Models for grinding HSS Lathe Tools

[SonofHarold - Metal Carver]

I started out trying to do this more or less freehand, I remeber see in the old man do it like that, even sharpening 1/8" drill bits in less than a minute freehand. I 'd try it and the bit would not cut wood.... I guess I though I had inherted the skills.
Anyway for anyone interested like I said I just stumbled on this the other evening actually looking for some photos to guide me along. The web sight is Blondiehacks- http://quinndunki.com/blondihacks/?page_id=3338 Actually several good projects for the novis to learn with. Thnx again!

 

[mikey]

Whatever it takes to learn this skill, use it. Just keep in mind that knowing how to grind a tool is only part of the process. You need to understand what the angles that you are grinding actually do, and it is even better if you understand how to alter those angles in order to get the tool to do what you need it to do.

Not to criticize that guy but to make it clear to you, John, about the deficiencies of his tool.

• The angle between the side and end was originally laid out to be 90 degrees; this will not allow the tool to cut into a shoulder and face out the shoulder because the tool will rub. Make yours less than 90 degrees.
• His rake angles are inadequate. He has almost no back rake and I can't tell how much side rake there is but I suspect is isn't much. This tool will cut but it will not cut as well as it could. He needs to fix the rake angles.
• His nose radius is huge. That tool will deflect and not cut accurately with very small depths of cut. It may finish okay, though.

Again, I'm trying to point out that the actual grinding of a tool is only a part of the process. You have to understand WHAT you're grinding and WHY the tool is ground the way it is. So, use what you need to use to understand how the grinding process works but learn to grind the tool so that it cuts the way it needs to cut.

 

[SonofHarold - Metal Carver]

I did last evening revist earlier pages in this thread and get that some different angles ect are nessasary for different materials etc. are needed, but I am doing better than I've done previously, I think tho mostly because I trying to do it more free-hand... maybe.
So if I understand that 10 degree angle obtianed by the angle of the rest to the wheel should be increased? And I did get that a angle beyond 90 was necessary and that is how what I am showing in the pics turned out, but only a little better than 90 tho
But here is what I did this afternoon hope these pics are decent enough. Let me know what you think... I will be down in the shop for a while tho. Thnx

 

[SonofHarold - Metal Carver]

Post away. Anything that helps understanding is a good thing.

I like this video too, and should help. I guess the direction on Blondiehachs were maybe "poor" but still using those and getting repeatable imporved results from what I had done before... I guess what I was doing previoulsy must have been terrible ( at least half the time ) the learning continues...

 

[mikey]

The overall shape is good.

• Your nose radius is a bit on the large side and was ground with the wheel. You will find that a smaller nose radius works better. It is also better to form the radius with a diamond stone so you can control the size and contour of it more precisely.
• It looks like your rake angles are okay but look a bit shallow for a square tool. Both back and side rake are sloping in the right direction so you got it!
• Did you hone this tool?

I think you did great overall. This is a somewhat difficult thing to learn, especially on a bench grinder. Keep at it and the manual skills will come. You are well on your way, John!

 

[mikey]

I like this video too, and should help. I guess the direction on Blondiehachs were maybe "poor" but still using those and getting repeatable imporved results from what I had done before... I guess what I was doing previoulsy must have been terrible ( at least half the time ) the learning continues...

As I said, if those pics and instructions helped you then they are not poor. Use it if it helps you to learn this skill, nothing wrong with that. I pointed out the deficiencies as I saw them so that you would understand that tool geometry is a real thing. Every single feature on the tool is meant to accommodate or mitigate cutting forces in one way or another, and every feature is purposely ground to do a particular thing. For example, if you need to reduce radial forces, you would reduce the size of the nose radius and boost back rake. If your nose radius is huge and you have no back rake then you may wind up increasing radial forces instead. That is why I pointed out the deficiencies of his tool ... you can grind a tool but you have to understand what you're grinding.

I meant no disrespect for that guy or you. Far from it. I have been exactly where you, and he, are. I just happen to be in a place right now where I can see tool geometry and can predict how the tool will cut. Anyone can grind a tool; not everyone knows what they're grinding or why they're grinding it that way. I wish for you to understand the what and why; the how will come in time.

 

[SonofHarold - Metal Carver]

The overall shape is good.

• Your nose radius is a bit on the large side and was ground with the wheel. You will find that a smaller nose radius works better. It is also better to form the radius with a diamond stone so you can control the size and contour of it more precisely.
• It looks like your rake angles are okay but look a bit shallow for a square tool. Both back and side rake are sloping in the right direction so you got it!
• Did you hone this tool?

I think you did great overall. This is a somewhat difficult thing to learn, especially on a bench grinder. Keep at it and the manual skills will come. You are well on your way, John!

I think after a couple of really bad results I got intimidated/discouraged with it in some way.
No on honing, how important is it for just practicing? does it make a big difference? that was done with a 60 grit wheel, just installed a 120 grit today, I also got a print out from page 4 of this thread (no wireless in the shop-yet, and had to cohorse my printering into submission) but am going to be back it for a "bit" shortly. Thanks much!

 

[mikey]

I think after a couple of really bad results I got intimidated/discouraged with it in some way.
No on honing, how important is it for just practicing? does it make a big difference? that was done with a 60 grit wheel, just installed a 120 grit today, I also got a print out from page 4 of this thread (no wireless in the shop-yet, and had to cohorse my printering into submission) but am going to be back it for a "bit" shortly. Thanks much!

Brother, I totally understand the intimidated/discouraged thing, and I OWN the concept of bad results. Nobody, and I do mean nobody, could start off as badly as I did. The difference is that I didn't let that stop me and I sincerely hope that you don't, either. Tool geometry is not intuitive. To understand it, you actually have to put some effort into it. What we are doing here is to try and make that as painless as possible. If you don't understand something, ask and one of the guys or I will try to help.

Yes, honing makes a difference, at least to me. The cutting edge as ground is a bunch of peaks and valleys that will cut corresponding peaks and valleys in your work. Honing makes those defects much smaller and if you hone the tool well, those defects will usually be too small for the unaided eye to see. Moreover, the cutting edges will last longer, much longer. You should hone your tools to remove all visible grinding marks if you can. Use a diamond stone - works faster.

 

[SonofHarold - Metal Carver]

Thanks much! Success breeds more success, The details and nuances will come in time but I think I am over the hurdle after the fairly decent results I had yesterday and today. Couple more issues to address in getting my shop set up and I want to start making things... not just chips, though there is some strange satisfaction for me in watching a tool cut into material on the lathe and watching the chips fall, so to speak. That was a part of what got me interesting in doing this in the first place.
I just noticed sir your in Hawaii and as of today it makes me very jealous... in Western PA we have only had like two days of sunshine since Christmas, and for me moving here just a year ago from Colorado, that's tough been... then imagining you in the warm breezes and blue skies of Hawaii - very jealous indeed! Aloha!

 

[mikey]

Well, its 78 degrees with light tradewinds and sunny. Not a snowflake in sight so no skiing going on but then again, I'm not freezing my butt, either, so there's that. Yup, living in Hawaii is pretty nice. On the downside, we do have hurricanes that try to eat us every year so ...