Sharpening HSS

[parrisw]

Ok, I set up my grinder yesterday with a white alu oxide wheel, though the only grit I could get locally was 60, is that going to be too rough? What should I do after? I've heard of lapping them in? With what kind of stone?

[Fasttrack]

Not "lapping" but "honing".

To get a really keen edge, you can touch the bits up with an oil stone. I normally don't bother. I rough in the bit with a 60 grit aluminum oxide wheel and touch it up on an 80 grit silicon carbide wheel because those are what I have on my grinder

It's not rocket science. The geometry is the most important part - if you can get that down, then you can worry about getting a really good cutting edge with different wheels, etc.


The stone you use for honing can be bought from various places as a sharpening stone, or you can use a piece of a grinding wheel (a fine wheel). I had a 120 grit? (iirc) wheel that was too small to use as a grinding wheel anymore so I broke it into pieces.

[parrisw]

Thanks!! I'll hopefully give it a shot this weekend.

Oh, are there any certain angles to go by for a right hand and left hand bit? I know the 10° on the front, but what about the shape of the cutter? If your looking from the top, I know the approximate shape, but does it have to be exact?

[Dr Stan]

Thanks!! I'll hopefully give it a shot this weekend.

Oh, are there any certain angles to go by for a right hand and left hand bit? I know the 10° on the front, but what about the shape of the cutter? If your looking from the top, I know the approximate shape, but does it have to be exact?

Pick up a copy of "How to Run a Lathe" by South Bend Lathes. It has excellent drawings for many lathe tools. Just keep in mind these were designed for use in a rocker type tool post and you will need to modify the front angle if you are using a drop in (Alloris type) tool post.

[Black_Moons]

the angles are a function of many things.. realise you'll likey want bits with all kinds of front/side angles and nose radiuses so just give it a shot and see how it works, if it sucks you can just adjust the grind.

Lots of people here use hand diamond coated laps of verious grits (150~600) to put the final hone and fine tuning of angles on HSS bits
Also, dremels (mainly the cutoff wheels) can be used for things like roughing in notchs for chipbrakers etc, and diamond coated files can be used to smooth them out and get them to the desired size.

[smiller6912]

I think that this is a good place to start learning about grining a tool.....
http://www.sherline.com/grinding.htm

And, if you scroll down to "TOOLS AND EQUIPMENT
GENERAL PURPOSE CUTTING TOOLS ", there is a good description of tool shapes (geometry) here..........
http://www.americanmachinetools.com/...se_a_lathe.htm

[parrisw]

Ok, just went and made a left hand cutter, angles to 10°, and a top plate relief of 10° as well, I think I need that with the QCTP(aloris style). Tried it right off the grinder on some mystery steel, and seemed to pull a good chip. I'll keep playing.

[MotorradMike]

This guy is worth watching.


Mike

[parrisw]

This guy is worth watching.


Mike

Yes, thanks. I've watched all his vids many times!!

[Black_Moons]

parrisw: Congrats! success.
I mean, if it seems to cut, then it works and its a success. Next see how good a finish you can get on verious materials (realise mild steel almost allways results in a poor finish, aluminum alloys are much easyer most of the time)
Finish is mainly a factor of the nose radius, and how smooth its cutting edge is (as in, no tiny chips from a rough sanding process) (I make small radiuses JUST with the diamond file, no need for the grinder, larger radiuses might be roughed in ever so carefuly on a grinding/sanding tool, a tiny point of contact = large amount of metal removed easily)

Or if you can get your bit to produce short chips insted of long stringy ones.

[parrisw]

parrisw: Congrats! success.
I mean, if it seems to cut, then it works and its a success. Next see how good a finish you can get on verious materials (realise mild steel almost allways results in a poor finish, aluminum alloys are much easyer most of the time)
Finish is mainly a factor of the nose radius, and how smooth its cutting edge is (as in, no tiny chips from a rough sanding process) (I make small radiuses JUST with the diamond file, no need for the grinder, larger radiuses might be roughed in ever so carefuly on a grinding/sanding tool, a tiny point of contact = large amount of metal removed easily)

Or if you can get your bit to produce short chips insted of long stringy ones.

Thanks!! I'll go take a pic of what I did, then you guys can see if I did any good!

[parrisw]

Ok here is a few pics. Criticize me please!!







I think the finish actually came out better then the carbide I was using.

[lakeside53]

Sure it did.. your lathe can't really spin up or take the load carbide needs... You'll be much happier with HSS for much of what you'll do.

[parrisw]

Sure it did.. your lathe can't really spin up or take the load carbide needs... You'll be much happier with HSS for much of what you'll do.

Thanks!! Ya, I should of done it sooner, rookie I guess, LOL. Now just need to make ummm at least another half dozen bits, and more.

[mf205i]

Your bit looks nice but it appears to slope down with negative back rake. It needs to slope upward, positive rake, as it is presented to the work, a hook. Try about 16 degrees for finish on mild steel with a rounded tip or a VERY SMALL flat on the point. Honing your finish bits seems to help control built up edge and improves finish but does little on a rougher. Increase speed for the last light finish pass and use a sulferised cutting oil.
Check out these.
http://www.archive.org/details/textb...vanc00smituoft
http://www.youtube.com/user/mrpete22...72/mArZFFCQDek GREAT VIDIOS
http://www.bbssystem.com/manuals/Lathe-Tutorial.pdf
http://metalwebnews.com/machine-tools/fmt.html
See HTRAL at http://www.wswells.com/index.html
http://www.jjjtrain.com/vms/library.html
https://atiam.train.army.mil/soldier...dlservicespage
http://opensourcemachine.org/node/10
http://www.metalwebnews.org/ftp/machinery-repairman.pdf
http://www.americanmachinetools.com/...se_a_lathe.htm
http://www.sherline.com/grinding.htm
http://www.machinist-guide.com/lathe-threading.html
And don’t forget to download your FREE copy of Machinery’s handbook, Edition 5, at Google books.
http://books.google.com/books?id=VkEYAAAAYAAJ
And if you have an Atlas or Craftsman product, http://www.roseantiquetools.com/id116.html
Have fun, Mike