Alum again

[blackfoxsteam]

After breaking a 2-56 tap in a piece of brass and a 0.063 drill bit in a brass steam engine cyliner passage, I decided to try the alum trick described in posts on this site to clear the steel from the brass parts. It worked fine!

I got a 2 ounce jar of Alum at the grocery store, put it in a cup with ½ cup water, dropped in the brass piece, covered it to reduce evaporation, and left it on the cup warmer in the shop. After 2 days the tap came out easily looking like a black paste. The 0.063 drill bit came out after 5 days.


http://www.homemodelenginemachinist.com/attachment.php?attachmentid=56850&stc=1&d=1345243081


Thanks to the contributors to HMEM, I've learned a lot from you guys.

 

[steamin]

FYI- tap drill charts indicate drill sizes for 75% thread contact. I consider this way to much for my model building. I will go at least 1 drill size and even 2 drill sizes larger for these small threads. I use a good thread cutting fluid for all my tapping. Sometimes I even use some good old fashion spit on the tap. Another good cutting media is Crisco cooking grease. It sticks to the tap and then turn to a fluid from the friction of the tapping process. The Crisco makes for some very bright looking threads in brass and aluminum.

Keep on gettin' it.

Just a few tricks from an ole machinist.

Larry

 

[trumpy81]

Steamin, could you expand a little on the Crisco cooking grease for those of us who are not native to the US.

Is this cooking grease a vegetable oil based grease or something else?

Whatever it is, I'd certainly like to try it. Thanks for the tip

 

[rhitee93]

Wow, I never realized that Crisco didn't make it outside the US. It is a vegetable based replacement for lard.
http://en.wikipedia.org/wiki/Crisco

It's handy stuff and you can even spread it on bread to eat, but tastes about as bad as Vegemite. Just not salty

 

[steamin]

Brian has said it all. Thank you.... My first real job was in a shop across from the high school I was attending. I was running a shaper and asked where the cutting oil supply was. The old man near by said," what cutting oil, go get a can of Crisco over there" as he pointed, so I did. I wondered what has this world come too. So as I applied the white thick grease to the part; I thought what my father would say about what I was doing. But when I turned the shaper on and the tool bit started cutting; low and behold the white thick goop tuned into a nice clear fluid coating the entire surface of the metal. It worked great ! The only thing is, it started to smell like someone was cooking a big batch of french fries. Boy was I ever hungry when I got home !!!!
Larry

 

[Aydelott]

that such a neat trick im sure it will come in handy in the future do you know if it works on bronze, or aluminum bronze

 

[trumpy81]

Wow, I never realized that Crisco didn't make it outside the US. It is a vegetable based replacement for lard.
http://en.wikipedia.org/wiki/Crisco

It's handy stuff and you can even spread it on bread to eat, but tastes about as bad as Vegemite. Just not salty

What's wrong with vegemite?

I live on vegemite and it's had no effect on me :wall:

The trick to vegemite is to spread it super thin on toast with melted butter .... yum. Or you can use it for soups or stews, makes a great flavour enhancer.

Thanks for the link and info BTW. I'll check it out soon, I'm sure we have something here that is similar just a different brand name.

 

[trumpy81]

Brian has said it all. Thank you.... My first real job was in a shop across from the high school I was attending. I was running a shaper and asked where the cutting oil supply was. The old man near by said," what cutting oil, go get a can of Crisco over there" as he pointed, so I did. I wondered what has this world come too. So as I applied the white thick grease to the part; I thought what my father would say about what I was doing. But when I turned the shaper on and the tool bit started cutting; low and behold the white thick goop tuned into a nice clear fluid coating the entire surface of the metal. It worked great ! The only thing is, it started to smell like someone was cooking a big batch of french fries. Boy was I ever hungry when I got home !!!!
Larry

It's funny how we learn about things sometimes, but you have to ask, whatever made someone even think about using this stuff in the first place ... lol

I'll give it a try soon. That probably means I'll have to venture into a supermarket .... ooooohhhhhh scary stuff ... lol

Thanks Larry!!

 

[terrywerm]

Crisco = hydrogenated soybean oil. Used to haul the stuff in hot liquid form, 6500 gallons at a time. Everything was great until I broke down one trip in the winter, out in Wyoming, and the stuff cooled off enough during the several days it took for repairs to set up solid in the tank. Not fun to get it out of there! Melts at 110 to 150 degrees farenheit, depending on the specific blend.