Floating O-Rings for 1" QDV

tony48 · Wed Jul 27, 2011 1:58 pm

I'm using 1" nominal PVC pipe for the valve body of my QDV cannon. I want to make a floating o-ring piston. The ID of 1" PVC is 1.029". At my local hardware store I can only find 1" and 1-1/16" (1.0625") o-rings which are a tad to small and a tad too large. I guess I need 1-1/32" o-rings (1.03125"). So what should I do? Sand the pipe out to fit the 1-1/16" o-rings? Anyone know where I can order 1-1/32" o-rings?

Technician1002 · Wed Jul 27, 2011 2:03 pm

I used an iron pipe. It has thinner walls. When sanded smooth, it works very well.

Gun Freak · Wed Jul 27, 2011 2:21 pm

Could make your own rings or stretch out the 1" ones, maybe a tiny bit of heat will do the trick.

Gaderelguitarist · Wed Jul 27, 2011 9:19 pm

You might try Mcmaster-Carr. They generally have a very large selection of things.

tony48 · Wed Jul 27, 2011 9:36 pm

Yeah I'm thinking I may have to order from mcmaster. I don't want to pay 5 bucks shipping for a couple cents of o-rings though.

Gun Freak · Wed Jul 27, 2011 9:44 pm

I wouldn't either. Here is an idea. Try putting the 1" o ring around 3/4" PVC and I think it will stretch but I haven't looked up the diameter. Then submerge it in very hot water and I think it will widen a bit.

Mr.Tallahassee · Wed Jul 27, 2011 10:10 pm

I used floating o rings in my piston and they were almost the same OD as the pipe. They weren't hard to get in and with a little grease, which is advised for any o-rings period, the piston moves beautifully. You just need the piston to be a very close fit or you need really thick o-rings.

tony48 · Wed Jul 27, 2011 10:47 pm

Ok I'm waiting for my Hdpe so when it Arrives I will turn my piston and see what I can get to fit. I have 1" and 1-1/16" o rings so hopefully one of those will work with stretching and/or cutting and re glueing.

tony48 · Fri Jul 29, 2011 10:47 pm

Now I'm having trouble turning down my round stock on the wood lathe. It starts to chatter and makes the surface very rough. I can't seem to get it to cut smooth and I'm not sure why....

Gun Freak · Fri Jul 29, 2011 11:24 pm

Have you tried higher speed and slower cutting?

Gaderelguitarist · Fri Jul 29, 2011 11:26 pm

It means your stock isn't perfectly straight, or your tool isn't sharp enough.

Technician1002 · Fri Jul 29, 2011 11:35 pm

I found the best cutting angle for HDPE to be about 90 degrees. Cut straight toward the center of the stock and don't try to shave it like you do wood with a wood gouge. Use very sharp tools. It will turn a curl much like turning metal on a lathe. Use the tool rest as close to the work as physically possibility to reduce chatter.

tony48 · Sat Jul 30, 2011 9:00 pm

Stock may not be perfectly straight and I will resharpen my tools. Thanks for the help

Technician1002 · Sat Jul 30, 2011 10:06 pm

Perfectly straight is not a requirement. I started with a square and turned it down to round with no problems. The rest of the photos are in the how to section as a sticky.
http://www.spudfiles.com/forums/tutoria ... 21740.html

Started with this.

Ended with this.

Gaderelguitarist · Sun Jul 31, 2011 12:26 am

Tech, I was referring to the possibility that the stock may have a bow to it. Corners are no issue with tool chatter. They just need to be "broken" as the term is.

In pen turning, where the hollow material is threaded over a mandrel, the straightness of the mandrel is paramount. One millimeter of bowing results in oval pens and lots of tool chatter.