Weldable Backhoe Pin Bushings

[Willie B]

I,ve wished for many years I could find weld in bushings like I see on lots of light duty machines I.E. backhoes. I've found salvation in DOM (drawn over mandrel) tubing. Typically I can buy it to fit well over my pin. The devil lies in the welding. The physics are simple: heat affected steel wants to expand. If you take a bushing laid in ashes, heat it cherry red, it will expand. As it then cools it shrinks. Size doesn't change by much. In some cases the pin might still fit! If we place the same bushing in a hole in structural steel, and weld it in place the cooler structural steel comparatively stronger will restrict its expansion. Unable to expand, the bushing will be crushed, or more accurately, not expand. Even though it wasn't allowed to expand when heated, it will still shrink, making it too small for your pin. JMC suggests wrapping the pin in shim stock. If you can't fit shim stock, or have access to a lathe to turn down your pin, weld it with a sacrificial pin in the bushing. After it cools the pin won't easily pull out. Don't pound on it! That will "upset" it,(make it larger in diameter), instead, heat it almost cherry red using care not to heat the bushing as hot, like the bushing did it will try to expand, being restricted it can't expand. The molecules will be compressed tightly together, then, as it cools it will shrink. When completely cool it should come out freely.
Preheating the surrounding area may help to some degree. Using a bolt with valve grinding compound from an auto supply store should help to ream it to fit. Though expensive reamers are available.

 

[Tractor Seabee]

I beat my brains out looking for weldable bushing stock. Lots out there if you want to buy 10 or 20 FT. The light finally came on and I looked up shaft couplings on Amazon. There was my solution. Used the ones w/o the keyway and cut to fit. They are heavy wall so do not distort when welding w/ a line up shaft or pin.

Ron

 

[PILOON]

Better still, a reamer of the desired size is the proper method, bit costly but generally all bushings on a given equipment will be the same size.
Over a relatively short period of time I accumulated popular sizes from EBay at reasonable prices. i.e. 3/8.1/2,3/4, 1"etc. I also found a bucket full of heavy DOM stock (like 3/8 wall) that was ideal for bushing stock. I purchased everything they had from 1/2" to 1" id. Has served me well on projects.
All the stock was 4" long and I presumed that was the last piece that was in the lathe chuck left over from fabricating bushing lengths. Luckf find!

 

[BHD]

I have seen pictures of on the big machinery of there reaming out the bushings with a special line boring machine,
Portable Line Boring Machine Tools for Heavy Equipment Bore Repair

or
http://jrsmithwelding.com/featlineboring.htm

I think for the small guy the expandable reamer is about the best for most home projects.

 

[Iplayfarmer]

... I also found a bucket full of heavy DOM stock (like 3/8 wall) that was ideal for bushing stock. I purchased everything they had from 1/2" to 1" id. Has served me well on projects.
All the stock was 4" long and I presumed that was the last piece that was in the lathe chuck left over from fabricating bushing lengths. Luckf find!

Yeah that was a lucky find! Maybe I will be so lucky some day.

There are a lot of machine shops in the area liquidating via auctions lately. My problem is that whenever the good stuff comes up, I'm either out of town or out of money.

 

[dfkrug]

The sources for DOM tubing has expanded greatly since I bought my first chunks
mail-order from Metco Supply back in the mid 90s. My 1.000" reamer was $35
from Enco back then, before I learned to manage my heat distortion better.

QS Components will sell a 2-ft stick of 1.00-inch ID (1.5" OD) DOM for $21, with
$6.50 shipping from Indiana. That makes a lot of bushings. And no wasting gas
driving all over town.