Portable Line Boring

Guy Lautard had a description/rough diagram of such a setup in one of the Machinist's Bedside Readers, the one he described was used for blower housing reboring. I've also seen similar rigs shown for reboring steam locomotive cylinders in situ, basically a keyed rotating bar with two end plates and a drive pulley, the cutter holder slid on the keyed bar and was advanced using a screw with a star wheel on one end. The trick was to get the two end plates lined up in the center of the hole to be bored, then fastened into place so they didn't shift under cutting load. I've seen similar rigs in Model Engineer magazine in the past for boring stuff that was too big to swing in the lathe. So not a new idea. Just something that's not really a commercial product these days.

Stan

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Can you borrow the head from a Bridgeport? Then all you need to do is scab together a mount for the head, a boring bar, and a guide bushing.

I know of a place in Roberts Wisconsin that has (or at least had) a pallet load or two of J heads. When they rebuild a Bridgeport, they always take the J head off and upgrade at least one notch.

Pete Stanaitis

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Ned Simm> >

I know this isn't exactly what you are looking for, but why not have it done for you, since you are probably only going to have it done once? Friends of mine in Rochester, MN run a fab shop/repair welding company where they do exactly what you are talking about on a regular basis. There must be others.

I bet my backhoe is older than your backhoe, and even if it isn't, I bet mine is uglier, Pete Stanaitis

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Ecnerwal wrote:

Not much in Backside of Nowhere, Vermont. I went though a round of trying to get this done a few years back - I was able to get one part done at a local machine shop (the "shoulder" casting from the backhoe, or main pivot, which I could get into the truck and bring to them), but I couldn't find anyone for love nor money to do the matching part on the hoe, so it's clap-trapped together with a new bushing, and key stock + "plastic titanium" (whoop de do, a lousy 18KSI, but it's better than "plastic steel" at 9KSI) to hold the bushing in the oval hole.

I looked at renting a portable line boring rig, and about gagged on that price, too - pretty much the cost of buying one new. I might be able to haul the thing a few hours to have someone work on it, but hauling it costs money, and having it worked on by someone else costs more money.

You can hire folks that will drive in from wherever and do this sort of work for you, but they are big bucks - nice to have on call if your factory is down due to a spun bearing, not so much for your personal backhoe...

Exceeding its actual value in repair costs is quite feasible down that road, and that's not an amount of money I'd like to put towards this project.

How big, how long, how smooth/accurate?

I've cobbled up a few hole-aligning rigs from reamers and drill rod. AFAIK a single-bit boring bar needs controlled feed but you might be able to drive a shell mill with a hand drill.

How about modifying a ridge reamer to be able to go fell depth? Maybe on a threaded feed rod of some kind. Would it even work or would it just go back and forth in the hole?

Self aligning pillow block bearings like:

Shafting that fits bore of bearing.

Cross drill it for a piece of a square HSS lathe bit. Use a square file to square only the corners of the hole so the HSS won't rotate and tap it for a set screw to press the bit out each pass.

Now you have something you can pass though your boss from one side to another. The bearing nearest the boss will support the cutting forces.

If you buy yourself a third similar bearing, you can lock that one to the shaft and use two pieces of threaded rod to pull the bar though. Welding a couple nuts to your work piece to hold the rods and using nuts on the bearing flange will let you create a forced feed of sorts.

Wes

-- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller

My dad use to sleeve Hopto's. He attached a engine cylinder boring bar machine to the side of the boom. Can not remember exactly how, been 40 years. then bored to size.

...

... Looks like the gauntlet has been thrown down. My Sherman is 55-60 years old and looks it. It sits on a Ford NAA golden Jubilee (1953) I think it came with the hoe but can't be sure.

Are you boring out pivots that have wore out? I repaired mine by bolting/welding/clamping a plate orthogonal to the hole. Then using a mag drill to enlarge the hole. You'll need a sacrificial piece to start the drill and then act as a drill bushing. When you're close use an expanding reamer to ream perfectly perpendicular.

An alternate to enlarging is to weld in the pivot point then die grind kinda close before doing the above.

Its not that bad a job to do it this way once you've done one to get the hang of it. I've rebuilt loader, scraper and backhoe pivots this way.

HOWEVER, I did buy a monster radial drill press to make this job easy. Of course, I waited to buy the drill until after I had all my equipment rebuilt.

Karl

---------- Some of the old old time machinist's books [reprints] that Lindsay books sells covers the technique of boring a cylinder in place including line drawings of the set-up. This apparently was for steam engines with the cast iron of the day, so I don't know about the accuracy.

if you have a high speed internet connection and adobe reader installed [free] download take a look at pages 224-230 [247 on reader]

Looks like a perfect RCM project. Lots of moving parts and dangerous as hell. Unka' George [George McDuffee]

------------------------------------------- He that will not apply new remedies, must expect new evils: for Time is the greatest innovator: and if Time, of course, alter things to the worse, and wisdom and counsel shall not alter them to the better, what shall be the end?

Francis Bacon (1561-1626), English philosopher, essayist, statesman. Essays, "Of Innovations" (1597-1625).

I'll try for an omnibus reply.

A few commercial sources for those that think this is just old-tyme stuff.

Yes, I'm (hopefully) redoing some worn out pivots - or eventually I am - I may need to keep abusing them for another summer to get work done, but if I can do a bit at a time and get the worst ones done, it would help.

Wes has the basic idea down, and one can buy exactly that from several places, but I see no reason (thus far) I can't put it together myself for about $1000 less.

Hole size ranges from an inch or so (too small for most commercial versions) up to 3 inches. It may actually be that the pin in the hole is an inch, which means that the bore for the bushings (MIA, or I'd just drive out and replace with new) is bigger - the smallest ones are for the steering linkage, and lord knows what some idiot did, but there's no trace of the bushings on those parts. Of course the loose pins have beat the heck out of the holes. The big ones are either a 2 or 2.5 inch pin with a bushing for another half inch diameter. Those 1/4" thick hardened steel bushings were worn right through and wear continued quite some distance in to the base steel.

George's book link is good, and he's got the right spirit - complicated and dangerous, that's us. The main difference with the newer systems is that the moving cutterhead is generally replaced by moving the whole boring bar through bearings, and setting the bit in a hole in the bar itself. This would seem to allow a thicker bar relative to the size of the hole, and that keeps deflection down. I don't think any of the modern ones try to run a pair of bits, either - getting them matched precisely must have been fun.

The mag drill by itself places a lot of dependence on getting its mounting perfect. At least one of the commercial bars does use a mag drill as its drive (and feed, perhaps...)

Bridgeport head as drive and feed is not a bad idea at all, though I'm willing to trend cruder. It limits to driving from one end, but that is not an issue for backhoe parts as far as I can tell. Some of the commercial bars tout flexible drive options for getting into more difficult situations, but the hoe (and loader bucket) are comparatively accessible, on that basis.

Radial drill press - I've had one on my list since I first learned about them, but haven't gotten one yet. I'll up my shopping effort.

Age and ugliness - Hoe is a ford 4500 industrial TLB, only 40-41 years old. Many joints and pivots are severely ugly (in the more important mechanical sense) through some decades of no grease, at a guess. I might have continued shopping had I known better at the time, but this was also less than half the price of the next contender when I was shopping, and a considerably better machine in the sense that it's a hoe built on a hoe platform (27gpm pump!), not a tiny hoe stuck on an ag tractor. I've certainly made it pay for itself - I've also wished it was bigger (it's a 13 foot hoe) which would have surprised the heck out of me when I was shopping and thought it was a bit intimidating size-wize - that was before I started stumping hardwoods in bony gravel. The paint is a crude job, and is has scars and bad welds (many not mine, some mine - mine are at least not the worst on it), plus some big plates that the previous owner was fond of tossing over cracks. My old welding instructor would have looked at those and yelled stress riser, and I agree, but have not had time to go over them and "fix them right". I do at least try to make my repairs somewhat better designed. The buckets both need work - I have a strip of old road grader edge my brother donated to fix up the severely worn front bucket - the hoe bucket needs teeth - well it needs shanks, too, as the "teeth" it has are actually terribly worn shanks that were dug a long time without teeth on them. Actual hard, sharp teeth would make root breaking about 9 times easier, and that's the key to stumping - but at this point I have most of the stumps out - the road is built, etc. Several cylinders are scarred, and most could stand to be repacked, but time is finite and work to be done is infinite...

What I really need is some sort of tractor restoration nut in dire need of a project, but that sort of thing doesn't happen, or they get terribly upset when you take the newly refurbished, tight hoe out and scratch the paint on it, or get it dirty.

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Info on one version here:

Click on the pdf specs on the right side--has some good drawings.

I've also seen one that used a power head kind of like a handheld electric pipe threader. We had a guy come out and line bore the front axle pivots on a large

4x4 John Deere tractor. Took him a couple of hours, cost around $150.

...

They're using the mag drill the way I did it. I was lucky my biggest holes were two inch. My bucket was similar to the one in the picture. I set up the drill four times - each side of each support. I see this line bore would do it in one shot.

For mounting the mag drill you got to think outside the box sometimes. The vertical pins that swings the whole backhoe were totally shot. There's nothing left to mount to after removing the hoe. So, I mounted the drill to the loader bucket of another tractor, got a pile of blocks and pressed the bucket down on it. This worked really neat cause adjusting the angle was just bucket tilt.

My efforts were REALLY rough. A carbide burr on a die grinder will move a hole over quickly.

Good luck in your project.

Karl

No, I was not aware of that, though most of the web-links that come up on align honing are about engine building and concerned with working to tenths. I do find a few things more in the line of the work I'm doing.

Mind, for most of the stuff I'm doing, if I can press in a bushing without deforming its inside surface too much, I don't have to get too fussy about the bore finish.

And I freely admit (and would welcome enlightenment) that I don't have a great understanding of honing - I've got one of those "three swivelling stones on a spring spider" cylinder hones which I've used to reduce some burrs in a hydraulic cylinder, but those seem to be dependent on having a good round, straight hole to start with.

Something like this:

These look somewhat different, though there's not enough detail to see how the head works in terms of stone movement. I gather it might be somewhat more controlled than the above type.

Honing has changed a lot in the last ten years. It used to be strictly a finishing operation. Now, thanks to the diamond abrasive and non-compliant production-honing techniques developed by Sunnen and others, it can be used to remove remarkable amounts of metal and it can correct out-of-round and out-of-line conditions that were impossible years ago. It's replaced boring in some production applications, combining what used to be two steps into one.

That's all done with fairly hefty stationary machine tools, but the portable honing equipment used by small-time engine rebuilders and so on has benefitted from some of this technology. I knew the subject fairly well six or seven years ago, when I was researching and writing about it, but it's slipped away from me. I don't know where we are today except that it's somewhere better than we were with the compliant-hone tools you're talking about.

Maybe someone involved in engine work or commercial machining applications can fill you in. If not and if you want to know, get back to me and I'll see if there's still anyone at Sunnen I can call.

-- Ed Huntress

--I'm having a little trouble visualizing the problem so take my suggestiong with a grain of salt but could you not blacken the shaft with lampblack and pour a babbit bearing in place?

If you do compress the bore too much, you could try this:

The head needs to be hardened steel, like a large socket, but the shank could be water pipe turned smooth and guided by drilled plates, with enough end clearance to start the cutter. You might be able to anneal the socket, bore it to fit over the pipe, tap some holes to attach it to the center of the pipe, mill teeth, and harden it. Before I bought the surface grinder I sharpened home-made annular cutters on the lathe with a Dremel on the toolpost.

Check the pipe's roundness before you buy it. Some that I've bought recently cleaned up round with a 0.005" cut, other pieces were pushed in along the weld line. You don't have to clean it up all the way around but a dip can throw it off in the 3-jaw and tailstock center.

Weld a socket onto the end and drive it with a flex extension so you don't put a bending force on the shaft.

Keyed shafting is less expensive than drill rod and quite useful for homebrew lashups. I've had good luck with Enco's import keyway broaches and home-made shims and guide bushings.

Jim Wilkins