iDRY Vacuum Kilns

Sponsors:

Center Pins

Started by Frank H., September 05, 2010, 09:28:21 AM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Frank H.

On my old skidder, an s-7 IH, the center pins and bushings were really tired, so I had new bushings turned for it, and before I throw it back together, I was wondering if center pins are hardened?  I was going to make new ones out of cold rolled round stock, but am now wondering if I need something hardened?   

Bobus2003

I'm gonna say that they hardened, For the stress there put under i would think cold rolled would deform

StephenRice

I would bet that they are.  Cold rolled stock should work, but may not last nearly as long as the originals.  If you want to, you can harden them yourself. 

First, make sure that you are using high quality high carbon steel, not some crappy low carbon Chinese stuff.  Then, if you can use tongs to hold the pin from the ends, use a decent sized torch with the largest tip you can find to heat up the metal as evenly as possible until it gets red hot.  Then, drop it into a metal bucket of motor oil (used engine oil is okay).  Make sure to have a plate or something to put over the bucket in case the oil catches on fire in order to smother it. 

That should harden it substantially over its previous state.  Do NOT, however, quench it in water instead of oil.  That will harden it, alright, but too much, so that it could become brittle and possibly crack or break under operational stress.  Also, if you have to have the metal turned down in a lathe in order for it to fit, I would do so before hardening it. 

Then, I would just double check the pin with a micrometer or calipers prior to installation to make sure that the pin had not deformed during the hardening process.  You may put the pin back into a metal lathe and turn it slowly with a dial guage hooked up to make sure that the pin is still straight and not deformed.  Alternatively, a poor man's method would be to lay the pin down on a flat surface (like a laminated table or countertop) and roll it slowly and try to see under it with a flashlight shining towards the bottom of the opposite side.  Or, use some sort of light adhesive like a kids glue stick or spray adhesive applied to the back of a sheet of fine sandpaper to adhere it lightly to a pane of glass laid down on a table.  Then, sand the pin lightly by sliding it across the paper while slowly turning it. (This is how overheated aluminum boat engine heads are often straightened.)  That will show you quickly if the surface of the pin was deformed at all during the hardening process.
"Pure gold fears no fire!" - (Ancient Chinese proverb)  What do you fear?

Autocar

If I was do make them I would have them turned out of brass I would think that would wear alot better plush wouldn't break as fast as hardened steel. But thats just my opinion  ;D
Bill

StephenRice

Quote from: Autocar on September 05, 2010, 11:39:27 AM
If I was do make them I would have them turned out of brass I would think that would wear alot better plush wouldn't break as fast as hardened steel. But thats just my opinion  ;D

Brass is VERY soft compared to steel.  I don't think those would last very long at all.
"Pure gold fears no fire!" - (Ancient Chinese proverb)  What do you fear?

Reddog

Quote from: Frank H. on September 05, 2010, 09:28:21 AM
I was wondering if center pins are hardened? 

For all of the Clarks and Ironmules, Yes.

When remaking them we would use 4140 for both the pin and bushing. Having them both heat treated to a range of 38-42 Rockwell C hardness.


StephenRice

How much does it cost just to buy a new OEM pin versus a shop built pin?
"Pure gold fears no fire!" - (Ancient Chinese proverb)  What do you fear?

Okrafarmer

Quote from: StephenRice on September 05, 2010, 11:41:55 AM
Quote from: Autocar on September 05, 2010, 11:39:27 AM
If I was do make them I would have them turned out of brass I would think that would wear alot better plush wouldn't break as fast as hardened steel. But thats just my opinion  ;D

Brass is VERY soft compared to steel.  I don't think those would last very long at all.

I'm thinking Autocar's just messing with us here. If you think brass is harder than steel, Autocar, you should see all the bent brass keys on my key ring.
He that dwelleth in the secret place of the most High shall abide under the shadow of the Almighty. Psalm 91:1

Operating a 2020 Woodmizer LT35 hydraulic for Upcountry Sawmill, Dacusville, SC

Now selling Logrite tools!

Writing fiction and nonfiction! Check my website.

Autocar

No I wasn't kidding my dad was a tool and die maker ,just about everything I ever rebushed he made out of yellow brass. But Iam no expert just my two cents  :D
Bill

bushmechanic

Autocar has a point where two dissimilar metals will not wear as quick as two similar metals will.But I think that frankh already has the bushings turned and probally out of brass.When I have pins made I get the machinest to use Superior shafting as it is much harder than cold rolled,and cold rolled is pretty soft and will bend rather than break.

StephenRice

Quote from: Autocar on September 05, 2010, 05:32:26 PM
No I wasn't kidding my dad was a tool and die maker ,just about everything I ever rebushed he made out of yellow brass. But Iam no expert just my two cents  :D

Okay, I understand where Autocar is coming from now.

Two similar metals do not wear quicker than dissimilar metals.  Two dissimilar metals WILL corrode much faster through electrolysis than two similar ones.  However, the reason that Autocar's father used brass for bushings and not for shafts or pins like we are discussing here is because, on smaller equipment with lower loads, the softer brass bushing will act as a sacrificial metal, sacrificing itself and wearing more quickly than the harder shaft to save the shaft itself from wear.  That way, most of the wear will be upon the softer bushings.  They can be replaced more cost effectively usually than shafts that ride in them.

However, as we are talking about a pin that is taking a very high load, not even the bushings should be as soft as brass because they would wear out too quickly.  There is a big difference in application here.  In order to prevent wear on a heavy equipment bushing, special hardening is applied both the pins and the bushings and the joint is kept well lubricated with a high tension grease.

Also, because of the extremely soft characteristics of true brass (an alloy of copper + zinc), most bushings are actually made of bronze (an alloy of copper and tin).  It is easy for many to confuse the two.  Bronze is just a little harder than brass.  Brass is more of an ornamental metal or used in low pressure bearings where no sparks can be generated, such as in tools used around explosive gases.
"Pure gold fears no fire!" - (Ancient Chinese proverb)  What do you fear?

Okrafarmer

Copper brass and bronze have many good uses which make them valuable for certain things. They are more easily worked than steel, brass is very easily cast and cut, and copper conducts electricity much better than steel or any other relatively low cost conductor. Copper also has an extremely high heat transfer value, making it good for applications like soldering irons. Although these metals do corrode, they normally don't corrode as quickly as steel especially in salt water. As mentioned, they don't spark when struck. They are not poisonous, like lead. They have a tendency to kill germs, as in drinking water pipes.  They have more uses and applications than I can think of.

He that dwelleth in the secret place of the most High shall abide under the shadow of the Almighty. Psalm 91:1

Operating a 2020 Woodmizer LT35 hydraulic for Upcountry Sawmill, Dacusville, SC

Now selling Logrite tools!

Writing fiction and nonfiction! Check my website.

Stan snider

"Two similar metals do not wear quicker than dissimilar metals"  Lets see now,Do engine bearings need to be steel for really long life? Maybe not.

"not even the bushings should be as soft as brass because they would wear out too quickly." Your opinion of brass is drastically different than mine or you assume a much higher load on a center pin than I. I would use coldroll  if 4140 or stressproof wasn't handy.

John Woodworth

Roddog is correct, you don,t get bushing wear from the metal content, it's lack of lubrication and the stress put on the center pins both side to side and end to end will eventualy hammer out a brass bushing even if it's greased, been there,did it,regreted it even though it was a tempory fix at the time.
Two Garret 21 skidders, Garret 10 skidder, 580 Case Backhoe, Mobile Dimension sawmill, 066, 046 mag, 044, 036mag, 034, 056 mag, 075, 026, lewis winch

Buck

Its a shame you couldnt upgrade to a self centering bearing like you see on backhoes and loaders. 
Respect is earned. Honesty is appreciated. Trust is gained. Loyalty is returned.

Live....like someone left the gate open

Frank H.

The original bushings were brass, and were worn out, but not worn through.  These were on the winch end of the skidder.  There was no bushings on the engine end of the skidder, but the pin did not turn on this end, as the end had a welded tab that kept it from turning.  These holes were worn very little, and I welded lightly on them, then, using a piece of cold roll that was pin size, I kept grinding a little, then test fitting, grinding, test fitting, etc, until they were just able to barely slip through with a little tapping from the hammer.  I guess I am going to see if I can get 1 1/2 inch pins original from somewhere.  I could have new bushings turned from steel, as the only thing they will wear on will be the pin.  Thanks for the information everyone!

madmari

I'm in the process of stripping an old IH S7. I've got the pins and other parts) if you want them.
I know why dogs stick thier head out the car window.

StephenRice

Quote from: Frank H. on September 06, 2010, 03:56:30 PM
The original bushings were brass, and were worn out, but not worn through.  These were on the winch end of the skidder.  There was no bushings on the engine end of the skidder, but the pin did not turn on this end, as the end had a welded tab that kept it from turning.  These holes were worn very little, and I welded lightly on them, then, using a piece of cold roll that was pin size, I kept grinding a little, then test fitting, grinding, test fitting, etc, until they were just able to barely slip through with a little tapping from the hammer.  I guess I am going to see if I can get 1 1/2 inch pins original from somewhere.  I could have new bushings turned from steel, as the only thing they will wear on will be the pin.  Thanks for the information everyone!

If the pins are only 1 1/2" in diameter, perhaps you could find some old worn out hydraulic cylinders with a shaft the same diameter?  If so, then they should be plenty hard enough and you could get more than one pin from them.  Just use a metal cutting bandsaw with lots of lube to cut the shafts off.  Do not use a torch to cut open the cylinders though.  If you were to try to open the cylinders to get all of the shaft, I would wear heavy leather gloves and eye protection and use a drill to drill a hole in the side of the cylinder to relieve any pressure before using a bandsaw to cut open the cylinder.
"Pure gold fears no fire!" - (Ancient Chinese proverb)  What do you fear?

Frank H.

I dug out a hydraulic cylinder shaft from under my workbench, just the right diameter.  Took the two bushings I had made from brass and told the machinist to make them from steel.  Its the same price.  Thank you everyone for your input.

StephenRice

Quote from: Frank H. on September 07, 2010, 04:38:55 PM
I dug out a hydraulic cylinder shaft from under my workbench, just the right diameter.  Took the two bushings I had made from brass and told the machinist to make them from steel.  Its the same price.  Thank you everyone for your input.

Wow!  That was great!  I was thinking you would have to go to a scrap yard when I made that suggestion, but right under your bench?  Providence sure seemed to be working on your side this time, didn't it?  I am glad that you were able to get something to work. Sounds like you may be on the right track now and for an even lower cost.

Let me know how it all works out in the end, okay?
"Pure gold fears no fire!" - (Ancient Chinese proverb)  What do you fear?

Frank H.

Mainly it works out, cause I can't seem to throw stuff away.  Thank you for the suggestion.  I can't wait to get the steel bushings back now and stick it back together. 

John Mc

Quote from: StephenRice on September 05, 2010, 07:47:08 PM
... the softer brass bushing will act as a sacrificial metal, sacrificing itself and wearing more quickly than the harder shaft to save the shaft itself from wear.  That way, most of the wear will be upon the softer bushings.  They can be replaced more cost effectively usually than shafts that ride in them.

The other consideration here is that if the bushings wear instead of the pin, you still have a "full strength" connection. The bushings are captured inside a steel hole. If they wear, the surrounding steel is still there - it may be sloppy, but things are still in place. If the pin wears, you've now got a smaller pin holding things together. That's one of the reasons that you use sacrificial materials in the bushing.
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

StephenRice

Quote from: John Mc on September 10, 2010, 09:55:24 AM
Quote from: StephenRice on September 05, 2010, 07:47:08 PM
... the softer brass bushing will act as a sacrificial metal, sacrificing itself and wearing more quickly than the harder shaft to save the shaft itself from wear.  That way, most of the wear will be upon the softer bushings.  They can be replaced more cost effectively usually than shafts that ride in them.

The other consideration here is that if the bushings wear instead of the pin, you still have a "full strength" connection. The bushings are captured inside a steel hole. If they wear, the surrounding steel is still there - it may be sloppy, but things are still in place. If the pin wears, you've now got a smaller pin holding things together. That's one of the reasons that you use sacrificial materials in the bushing.

I hear you, John.  And, you have a good point.  My main concern was that true brass is really soft and would wear quickly on a high load application like on a center pin.  However, I think there is a good chance that a lot of the supposed "brass" bushings that people use are really bronze or a similar alloy that, while softer than the hardened steel and still sacrificial, are still a lot harder than true brass and would at least last for a while.

Another thing to consider here as well it seems is that he has a whole hydraulic cylinder ram to use for additional center pins if he ever needs to change one again.  That way, he would be less likely to let the center pin wear so badly that it was in danger of breaking.  It would have to be very very worn to be in danger of breaking anyways.  So, if in several years it wears down, then he can just pull out his hydraulic shaft and cut himself a new pin if needed.
"Pure gold fears no fire!" - (Ancient Chinese proverb)  What do you fear?

timberjake

Depending on the machine I have heard of some bushings being replaced with a hard material and making the pins out of a softer steel.  On my old iron mule it is much easier and cheaper to replace or repair a pin than the bushings or bearings.
"Never hire a man who doesn't wear suspenders and smokes.  If he ain't lighting a cigarette he's pullin up his pants."

StephenRice

That makes a lot of sense.  I am not familiar enough with his machine to know which is easier on it.  I would imagine that the center pin would have to come out to replace the bushings, though.
"Pure gold fears no fire!" - (Ancient Chinese proverb)  What do you fear?

John Woodworth

The thing that is being failed to be recognized here is the enviornment these bushings and pins are working under, these machines are not farm tracktors and are built differently and built accordinly to the stress and enviornment they will be working under, mainly water, dirt and whatever else makes irs way to them besides the tremendos stress placed on them under their normal work enviornment, Anybody woy has ever been around equipment in the construction industry known and will tell you what bushings for machinery are to be made from and if you are wearing pins and bushings you had better get a new greese gun or someone to greese for you.

This can be debated forever and you can do whatever you want but cutting corners does not work and can lead to more costlier repairs later. Use the correct material to start with and do your greasing and you wont have to worry about pin and bushing wear, the pins and bushing are not ment to be a sacrifical point to be replaced every few years and if you are you better change your ways.
Two Garret 21 skidders, Garret 10 skidder, 580 Case Backhoe, Mobile Dimension sawmill, 066, 046 mag, 044, 036mag, 034, 056 mag, 075, 026, lewis winch

StephenRice

Quote from: John Woodworth on September 11, 2010, 12:39:02 AM
The thing that is being failed to be recognized here is the enviornment these bushings and pins are working under, these machines are not farm tracktors and are built differently and built accordinly to the stress and enviornment they will be working under, mainly water, dirt and whatever else makes irs way to them besides the tremendos stress placed on them under their normal work enviornment, Anybody woy has ever been around equipment in the construction industry known and will tell you what bushings for machinery are to be made from and if you are wearing pins and bushings you had better get a new greese gun or someone to greese for you.

This can be debated forever and you can do whatever you want but cutting corners does not work and can lead to more costlier repairs later. Use the correct material to start with and do your greasing and you wont have to worry about pin and bushing wear, the pins and bushing are not ment to be a sacrifical point to be replaced every few years and if you are you better change your ways.

Where has this failed to be recognized, John?  Unless I am missing something, I think the issues you brought up are the sorts of things that we have been discussing all along.
"Pure gold fears no fire!" - (Ancient Chinese proverb)  What do you fear?

Thank You Sponsors!