what makes end mills and drill bits dull quicker than normal

[AlanR]

One thing I did in the hopes of extending the life of milling cutters was to buy a Noga Minicool which I use with Koolmist. The Noga unit is really nice and easy to use, the misting is well worth the trouble.

 

[Hawkeye]

Keep in mind that carbon content isn't the only issue when choosing cutting speeds. The actual hardness of the material will have the biggest effect. I think most charts are assuming that the steel is in its normalized state for machining.

Bed rails have a higher carbon content than mild steel angle iron because you don't want them suddenly buckling under the normal stresses experienced by a bed. For this reason, they are also hardened and tempered. Really nasty to drill or machine, unless you soften them through heat treating first.

If you are trying to machine materials that are hardened, you need to use lower speeds than the charts show for normalized metals. And probably use carbide very carefully instead of HSS.

 

[george wilson]

Back in the 70's,I was walking down the railroad track with a friend. You could actually pull the spikes out with your fingers(though we did not go pulling them out and leaving them out!!) It's a wonder that those mile long heavy coal trains do not instantly spread the rails apart and crash. There was a derailment many years ago. In fact,there have been 2 of them.

 

[SE18]

George, deferred maintenance was legendary in early 70s. I think railways were at their low point. I tried to get a job then with a number of railroads but they weren't hiring so I joined the Marines and spent 20 glorious years. Sometimes wish I'd been a railroader though

 

[Ed T]

FWIW, bed rails are gnarly because they are made from reprocessed railroad rails. This produces a high strength, high carbon, angle iron that is pretty tough stuff. Jersey Shore Steel is one company that produces this material and bed frames are the largest user.

 

[george wilson]

Back in the old days,the Arabs would steal British railroad rails and make them into copies of British rifles and pistols. They did this sitting on dirt floors in caves by hand. I would like to have been there to see how they managed to do that!! And,railroad rails are not the easiest steel to work with.

Of course,in Williamsburg they make flintlocks completely by hand. But those are not as complex as modern fire arms. And,a Webley break top pistol is by no means the simplest pistol to make. It was the only pistol they usually could get their hands on to copy.

 

[Don B]

Back in the old days,the Arabs would steal British railroad rails and make them into copies of British rifles and pistols. They did this sitting on dirt floors in caves by hand. I would like to have been there to see how they managed to do that!!

I would have like to have seen that as well, many years ago I was shown one of these by a Gunsmith, the receiver and barrel where cast as one piece, 303 I think, it may have just been my inexperience but it looked a good copy to me.

 

[Hexhead]

cold rolled and other steels have a mill scale make sure you take a deep enough cut to get under this or it will dull up your end mills

 

[Andre]

cold rolled and other steels have a mill scale make sure you take a deep enough cut to get under this or it will dull up your end mills

Aluminum has this, too. Aluminum oxide is very abrasive, but it's so thin you don't notice it when cutting.