Bucket Cylinder Pin Repair

[SkidRoe]

Here is what I fixed today, for anybody who is interested:
The rod end pin has had some slop in it ever since picked up the machine from my dad. I have been greasing it regularily to try and keep it going, but I knew that I was going to have to do something someday.
The last time I tried to greas it, it wouldn't take any and I has noticed that the pin had started turning in the bobtach rather than the rod eye. I was figuring on having to repair the bobtach as well.
Well, the welding job that I was supposed to do for a guy today was cancelled, and I already had child care for the kids, so I had a look around and figured that this would be a good job to tackle. I popped the pin out and it seemed to be the main culprit for the wear.

Checked the holes in the bobtach with a bore gauge. Other than being worn about 40 thou oversize, they were only about 10 thou out of round. The eye on the cylinder was worn a bit worse, it was close to 90 thou in it's worst spot. Also, much to my disappointment, there is no bushing in the eye on my machine. So, I went at it with the die grinder and was able to get most of the spots to clean up at about 45 thou over.
I went and picked up a piece of 1-1/4" 4140HT (pre-hardened) to make a new 1.045" pin. I gun drilled it for a grease fitting and cross drilled it completely, so that there are now 2 points for the grease to lube the pin. Last of all, I made a new tab to weld to the pin to keep it from rotating and hold it in. The 4140 machines nice with carbide tooling, but I had to re-sharpen my 1/8" drill a few times to get it drilled.

Not an ideal fix, but way better than it was. I will have to pull the cylinder at some point and bore the rod eye for a bushing.
After fixing this joint, I noticed that there is a bit of wear in my lower pins as well. Have to order up some parts to do them.

 

[mahans7]

SR, always enjoy seeing pics of repairs. Never know when we'll have to do something similar. Thanks.

 

[Tazza]

SR, always enjoy seeing pics of repairs. Never know when we'll have to do something similar. Thanks.

Nice repair. Never thought you could drill hardened 4140 without tungsten, even then it's hard.
I had some pins nitrided that i made from 4140, wow is that stuff hard! but only a fee thou in, then it tapers off. The pins have no signs of wear after about 400 hours.

 

[SkidRoe]

Nice repair. Never thought you could drill hardened 4140 without tungsten, even then it's hard.
I had some pins nitrided that i made from 4140, wow is that stuff hard! but only a fee thou in, then it tapers off. The pins have no signs of wear after about 400 hours.

Hopefully this repair will last awhile. This material is through hardened to about 125 ksi tensile (Condition T). You can drill it with regular drill bits, you just need to be able to "feel" when the drill is getting dull, then re sharpen it.

 

[Tazza]

Hopefully this repair will last awhile. This material is through hardened to about 125 ksi tensile (Condition T). You can drill it with regular drill bits, you just need to be able to "feel" when the drill is getting dull, then re sharpen it.

Ah got ya, still hard but not so hard that you can't machine it.

 

[melli]

Hopefully this repair will last awhile. This material is through hardened to about 125 ksi tensile (Condition T). You can drill it with regular drill bits, you just need to be able to "feel" when the drill is getting dull, then re sharpen it.

Nice repair. Now, if you wouldn't mind making up a half dozen pins for my machine...lol

 

[SkidRoe]

Nice repair. Now, if you wouldn't mind making up a half dozen pins for my machine...lol

Hey melli, making parts is half the fun!! You will have to find yourself a good second hand lathe. You would be surprised how often you use it.

 

[melli]

Hey melli, making parts is half the fun!! You will have to find yourself a good second hand lathe. You would be surprised how often you use it.

I wish. Unfortunately, I am in a rental with no garage, and plonking down a lathe in the middle of a rainforest with no power doesn't seem to be a priority right now. Not that it has stopped me before... I cannot wait to get a real house with a massive triple bay garage to put all my toys/tools into it.

 

[Tazza]

Hey melli, making parts is half the fun!! You will have to find yourself a good second hand lathe. You would be surprised how often you use it.

You are spot on there, i'd never be without my lathe. It's amazing just what you can do with it, machining threads on new ram sticks, pins, bushings, ram glands, even cutting key ways in pulleys and gears.

 

[Zorack]

You are spot on there, i'd never be without my lathe. It's amazing just what you can do with it, machining threads on new ram sticks, pins, bushings, ram glands, even cutting key ways in pulleys and gears.

Thumbs up on a nice repair there,SkidRoe

 

[SkidRoe]

Hey melli, making parts is half the fun!! You will have to find yourself a good second hand lathe. You would be surprised how often you use it.

Continued the repair yesterday. After seeing how oblong the hole in the cylinder rod was and how much slop there was in the bobtach pivot pins, I picked up a new set of pins and bought some oilite bronze bushings. As I stated earlier, Bobcat did not see the 440b worthy of putting in bushings on any of the bucket pivots from the factory, so I made my own.
The bobtach came off without too much drama, other that the head of one of the pin bolts had rusted round (thanks to many years of a bovine fecal marinade), so I drilled it out. Cylinder was removed too.

The pivot holes were worn about 1/16"evenly, so rather than boring them, they were reamed with a 1-1/8" reamer. It was easier to do them in the lathe, clamping the bobtach to the tool post and supporting the opposite end with a 1" drill in the tailstock.

Here is an action shot:
http://s851.photobucket.com/albums/...&current=e4ad3cf0860fa4b9399d16c54cbc6920.mp4
I did the cylinder with the same reamer, but set it up in the mill.

The bushings I bought were 1-1/4" OD, so they were turned to provide a 2 thou interference fit to the reamed bores. The installed bushings were then reamed to provide 3 thou of clearance to the pins for grease.
While the bobtach was off, I replaced the slider blocks for the locking pins. This design of bobtach is unique to the 453 and older 4xx and 3xx machines, and has square pins that engage horizontally.
I painted the bobtach while it was off, as it was pretty rusty. Re-assembled it this morning, every thing is snug and tight, just like it should be. Hopefully good for another 20 years.

 

[Tazza]

Continued the repair yesterday. After seeing how oblong the hole in the cylinder rod was and how much slop there was in the bobtach pivot pins, I picked up a new set of pins and bought some oilite bronze bushings. As I stated earlier, Bobcat did not see the 440b worthy of putting in bushings on any of the bucket pivots from the factory, so I made my own.
The bobtach came off without too much drama, other that the head of one of the pin bolts had rusted round (thanks to many years of a bovine fecal marinade), so I drilled it out. Cylinder was removed too.

The pivot holes were worn about 1/16"evenly, so rather than boring them, they were reamed with a 1-1/8" reamer. It was easier to do them in the lathe, clamping the bobtach to the tool post and supporting the opposite end with a 1" drill in the tailstock.


Here is an action shot:
http://s851.photobucket.com/albums/ab73/SkidRoe/?action=view&current=e4ad3cf0860fa4b9399d16c54cbc6920.mp4
I did the cylinder with the same reamer, but set it up in the mill.

The bushings I bought were 1-1/4" OD, so they were turned to provide a 2 thou interference fit to the reamed bores. The installed bushings were then reamed to provide 3 thou of clearance to the pins for grease.
While the bobtach was off, I replaced the slider blocks for the locking pins. This design of bobtach is unique to the 453 and older 4xx and 3xx machines, and has square pins that engage horizontally.
I painted the bobtach while it was off, as it was pretty rusty. Re-assembled it this morning, every thing is snug and tight, just like it should be. Hopefully good for another 20 years.

Awesome job, i cut mine off and made new bushings and pins. My lathe isn't long enough to do that, yet it is a great way to do it! very well thought up indeed.
The way i lined mine us was to install it on the bobtach so the pins held the bosses in line I then welded them into place. Worked pretty well indeed.
I have a 763 that i have the bobtach apart. I made new bosses, i just need to get them installed. I made 4140 bushings to suit it too.

 

[SkidRoe]

Awesome job, i cut mine off and made new bushings and pins. My lathe isn't long enough to do that, yet it is a great way to do it! very well thought up indeed.
The way i lined mine us was to install it on the bobtach so the pins held the bosses in line I then welded them into place. Worked pretty well indeed.
I have a 763 that i have the bobtach apart. I made new bosses, i just need to get them installed. I made 4140 bushings to suit it too.

Hey Tazza, I was thinking of going the weld on route, Bobcat would have you go that way, as they sell new pivot tubes. I was thinking the same as you for lining them up, using the loader frame. But since we have the tools, this seemed easier. This is our big lathe (between Dad and I, we have three), it has a 20" swing and an 8 foot bed, 60" between centres. Full size bobtachs could be done in this machine as well.

 

[mahans7]

Hey Tazza, I was thinking of going the weld on route, Bobcat would have you go that way, as they sell new pivot tubes. I was thinking the same as you for lining them up, using the loader frame. But since we have the tools, this seemed easier. This is our big lathe (between Dad and I, we have three), it has a 20" swing and an 8 foot bed, 60" between centres. Full size bobtachs could be done in this machine as well.

SR, that was an amazing repair. I've been looking at metal lathes and am wondering, what would be a good all-purpose size that would be reasonably priced.

 

[Tazza]

SR, that was an amazing repair. I've been looking at metal lathes and am wondering, what would be a good all-purpose size that would be reasonably priced.

That is a monster of a lathe! Sime times i wish i had one that big, but the one i have gets 99% of the jobs i need doing.
I'm glad my lathe is a bit smaller as i used a big one that a mad mate has, it sure did wear me out fast when i had to wind the handles for a hour or so

 

[HarryN]

That is a monster of a lathe! Sime times i wish i had one that big, but the one i have gets 99% of the jobs i need doing.
I'm glad my lathe is a bit smaller as i used a big one that a mad mate has, it sure did wear me out fast when i had to wind the handles for a hour or so

Really... thanks for the pictures and fix procedure. I think every Bobcat I've ever heard of has this problem or will have it. My pin is getting pretty sloppy too. But, I don't have the tools to do it myself. Now I'll know what it entails someone to do it for me. Would have been so much simpler for Bobcat to put in a replaceable bushing in the first place. As that is certainly a high stress point.

 

[mahans7]

Really... thanks for the pictures and fix procedure. I think every Bobcat I've ever heard of has this problem or will have it. My pin is getting pretty sloppy too. But, I don't have the tools to do it myself. Now I'll know what it entails someone to do it for me. Would have been so much simpler for Bobcat to put in a replaceable bushing in the first place. As that is certainly a high stress point.

Tazza, what size is your lathe. The ability to do 99% of all repairs would work very nicely.

 

[Mikefromcny]

Tazza, what size is your lathe. The ability to do 99% of all repairs would work very nicely.

I have a 9 x 36 atlas from the late 40s. Quick change gears need repair..someday. It does everything I need it to do and then some, would like to find a smallish all manual single phase bridgeport mill though. That would be the best thing ever. Big lathes can often be had pretty cheap, sometimes free or scrap value, I will get one eventually as well. I would also love to find a place that sells like a brass bushing stock...like a real thick brass pipe within a certain rough dimension, so I can turn or bore as needed and keep it on hand as opposed to buying exactly what I need when I need it. I know I can buy regular brass round stock but its a awful waste turning it into a bushing.

 

[mahans7]

I have a 9 x 36 atlas from the late 40s. Quick change gears need repair..someday. It does everything I need it to do and then some, would like to find a smallish all manual single phase bridgeport mill though. That would be the best thing ever. Big lathes can often be had pretty cheap, sometimes free or scrap value, I will get one eventually as well. I would also love to find a place that sells like a brass bushing stock...like a real thick brass pipe within a certain rough dimension, so I can turn or bore as needed and keep it on hand as opposed to buying exactly what I need when I need it. I know I can buy regular brass round stock but its a awful waste turning it into a bushing.

Mike, I recently saw an old Atlas lathe like yours on craigslist for $900 with a bench and lots of accessories. I thought it was too old and never even went and looked at it since I didn't realize it would still be serviceable. I'll be on the lookout for another. Was that price too high?