Models for grinding HSS Lathe Tools

[WobblyHand]

for those of you that can't grind HSS worth a damn.
I recommend these 4 videos from Mr. Pete. They will help you grind if you insist you can't

I can grind them ok. Where I fall apart is in honing them. I end up ruining the edges more often than not. I need to make a couple of honing guides. Just can't hold the small faces consistently flat to the honing surfaces. The largest face is easy, it's the smaller ones that I have trouble with. Keep on rocking them and wrecking the edge. Kind of like Sisyphus, almost there and the rock goes tumbling back down the hill

I will watch these videos. Hope to find something that works.

What do you do for small HSS tools, the kind you need to inspect or grind under a microscope? I need to make a grooving tool with a 0.05" radius. Hogging out the material is not that hard, but how to do the fine work in a reasonable amount of time? Seems like one needs a fixture, but I'm having trouble even imagining one. Can you point me in the right direction?

 

[mickri]

I have several different belts for my belt sander. I mostly use an 80 grit to start with. Depending how rough the grind is with the 80 I will sometimes touch it up with a 300 grit. If I want really polished faces I finish off with a leather strop belt. To get the compound angles I tilt the table for one angle and use a combo square for the other angle. That way the tool bit is always flat on the table. No rounding of the edges.

 

[mikey]

I don't grind tools that often but I hone them all the time. You screw up honing when you get in a rush. One bad pass on a diamond stone will take multiple good passes to fix so make each pass count.

Each of us has physical differences. Some of us can hold an angle better on the push stroke and some can pull more steadily; you need to find out which way is best for you and hone that way. Some folks need the stone flat on a bench, some need to have it in their hand; figure out what works for you. Sort out your specific needs and then practice. Honing actually takes time to learn. It is harder to hone well than to grind well. Take your time, make each stroke count.

 

[WobblyHand]

I don't grind tools that often but I hone them all the time. You screw up honing when you get in a rush. One bad pass on a diamond stone will take multiple good passes to fix so make each pass count.

Each of us has physical differences. Some of us can hold an angle better on the push stroke and some can pull more steadily; you need to find out which way is best for you and hone that way. Some folks need the stone flat on a bench, some need to have it in their hand; figure out what works for you. Sort out your specific needs and then practice. Honing actually takes time to learn. It is harder to hone well than to grind well. Take your time, make each stroke count.

If I were to hone any slower it would be 2122 before I finished. It's pretty apparent this is a learned skill that requires tactile feedback. It's very frustrating because I am not getting it. I know it is possible, but don't know exactly what to do, what grits to use and when to change, and how it feels when it is being done right. So I guess, and guess and seem to be getting it wrong every time. Since I cannot feel when it is going right, there's no feedback to me. I can tell if something went bad - it feels a little different, but at that point, I've lost 4 or more hours of work. This is one of the most frustrating things for me.

I may make a fixture to help me maintain honing position, especially for the small faces. Perhaps then I can learn how one can guide the piece and feel the correct cutting/honing action by sheer repetition. Later I may not need the fixture, or maybe I will. I'm avoiding HSS for the most part because I'm ruining the edges and spending weeks on it and getting nowhere. I'd like to learn this skill, but have to say, so far this has been eluding me.

 

[mickri]

There's got to be someone close to you who could watch you and give you some tips to get you up to speed on honing.

If you are pulling towards you there can be a tendency to lift the back end of the tool bit towards the end of the stroke. This will round the edge slightly. Also are you honing up and down or front to back. I don't know if that makes sense. The first picture is front to back. The second picture is up and down. Very easy to round the cutting edge honing up and down. Just the opposite for front to back



Sorry for the poor quality of the pictures. Just some quickies to show the orientation of the hone to the tool bit.

 

[mikey]

It might help to know that the goal of honing a lathe tool is to simply make each of the three faces flat. As for grits, I suggest using three grades of diamond stones - coarse, fine, extra-fine. You are simply trying to create a homogeneous finish for each stone you use. For example, when going from a freshly ground face you use the coarse stone to remove the grinding marks and produce a consistent scratch pattern from the coarse stone. Once you get that consistent pattern across each of the three faces, move to the fine stone and do the same thing, then repeat with the extra-fine.

If you can do this while keeping each face dead flat then the intersections between those faces will be razor sharp. Other than putting a nose radius on the tool, that's about all there is to honing. Not sure how to make it easier than that.

 

[WobblyHand]

while keeping each face dead flat

This is the problem. I am having difficulty doing this.

I understand conceptually what needs to be done, but my execution is flawed.

I've tried drawing towards me, pushing away and probably a few other things. It's ok for a while then acckk, I lift or roll the edge. My hand sort of cramps, it doesn't feel like a cramp, but my hand changes position or something. The smaller the face, the harder it is for me to keep the face flat to the hone. Basically my hand can't tell if the tool face is truly flat to the surface. I can feel if I have ruined the edge, but can't tell that I'm about to ruin it. Been a tough way to learn this skill, since I can't sense when it is ok, or when I am slightly off. Definitely an exercise in frustration.

On the other hand I have no issue with grinding the faces on a belt sander, I generally get that part fine. This is because the tool is on the rest, and I can control 2D with my hand ok if the tool is flat on the table. It's the 3D, or more accurately the dual angle in space that I haven't got the hang of.

 

[mickri]

I put my index finger on top of the side opposite the face I am honing. Fairly easy to feel when the hone is flat on the face. The index finger also applies the pressure to keep the face flat on the hone.

Is your hone fixed to the work bench? Easier to feel if the face is flat against the hone if the hone is fixed in position. That way you can use both hands to guide the tool bit. Another tip. Don't move the tool bit back and forth on the hone. Take a stroke in one direction. Pick the tool bit up and return to your starting point. Then take another stroke. It should only take a couple of long steady strokes to clean up the face.

 

[woodchucker]

I can grind them ok. Where I fall apart is in honing them. I end up ruining the edges more often than not. I need to make a couple of honing guides. Just can't hold the small faces consistently flat to the honing surfaces. The largest face is easy, it's the smaller ones that I have trouble with. Keep on rocking them and wrecking the edge. Kind of like Sisyphus, almost there and the rock goes tumbling back down the hill

I will watch these videos. Hope to find something that works.

What do you do for small HSS tools, the kind you need to inspect or grind under a microscope? I need to make a grooving tool with a 0.05" radius. Hogging out the material is not that hard, but how to do the fine work in a reasonable amount of time? Seems like one needs a fixture, but I'm having trouble even imagining one. Can you point me in the right direction?

I was honing a tool the other day for cutting threads, and it was so sharp I cut myself on my thumb while holding one of the other edges down... I guess it was sharp enough...
I don't fully agree with the left and right turning tools many times. I use them opposite so I can get close to interferences.. I use my left turning for threading next to a shoulder for instance.

 

[WobblyHand]

I put my index finger on top of the side opposite the face I am honing. Fairly easy to feel when the hone is flat on the face. The index finger also applies the pressure to keep the face flat on the hone.

Is your hone fixed to the work bench? Easier to feel if the face is flat against the hone if the hone is fixed in position. That way you can use both hands to guide the tool bit. Another tip. Don't move the tool bit back and forth on the hone. Take a stroke in one direction. Pick the tool bit up and return to your starting point. Then take another stroke. It should only take a couple of long steady strokes to clean up the face.

I do something similar. I can easily tell when the hone is flat on the face when on the big face, but for the top face and the front face, it isn't that easy for me to feel it.

Hone is on a flat machined 3/8" thick aluminum plate. It isn't fixed to the bench, but just sits on it. I just move the tool in one direction, pick it up and return to start. I think I'm basically doing what you have written.

I think I'm not grinding enough with a fine grit on the belt sander. That's forcing me to get a workout honing to get rid of the grooves. I'll try a finer belt for the finishing before moving on to honing. That might be the root issue.