A Little Bit Different Machine Work

[jackieschmidt]

Beware of the nil ductility material property that can result in brittle failure when steel is exposed to cryogenic temperatures!

Just to clarify your remarks, the loss of ductility in certain metals at extremely low temperatures is only a concern if that material is subjected to extremely low temperatures while in actual use. For instance, a high stressed item such as a vehicle suspension part or frame can loose considerable ductility under use if the vehicle is used in temperatures well below 0 degrees F.

This is a non issue when installing parts that are a interference fit by freezing them in either Dry Ice or Liquid Nitrogen. Once the part warms to it’s normal temperature, the mechanical properties are restored.

At our Shop, and in the Field, we often use liquid nitrogen to install bronze and non metallic bushings rather than pressing them in.

 

[rwj]

Just to clarify your remarks, the loss of ductility in certain metals at extremely low temperatures is only a concern if that material is subjected to extremely low temperatures while in actual use. For instance, a high stressed item such as a vehicle suspension part or frame can loose considerable ductility under use if the vehicle is used in temperatures well below 0 degrees F.

This is a non issue when installing parts that are a interference fit by freezing them in either Dry Ice or Liquid Nitrogen. Once the part warms to it’s normal temperature, the mechanical properties are restored.

At our Shop, and in the Field, we often use liquid nitrogen to install bronze and non metallic bushings rather than pressing them in.

My concerns are not when in-service, but during handling while being installed.

 

[FNSafari]

Soaking them into nitrogen shrinks them a tiny bit? Or what does it do?

Yes, he said they were .001" over hole size. We used to do the same thing when assembling items for the military at Philips Elmet years ago, we would heat the housing and chill the bolts in a mixture of CH3OH and dry ice which got the bolts down to about -78 C. Liquid N is about -195C. Very interesting post and thanks for putting it up.

 

[Chiquita]

Yes, he said they were .001" over hole size. We used to do the same thing when assembling items for the military at Philips Elmet years ago, we would heat the housing and chill the bolts in a mixture of CH3OH and dry ice which got the bolts down to about -78 C. Liquid N is about -195C. Very interesting post and thanks for putting it up.

I didn't catch the part that they were .001 over.

I bet they have to be quick installing them and it has to go in square otherwise they will have a hard time getting it back out.

 

[JPB3]

Jackie, you have great talents !! Nice work.

Pat B.

 

[ridgeway]

I didn't catch the part that they were .001 over.

I bet they have to be quick installing them and it has to go in square otherwise they will have a hard time getting it back out.

Yep...gotta be quick and precise to get em in. I've shrunk lots of interference fit pins with liquid nitrogen and can be very stressful on high $$ critical parts. Either shrink the pin or heat the hole, lol.

 

[skeeljc]

I like the 16 foot tape measure in the bolt threading shot.

 

[Cryhavoc]

wow.....impressive work!.......although....I cringe whenever I see someone operating machinery without safety glasses...I had an industrial accident once but saved my eyesight thanks for the safety glasses....just saying... ...thanks for sharing though!

 

[AlNyhus]

Makes what we do with these rifles seem like childs play!

Thanks for taking the time to document and post these, Jackie. -Al

 

[Medic505]

I'm shocked the guy operating the lathe isn't wearing eye protection.

 

[Steve Blair]

That EMD blower will swallow a 671 blower.

Yes, but they are both Roots superchargers and built similarly. The poster to whom I responded wrote that it "looks like" an automotive blower and he is correct. It also looks like the pictured units incorporate an air to water intercooler, which is rarely used with a Roots blower in cars.

 

[sdean]

Yes, but they are both Roots superchargers and built similarly. The poster to whom I responded wrote that it "looks like" an automotive blower and he is correct. It also looks like the pictured units incorporate an air to water intercooler, which is rarely used with a Roots blower in cars.

Or maybe that's a cooler for the gearbox.

 

[Steve Blair]

@jackieschmidt - Do these engines incorporate an intercooler after the blower?

 

[jackieschmidt]

I'm shocked the guy operating the lathe isn't wearing eye protection.

The guy running the lathe is me. I’ll remember to chew my own ass out tomorrow.

But you are right.

 

[jackieschmidt]

@jackieschmidt - Do these engines incorporate an intercooler after the blower?

These particular 16/645 EMD’s have a charge cooler on the intake side of the blowers. This same engine at 3200 HP has a rather large Turbo Charger In place of the positive displacement blowers.The Turbo Charger has a mechanical connection to the crank shaft with a large sprague unit. The sprague allows the Turbo to spin fast enough to pressurize the cylinders on the two stroke diesel during the start up cycle.
Once exhaust builds enough to power the Turbo, the sprague joint acts as a disconnect from the crank shaft.
if that sprague joint wears out, the engine will not start.

 

[jackieschmidt]

Yep...gotta be quick and precise to get em in. I've shrunk lots of interference fit pins with liquid nitrogen and can be very stressful on high $$ critical parts. Either shrink the pin or heat the hole, lol.

When we heat something to shrink it on, or cool it to slip it in, we mic the part at room temperature, then mic it after heating or cooling to be sure the piece has indeed expanded or shrunk sufficiently to insure trouble free installation.

 

[Fast14riot]

Yes, he said they were .001" over hole size. We used to do the same thing when assembling items for the military at Philips Elmet years ago, we would heat the housing and chill the bolts in a mixture of CH3OH and dry ice which got the bolts down to about -78 C. Liquid N is about -195C. Very interesting post and thanks for putting it up.

I've used acetone (C3H60) and dry ice for poor-mans cryo treatment during quench of some steels, but have not tried methanol and dry ice. C3H60 would get solution temp down around -100F. It was colloquially known as Panther Piss, lol!

Jackie, is this a tractor tug or conventional? Cool stuff to see!

 

[jackieschmidt]

Yep...gotta be quick and precise to get em in. I've shrunk lots of interference fit pins with liquid nitrogen and can be very stressful on high $$ critical parts. Either shrink the pin or heat the hole, lol.

We also shrink a lot of liners on shafts.
The liners are a piece of mild steel tubing with a .050 thick Nickel Chrome Boron coating that is around 65 Rockwell C hardness, and corrosive resistant. Quite a few of our customers use them.

the next time we are shrinking liners onto shafts, I will take some pictures.

Here is a finished shaft with NCB liners.

 

[Steve Blair]

These particular 16/645 EMD’s have a charge cooler on the intake side of the blowers. This same engine at 3200 HP has a rather large Turbo Charger In place of the positive displacement blowers.The Turbo Charger has a mechanical connection to the crank shaft with a large sprague unit. The sprague allows the Turbo to spin fast enough to pressurize the cylinders on the two stroke diesel during the start up cycle.
Once exhaust builds enough to power the Turbo, the sprague joint acts as a disconnect from the crank shaft.
if that sprague joint wears out, the engine will not start.

Thanks, Jackie. Here is an article describing the origins of EMD and Detroit Diesel engines.

Marine Engineering history on www.dieselduck.net

Historical matter relating to Marine Engineers.

www.dieselduck.info

The large number of men exposed to DD engines during the war and subsequent cheap availability greatly contributed to their blowers use by hot rodders.

 

[liljoe]

Looks like another customer getting the shaft.
Nice work Jackie.
Sure would be nice to take a shop tour and see all this stuff in person.
Joe