The boom stick pivot and my PC-120 is getting really sloppy. Not for lack of grease but the machine is just getting old. A guy locally wants a set up fee of 800 dollars and then 500 per joint after that. I want to get all three pivot points done at once so its going to be right at two grand to get them done. He says he can weld them first before he align bores them so they end up within factory specs. Heres what I was wondering. Do they really needed to be welded first, or is okay just to get a larger bushing? Because if they dont need to be welded I could get this align boring kit and use it on all my equipment. http://www.americanmachinetools.com/line_boring.htm I already have a mag drill so it would be a little more than two thousand dollars for everything I need except new bushings. I think if I had this set up I would find a lot of uses for it but I want to make sure I dont need the computer controlled welder for it to be a quality repair.
Three advantages to welding bushing bosses then boring them back to spec; 1) you can use bushings right off the shelf, 2) you may find (or have made) oversize bushings, but what about the seals? Don't know a source for oversize hole seals myself, and 3) the welded bushing boss is now going to be harder (more wear resitant) steel since it's weld metal. Just a few thoughts for you to consider, hope it helps.
A friend of mine made a simple one from a through hole 60 to 1 gearbox. he turned some self centering cones and did alot of boring. He bored out some idlers on a Case dozer e was reparing and a small backhoe swing. Im wanting to build one for my 3550 Ford boom. When I worked for Huffman we had a remanned 300 Komatsu. It was an older series blue and yellow. When we unloaded It I greased it and the top crowd/boom pivot never let any grease out of it. Againste my judgement the boss told me he wanted it moving. I started out and the first bucket it sqaulled. We pumped 4 more tubes of grease in it and nothing came out the side. Called the head shop and they told us it had a new bushing job and other things done to it. Just run it they said. Iput in about 14 hours in it and I was off bearing stock piles we had inthe woods out to a loader. I had to knuckle up pretty close and in a swing when I stopped the bucket almost hit the cab corner. When we downed it the pin had gone through the bushing into the boss. The pin was dry but a small spot in the center. We cleaned out the bore good and the problem was that the bore had been gouged at one time with an arc gouger it looked like. THe grease was going to the least resistance and down the stick. When the bore man got there he was reluctant to set it up infront of me. He had a set of home built rigs. I got to talking to hi mand told him I was a machinist at one time and gave him a large landscaping rock he showed me how to set up with the cones. He set it up and then took out the bar. He used a silconbronze alloy wire/rod I cant remember now. He welded the bore up and then put the bar and cutters on it. He bored it back to spe to use the factory bushes. The reason he used silicon bronze was the cut could be made quicker and easier with less chatter and still be hard enough to take a beating. I think he was done in 2 hours.
On the pin bosses I've tried bushings years ago and found the bushings just get beat out and you now have to do a really big welding job. I've seen the silicon bronze used also and it works pretty well. Anymore there are plenty of people with those bore welders. You should be able to call someone else to get a more competitive bid on doing the holes. A PC120 is a small pin diameter. I've not had to prep a machine that small. Do you have to pull the cab and punch a hole in the frame under the cab mount to be able to bore the boom cylinder bases?
Hi John, with my set up i was able to do a pc120 with the cab still on! In fact i can do most with the cab still on!