Learning how to grind HSS

[Standingbear]

Here is another attempt at grinding HSS bits. Look at the two bits and let me know what you recommend. Last one Mikey recommended I hone more so I did. The finishing bit with .002 pass seems to leave a much better finish with no chatter this time. Still getting some lines that I can’t feel but can see. Is that just the chips not cleaning out properly?

 

[markba633csi]

You're getting there- you can make the tip a little more rounded if you want a smoother finish. A little more side relief would help too.
-Mark
1018 steel is hard to get a smooth finish with, I usually resort to emery cloth+ oil

 

[ttabbal]

What are you cutting? For example, 1018 will show more tool marks than some other materials. There are almost always some marks though.

 

[Standingbear]

What are you cutting? For example, 1018 will show more tool marks than some other materials. There are almost always some marks though.

The steel is just some cold roll mild steel I had left over from another project. I do have a SS barrel I want to try and profile at some point.

 

[mikey]

One reason you may be seeing those fine lines is because the angle at the tip of your tool is rather severe, such that you have no end cutting edge in contact with the work. This leaves just the nose radius to do all the finishing and that is not what a nose radius does well.

I suggest you contact @Z2V and ask him to send you the model tools he has and try to duplicate the shape. You will see the difference when the end cutting edge is there to shear the work surface.

You're doing good. Get those models and try a different shape. Don't give up because it is worth learning to do this.

 

[projectnut]

The general rule of thumb for nose radius on a HSS cutting tool is 1 1/2 times the distance the carriage moves with each revolution of the spindle. As an over the top example if the carriage moves 1/2" for each revolution of the spindle the minimum radius to eliminate tool marks would be 3/4". A more reasonable example would be if the carriage moves .010" per revolution of the spindle the minimum tool radius should be .015"

 

[Standingbear]

Thanks for all the input on this, I could deff see how for a hobby this is a good way to go. I been reading thru allot of past post and the pinned one about grinding HSS. Using my grinder will work but I can see where a 2x72 grinder would be easier. So thanks to this new hobby of learning HSS grinding I now have a new project of making a 2x72 grinder lol. I was wanting one anyways so this just made the decision to start easier. Picked up the steel for the build and going to order some rollers today.

 

[markba633csi]

Back in the 70s when I was in High School metal shop learning to grind a lathe bit on a bench grinder (actually a pedestal grinder) was part of the class. You needed to learn it, if you wanted to use the lathes
-M

 

[Standingbear]

I wish the high school I went to had shop, was way to small for any of that.
I tried again and way better looking cuts so I must be getting closer. First pass took off .02 the came back and split my dial marks which are .002. I know my bit looks butchered but I think the edges are closer to where they need to be. Also been reading mikeys write ups on it and tried turning my lead angle and wow. Made it way smoother turning the point towards the tailstock.

 

[Standingbear]

Without the fuzz on the bit