Making bushing & pins for a JD Dozer

[rangerman]

You're welcome, Joe.



I think that bottom flange on the brackets where there seems to be a stub used for accurate installation would be a good reference surface to measure and establish the correct center location of the hole after you have bolted it to a rigid flat and straight surface.
I would assume the mating parts where they were originally bolted to in the machine were also in line, flat and at the same plane of reference, thus a rigid and straight flat surface to bolt them together temporarily during machining would be a sound setup.

Normally, in line boring is done while the parts are still installed to the original component as they should be, but in your case the components are already disassembled so there is a need to duplicate the relative location as accurately as possible by securing them to a flat straight surface.
I don't think the location of the bore has to be exactly dead on center withe reenforcing collar or exactly on the original spot as they were before, although that's surely preferable or desirable.
What's critically important is that the two pivot holes are in line as perfectly as possible, perpendicular/square with bracket movement and free to pivot at the same rotational axis center during operation.

 

[Tony Wells]

If the OEM did not line bore those in-situ , then I'd look for evidence of datum surfaces somewhere on the forging/casting, or burnout.....whatever it is. On the original drawings, those points are specified for fixturing, and if you can see any evidence of a small machined area that is consistent between the two parts, you can set up using them and duplicate the factory machine work.

 

[tazza]

I used 1/4" round tool steel with one set screw and one behind the tool so i could use it to slowly push the tool out to enlarge the hole i was cutting. I could get it accurate within .001 to .002 with that screw.

The hole i was machining stared out as 1 1/4"

Sadly i can't take credit for this setup, a guy off the skidsteer forum i'm on came up with this idea for jobs he did, i just copied them You will note holes in the tubes that hold the bearings, these are to allow you to adjust the tool steel for the cuts.

 

[Cabro32]

Opinion needed. The holes in the brackets that need bored range from 1.5 inches to 2 inches. Do I need to make 2 boring bars or will one 1.250 inch bar be strong enough for all holes?
Joe

 

[DAN_IN_MN]

Re: Making bushing & pins for a JD Dozer

Opinion needed. The holes in the brackets that need bored range from 1.5 inches to 2 inches. Do I need to make 2 boring bars or will one 1.250 inch bar be strong enough for all holes?
Joe

How long is this 1.250 bar going to be? How much per cut are you planning on removing? I suppose if the 1.250 bar flexes you could either take a smaller cut or add an additional bearing at some point. If that's possible. I suppose another variable would be how sharp the cutter is.

- - - Updated - - -

If the OEM did not line bore those in-situ , then I'd look for evidence of datum surfaces somewhere on the forging/casting, or burnout.....whatever it is. On the original drawings, those points are specified for fixturing, and if you can see any evidence of a small machined area that is consistent between the two parts, you can set up using them and duplicate the factory machine work.

If OEM did have a fixture that was used to machine the hole in the bushing, that might explain the offset we're seeing here.

It would be interesting to see how close to coaxial the outside of the bushing to the inside hole that is if we could find any part of the original machined hole. (I hope someone else can make sense of that!)

 

[Bill C.]

Question on blade mounting bracket. The first 2 pictures shows a worn 2" out of round hole which takes a 6" long pin. If you look at the first picture and through the top hole you can see the wear in the bottom hole. I intend to build up the worn area with weld. The top hole is also worn.

Questions:

1. Picture 3 shows a boring head and 3/4" various length boring bars. Is this a suitable tool to
mill the ID of the hole or should something else be used?

2. How do you find the center of a out of round hole or I should ask how should this be setup in a mill so the hole ends up in the original spot?

Thanks
Joe

I think Keith Fenner of Turn Wright Machine Shop had a video of a similar project. I would clean the outside diameter then indicate it to get a rough diameter. Secondly, I would measure the wall thickness to see where the center of the inside diameter used to be. You may need to weld up the low areas then carefully bore out the hole. Good luck

 

[Cabro32]

I finally got back on the crawler project.

Next questions:

Using 4140 steel

I bought a can of Cherry Red and the instructions were slim. It says to heat to cherry red [ wonder where it got it's name ] anyone know about what temperature that would be?

If I have a 2" diameter pin and treat it to the Cherry Red power, about what diameter pin will I end up with?

Joe

 

[Cabro32]

Re: Making bushing & pins for a JD Dozer

Time for an update. It's been a fun learning process so far. I assembled all the parts of the basic frame on the floor and leveled everything.
Made two brackets with a brass bushing to hold the boring bar on the inside of the side frames where the flange bearings wouldn't fit. Centered them in the hole and welded them in. Then tore the frame apart and started welding up the bores. Still have six bores to weld up.
Made up a 1 1/8" boring bar out of 4140 cold roll. I hope to use HSS cutter to smooth out the welds and then switch to carbite. I got a power source off ebay for $70.00.

- - - Updated - - -

Few more pictures.

 

[Cabro32]

Few more pictures.

 

[oldgoaly]

Hi Joe!
Glad to see your are busy! some good ideas, I'll need to do something like that on the 883 bobcat we have.
send me an email sometime oldgoaly on gmail. lost my address with the computer hacks at the repair place.
Take care! tt