2.5 inch QDV build

[CpTn_lAw]

I love to see work in progress! Looks very very promissing

[Willdebeers]

Wow. This will definatly have some kick to it! Good luck with filling it though.

[dewey-1]

Here is a possible method for the piston stop.
Use a thread sealant to seal the screw. SHCS = socket head cap screw

Click to enlarge.

[Technician1002]

Here is a possible method for the piston stop.
Use a thread sealant to seal the screw. SHCS = socket head cap screw

Click to enlarge.

I was thinking more along the lines of simply drilling a pair of holes and putting in a cut piece of chain. I can get cut links free where they cut chain at the hardware store. The ends on the inside would provide the piston stop and the outside would provide a connection point for a shoulder sling. It would be welded or brazed onto place.

Nice graphic by the way. Nice job. It looks like something I would build.

[Technician1002]

Wow. This will definatly have some kick to it! Good luck with filling it though.

Bumped for the update.

I expect it to kick like a mule, but filling it will be no problem. It's about the same size as my 2 inch.

This weeks update for today. The sanding is finished. I finished off with 320 grit sandpaper which left a nice shiny and smooth surface. A golf ball is in it to provide a reflections and light background so the detail of the remaining pipe seam can be seen. It's almost completely gone. Click to enlarge and see the remains of the pipe seam.

[Brian the brain]

That'll do just fine.
Looks just like the inside of Mr.Porters piston housing.

But your design depends highly on O-ring seal.Make that soley ( sp?)

You could use some epoxy filler to bring up those pits.
I would not have chosen that particular pipe..
It looks like it was part of the RMS Titanic.

Great name for the cannon btw..

[dewey-1]

Tech;

If you get a chance, make measurements of the tank and the piston sleeve and I can create some 3D drawings to post on this thread.

[Technician1002]

@ Brian, This is my 4th QDV. Getting the rings to seal will be no problem. The 2 inch has a fairly deep weld groove. I did epoxy fill it. In places the epoxy is starting to come lose. I am going to try to avoid filler at first. With all the edges rounded the o ring will seal. My other 3 are the Cellular Core Test Cannon (apple cannon) the T Shirt Cannon (2 inch QDV) and the Marshmallow Cannon (1 inch QDV)

Tech;

If you get a chance, make measurements of the tank and the piston sleeve and I can create some 3D drawings to post on this thread.

Thanks Dewey. I'll get them for you.

It's cold and wet today. I'll probably wait for nice weather to get good photos to mark up. I'm planning on cutting the ports tomorrow or Saturday. If I do, I'll be sure to get good photos to mark up. I have a benefit of the way I cut the tank. I can easily measure the tank thickness.

Edit; Nice halloween math class.. I wish I had this guy as my math teacher. He's fantastic.
[youtube][/youtube]

[rikukiakuchiki777]

Looking good tech. Can't wait to see damage pics

[Technician1002]

I got the measurements for Dewey-1. So everyone can see the parts measured, I took photos. Sorry for the more than 6 photos in one post.

Edit; adding to my last post instead of bumping the same day.. I got the ports cut. Photos below.

[c11man]

that looks great tech. now you get the fun job of rounding all those edges

[dewey-1]

Tech;

What are the sizes of ports and width of ribs before filing?

[Technician1002]

Tech;

What are the sizes of ports and width of ribs before filing?

The ports are 1.5 inches tall. The ribs are .5 inches wide.

[theBOOM]

Tech how heavy is the obsolete tank yor using?
Give us pictures of the piston once its finished

[Technician1002]

Tech how heavy is the obsolete tank yor using?
Give us pictures of the piston once its finished

For this weekend update, I have good, bad, and ugly news.

The good, the piston is done. The port rounding is done.

The bad, I depleted my camera batteries at the event I attended over the weekend so when I got to the lathe, the batteries were flat, so no turning pics.

The ugly, my computer had a fan failure on the graphics card while I was gone. It smoked. I'll have to get a new card next weekend before I can download and edit the photos to websize. I have to borrow time on my wife's computer, so time in chat from home will be severely curtailed until I get my graphics card replaced.

To answer the above questions, the modified tank is 10.5 lbs. The tank with the pipe in it is 17 lbs. (on my bathroom scale)

Some info on the piston, to get the maximum performance, the piston was shortened to the bare minimum. The o rings will seal right on the edges of the port. This will limit the area I need to polish leak free for the rings as well as cut the piston mass to the minimum. The ring at the front is very near the front edge so when the piston unseats, the nose of the piston will be out of the way. The nose of the piston is also rounded to help this. The rear is a little thicker so the edge doesn't get broken from hard landings in the bumper.

For those taking measurements, the recess in the front of the piston extends in so only 1 inch of material remains at the rear of the piston. I didn't take measurements yet of the overall new length or the diameter of the hole in the front. The hole was enlarged with a home made boring bar. Sorry I didn't get pictures. The boring bar is made from a valve stem from a car engine. The valve head was cut off. The end bent over with a torch and then ground to a side cutting round nose boring bar. It worked like a champ.

The piston slides freely in the pipe without o rings with barely any sideways wiggle room.

I'll put some pics on a flashdrive and see if I can get a few posted tonight at work.