7018 Vs. 7018AC, Need Layman's translation please:

[Big Wave D]

In a properly equipped shop, what kind of a tip would I be using to get that kind of heat into that tweaked blade? Is my standard cutting tip something that would work or is it to narrow? Does one use more of a rosebud?

I have a small hobby sized O/A torch kit and don't think that with even full tanks, I could do a whole lot of heating before I'd be empty.

Here's similar to what I own. Is it next to worthless???? You can be brutally honest, I can take it.

 

[shade tree welder]

In a properly equipped shop, what kind of a tip would I be using to get that kind of heat into that tweaked blade? Is my standard cutting tip something that would work or is it to narrow? Does one use more of a rosebud?

Rosebud.

I have a small hobby sized O/A torch kit and don't think that with even full tanks, I could do a whole lot of heating before I'd be empty.

Here's similar to what I own. Is it next to worthless???? You can be brutally honest, I can take it.

Those small tanks will not support a rosebud if it is Acetylene.

For any serious work they are useless, I would not even try to heat a bush
hog blade with that small of a unit.

They have their place I was given a set of those by a friend, they are great
when you have a small repair job and you do not have to lug out the big
tanks. But then my O2's are 220 cf and my acetylenes are 140 CF or 340cf
sizes.

You might want to try a MAPP cylinder with air, that might get you close, I
have never tried it but it might work. With MAPP gas you do not have to
worry about pulling gas out of the cylinder too fast, as you do with
acetylene.

 

[Soundguy]

"lugging" a high rpm diesel to save fuel is hard on bearings...

yep.. and what most people forget is that the biggest determiner of fuel usage in a good running diesel is work load or amount of work. if you have x ac to cut.. it's gonna be about the same fuel to cut them at pto speed in y hours, or half pto speed at y+y hours.

also.. most tractors I see put their efficient power band at the pto speed.

takes me 5g diesel to cut my 10ac pasture with my 95hp NH 7610s and 15' batwing.

takes me 5g diesel to cut my 10ac pasture with my 70hp Ford 5000 and 10' 3pt mower.


same fuel.. just takes me nearly 1/3 longer on the 10' mower.

same load..same fuel.

it continually amazes me why people spend multi thousands of dollars to buy a tractor with a rated pto rpm.. and then are afraid to run it at it's own spec...

kinda like buying a 5 tine fork, but being carefull to never use more than 3 tines while stabbing food so as to not overstress it or wear it out...????

soundguy

 

[Shield Arc]

"lugging" a high rpm diesel to save fuel is hard on bearings...

Hey Mark, when you get some time can you explain that to me? Just for my education.
I don't believe in lugging any engine, just would like to know how it's hard on bearings?
Thanks!

 

[rjmack]

I think someone is confused about 500 degrees. If you are talking F then you aren't doing anything useful or harmful. Until you get above 800F there is absolutely no risk. 500c is 930F and you are approaching the point where rapid cooling could make some slight changes. In the annealing process, you want to rapidly cool the specimen by immersion in water or spraying with water to quickly cool from 1300 F or higher to below 800. This softens the steel which you would want to do to a cutting blade. Surface hardening will occur when you surface cool (dipping quickly in and out in oil or water) and then allowing the internal residual heat to heat the surface again then repeat the dipping process till the specimen is cooled below 800F.

you might want to look into the particulars of heat treating tool steels.

the process that was being referred to was the tempering process... also, i believe your understanding of annealing is way off base.

Here's similar to what I own. Is it next to worthless???? You can be brutally honest, I can take it.

i have never used bottles that small, but oxy acetylene welding alone doesn't require all that much volume.

rosebuds do come in different sizes... you can also get quite a bit of preheat out of a cutting torch, but i doubt that it would work for long before you ran out of fuel.

"lugging" a high rpm diesel to save fuel is hard on bearings...

first time i ever heard that. i've lugged every diesel i ever owned, not one ever complained. i think the biggest threat to the bearings in my 2410 was the seat/safety switch that kept abruptly turning the fuel off and then on again all the time. i bet that took more service life out of the bearings (before i disabled it) than all the lugging i will be ever be able to do... and yes, i lug it as much as the hydro will allow.

 

[Soundguy]

there is -0- doubt that lugging an engine is harmfull.

soundguy

 

[dstig1]

Hardening in steel is by carbide precipitation. It essentially comes from "cheating" on the normal phase diagram. If you quench the material fast enough it does not have time to equilibrate like it should. It's been a looong time since I had a metallurgy class, but a few of the basics stick with you...

A couple references.

Carbon steel - Wikipedia, the free encyclopedia
Iron-Iron Carbide Phase Diagram Example

 

[Mark @ Everlast]

Keeps going this thread may have to split...

Lugging an engine puts extra stress on bearings, particularly at a point where the oil pressure produced and bearing surface area may not support the pounding long term. It pounds and beats more slowly, producing piston slap, scuffed cylinders, hot spots, higher temps, extra soot to contaminate the oil, and a whole host of related issues like vibration etc.

 

[rjmack]

Hardening in steel is by carbide precipitation.

i think carbide precipitation is a bit different thing. basically, you get carbide migration resulting clusters of cementite in an otherwise softer material,and that causes cracks, but i don't think that is caused by quenching as much as overheating.

i also read somewhere that chrome plating spring steel causes carbide precipitation, as such this process in not done on a large scale. not exactly sure how that works.

 

[rjmack]

there is -0- doubt that lugging an engine is harmfull.Lugging an engine puts extra stress on bearings, particularly at a point where the oil pressure produced and bearing surface area may not support the pounding long term. It pounds and beats more slowly, producing piston slap, scuffed cylinders, hot spots, higher temps, extra soot to contaminate the oil, and a whole host of related issues like vibration etc.

okay, okay.. i give

i still run my machines as slow as i can and still do the job, just above the range where they start shaking themselves to pieces... with the exception of the backhoe, where i 'pin er' and hang on'.