively.  It does great pulling the sawdust from the machines because it is a closed system.  When I attach the floor attachment it does not seem to pull enough with the separator attachment.  Maybe I need a vacuum that pulls more CFM, but that is something I am not going to worry about.  I like how it works now.

Here is an update to the last paragraph.  Since I filled up a bucket, I swapped out to a new bucket.  The new bucket was purchased last year for the wood working class.  That bucket worked so much better.  Apparently a used beat up bucket does not work as well as a new one.