HSS Lathe Tools chipping, what might cause this?

Mikey has contributed more to this site on the subject of grinding HSS lathe bits for beginners on up than anybody else here. There is a megathread here where you can read several "a-ha!" moments per page from a number of folks new to grinding the hard stuff.

There is quite a difference between different belt sanders, and belt grinders deserve a category of their own. Belt grinders have 4-pulley systems that eliminate belt hop and wander, and they are always equipped with a glass platen or better. They are usually a prized tool by those who build them. All I have to work with is a 2x48 belt sander, same as WobblyHand. The Jet that I've had since the 1980s runs pretty smooth, but the pop-pop-pop from the belt seam (Norton or USA zircon belts only) is enough to discourage me from grinding lathe bits with it. I guess it's different from free-handing a drill bit in that with the drill you only need to make the correct sweeping movement once or twice per side. That's like a blind hog finding some acorns compared to grinding a perfect plane on lathe bit, which would take much more practice.

The reason I advocate fixtures is they give practically perfect results. Machine work is done in a fixture because the work gets located and held precisely, so I look at lathe bits as a machining process rather than an artistic one and seek a way to hold the work while removing metal.

I always welcome discussion, even if it means I have to modify my opinions (oh, darn!). I'm here to learn, and I don't mind a little back and forth when it comes to growing my understanding of it all.
 
I must of read all 35 pages in one sitting. (Now there's more!) Quite the storehouse of knowledge which @mikey and others have shared. Quite the amazing thread.

@pontiac428 , there's nothing wrong with fixtures or jigs. In my case, the simple fixture will be a better, more stable table for the grinder. I'll fly cut the surface to make it smooth. As mentioned previously, I have a some 1/4" plate that I thought I'd start with. Not sure if it should be thicker, but that's what is in the shop junk pile.

Went out to the garage to get my plasma cutter to carve off a piece of plate. No arc. Air solenoid cuts off in 5-6 seconds. Drat. Yet another thing to fix... Put in new consumables, but that didn't make it better. Idiot lights all ok. Pounds head against wall. Guess there's tomorrow to sort it all out.
 
pontiac428 said:
Mikey has contributed more to this site on the subject of grinding HSS lathe bits for beginners on up than anybody else here. There is a megathread here where you can read several "a-ha!" moments per page from a number of folks new to grinding the hard stuff.

There is quite a difference between different belt sanders, and belt grinders deserve a category of their own. Belt grinders have 4-pulley systems that eliminate belt hop and wander, and they are always equipped with a glass platen or better. They are usually a prized tool by those who build them. All I have to work with is a 2x48 belt sander, same as WobblyHand. The Jet that I've had since the 1980s runs pretty smooth, but the pop-pop-pop from the belt seam (Norton or USA zircon belts only) is enough to discourage me from grinding lathe bits with it. I guess it's different from free-handing a drill bit in that with the drill you only need to make the correct sweeping movement once or twice per side. That's like a blind hog finding some acorns compared to grinding a perfect plane on lathe bit, which would take much more practice.

The reason I advocate fixtures is they give practically perfect results. Machine work is done in a fixture because the work gets located and held precisely, so I look at lathe bits as a machining process rather than an artistic one and seek a way to hold the work while removing metal.

I always welcome discussion, even if it means I have to modify my opinions (oh, darn!). I'm here to learn, and I don't mind a little back and forth when it comes to growing my understanding of it all.
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John, we've just had a difference of opinion, that's all, and it was based on our personal experiences. I respect that and I hope I didn't upset you; I did worry about it.

To be honest, I think that most guys in our hobby would rather use a fixture to make grinding lathe tools easier and more reproducible. Heck, I was one of them in the beginning because I was sooo horrible at freehand grinding back then. The reason I took the plunge to grind them freehand is because I discovered that altering the angles found in grinding tables made for a better cutting tool, so much so that no jig or fixture really worked well. Now I know that the key to a lathe tool is its geometry and you must be able to grind that tool so it does what you need it to do. Can't do that with fixtures until you finalize a design; maybe then it might work.

I only have a simple Sears 2 X 42 belt sander BUT I have used a Wilton Square Wheel and a Burr King belt grinder and those are beasts of a different sort. With that said, my sander will grind tools just as well on my humble machine, albeit slower. I only use it with coarse belts to shape nowadays and my go up to an 80 grit belt to take coarse marks off but I don't go much finer anymore so I don't deal with the hump thing much. What my grinder does have is a really good tool rest and a glass platen and those things make all the difference.

I was going to relate a funny story. I bought a new smartphone a few years ago and my son helped me. We were trying to register my fingerprints to turn on the phone but we couldn't do it with my right hand; had to use the left. That right hand has honed so many lathe tools and has been cut and ground down so much that I have no fingerprints left on my fingers - true story! I have learned to turn the phone on with my left hand but only two fingers have any prints left on them; the rest are gone. When I said I paid my dues honing lathe tools, I wasn't joking!
 
WobblyHand said:
Went out to the garage to get my plasma cutter to carve off a piece of plate. No arc. Air solenoid cuts off in 5-6 seconds. Drat. Yet another thing to fix... Put in new consumables, but that didn't make it better. Idiot lights all ok. Pounds head against wall. Guess there's tomorrow to sort it all out.
Click to expand...

The last time I saw that on mine, I had neglected to fully tighten the new electrode.
Pleasantly surprised by the quick fix.....once I found it.
-brino
 
Wish it was as quick fix as you experienced. Swirl ring is broken in 3 pieces. That surprised me. Guess what part I don't have spares of? Off to order one. No make that a couple of them. If I have 3, I'll never need one again! I'll buy the parts. To be honest, I don't even know if this will fix the problem, but it is a step in the right direction.

Save for the tiny holes, it doesn't look that hard to make... My original is ceramic. Replacements seem to be made out of a different material. Almost phenolic looking. Those tiny holes allow a wire that's 0.024" in diameter to pass. So the hole is a little larger. Found a carbide machinable ceramic material called Macor on McMaster, but at the diameter I need, about 5/8", the expense for the raw stock is far more than buying multiples of the finished product. On evilBay, machinable 15mm diameter ceramic isn't cheap either. ($65) Can buy a lifetime supply of swirl rings for that price. And avoid breaking a lot of #73 drills! So the wait begins. A swirl ring from eBay might show next week. I also ordered a bunch of consumables from Aliexpress. If they show up by the end of October, it would be good. That eBay swirl ring should get me going.
 
Been busy. Can't say productive, but you will find out why. So the idea was to make a new steel table surface for the belt sander. Had a piece of scrap for the table that needed trimming. But just couldn't get the plasma cutter working. After 2 days of this, I gave up on it (for now). It doesn't seem like the pilot arc is igniting. (New consumables, etc.) So, found a 14 tpi hacksaw blade and went after the plate. After what seemed like forever, the plate was cut. Stuck in my mill and squared up the edges and fly cut the surface. Came out ok, well, except the holes (in the plate) were in awkward places. Turns out it didn't matter. Made a cardboard template and cut it away in places to fit it to my belt sander.

Milled out the notch for the belt. Then thought to myself, it would be nice if the edge was cut away beneath the table so it could be snugged up close to the belt. Found an angle vise that I had tucked away and mounted it to the mill table. Attempted to tram it. Let's just say it was pseudo-trammed. Aka not very well trammed. Proceeded to cut a 15 degree cut off the edge. Surprisingly worked ok.

Today made some 8-32 transfer screws to locate the plate to the belt sander table. I made them from SHCS's that I chucked in my hand drill and ran against the belt sander. In no time I had four transfer screws. It was simple to transfer the hole locations to the plate. Back to the mill. Drilled out the 4 holes and made my fatal error. Yes, the counter-bores for the SHCS's are on the wrong side. Yes, there is insufficient material to flip it over to counter-bore. I'm unhappy with this result. Guess I need to chalk it up as a practice run... Slaps the side of his head, just why didn't I see that?

So, next time, I'll use a thicker 3/8" piece (no holes!) and try again. I have a metal template now (save for the counter-bores). Can't say I'm that sad. This plate was pretty rough and the holes didn't help much...
PXL_20200915_000822790.jpgPXL_20200915_000936350.jpg
So I just chalk this attempt as a practice run? Hope the second one is a lot nicer!
 
Or instead of using SHCS use flat head screws so you only need a c"sink?
 
Flyinfool said:
Or instead of using SHCS use flat head screws so you only need a c"sink?
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Can try that. The piece is 0.240 thick. I counter-bored 0.170. At this point there's not much to lose. To be honest, I do want a redo. Just think those holes and points on the corners are an accident waiting to happen. I can file them, but not sure how to make them look nice. Will try the countersink and see how I like the basic design. If it's ok, might leave well enough alone. If not, there's always version 2.
 
.......or can you fill 'em full of weld, grind/machine flat and re-drill the holes.

-brino
 
@brino, think I like that idea. Gives me a chance to fire up the welder. Haven't done that in a while. MIG ok? How do I avoid plug welding to the table? Copper strip?
 
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