HSS Lathe Tools chipping, what might cause this?

OK understood. Try then to get as flat as possible on those tool faces, then hone carefully without rounding over the edge. Your bits should be dangerous when you are done :cupcake:
Personally, I don't even hone mine. I just use 'em right off the wheel. ("Free Bird" begins playing)
 
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Granted phones do not take great pics. BUT in all the pics the "chipped" edges look a lot more like built up aluminum than chips.

It could be the pics and the lighting but the ground surfaces look awfully rough. I see almost no evidence of honing which should almost look polished. What grit is your stone?
I have found that the direction of the grind also has an effect on the performance of the cutting edge. When the grind is parallel to the cutting edge the chip has to flow across all that roughness rather than flowing with the "grain".

When you are honing the edges, are you holding the stone in your hand? Are you holding the tool in your hand?
If holding both it is nearly impossible to get a good edge. Best result will be with the stone on a hard steady surface. hold the tool lightly with just thumb and a finger. This will allow the tool to follow the ground edge and not try to change the angles.
 
There was aluminum on the tip, I can't deny that. Maybe what I thought was a chip is aluminum. Under a microscope those two areas look very different. One day I'll figure out how to get photographs through my microscope.

@Flyinfool the new bits are rough. They were sanded with 100 grit ceramic belts. No honing on the new bits. As for the first bit, guilty as charged. Got lazy. I'm working on the new bits now. They take forever to hone. I think I need to get a decent 220 or 320 grit belt so I don't have to work so hard getting the grooves out.

The stone or the tool is on my desk. I usually try to draw the tool across the stone. Unfortunately, after a couple of minutes I sort of relax and the angle shifts. It's hard for me to hold the tool in the in the correct complex angle relative to the stone. My hand wants to twist as it's uncomfortable for me. I'll keep trying. At one point I rubber cemented some silicon carbide sandpaper to a machined surface to use it as a longer hone. To be honest, it worked pretty well to get rid of most of the gouges on the big long surface.
 
It might be cheaper and easier to just get a cheap 6 inch bench grinder. It dont take up much space and is specifically made for the job at hand. A 100 grit grinding wheel leave a much smoother surface that a 100 git belt.

If you are trying to hold the bit at the angle you are trying to hard, let the bit float in your fingers and it will follow the angle that the grinder made. Your fingers are not to hold the bit, just to move it back and forth and give a bit of down force. When you get it right it will just click, till then it is maddening.
 
Definitely will look into both getting a grinder and more likely just putting on a finer belt. Issue with a grinder is making a decent tool rest. Most grinders these days come with sheet metal rests. Those rests are utter junk. That's one of the reasons I went with a belt sander. Still, I'll look at my 8" and see if there is some way to rig up a better tool rest.

Polishing the long face of the tool is easy. Don't have a problem with that. The face is roughly an inch long and 3/8 wide. As you say, just guide it along and it does it's thing. It's the smaller faces that are hard, because the size of the face(s) isn't really big enough to plop down and stay, especially with gravity. The small faces are roughly 0.3 x 0.35 and 0.25 x 0.35. It's just harder for me to keep it flat, especially the top relief face. The bit tail is facing downward so I need to support it, and the back side my fingers are split between the two faces. If I press on the edge between the two faces, it becomes uncomfortable after a short while. Gravity wants to make the tool move away from the surface. It's not impossible, just difficult. I need a better way to do this, just haven't found something that works for me yet.

Don't know, maybe your set up is totally different. So far, mine leaves a lot to be desired.
 
WobblyHand said:
@mikey, flattery will get you nowhere;)
I think I am messing up the edge with my grind, and hosing the edges with honing. I really do have a devil of a time doing the honing. So much so that I've been looking at diamond disks today.
Click to expand...

I wasn't trying to flatter you; just being honest. There are a lot of guys on this site who cannot do what you did.

Honing comes with practice and time. It helps to get the face you're sharpening flat on the stone and lock your wrists, then make a single stroke pulling towards you. Then go back and re-orient the face on the stone and repeat. It doesn't take a lot to hone a face if you do it that way. Try not to put a lot of pressure on the stone; let it do the cutting. When the tool is sharp, the cutting edges will not reflect light; let that be your guide. I hold the stone and tool in my hands; I don't put them on a surface because I cannot feel the tool that way.

My tools will slice paper like a sharp knife. There is no magic to honing, just technique. A coarse diamond stone will take all the grind marks off. A fine stone will flatten the faces quickly. An extra-fine stone will put a near mirror finish on the face. Take your time and learn to do it and it will pay off.
 
WobblyHand said:
On my part, I will try to grind a new square bit from the same lot (no quenching of any sort) and maybe from some cobalt steel (also no quenching).
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It is fine to quench HSS. The cast alloy tools are pretty uncommon and on the order of 10X more expensive than HSS. I thought that perhaps you got a bunch of unknown tool bits with the machine and might be unknowingly dealing with an odd duck.

What are you using for honing? Oil stones, water stones, diamond, ...? How coarse or fine? How big are your hones?

For honing tool bits, I like the folding style diamond hones. Like these:


It usually only takes a few swipes with the fine hone to form the bright, polished, sharp edge. Repeat for the three surfaces that form the cutting corner and polish the nose radius. Only the cutting corner needs honing but the polished portions must go right to the edge. Apply some black marker before polishing to make it easier to check your progress. As you say, it is really difficult to photograph this intersection but pretty easy to check with magnification.

HTH

Craig
 
mikey said:
Try not to put a lot of pressure on the stone
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This, is in fact, what I am struggling with. To have the face flat to the stone (actually diamond coated 2" x 3.25" steel) I seem to need too much pressure. And more pressure makes it hard to pull and maintain contact. If I relax, it works a little better, but then the tool sort of slips from my fingers. If the slip is during a draw stroke, that puts a defect on the surface, (usually rounds an edge) which takes a lot of honing to take it out.
 
WCraig said:
It is fine to quench HSS. The cast alloy tools are pretty uncommon and on the order of 10X more expensive than HSS. I thought that perhaps you got a bunch of unknown tool bits with the machine and might be unknowingly dealing with an odd duck.

What are you using for honing? Oil stones, water stones, diamond, ...? How coarse or fine? How big are your hones?

For honing tool bits, I like the folding style diamond hones. Like these:


It usually only takes a few swipes with the fine hone to form the bright, polished, sharp edge. Repeat for the three surfaces that form the cutting corner and polish the nose radius. Only the cutting corner needs honing but the polished portions must go right to the edge. Apply some black marker before polishing to make it easier to check your progress. As you say, it is really difficult to photograph this intersection but pretty easy to check with magnification.

HTH

Craig
Click to expand...
@WCraig yes, this helps. Great idea on the marker. I'm using diamond hones. Have two different hone sets. One is an Eze-Lap which is easy to hold but has a smaller active area and the other are 2x3 steel cards coated with diamond. The coarsest grit is on the Eze-Lap which is allegedly 150. On the bigger cards the coarsest grip is 325.

Altogether, I have grits ranging from 150, 250, 325, 400, 600, 1200

I need to use a finer belt grit before using the diamonds. The diamond hone's material removal rate is really slow, especially compared to a belt sander. Like well over 1000:1 ratio. It's taken me over 6 hours of honing just to get to what you see below. There are still remnants of the coarse grooves in the tools. First pic is HSS, second Co. Can't get decent lighting on both bits at the same time. You can see the groove near the tip on the HSS bit. On the cobalt, I'd just use finer grits as the defects are away from the cutting edge.
IMG_20200908_093206 hss.jpg
IMG_20200908_093305 co.jpg
Once the grooves are gone, going to finer grit is relatively smooth sailing.

Edit: One thing I am finding is that the stones that I do have aren't really flat. Not potato chipped, but not really flat either. I can tell because the material being removed is from different places depending on what stone I use.
 
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Holding things at weird and uncomfortable angles is certainly an acquired skill. I find that the key is not to be in a hury. Honing can be a bit zen if you let it.

Try a few different ways of holding the bit and the hone. Find what works best for you. I started with putting the hone on the grinder table. Then it's already at 15 degrees. I also rest my hand on the table while honing. My whole hand and arm move the bit. Then I'm using my hand to position and arm to move. It helps me to keep a reference and feels more natural. The smaller faces are definitely the most difficult to keep aligned.

Maybe hold the bit in a vise and use both hands to position the hone? I've never tried that, but it might work for you.

Switching belts didn't work as well for me. I ended up creating facets most of the time. I found it best to grind with 36 grit and just hone out the grinding marks. But maybe it will work better for you.

I'm not sure what would cause the chipping. I have done it, but it was me crashing into steel. I was learning and got the direction wrong. I have some steel that will dull them fast, at least the import M2.
 
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