Seems these were popular in the 70s , I think . I only find them on older surveys , does anyone know what machine or cutter was available that produced these irons .
I see them in certain areas of Illinois. The one area where they were popular they came from a scrap yard and I think some kind of hydraulic cutter was used to cut them up. Picture a something like a giant pair of wire cutters, it smashed the pipe part way flat before it cuts them.
I dont know if this was how all were made but years ago I tried to use a punch/shear to chop off a piece of pipe and ended up with two pinchtops. These machines used to be common place in steel supliers and constuction supply houses. They were used to chop angle iron and solid bar to length for sales. I now wonder if they did not just chop up pipe with em as surveyors needed em.
I find a lot of them here in NE Ohio, typically from the 70's and earlier. I've been told surveyors would get them from the scrap yard back before capped rebar took over. I've found them pinched on both ends and only one end, which supports that lengths of pipe were being "snipped" up.
I used to go to auctions in St. Louis. One such auction had a good bit of survey equipment. Along with the transits and such was a homemade cutter. Someone had mounted a huge bolt cutter on a section of rail and welded a 6 foot bar to the 'free' handle. That sucker cut number 5 rebar with no effort, but it would deform the tops a bit. I imagine using it on a pipe would pinch it...
I don't know for sure, but I always assumed that they were bent over, back and forth, until they broke through fatigue.
That would be the 'refined version'. The one I bought was a hand-held tool with one handle removed. The head was welded into the channel of a section of track laying on its side. The track 'aimed' the short piece for you...
I know they were quite common in older surveys in MI. Except they were always a 1/2" or 3/4" pipe that seemed to have just been hit a few times with a sledge to flatten the one end (gave the helper something to do, while the boss did comps & stuff). Every once in a while you'd find one with a tack in it, if not just shoot the middle.
One thing for sure, if you find a pinched pipe it was likely set by a surveyor. Not saying somebody didn't move it or disturb it, but the lay person won't typically go through all the effort to beat up on a pipe.
A previous surveyor here from the 1950-70's took a long piece of pipe and measured where he wanted to cut it. Then he took the sledge hammer and sort of hit the pipe at an angle with the edge of the face of the sledge. Then flipped over the pipe and did the same on the reserve side. He repeated this until the pipe was sufficiently crimped. Then he held the pipe with both hands and bent it back and forth until it snapped apart. An older guy that I worked with who worked with him told me this. We would find short 4" - 6" lengths of pipe at section corners with the pinched end down over a lower pipe. The guy I worked with said the old guy would do this so he would not have to dig the extra 4" the next time he had to use the corner.
These are common in Minneapolis & St. Paul, MN and in the older suburbs surrounding them. I believe they were cut from scrap pipe with a large hand operated shear. Minnesota has required the irons be marked with the surveyors licence number since 1967. Most Minnesota surveyors use iron or mild steel pipes with plastic caps marked with their number for corner monuments.
That is the way my mentor explained it to me. Jp:good:
I'm guessing an alligator shear
They were (and probably still are) very common at metal-recycling facilities, used to process scrap to the buyers' specifications.
Real quick cuts on pipe (if the crimped ends are acceptable) and easy enough to be accurate to half an inch or so.
As mentioned in Wikipedia, the old ones ran continuously so were a bit scary.
GB
Here in the Piedmont of North Carolina we had a local surveyor who used a lot of pinched tops. His son formally worked with our firm when he was in his late sixty's. He referred to a pinch top as a dove top iron. I ask him why. He said they used to get the irons from a local machine shop that would shear the pipe at lengths his dad wanted. The large shear would pinch the ends shut. The dove tail phrase came from the fact it looked like a birds tail that was flat.
How do pinch tops fare when driven into hard ground? Back before I bought a driving adapter (the steel gizmo that fits into the top of a pipe to limit deformation), I'd sometimes mushroom the end pretty badly in very hard ground. I would think a pinched top would start folding over instead of mushrooming, unless it starts to open and behave more like an unpinched pipe.
Common in CT
I see a ton of these around. Boss remembers getting them cut at scrap yards with a shear.
I ended up with one in my van, forget how it got there. It had both ends pinched and I needed an open end to manipulate a pin that was just set. I hit the end a few times with a hammer to reround it. It was actually under pressure and popped and sprayed out a bit of dirty water and old air. I think it was probably 1970s air. Kinda cool.
Pinch BOTTOM irons
In hard or rocky ground like I have, a pinched top would certainly be a problem.
On the other end, however, I pinch the bottom with a sledge before driving. I think it drives easier, and is harder to pull out. Also, I have a pipe cutter in the truck and a vise on the tailgate to cut pipes to whatever length I need.
Most of them that I found were in good condition, but were about 0.8-1.0 below the surface. I don't know how hard the soil was when they were driven. I've never driven any myself, because of the requirement for the monument to be marked with the surveyor's license or registration number.
