I have a Case 310 E that has a worn out idler and I'm wondering if anyone has experience rebuilding with weld and then machining back to correct size. I'm not a machinist but have access to a lathe and a bridgeport and some minor skills. I have been searching for a used take off unit for a while now without luck. I appreciate any information or advice. JD49
It used to be very common to rebuild idlers with weld. You just don't want to get it so hot it cooks the bearings or what ever it turns on. You could do it on the machine too and you don't have to machine it flat. Just try to make the welding fairly smooth. Any lumps or high spots you could grind down. Best stick electrodes to use are Stoody Build up, Lincoln Wearshield BU or equivalent. It's a medium hardness and won't mushroom like 7018. https://esab.com/us/nam_en/products...ing/stick-electrodes-smaw/stoody-build-up-lh/ https://ch-delivery.lincolnelectric.com/api/public/content/e0dc0b1ac6bd4ec3801916bd4149ee02?v=c2e1f9b9
Before China started making everything cheap it was common practice to build up idlers and rollers. Welder Dave covered it well. It’s not a precision operation by any means.
There is a shop here that used to run 2 sub-arc automatic idler build up machines 24/7. The idlers turned in a tray filled with water to control the heat input. Of course the idlers were completely disassembled. Fabricated idlers had to have about a 3" plug cut out of the hub to relieve the build up of pressure from welding. You'd see D8 idlers with a couple plugs welded back in indicating they had been built up in the past. Rollers used to be built up too. It's good to have a template to build them up to the proper profile. Not real critical on a small machine like a 310 but you don't want the tracks coming off or the bushings hitting the center portion of the idlers. I've seen idlers partially built up by running a wide (width of the idler surface) zig zag weave with the weaves about an inch apart. This might be a good option if your idlers aren't totally worn out.
Thank you both for the information, this sounds like a job I can handle. I'm going to remove the idler and get it up on a shop table. The opposite side looks like it was replaced recently so I think I can make a sheet metal template from that one and have something to work toward. I also have a repair manual that has dimensions for this part. I'd like to see one of those automatic idler buildup machines at work.
There was a video of a huge floating bucket gold dredge in NZ that mentioned the crew required to run it, a good fraction of them were building up parts full time. A bucket dredge being not that different from dozer track in form and function.
Another way to rebuild them is to get flat bar of the appropriate thickness rolled to the diameter of the idler then weld in place. Saves a lot of welding time and frustration.
A big ol' Lincoln LN- model, flux-cored wire feed welder, is an asset when doing track component rebuilds. I used to have a prehistoric SAE300 Lincoln Bullet welder with CC and an LN-5 wire feeder, and man, could that old girl lay down the weld metal! We built up several sets of Cat D7 track chains with that welder! - plus the idlers. But we bought new rollers, building up rollers is a PIA.
A Case 310 is a small idler. I'm surprised in the video above they aren't cooling the idler. The Stoody brochures on rebuilding crawler undercarriage in the 80's/90's featured one of the large contractors from Alberta, Ledcor.
Have never heard of this. It wouldn't last as long as the weld overlay because it wouldn't have the same type of alloy as the weld filler metal.
It's a cheap-a** way of rebuilding idlers. Some company also made cup-shaped inserts in the 70's, to weld into sprockets, to take out wear. It was an idea that had little merit, and they soon disappeared off the market.
I think I've seen the sprocket cups before.
Thanks for posting that video Delmar, nice piece of equipment. Being a strickly amateur welder I've never seen that welding process, what is the material that's building up and falling away? If a coolant was used would it be water? Seems like the heavy equipment repair and maintenance industry is as interesting as the machines themselves. I'm guessing there are a lot more single purpose machines and tools familiar to you guys.
Submerged arc welding is just a wire feed welding process with a granular flux instead of an inert gas or a flux cored wire. I believe the flux that falls off is reused over and over, and the wire is cheaper. Used in large volume repetitive processes where the savings are big enough to matter. The wire will be fed out of barrels or larger spools. Dave was describing the cooling, I'd guess they just rotated the wheel around for the welding and the bottom went through water for cooling, and would be dry again by the time it got to the top to be welded.
The sub-arc flux turns into hard slag that is easily broken. A lot of sub-arc setups have an air powered vacuum to suck up excess flux so it isn't wasted. The slag can be ground up and reused as long as it's clean. Non critical things like storage tanks will use a 50/50 mix of new and re-ground flux. Things like pressure vessels usually use all new flux or a smaller percentage of re-used flux. The cooling trays I think allow the idlers, axle and bushings to stay intact. It was in 1980 when I was on work experience I saw the rebuilding machines. Fresh water is supplied and the trays overflow into a drain so the water stays cold. There's plenty enough heat that the idlers stay warm and are dry when they come up to the top for welding. Manually building up idlers you could weld circumferentially or side to side. In order to limit heat you could weld a few beads and then skip a section, weld a few more eventually filling in all around the idler.