Reclaiming some iron well pipe - stop the screeching!

[Reddinr]

So, I pulled some old steel, galvanized well pipe out of my well last year and replaced it with plastic. I couldn't find my way to throw it away. It was very corroded at the lower end but I have about 100 Ft. of good stuff. I thought it might make good legs or something for some future projects. Anyway, I tossed a piece on my lathe today and ran an insert across a 32" section of it. I ran at 550 RPM and the diameter was about 1.6" when done. The depth of cut was about 23 mils, and the feed rate was 4mils/turn. I just pulled the feed/speed out of the air. The insert was a cheep one from Grizzly from a kit of 6 tools they threw in with the lathe. The finish was really great but the screeching was terrible! I tried cutting oil and that quieted it down but the smoke was worse so I just put on ear plugs and muffs and cut the rest dry. On the plus side, I found that my tail stock was pretty well aligned. I've never cut anything that long before. I got 1.601 at the tailstock end and 1.600 at the headstock end measured with calipers. I was pleasantly surprised. Not bad for a Grizzly that I have not spent much time tuning up. Also, the 1.600" was sheer luck as I wasn't shooting any particular diameter. The stars were aligned or something. The center was about 6 mils bigger because I was not using a follow rest but that I expected from the flexing.

Anyone know what kind of steel might be in galvanized pipe from the early 1990's? Do I need to worry about the fumes if the galv. metal gets hot when cutting? How do I stop the screeching?

On another note, how do I go about working an 8 Foot piece if the stuff? It does fit through my head-stock.

 

[4GSR]

You will always have this problem with thin walled pipe or tube in long lengths.

First thing I would do is slow down the RPM's a bit and see if that helps. Next fill the tube with bird shot by filling the shot into a length of bicycle tube with the ends tied off. I've seen several things done over the years to dampen the harmonics created from cutting.

 

[Reddinr]

I'll give the change of RPM a try first off. Anyone have ideas on how to deal with extra long pieces and how to support the ends? I'm thinking of a heavy stand with bearings to make an extended steady rest type thing. Is that about what is needed?

 

[RJSakowski]

As long as the zinc doesn't start to burn, you should be OK. Zinc doesn't have a high vapor pressure so very little would be present. It vaporizes at 907ºC and will burn in air before that point. The resultant zinc oxide is a fine white powder which can enter the respiratory system. Grinding can create fine particulate matter as well. Welding, flame cutting, or plasma cutting galvanized steel will create large amounts of zinc oxide which can create short term health problems.

Small amounts of zinc are essential to good health. About 10 mg/day are required by adults.

 

[4GSR]

...............
Small amounts of zinc are essential to good health. About 10 mg/day are required by adults.

Talking about words of encouragement. Remembered a family in my younger years that built a BBQ pit out of galvanized pipe and plate salvaged from the local junk yard. Put about 20 people in the hospital for zinc poisoning from the zinc oxide put off and absorbed by the meat.

 

[Reddinr]

I guess I won't be making a BBQ out of the pipe then! Maybe I should skip my zinc supplement today. It reminds me of those sad news stories that seem to get reported about annually where people were carbon monoxide poisoned using the BBQ indoors.

 

[e189552]

Back in my shop days I machined many thin walled tube type parts.
We would tie shop rags into a length that would fit into the tubes, wet the rags and stuff'em in.
On larger parts we would roll cardboard to fit snug & tape it so as not to unwrap.
Anything that dampens the vibration helps.

 

[barnett]

Anyone else ever tried rubber bands, I have used them with some success, seems odd but I wrapped them around a piece of bearing bronze I had to turn and bore. O.D and I.D.

 

[cg285]

Anyone else ever tried rubber bands, I have used them with some success, seems odd but I wrapped them around a piece of bearing bronze I had to turn and bore. O.D and I.D.

fwiw very large rubber bands are used on drums and rotors when turned

 

[Ray C]

As long as the zinc doesn't start to burn, you should be OK. Zinc doesn't have a high vapor pressure so very little would be present. It vaporizes at 907ºC and will burn in air before that point. The resultant zinc oxide is a fine white powder which can enter the respiratory system. Grinding can create fine particulate matter as well. Welding, flame cutting, or plasma cutting galvanized steel will create large amounts of zinc oxide which can create short term health problems.

Small amounts of zinc are essential to good health. About 10 mg/day are required by adults.

RJ, You are correct about this but, I'd also like to mention that a really good dose of zinc vapor from welding can kill you. In low exposures, people get what is called "zinc fever" and it consists of flu-like symptoms for a day or so. Many people have gotten their lungs coated with the vaporized powder which causes severe inflammation -and is very often fatal.

Take extra precautions with welding by pre-grinding it off while wearing a respirator in a ventilated area. On a lathe, I would recommend mist or flood coolant to keep it from getting airborne.

Ray