Some Line Boring Pics

[RayF]

I had that happen on 777 "A" frame pivot bore. I welded it up and after it cooled there was a crack right through the bore down to the bolt hole below it.

They have a habit of doing that. The hole circle is quite close to the edge of the bore. Cat have got a mod where you machine that bore oversize and a hardened sleeve is installed and the bearing fits into that.

 

[rippy154]

Great work. I love all the photos.... I always considered myself a heavy equipment mechanic (the largest excavator the company I work for is a new holland EC600 and our largest loaders are cat 980's) after looking at what you work on I think I may call my self a wrist watch mechanic LOL....... I have done many line bore jobs at work and I feel like I haven't even scratched the surface after looking at the quality of your work keep it up

 

[Nige]

Here's a few pics of the lever I mentioned a few posts up. As soon as I did the precut before welding I knew I was running into a mess. You can see the old weld pattern from a previous bore refurb. What the last machinist did was weld into an alloy steel bore without taking out a cut first. That means that the final sizing cut is right on the fusion zone of the weld. You can see the hard spots in the weld which is not consistent anyway. Unless you have the bearing sitting in a layer of nice ductile weld metal you are asking for cracks to start. Less than half way through with the welder I seen the black welding dust gathering alind a 4 inch crack. Had to stop the bore welder and I used a die grinder with a round burr and ground it out.Went down an inch before I got to the bottom of it.I was able to get in their with low hydrogen electrode and fill it up.

For the life of me I can't understand why people try to skip a step (taking a decent cut to clean up the bore) before hitting the bore with weld. Like Ray says all you end up with is the fusion zone right where you want to machine when you're taking the bore back to final size. Refurbishing a bore is a 3-step process - clean-up cut, weld, & then machine to final size. Get over it .....!!

truckdoctor - Cat A-frame pivot bores are pretty much a no-no for welding. The casting is heat-treated and will (as you discovered) crack if you try to weld it. Boring and sleeving is the way to go but you only get one shot at it.

 

[RayF]

I did find a few old pics to post the other day. But you will have to wait till I finish some house renovations.
Work is dead here at present. My big job this month was 2 45mm bores on a Komatsu skid steer.
Got a pallet load of haul truck tank components today I will start after Easter.

Nige,is right. Prep cut the bore first. I built my business on it. 25 years ago all my competitors ridiculed me for it.Most of them are gone years ago

 

[Nige]

Ray - if work is quiet at the moment might this be a good moment to remind you that you still owe me those sketches for the 994 fully-floating B Pin idea that we were talking about the other week ....??

Also back to the A-frame pin bore. Liquid nitrogen is the ONLY reliable way to install the repair sleeve BTW.

 

[RayF]

Ray - if work is quiet at the moment might this be a good moment to remind you that you still owe me those sketches for the 994 fully-floating B Pin idea that we were talking about the other week ....??

Also back to the A-frame pin bore. Liquid nitrogen is the ONLY reliable way to install the repair sleeve BTW.

I have some drawings sitting on my bench to scan I'm in the middle of house renovations at present and the inside looks like its been bombed and access to the scanner in limited because of the dust.I'll get to it next week.

 

[truckdoctor]

That "A" frame bore was done as per the bosses request. Apparently the management doesn't know about that repair. I started out doing cleanup cuts and then I was pressured out of it for the sake of time. I have since gone back to cleanup cuts after I had a couple of holes peel right at the fusion point. Lesson learned. I've been boring a 993K bucket this week and it has been a thrill. The job is straight forward but everybody at the mine is in a panic because it is not shoveling muck. I came in to help the resident weld/bore man get the job caught up. FYI do not trust the Cat print for the lower cartridge pin measurements, they are way off. This is the second time in a week they have had the bucket off this 993 and it was the result of wrong print measurements and .015 too small bore for a cartridge pin. I'm sure you can guess the rest.

 

[Nige]

There is a document detailing the method of installing a wear sleeve in the A-frame pivot. I'll see if I can find it.

What document are you using for the measurements on the 993..? I may have something that could help you. TBH I didn't even know the 993 used cartridge pins and I agree with you that you have to get the bore spot on or the pin won't last.

 

[RayF]

I've not done a 993K. The 992K's that I have done don't use cartridge pins. Are you saying its the old system like the 992C and D's (and 994) where the split bore clamped onto the pin? If that is the case from memory the bore was machined to the same diameter as the pin. To install, the bore was jacked open,the pin slid through and then the bore was tightened onto the pin. There was a spacer that stopped the bore from being over tightened but most ones I done that had been tossed away. If installed correctly and maintained it seemed to me to be more durable than all the fancy stuff Cat have gone to with the 992's. They don't seem to be able to get that right.
Another thing I do with the bucket bores that take the collet's is cut them 2 to 4 thou interference instead of the 4 thou clearance that Cat specify. They still tap in easily and they never move as they sometimes do when cut to spec.

 

[Nige]

Ray, I've never even seen a 993K in the flesh yet but from what I can see from looking at it on the Cat system it's a bit of a half-breed between the 992K and the 994F. Instead of the box-boom of the 992 it uses a set of regular H-shaped lift arms like a 994, but some of the pins in the bucket control linkage (not sure which ones) are pressed-in cartridge pins like on the latest generation of 992K. I'll see if I can find some more info and e-mail it to you.

Regarding collets I NEVER do what Cat suggest by putting anti-seize both inside & out. I just put it on the inside and they never move - but they DO come out when you want them to. Also worth commenting is that when a collet pin is first assembled and torqued you need to keep beating the bejasus out of the collets until it won't torque any more, then go back once every operating shift thereafter and keep torquing the bolt until it does not move for 2 consecutive days. They always move a bit after first assembly, the only variable is how many days it takes them to stop moving. Then, and only then, do I consider a pin "Tight".

 

[RayF]

I remember the early 994's having trouble with collets turning in the bore.Cats solution was to copy what some line borers were doing and tightened the bore size. Geographe bought out a modification that put hardened sleeves in the bucket and loader frame and just put a standard 950B type pin in. I checked a lot of new 994's for bore alignment for the mod and it was surprising how far they were out.
Collets moving is still a problem in Elphinstone 2900 loaders and similar. The tolerance is 4 thou clearance and I generally tighten that up to size or a bit under.

 

[truckdoctor]

The problem with the 993K pins is there a stepped cartridge center going into a solid arm bore. They are not like the 992 arms. Cat has been having issues for years with the cartridge pins leaking after a short time and they haven't been able to remedy it. I went to bore the loader arms and I was handed five or six different measurements for what the loader arm bores were supposed to be. The worst part was when I was close to starting the finish cut the boss walked in with another set of updated measurements that were different then what I started the job with. Needless to say I was a little upset. These cartridge pins don't take alot of crush. An 8.304"/8.273" cartridge center pin is spec'ed by Cat for .005" crush. I think it's 211/210mm pin size with .01 crush for those who measure in little inches. I cut the finish cut on the smaller bore diameter and then reset the tool and cut in the next step in the bore. The outer part of the cartidge pin that sits in the bucket is dowled around the outer circumference and is held in by a retainer plate. The inner part of the pin that sits in the bucket is a slip fit by the book. We will see if the pins hold up. I know they have two other 993's up there that will need th same thing soon.

 

[RayF]

For the next one either ask them for dimensions that they take responsibility for or have them supply a pin and all the bearings and sleeves that go with it and you can then nut it out yourself. Trouble is Cat will likely have a mod out that will change everything. They went through 3 different arrangements that I know of with the 992G.
At least when they do a redesign they put out a service sheet which gives you the new sizes. With the 992K we could not find sizes on the SIS system for it.

 

[SE-Ia Cowman]

I have a question for you Ray
I was looking at Hoffmans web site the other day and saw that they advertise a flux cored mig wire fore bore welding I was wondering if you ever used it and if so how it worked?
I tryed some dual shield a while back and it worked well in the vertical and not so well in the horizontal because the excess flux puddled at the bottom and snagged the tip as it came around.

 

[RayF]

Yes. I have used a heap of it.Its a very good all positional wire and a lot tougher than mild steel. In small bores say 5 inch and under it cuts nice as the bores can get nice and hot.In a big bore it chills a lot quicker and can be tough to cut. Bores last a lot longer between rebores. I've used it a lot on bores that tend to wear quicker than is acceptable.Bore the hole oversize and put a few runs of the Hofmann stuff in and that will fix the problem.Its a great wire for outdoors when wind is a problem when using shielding gas.
The not so good things are its expensive compared to hard wire and much slower to use. You are only putting in around half the metal with it as its half flux.
Send me a PM or get me on Skype at portablelineboring. for more info

 

[RayF]

I found some old pics of a steam loco that we bored years ago. The cylinders were around 16 inch and so worn that it could not be used because of to much steam getting past the rings. We bored it to 16.25 from memory and they made a new piston and rings to suit.

 

[RayF]

A few more.

 

[OldandWorn]

Now that's just cool Ray. It's funny, not too long ago someone posted a 1930's LMS video showing the rebuild of a steamer. I think they were boring a cylinder and I immediately thought of you.

 

[rare ss]

been there.. bored that eh Ray

 

[RayF]

been there.. bored that eh Ray

Yep