I search the forum frequently, but because I am able to find the answers to my questions, I rarely post. That changes today as I reveal:
A solid copper auto-siphon.
It seems that people bring up metal auto-siphons from time-to-time, but either nobody's bothered to make one (except one guy who posted pictures and nothing else), or if someone's made one, they haven't posted a how-to.
Why make a metal auto-siphon?
Until I get a 7+ gallon boiling pot, I don't want to add a spigot to mine, not do I want to use co2 to transfer beer from ferementers, as I don't keg. I also want one siphon that I can use with both lambics and regular beers. Most importantly though, I think we can all agree that the plastic auto-siphons suck. I've melted one and nearly melted another. This one can take higher temperatures and could be used with a counterflow chiller. (might need a different ball for the check valve, though - I think acetal is only good to 180 deg. F)
Copper is easy to find, and from my searches, is either cheaper in small quantities, or had a smaller minimum order (the min. length of pipe I found was 2') than stainless steel. Plus, you can polish it to look absolutely amazing. You could probably use the same basic design to make this out of stainless, but I'd image sourcing the parts would be more difficult. Copper has many of the same advantages as stainless, is easier to source in small quantities, and is easier to work with.
Why only basic tools?
I wanted to make a version that doesn't require a lathe (since I don't own one) - one that most people who do the DIY thing can make.
This is going to be a bit of an abbreviated How-To. There will be some annotated images showing how it's assembled, and a few parts highlighting exactly how I did a specific task. Most of the assembly, however, is straight-forward and doesn't need explaining.
The valve. There are 2 halves, the bottom and the top. The ball, which prevents backflow, is in-between the two. That way it can be removed, changed, and sterilized. The 2 halves are connected with a 1/2" screw fitting.
The bottom half of the check valve:
There is an 8mm SS washer placed above the pipe in the threaded connector. Bring the 12" male threaded adapter with you when buying the washer to make sure it sits on the stop. I had a few laying around. If ordering online, make sure the product lists the OD. Measure the ID of the threaded adapter with a vernier caliper.
I left the cap unsoldered so it can be removed for cleaning.
The top half of the check valve:
Before I soldered on the pipe, I cut a 12 ga copper ground wire from a piece of romex so that it would sit on the stop in the connector in the middle without falling through. This is to keep the check valve ball from traveling upwards into the siphon. (all copper wire today is 99% o2 free, solid copper, so it's safe. I'm not aware of any copper-clad ground wire).
The piston seal:
This is the tricky part. In order to do this with normal tools (and since I don't have a lathe), I first used an adapter to go from 3/8" to 1/2" copper pipe. The 1/2" copper pipe has a 5/8" outside wall.
To make the grooves for the O-rings, I cut up a no-stop butt connector into ~1/4" rings, and soldered them on, leaving a ~1/16" recessed gap between them. I used a bandsaw as I couldn't get a pipe cutter to work for such a small cut. A radial arm saw, miter saw, or chop saw with a metal blade would work, too. If you have to use a saw other than a bandsaw, I would solder the fitting to a length of copper to make it easier to clamp down.
IMPORTANT: O-rings typically come in 1/16" thicknesses, so allowing for both sides, they will add 1/8" to the width of the copper pipe, so we need an outside pipe with 3/4" inside diameter. (5/8" OD of 1/2" pipe + 1/8" for O-ring = 3/4") THIS IS KEY. ONLY type K copper pipe has an inside diameter exactly the nominal size. So 3/4" type K copper pipe will have a 3/4" inside diameter. Both type M and L (what they have at HD/Lowes) WILL NOT WORK - They have the same OD, but thinner walls and a large ID which will cause the piston not to seal. I purchased mine from Grainger.
Stick the 3/8" pipe on the piston (and an elbow if you desire), insert the ball in between the 2 parts of the check valve, and start siphoning! Also: I choose to polish mine - polished copper looks amazing, and an unpolished copper auto-siphon seemed like a travesty.
Because of the ID of the 3/8" pipe, it flows much faster than the biggest plastic auto-siphon. It takes 2 pumps to get started. Because of this, if I were to do it again, I would use 1/4" pipe in place of 3/8", keeping all else the same.
The check valve works great! No need for a seal. The washer seals just fine to the delrin ball. You can hear it bouncing around very quickly when fluid is flowing - I'd bet that you could even use a metal one without any issues.
Follow up questions that I want to make sure we get right:
My Home Depot doesn't carry the right copper pipe (either 3/8" or type K 3/4"). Where can I get it?
Grainger. Also, any plumbing supply store should have it, but you might have to buy 10'. Type K is for underground outside applications. When buying copper pipe, don't buy coiled. This needs straight, hard pipe.
Where did you get the balls and seals?
Amazon. The balls are 3/8" acetal balls, 100 pack shipped Amazon Prime. The o-rings are 016 Silicone O-Ring, 70A Durometer, Red, 5/8" ID, 3/4" OD, 1/16" Width (Pack of 100), also shipped Amazon prime. The seals are also available from Grainger, but are much more expensive.
(Special thanks to BrewBeemer for recommending delrin balls. They work great!)
The 3/4" pipe is 2' long, plus the fittings, so it is taller than the fermtech siphon by a few inches.
The 3/8" piston pipe is about 2' 2" long, and the elbow is about 4" long.
The pickup at the bottom is designed to pick up fluid about 1/2" above the bottom. I also made a second pickup/lower valve without the holes so I can pick up fluid from the very bottom of a pot - like a boil without sediment.
How much did it cost?
I'll subscribe to this thread, so if you have any questions, just add to the thread and I'll do my best to help out! I have a few pictures of the process and can take more pics of the siphon in case I didn't explain something well enough. Hopefully this is good payback for all the times I've found an answer to my questions here!