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.

Goals this Year

This year is going to be an interesting experience.  I have moved so I need to set up my shop again.  The good thing is that most of my tools are on wheels, so I need to find locations for everything.  My area is a little bit bigger, but I lost all the overhead space.  I am also going to need to watch the items that we will need to store in the garage as we get snow and the kids start getting larger outdoor toys.  This process will take some time, but I am currently able to manage. 

I have found another guild to participate in.  It is a marketing ploy because the people who run the guild also push their product (they sell tools and lumber at the location).  The group seems strong and active in the community.  There is no toy drive, so I am going to have to find my own charities to donate to.  I hope to be able to get a little more involved and participate in the guild.  I am a little out of my element and there is a lot of members, so it will be easy to get lost in the group.

I am working on more magazine articles.  I just got requests for three more.  Two are pretty simple and the other one is going to take more time.  With the move and the cold weather, it is going to be a struggle to get these complete, but I like the challenge. 

I am also looking at getting back into the plan sales through retailers.  Now that I have been published, I am hoping I have a little more leverage.  I need to reach out to them again and see if they are interested.  Etsy sales are doing well and hope to continue that platform.

The major projects this year’s is going to be a couple of nightstands.  I am going to take it a little lighter this year because of the move and adjusting to a new workshop.  I am hoping these will turn out nice with nice hardwood lumber and finish.  I plan to do some traditional joinery.  Design wise, I am going to be looking at the house.  I need to design some closet systems to make the closets a little more functional.  Not sure what the toy front will look like this year.  I think that I need to take a break this year.

Year in Review

It was a crazy year for woodworking.  It was also a very successful year.  The biggest project was all the donations this year.  It will be a while before I do that many again.  I was looking to reduce my lumber supply with all the donations and I am glad I did.  The donations included a lot of the small trucks, cars, boats and planes.  There were also cradles, rocking chairs, and high chairs that were also donated.  I think I was a little more invested this year because I chose the charities.  I may have disappointed some of the people that receive donations from the club.  This year I also tried to include more people in the process.  I had people help paint and build which was fun. 
In terms of projects this year it would probably be the build and grow cars.  I just like how all of them turned out.  They were fun designs and solidly built.  My least favorite was probably be the battle axes.  I really do not like making weapons especially one that has the ability to do a lot of real damage.  It was fun to work with my brother on a project. 
Tools I picked up this year.  The list is small, thank goodness. The branding iron was needed for marketing.  It works well and I am glad I have it.  The other was a long time coming and I have not had much of a chance to use it.  That would be the new shop vac with the dust collection.  It seems to work well for the few times that I have used it.  That is it for tools.
I was able publish two plans this year and I was able to install several cabinets for a friend.  These were the two big sources of income this year.  My etsy shop also did really well.  I think there was a fair amount of traffic that was because I was published in a magazine.
I accomplished the main goals that I was working towards.I ended the year with moving to the other side of the country.  It will be interesting to setup a new work area and a new group.  I am going to have to find a new lumber yard also.

My Last Project in California

Phone Stands

 My last project in the current shop was a couple of cell phone holders.  I have done one in the past but this time I cut out a butterfly on the top of it.  The other was an easel that proved to be more complicated that I had hoped.  The size of the easel made the angles very shallow and I did not want to feel like it was going to fall over.  The other thing that I did not realize was the dimensions of the stock.  I originally went with 5/8” thick stock but that looked too thick, but ½” was too narrow to hold the phone.  I actually needed to be creative to make the ledge look thinner than it actually was.  That is what angles are for. 

The tricky part was the drilling the holes.  I drilled one and then used tape and super glue to hold it all together to make sure all the holes lined up.  It actually worked really well.  This was a lot of compound angles.  For the most part I sanded to a line.  The project made me think a lot about the angles and order of operations.