2015 POTD Thread Archive

[chevydyl]

omg lol

 

[Lynrob]

I am still a novice hobby machinist but I think I (finally) have something to contribute that might come in handy for someone. Last night, just before bedtime, by wife discovered water all over our bathroom floor. Upon investigation I found a slow drip, drip, drip from one of the shut off valves under the sink. It looked to me like maybe the compression nut on the valve that connected to the copper pipe coming out of the wall was lose. Unfortunately, when I tried to tighten it things got worse... much worse. After getting the water to the house turned off and most of the water sopped up, I removed the valve. The only thing I could think of as the problem was that the compression ring was bad. Unfortunately, it was inside the compression nut that was pretty tight up against the wall. How to get it off?

I googled it and sure enough they make compression ring puller just for this application but it's 10:30 on a Saturday night. So I thought, "I'm a machinist... sort of. I'll make one!". Off I go to the shop. Here is a picture of what I came up with:

The pipe is just to give a reference in the photo to show how things line up. Here's another shot of the puller itself:
and from the top:
So, basically, there is a button that is machined to the same diameter as the outside of the pipe with a register the same diameter as the inside of the pipe to keep it centered. The button is inserted in the pipe first, then the puller threads into to the compression nut capturing the ferrule in between them. The the socket head cap screw is tightened against the button which pulls the compression nut and ferrule off. I tried it, and it worked!! I was very pleased since this was only my third attempt at single point threading. Luckily, I had a replacement ferrule on hand so I reinstalled the valve and got everything put back together and turned on the water. Still leaked... so I figured I must not have tightened the compression nut tight enough. I give it a little snug and bang! There's water everywhere! The thread part of the valve had broken off inside the compression nut!! Aaahhhhhh!! Luckily, my wife was near the cut off valve and we got the water turned off with out too much of an issue. So now, I'm looking at the copper pipe sticking 3/4" out of the wall with a compression nut, ferrule, and the broken off threads from the valve jammed on it tighter than a drum. Apparently, the valve had a crack in it causing the leak. Seems strange that a crack would develop after being in service for years though.

It was 01:00 by this time so I called it a night. I puzzled about how to get that ferrule off of there without damaging the pipe. Having everything so tight against the wall and the tight quarters under bathroom cabinet complicated things considerably. I finally decided that my best shot was to try to trim off an 1/8" or so of the coupling nut and then try to grab the now exposed threads and back them out. Thank God for my Dremel tool!! I trimmed the nut and after a few contortions beneath the cabinet, I got part of the threads exposed. I was then able to grab them with some water pump pliers and back them out of the nut. Now I'm back where I started... coupling nut and ferrule tightly jammed on the pipe. Hey! I've got just the tool for that!! This time, my new tool wouldn't work though. Since the nut was now shorter than it had been before, it didn't extend past the edge of the ferrule and my tool was matched closely to the pipe's diameter so it stopped at the edge of the ferrule. Not one to be easily defeated, I went back out to the shop and bored out some relief for the ferrule. This time, I was able to engage the nut and back off the nut/ferrule pair.

I happened to have a spare valve so I started over, once again. By now, the pipe seemed to be showing some signs of abuse. It was still smooth but its diameter felt as though it was a few thousandths smaller having had a tight ferrule pulled off of it twice. I didn't think I had many options, so I installed the new valve despite my misgivings. Water on... crap... it still leaks! By this time I was thinking I'd have to call a plumber. I didn't want to tear into the wall so I thought professional advice was in order. I was out in my shop putting things away and feeling defeated when I ran across a "shark bite" 1/2" PEX coupler. I remembered someone telling me fairly recently that 1/2" copper and 1/2" PEX have the same outside diameter so "shark bite" fittings will work on both. Given the condition of the pipe in the wall I wasn't too hopeful but I had nothing to lose so I decided to give it another go. I rummaged around and found a PEX shut off valve so I was ready for a third attempt. I used my brand new tool once again and the nut and ferrule came right off. I slid the "shark bite" fitting on with the new valve and, what do you know, it held!! SUCCESS!! I've got to say, it felt pretty good to get that thing fixed!!

Here a final picture showing the original valve with broken threads and the compression nut I trimmed. I've also included the second valve that tried and failed.
I hope none of you have to go through this but if you do, hopefully some of this might be of use to you.

 

[Tony Wells]

Exactly why I soldered all my stops.

IMO, compression is always for downstream of a within reach valve. I never have liked them. My Dad advised against them, and he was in the supply side of plumbing for 50 years.....I believed him.

 

[RJSakowski]

heres is the tool path for my pcb board, for the touch probe. not sure if I want to add holes for mounting it to delrin or not, pcb screws to the delrin, delrin screws into the the alu, or maybe use jack screw under the delrin for centering, also coming up with an idea to have the shaft that goes into the mill collet, so that I can adjust runout to provide a higher degree of accuracy
View attachment 116942

I made my contact disk from Delrin. I drilled holes for wires in the stainless steel balls and soldered the wire in. The wire is then bedded into a groove in the Delrin plate. The two end wires are connected to terminals where the external wires are attached. The vertical dowel pins prevent the probe from lifting and rotating in the event of over-driving the probe. The flats on the plate perimeter or engagement points for centering screws.

Bob

 

[brino]

Not one to be easily defeated

That part is clear!
Sounds like you wrestled with it a while, but came out on top.
Good work.

I have never seen a puller for the compression nut before.

Thanks for sharing.
-brino

 

[chevydyl]

did you use a BN em to cut the seat for the balls or drill or what? im at a toss up on what to drill those holes with on the pcb, maybe a center drill so that the balls have a seat, also thought of using a BN em with the same radius as the balls. or just drill holes undersize, the balls will be soldered to the pcb along with the wires, or I may mount a jack or connector

 

[rwm]

I made my contact disk from Delrin. I drilled holes for wires in the stainless steel balls and soldered the wire in. The wire is then bedded into a groove in the Delrin plate. The two end wires are connected to terminals where the external wires are attached. The vertical dowel pins prevent the probe from lifting and rotating in the event of over-driving the probe. The flats on the plate perimeter or engagement points for centering screws.

Bob
View attachment 117038

Would this device be useful as an edge finder on the mill? What degree of accuracy can be expected?
R

 

[RJSakowski]

did you use a BN em to cut the seat for the balls or drill or what? im at a toss up on what to drill those holes with on the pcb, maybe a center drill so that the balls have a seat, also thought of using a BN em with the same radius as the balls. or just drill holes undersize, the balls will be soldered to the pcb along with the wires, or I may mount a jack or connector

I used an 1/8" end mill with a pocket routine. I started undersized, checked fit with pin gages, and adjusted the holel diameter accordingly. I went for a light press fit. The depth was .110" and the ball diameter was .1875". I chose to seat to the bottom rather than on the edge of the hole because any variation in the hole diameter would cause a larger variation in seating depth. I put a drop of cyanoacrylate glue in the holes prior to seating them in place.

Bob

 

[RJSakowski]

Would this device be useful as an edge finder on the mill? What degree of accuracy can be expected?
R

R,

They can be used as an edge finder and they will also set the z axis height. They are reputed to not being the greatest for that purpose. Typical repeatability is around .002". I can repeatably hit ,+/-.0001 with a simple edge finder and .0001+/- with a one ten thousandth reading digital dial indicator. Active touch probes are better but they cost considerably more and would be beyond my level of expertise to build.

Bob

 

[chevydyl]

If you want to use a probe as an edge finder for part zeros, you should probably use a real Renishaw $$$, when mines done I'll report my findings on accuracy and repeatability