what makes end mills and drill bits dull quicker than normal

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SE18

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I was just browsing through some of the posts and like the one I saw on how to sharpen end mills. One guy was using a dremel in a video to do it. I didn't want to post the question there so I created this thread just to learn more about what makes drill bits and end mills dull, assuming you are using cutting oils and going at the right speed/feed rates.

I quickly dulled some drill bits going thru some carbon steel even using right speed and smaller bit followed by larger bit. Bedframe are particularly nasty.

I quickly dulled a new end mill while milling some railway spikes and tie plates. I think there was some carbon content in that steel.

Anyway, if anyone has some general info on this topic, much appreciate. Costs money to replace drill bits and end mills and I've tried sharpening them with some success but not complete success.
 
One thing that can certainly take you cutting edge off a tool is letting it dwell and rub against the material your cutting, if your tool isn't making chips get it out of there :))
 
Don B said:
One thing that can certainly take you cutting edge off a tool is letting it dwell and rub against the material your cutting, if your tool isn't making chips get it out of there :))
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A heavy cut, within reason, will be easier than a light cut on a cutting tool too. It will also give you a better surface finish. The cutting edge works best when it can get below the surface and shear the material off.

No matter if you do everything perfectly, eventually, a cutting edge just wears out, and eventually has to be resharpened or replaced. All we can hope to do is extend that time in between sharpening.
 
thanks; this already has been helpful. Guess I wasn't aggressive enough. Now that I think of it perhaps excessive dwell can work harden the piece as well, making things worse?!

I'm glad this forum hosts beginner questions as well as advanced!
 
I'm that dremel guy...
It works, but there are limitations. It will never give a factory grind, but good for touch ups and almost factory sharp.
I also discovered you can sharpen them on a bench grinder (you can also sharpen the ends of reamers) with some time and practice.

As for dulling them in the first place, bed frames are a nasty material. Who knows whats in them. And watch out with railroad spikes, there are two different kinds. One for straightaways (lower carbon content) and one for curves (higher carbon content). You need to machine them with carbide of possible.
 
Thanks, Andre, I'll keep that in mind! Your video was simple but inspiring.
 
SE18 said:
Thanks, Andre, I'll keep that in mind! Your video was simple but inspiring.
Click to expand...

Thank you :))

You'd be amazed what you can do with a few things around the shop. No Bill Gruby's cutter grinder though!
You can also use a small oil stone to tough up the ends and flutes.
 
The main reason mill bits dull faster is because more ot the bit is in contact with the material to pll a chip away from the base materialcooling, running the correct speed and chip loads will go a long way to help this and bedframe metal id ungraded and has hard and soft spots all through the metal so it is really tough to save bits if your using that as a source of material for a project. If you need any help understanding chip load PM me and I will give you my down to earth views on that too. Good luck and hope to hear from you soon

Bob
 
I'll throw this out there for what it's worth - I use a Drill Doctor to touch up and regrind drill bits. It is quick and easy and seems to work very well for general purpose. I'd hate to be without mine now. I can grind a bit by hand and there are a multitude of grinder attachments from very simple to complex - some worse and some probably much better than the Drill Doctor, but for the money, it makes quick work of keeping bits nice and sharp. Obviously that doesn't address keeping them sharp - all good suggestions in the posts so far on that subject. I was always taught to keep drills cool, apply just enough pressure to get a good cut, and to stop trying to drill when they stop cutting.
 
SE18 said:
I was just browsing through some of the posts and like the one I saw on how to sharpen end mills. One guy was using a dremel in a video to do it. I didn't want to post the question there so I created this thread just to learn more about what makes drill bits and end mills dull, assuming you are using cutting oils and going at the right speed/feed rates.

I quickly dulled some drill bits going thru some carbon steel even using right speed and smaller bit followed by larger bit. Bedframe are particularly nasty.

I quickly dulled a new end mill while milling some railway spikes and tie plates. I think there was some carbon content in that steel.

Anyway, if anyone has some general info on this topic, much appreciate. Costs money to replace drill bits and end mills and I've tried sharpening them with some success but not complete success.
Click to expand...

My 2¢ worth: most bedframes are really cruddy material, and even tough to weld sometimes. As for rail spikes and tie plates, I believe that they are
formed and not machined and also worked when the material is still hot.

_Dan
 
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