Repairing wallowed out holes with a holesaw

[Welder Dave]

Maybe cutting out a larger hole in the existing bushing to fit a properly sized sleeve for the hardened bushing is a better idea. The hole would still have to be pretty straight to have proper alignment. Another option is to use a spring tension bushing that allows for an out of round hole and up to .006" oversize instead of the hardened bushing. Doing a quick measurement when I was out there last week, I think it is just about the perfect height for my drill press. The drill press weighs about 300lbs. but I could move it with the skid steer and then hand position it. Would take a bunch of time to set it up square but would be worth the trouble. It's slightly fast. I think the slowest speed is 180 rpm but I plan on taking my time. What about using a 2 7/8" hole saw and then carefully sanding/grinding the hole to 3"? I wish they made a 2 15/16" hole saw. They do make a 3" x 2" long flap wheel that could be used for final finishing.

[smithdoor]

Here is a flap wheel 3x2 60 grit to 320 grit.

Dave


https://www.mcmaster.com/4734A932/

Maybe cutting out a larger hole in the existing bushing to fit a properly sized sleeve for the hardened bushing is a better idea. The hole would still have to be pretty straight to have proper alignment. Another option is to use a spring tension bushing that allows for an out of round hole and up to .006" oversize instead of the hardened bushing. Doing a quick measurement when I was out there last week, I think it is just about the perfect height for my drill press. The drill press weighs about 300lbs. but I could move it with the skid steer and then hand position it. Would take a bunch of time to set it up square but would be worth the trouble. It's slightly fast. I think the slowest speed is 180 rpm but I plan on taking my time. What about using a 2 7/8" hole saw and then carefully sanding/grinding the hole to 3"? I wish they made a 2 15/16" hole saw. They do make a 3" x 2" long flap wheel that could be used for final finishing.

[Willie B]

I look at modern backhoes & compare them to a similar one Dave offered. A hoe that size typically has significantly bigger pins, spaced farther apart. Still, wear at that point is significant.
I believe this machine was under engineered. This is why you're faced with a major repair. Avoid cutting away any more meat from the bore than necessary. You might cause catastrophic failure.

[smithdoor]

I agree
If get it before real bad you can put sleeves in now is replaceable.

But up side it makes more work for us .
All the owner of had to due is have line bore and sleeved.

I have rebuild the pin too by adding welding to the worn spot and machining like new.

Dave

I look at modern backhoes & compare them to a similar one Dave offered. A hoe that size typically has significantly bigger pins, spaced farther apart. Still, wear at that point is significant.
I believe this machine was under engineered. This is why you're faced with a major repair. Avoid cutting away any more meat from the bore than necessary. You might cause catastrophic failure.

[Welder Dave]

It was for sure under engineered. The reason the bore got damaged in the first place is because the whole plate including the bushing ripped right off when I had the boom extended and caught some frost. I welded it back up but mistakenly cleaned the bore with a flap disc. I think this is what caused the internal bushing to turn and eventually fall down in the bore. It's hard to see in the pic but I put a grease fitting on the side back towards the machine on an angle. This was so there would be some meat around it. Originally it had a grease fitting on the side where the plate around the bushing is at its thinnest. It was also a 1/8NPT which is almost a 3/8" hole. The plate is only 1 inch so the hole for the grease fitting is taking up about a 1/3 of the plate thickness. The crack started right down the middle of the grease fitting and then followed the outside edge of the factory weld (some slight undercut in spots) around the bushing ripping the entire plate and bushing off. I put a bevel a bevel on the plate where the bushing fits up to it to have more penetration and weld holding the bushing. It was a good repair as the hoe can pull the whole machine around in hard digging. Had the grease fitting not been there it may not have broke. Usually the hyd's. stall out before catastrophic failure but not this time. It also bent the lower mount that is 1 1/2" thick. I had to V that out to get it straight and then weld the V up. I had to start with it bent down and allow the heat from cooling to pull it into place. When it was close I tacked bars to keep it aligned with the top pivot. Putting bars to hold it in place before welding would have resulted in a lot of built up stress in the 1 1/2" plate. That's why it was bent down approx. 30 degree's before welding. I was so relieved when it fit back together. It was a pretty big repair to do in the field. At least now I have a shop to work in. I need to make sure the bore for the hard bushing is pretty accurate. If I can do that it should be good to go. The bottom pivot and bushing and pin look good with very slight wear and still a smooth surface.

I wish it was just the pin that wore. I have one of the original pins that is in good shape.

[smithdoor]

One thing I found was catastrophic failure makes more money 💰 for me.

As long not my equipment.

Dave

It was for sure under engineered. The reason the bore got damaged in the first place is because the whole plate including the bushing ripped right off when I had the boom extended and caught some frost. I welded it back up but mistakenly cleaned the bore with a flap disc. I think this is what caused the internal bushing to turn and eventually fall down in the bore. It's hard to see in the pic but I put a grease fitting on the side back towards the machine on an angle. This was so there would be some meat around it. Originally it had a grease fitting on the side where the plate around the bushing is at its thinnest. It was also a 1/8NPT which is almost a 3/8" hole. The plate is only 1 inch so the hole for the grease fitting is taking up about a 1/3 of the plate thickness. The crack started right down the middle of the grease fitting and then followed the outside edge of the factory weld (some slight undercut in spots) around the bushing ripping the entire plate and bushing off. I put a bevel a bevel on the plate where the bushing fits up to it to have more penetration and weld holding the bushing. It was a good repair as the hoe can pull the whole machine around in hard digging. Had the grease fitting not been there it may not have broke. Usually the hyd's. stall out before catastrophic failure but not this time. It also bent the lower mount that is 1 1/2" thick. I had to V that out to get it straight and then weld the V up. I had to start with it bent down and allow the heat from cooling to pull it into place. When it was close I tacked bars to keep it aligned with the top pivot. Putting bars to hold it in place before welding would have resulted in a lot of built up stress in the 1 1/2" plate. That's why it was bent down approx. 30 degree's before welding. I was so relieved when it fit back together. It was a pretty big repair to do in the field. At least now I have a shop to work in. I need to make sure the bore for the hard bushing is pretty accurate. If I can do that it should be good to go. The bottom pivot and bushing and pin look good with very slight wear and still a smooth surface.

I wish it was just the pin that wore. I have one of the original pins that is in good shape.

[Welder Dave]

I had another idea for repairing the bore that might be easier. I have more time than money and now that I think I've fixed my drill press I thought about making a drill guide I could tack onto the bushing. It wouldn't be a standard drill guide. I thought of marking out a 3" hole on 1/2" thick steel or thicker and then putting a series of small holes around the perimeter. The holes would 1/8" to 3/16" depending on the length of drill bit to drill 2 1/2 to 3" deep. There would be a lot of holes but they would give a good reference point to grind out to the 3" size. I could use a plug wheel in an angle grinder and then use a flap wheel for final finishing. Does this seem like a viable option? Would just tacking a 3" bore plate on top to use as a grinding guide work just as well? Thinking about setting the drill press up I think it could be quite hard to align it perfectly square with the piece on the machine.

[smithdoor]

I like line boring it is faster than setting up in mill or drill press.

I saw in old book where a guy was hand turning a boring bar. Looks simple to me.
Had a old AG equipment with a wallowed out holes. So dup the the drawing but use a 1/2" hand drill.
Clean up to holes and press a sleeve in new hole.

Work great
After that did improve by a mag drill and pillow block bearings.

Dave

I had another idea for repairing the bore that might be easier. I have more time than money and now that I think I've fixed my drill press I thought about making a drill guide I could tack onto the bushing. It wouldn't be a standard drill guide. I thought of marking out a 3" hole on 1/2" thick steel or thicker and then putting a series of small holes around the perimeter. The holes would 1/8" to 3/16" depending on the length of drill bit to drill 2 1/2 to 3" deep. There would be a lot of holes but they would give a good reference point to grind out to the 3" size. I could use a plug wheel in an angle grinder and then use a flap wheel for final finishing. Does this seem like a viable option? Would just tacking a 3" bore plate on top to use as a grinding guide work just as well? Thinking about setting the drill press up I think it could be quite hard to align it perfectly square with the piece on the machine.

[jmm03]

a well equipped automotive machine shop might have a portable line boring machine that could do what you need less expensively than an industrial repair facility, but obviously if you are out in the sticks you might not have that available. Your idea of setting up a guide bushing would possibly work if used in conjunction with a mag base drill. Jim

[smithdoor]

I have use automotive machine shop line boring machine.
It is a very basic machine it does have power feed witch very nice.
FYI There is a big difference in setting for Automotive/trucks engines and earth moving equipment.

Dave

a well equipped automotive machine shop might have a portable line boring machine that could do what you need less expensively than an industrial repair facility, but obviously if you are out in the sticks you might not have that available. Your idea of setting up a guide bushing would possibly work if used in conjunction with a mag base drill. Jim

[Welder Dave]

The machine is out in the boonies. I'll see how level it is (and if it can be adjusted a little) and if I might be able to set my drill press up. I might be able to borrow a mag drill but not 100% sure. If I can get the drill press set up square to the bushing, I think it would work and then use a flap wheel for final finishing to size. It has to be close but not within a thou. or 2. I think .006" would be acceptable.

[smithdoor]

I have found a mag drill very handing in welding.

To bore a hole you at less one pilot bearing or the mag drill will wiggle.

I like machine a sleeve on lathe to fit new hole with old bore I'd.

Dave

The machine is out in the boonies. I'll see how level it is (and if it can be adjusted a little) and if I might be able to set my drill press up. I might be able to borrow a mag drill but not 100% sure. If I can get the drill press set up square to the bushing, I think it would work and then use a flap wheel for final finishing to size. It has to be close but not within a thou. or 2. I think .006" would be acceptable.

[BrooklynBravest]

This repair was done in a manner like you stated, the machine uses DOM welded on and the customer did not want to pay for line boring.

That said, IC weld is gifted with a torch and I could never pull that off.

For a small enough hole, you might get away with a cheap boring bar in a mag drill if it had enough swing.

I think your issue with a 3” hole saw is it needs a tremendous amount of torch. Even cutting wood with one that big can be troublesome it’s just so much surface area.

[smithdoor]

You can use a hole saw like line boring. Simply position a plate with pilot hole in plate on opposite side.
Tack well in place .
Then use hole saw with a long pilot drill.

The pilot drill can be just rod in the hole saw if the plate with the pilot hole is same size.

I have used this way in pass but just remember.

Dave

The machine is out in the boonies. I'll see how level it is (and if it can be adjusted a little) and if I might be able to set my drill press up. I might be able to borrow a mag drill but not 100% sure. If I can get the drill press set up square to the bushing, I think it would work and then use a flap wheel for final finishing to size. It has to be close but not within a thou. or 2. I think .006" would be acceptable.

[Welder Dave]

You can use a hole saw like line boring. Simply position a plate with pilot hole in plate on opposite side.
Tack well in place .
Then use hole saw with a long pilot drill.

The pilot drill can be just rod in the hole saw if the plate with the pilot hole is same size.

I have used this way in pass but just remember.

Dave

You may have a good idea. I was going to use a guide for the outside edge of the hole saw but maybe having a guide for a pilot hole on the bottom could also be used. I intended to set my drill press up square to use with the hole saw and then use a 2 7/8" hole saw. Then I'd use a flap wheel to do the final sizing. I can cut good holes with a circle attachment on a torch but I don't have enough room to to swing a torch 360 deg's.

[SweetMK]

Clamp your drill press to the machine,, put this in place of the new arbor you just bought.

https://www.amazon.com/Precision-Bor...07&sr=8-5&th=1

For $70,, you can get a diameter within a half of a thou,,
The trick will be locating it exactly correct.



Do what BrooklynsFinest just did to some blocks of aluminum,, take small cuts,, it will work.
I have an actual Bridgeport set,, it makes an AMAZING hole,, and the single cutter takes almost no power, so, no grabs will occur,,,

[smithdoor]

I agree 👍
I was going draw of you gest said.
It is form of line boring. By using the hole saw and pilot drill makes it line boring.

Dave

You may have a good idea. I was going to use a guide for the outside edge of the hole saw but maybe having a guide for a pilot hole on the bottom could also be used. I intended to set my drill press up square to use with the hole saw and then use a 2 7/8" hole saw. Then I'd use a flap wheel to do the final sizing. I can cut good holes with a circle attachment on a torch but I don't have enough room to to swing a torch 360 deg's.

[villageblacksmith]

Good evening Welder Dave,
I have read most of the posts in this thread. I have looked at the picture of the worn out part. Is the original bushing one piece? In the photo you posted it looks like there is a groove or a gap about in the middle. It almost looks like a short bushing is inserted in from each side, and welded in. Does that leave a gap for grease? Also, has the pin worn completely through the bushing into the housing?
If the pin has left the housing untouched, or with very minimal wear, here is what I would do.
I would either air arc the old bushings out, or use a torch like has been suggested. Then I would make new bushings, or bushing, and weld it, or them, back in, using the line up techniques that are appropriate for the situation.
Notice I have left line boring of every stripe and hue out of the equation. And on purpose, to be sure. Not that I don't know how, or have line boring equipment. I have done line boring in a number of ways.
I have done much work of this nature. There may be, of course, things about your project that would look different in real life, if I was standing where you are.
But no matter, a I certainly wish you success.

Sent from my E6810 using http://tiny.cc/Forums_reader

[villageblacksmith]

But don't let me discourage anyone from line boring anything they may want to. In fact, I don't mind if you bore it too big and weld it back and then bore it back out a time or three. Try every method suggested in this thread!! It is, according to what I have read here, really quick. And fast! As always, best wishes from the villageblacksmith.

Sent from my E6810 using http://tiny.cc/Forums_reader

[Welder Dave]

Thank you villageblacksmith. The internal hardened bushing was a little too loose in the hole and slipped down causing all the damage to the welded in bushing. It's a single bushing 2" wide. I'm worried about cutting the existing bushing out because there isn't a lot of meat around it. It's also very difficult to get a good overhead weld on the bottom. When I welded the complete upper pivot/bushing on, after it ripped completely off, I put the frame on each side and welded vertical up from the 12 o'clock position. I don't want to take all the hoses off and separate the boom from the swing tower again. It's a lot of messy work to take apart and put back together. I'm pretty sure I can weld the bore up OK. Just need to figure out the most economical way to get the hole to the right size. Have also read where sleeves put in and welded top and bottom will pound out rather quickly compared to solid steel the full thickness. I have a couple questions about building up the hole but I'll start a different thread so it doesn't confuse what I'm asking about.

[Welder Dave]

Clamp your drill press to the machine,, put this in place of the new arbor you just bought.

https://www.amazon.com/Precision-Bor...07&sr=8-5&th=1

For $70,, you can get a diameter within a half of a thou,,
The trick will be locating it exactly correct.



Do what BrooklynsFinest just did to some blocks of aluminum,, take small cuts,, it will work.
I have an actual Bridgeport set,, it makes an AMAZING hole,, and the single cutter takes almost no power, so, no grabs will occur,,,

Read a lot where they say a drill press shouldn't be used for boring and/or won't be rigid enough. Would hate to spend over $120cad. and it won't do a more accurate hole than a hole saw. I need to go 2" deep as well that I think would make accuracy very difficult. Boring a welded steel hole is a lot different than boring aluminum. If I knew for sure it would work I'd go that route.

[BrooklynBravest]

Read a lot where they say a drill press shouldn't be used for boring and/or won't be rigid enough. Would hate to spend over $120cad. and it won't do a more accurate hole than a hole saw. I need to go 2" deep as well that I think would make accuracy very difficult. Boring a welded steel hole is a lot different than boring aluminum. If I knew for sure it would work I'd go that route.

I’d say in a drill chuck, it wouldn’t. But if you directly use a Morse taper i don’t see why it wouldn’t work.

It’s removing barely any material per revolution compared to a hole saw attempting to remove 3” at all times with poor chip evacuation making it even more difficult.

[SweetMK]

Read a lot where they say a drill press shouldn't be used for boring and/or won't be rigid enough. Would hate to spend over $120cad. and it won't do a more accurate hole than a hole saw. I need to go 2" deep as well that I think would make accuracy very difficult. Boring a welded steel hole is a lot different than boring aluminum. If I knew for sure it would work I'd go that route.

As to whether it will work, the only reason anyone would find it not to work is the depth of cut per pass.
If you expect to remove 1/8" per pass,, forget it.
If you spend the time to remove the minimum that carbide will cut, it will do it, and be as accurate as the drill press is.

I have used it to bore steel with a Chinese mill/drill,, with a resultant hole that looks like a new cylinder for a chain saw.

You might need to use high speed cutters rather than carbide,, high speed easily bores with less minimum depth of cut compared to carbide.
My set is OLD,, I doubt that I have any carbide cutters.

Where I used to work, we had two monster jig borers, as they were being removed, I saved some of the cutters, not knowing what they were at the time.
With a little stoning, (a toolmaker showed me how to stone the cutter) the cutting tools do remarkable work.

[smithdoor]

It is very good tool
But in field it is hard to use even in mag drill.

Dave

Clamp your drill press to the machine,, put this in place of the new arbor you just bought.

https://www.amazon.com/Precision-Bor...07&sr=8-5&th=1

For $70,, you can get a diameter within a half of a thou,,
The trick will be locating it exactly correct.



Do what BrooklynsFinest just did to some blocks of aluminum,, take small cuts,, it will work.
I have an actual Bridgeport set,, it makes an AMAZING hole,, and the single cutter takes almost no power, so, no grabs will occur,,,

[Welder Dave]

There's a tool place here that has the head, tooling and MT3 shank. Everything is separate and would cost about $140. I'd certainly go this route if I could get it close a bit undersize. Then I could finish it with a flap wheel. The shank pic. is wrong but the description says MT3 which is what I need. Not worried if I need to feed it real slow. I wonder if a guide plate with the size of hole I want tacked on top would help for starting the cut? I'm going out to work on the drill press today so will see how much run out it has. I do think if I can use the drill press, it is very important to align it as close to perfect as possible. I'll look to see if maybe I can put some leveling bolts in the base so I can make small adjustments. Cutters look to be carbide and I don't need 9 of them. Maybe I could just get a HSS cutter or 2. Do you think HSS would be better for cutting weld build up?

ttps://www.kmstools.com/magnum-2-quot-adjustable-boring-head.html

https://www.kmstools.com/magnum-9pc-...g-bar-set.html

https://www.kmstools.com/magnum-2-qu...ead-shank.html