View Full Version : Hand stoning cutters
02-22-2005, 05:10 PM
How do you hand stone cutters?
When ever I try to hand stone a cutter, it cuts like crap! What am I doing wrong?
Thanks for the help.
02-22-2005, 05:18 PM
Your hand stoning them with something that sucks. I bought a stone for doing just this, turns out that its just a block of A/O, argh. Try a diamond or a Jap wet stone.
02-22-2005, 06:19 PM
I think the tendency when honing a tool bit by hand is to “round” back the cutting edge ever so slightly. The bit will be sharp to the feel but the cutting edge will be just back a little so there is no cutting edge clearance.
For me the solution was practice, practice, and more practice! Another thing that helps me, is to use a magnifying glass or a loupe (10X or better) and look at my progress when honing. When I hone something, I start from the cutting edge and push forward (don’t go back and forth) – for me at least, this keeps the edge from being rounded.
[This message has been edited by Mike Burdick (edited 02-22-2005).]
A lot of my lathe stuff was done with carbide, but now I'm using more HSS in my home shop.
I try to grind the cutting edges flat on the sides so that the hand stone will be somewhat self-guided.
Does that sound like a reasonable way to do it?
I notice that HSS bits that end up with a subtle roundness to the sides makes for a bit that's hard to hand stone with any real degree of success.
02-22-2005, 07:14 PM
That is my problem I think? The rounding. What stones are you using? can someone give a link so I know what to look for? I see in previous posts they say an India slip?
Of course a pic is worth 1000 words!
02-22-2005, 07:24 PM
A lot of my HSS lathe tools I stone and have no problem with rounding the cutting edges. But my tool bits while they may be roughed out at the pedestal grinder are always finished on the surface grinder using one of 4 different special jigs. One universal and 3 different threading tool jigs (2 60D and one 29D acme). The only corners that get rounded are the ones below the cutting edge. Overkill. Probably but it works for me and that's all that counts in my book. Besides I usually only use HSS in the lathe for profiles, chamfers,threading and finishing work. End mills I sometimes will hone the bottom edge but I find that trying to hone the flutes is usually more trouble than it is worth. All honing done with hard and soft Arkansas Stones
02-22-2005, 07:37 PM
I have been making little jigs like crazy after seeing the treading one! I too am now using the surface grinder and getting excelent results! When using the surface grinder, do you still hand stone? I was going to try and see if I had beter luck then before.
I also need to get the proper hand stones.
02-23-2005, 01:09 AM
Make sure you're holding the tool firmly in toolpost or vise when you stone it. Holding it in your hand is begging for rounded edges. I use a fairly fine AO stone for HSS, diamond slip for anything harder.
02-23-2005, 02:11 AM
When I hand stone, I put the stone on a flat surface and try to hold the tool loosely enough so that it guides itself. I hold it near the tip with the rest of it free. My forefinger is about 1/4" above the edge I am sharpening and that edge is trailing as I move the tool. The finger pressure is a bit above and a bit behind the flat area below the edge being sharpened and tends to hold it flat against the stone.
I stop and observe the progress on the flat and adjust as needed.
I bought a small belt sander (1 x 30 I think) a while back and find that it is a far better way to touch up a tool. A fine belt and light pressure will allow you to make a mirror finish. Adding a bit of cutting oil will help.
All the above is for HSS of course. For carbide I use a diamond pad. It's amazing how fast it cuts. Only takes a few dozen strokes to cut back past a small chip on the edge.
02-23-2005, 05:57 AM
Bob, while I do use some 3/8ths HSS bits most of the ones I use on a regular basis are 1/2. This allows for much larger surfaces that can bear on the stone. The primary stone I use is a Norton Soft Fine Arkansas Stone with smaller stones used to stone chip breakers and such. With care and practice a great deal of contol can be achieved. The big problem when grinding tools on surface grinders or touch up on belt sanders is heat control. While too much hat can of course effect the hardness by tempering too much heat can also promote the formation of untempered Matinsite in the tool. This can lead to stress cracks and premature tool failure. This I got from a metalurgy class they ran at work taught by a metalurgist who had worked for both Ampco Corp and Timken. He really knew his stuff
02-23-2005, 08:41 AM
<font face="Verdana, Arial" size="2">Originally posted by Spin Doctor:
BThe big problem when grinding tools on belt sanders is heat control. </font>
Every belt grinder gives a rounding to the edge, because the belt isn't rigid. Even if backed up by a surface, it always has some give, and the top and bottom of the surface are ground more than the middle.
They are great for roughing out the bit though.
02-23-2005, 12:06 PM
First I have to say that I don't find any difference in heat on a belt sander vs. a regular grinding wheel. But now that you have mentioned it, I will look more carefully. I always keep a container of water near the grinder or sander and frequently use it to cool any tool that I am grinding. Or sanding.
As for any rounding, I would agree that it will occur. But I have examined the tools I have sharpened this way and I have to state that it must be very minimal. At least on my sander which has a solid, flat steel backplate behind the belt, no padding. It seems to work very well for me. Judge for yourself, of course.
02-23-2005, 01:33 PM
have you tried using the wheel on the end of a belt sander to get a concave finish that looks about the same as a grinder
Matt in AK
02-23-2005, 02:38 PM
When starting out, it will help if you "blue" the edge with layout die. This will help you see what's happening as you develop your technique.
02-23-2005, 03:56 PM
Ted Coffey beat me to the punch...Layout dye or magic marker works well to help you see what you are doing.
And, practice, practice, practice....I use Norton India stones exclusively on HSS tools. For most work a medium grit is fine.
02-23-2005, 05:32 PM
Mike was right on when he suggested magnification. But I go further than he does. I bought a cheap ($10) hand held microscope from Edmund Scientific. It has a built in light and a magnification of 30x. You can really see what is going on at the edge with it. You may reach the point where you don't use it as much, but at first you will use it a lot. Ten bucks well spent in my opinion. See link
02-23-2005, 07:56 PM
Thanks for all the sugestions! I am sure I can get it down!
Would it be possible for some one to give me a pic or link of the stone or diamond slip you are using? I am using the wrong stones for starters.
I am also going to order the microscope!
Also, good tip on the cooling of the tool, Thrud set me straight on that, I always use coolant.
02-23-2005, 08:35 PM
I stone things when they come off the surface grinder as there's still small burrs left by the grinder. Most of the technique, aside from the vise, is in feel. Same thing when sharpening a knife. You have to feel for when the stone is laying flat on the face, clearance, or edge. When this is difficult to do you have to inspect the surface you're stoning for the new surface you're rubbing on there. What you want to do is "lock" your grasp and angle of attack so you can repeat the stroke. When you've got the surface/angle you want, by inspecting, it will have a distinct feel that glides over the surface. Keep the stone wet with your choice of lube so it doesn't clog. Lighting is important here as if you can't see the progress you're making you won't know when you've finished. It largely is a matter of practice and there are days I have trouble holding the proper geometry on a cutter too. Use of a black magic marker is a good suggestion for the surface grinder as well as by hand, Sanford work well for me. If you can see a rounded edge don't even try to cut with it as it won't last long if at all. I use a coarse stone for setting the initial geometry and then switch to a medium or fine for a keener edge. It's easy to see the finer scratches on top of a coarser grade. I would avoid the white/black hard Arkansas stone at first as they're not easy to use and remove almost nothing. You can also screw up your previous work with one if you're not careful. The Japanese water stones are fast cutting but are really soft and will require frequent dressing or you'll just plow grooves in them. They're great for differentially hardened knives and the peerless swords of Japan but I see no benefit to them that I can't duplicate or exceed with oil stones in industrial applications. They're also on the expensive side. One set of stones set me back 500$ years ago. As an excersise, try learning to sharpen your pocket knife so you can dry shave with it. You'll have a sharp knife (safer than a dull one) and learn angle, body mechanics, and you won't screw up expensive cutting tools. The feel of where the stone is in relation to the object is everything. Sorry I can't be of more help than telling you to teach yourself. If I could learn to do this than just about anybody can with practice.
02-23-2005, 08:57 PM
HSS I find hones best on ceramic.I get mine at Homedepot in the floor tile department!
Look for a tile with a smooth back thats reasonably flat,add a little water and you will be supprised how well it works.
02-24-2005, 12:09 PM
This thread got me thinking about a little gadget I used when I could still see well enough to do detailed hand engraving. It's called a graver sharpener. A graver is the tool used to cut the steel or whatever is being engraved, and they are sharpened with angles much like lathe bits.
This thing is designed to hold the gravers while they are being sharpened on a stone, and is somewhat like the holders used to sharpen wood chisels, i.e the holder has a base that is slid or rolled on a flat surface while the chisel is held at the proper angle to the stone. The graver sharpener is different in that it can be adjusted to any angle on two axes (front to rear and side to side). This allows a compound angle to be honed onto a cutter.
The biggest bit I could get into it was a 5/16, but a guy could make up one that would take whatever size he felt like honing. It did a good job for honing the small bit, but I wound up doing the tip radius by hand anyway. I suppose the tool could be re-adjusted, and the side to side adjustment lock screw left loose so the nose radius could be honed by rotating side to side as the tool is moved front to rear.
Now that I've thought about it, I believe I'll just keep doing it by hand. It's been working fine and is a lot quicker. http://bbs.homeshopmachinist.net//biggrin.gif
02-26-2005, 11:15 PM
I got a new Norton India stone!
I plan on keeping it in a container, should I keep it totally submerged in oil?
How do I keep it from loading up?
Your Old Dog
02-27-2005, 07:31 AM
When I was learning to work wood a friend who was skilled at this sharpening thing said to avoid the deliberate sharpening of the cutting edge of the tools. Think of it as truing up the flat edges on each side of the cutting edge until both sides meet where the old cutting edge used to be and you can't help but end with a sharp edge. I've found him to be right! (Same principal applies when sanding furniture, don't sand teh edges when working over a varnish finish)
If you try to take the "quick" approach and deal only with the edge you can't help but round it off.
I also try not to let my entire hand influence the "lay" of the tool on the stone. I generally press it down with one finger and once the cutter has mates flat with the stone then I get some more digits on it so I can move it back and forth.
I have a stereo inspection microscope and a tool makers hand microscope and they are an immense help. The Edmund Scientific lighted magnifier will be added to my collection too!
Now if somebody here could help me know what to do with these bits once they are sharpened I'd be all set!
02-27-2005, 09:28 AM
The suggestions given here are good ones. Let me add that good lighting and magnification are a big aid when hand-honing.
I have magnifing glasses and microscopes, but I find that a fluorescent ring light with a built-in magnifying lens is all I need. I do all my critical work under it. When I'm not actually looking through the lens, I position the light directly over whatever it is I'm working on. It is the most-used item in my shop.