perhaps an odd request - doing tool grinding at the moment at school - still getting confused as to which angle is which, - have yet to see a CLEAR set of diagrams (the sort you can cut out and stick on the wall). Yes, theres lots of diagrams, my textbook has them, but they are usually plan views without clear labeling of the view/elevation.
Anyone got a pointer to a one page (or less) picture I can stick in the front of my textbook. Getting horribly confused......
Its frustrating - spent 8 hours on Monday, standing in front of a grinder, trying to get ALL the angles right - like I said, getting there, but more slowly than I would like..
======================= Biggest help is to have a model to work from. See if you can't get a set of preground tools or even carbide insert tools to use as models. After you use these for a while you won't need them. see
(expensive) Or get your instructor to rough out the 3 or 4 most common as patterns. Key stock is ok.
Also get catalogs showing the standards such as AL,AR, BL,BR etc. as these have been found to be the most useful. see
FWIW -- free hand grinding is not the way to go. It is impossible to repeat angles exactly, and thus you may have to go back and grind a tool several times to "get a good grind." If at all possible rig up a jig/fixture so you can repeat or increase/decrease slightly ( which is more important than getting the exact angle.)
one way to do this.
With this set-up, even the first-term students were able to get a "line-out" ACME thread tool, although it took them a few tries.
In many cases a belt sander will work as well if not better than a grinder for smaller lathe tool bits. You can put a mirror finish on the bits with a fine grit belt of disk. And one less machine in your shop is you already have a belt sander
For honing the edges, the easy way is to use an abrasive filled plastic bristle brush. The normal consumer on in the US is blue indicating a medium abrasive. These come with a 1/4 inch stem to mount in a drill press. Just one or two "swipes" is all it takes. Works on drill bits also.
Pay attention to the nose radius of the tool. A sharp corner will cut a bad finish no matter what you do.
Thanks to those who replied - while it didn't answer the specific question, it did get me thinking about what I was supposed to be doing.
Question in my school work book was (tool grinding section)
1.Tool Number One (Combination Turning/Facing-Right hand Knife Tool) freehand grind a tool to the following specs.
a) Rake angle 10 deg. positive b) Front clearance 8 degrees plus allowance for 15 deg. inclination on toll holder c) Side clearance 5 deg. d) Side cutting edge angle 0 deg.
My query was what angles were what - ie, what were they specifying...
I did figure this out , from a combination of searching here, my text book, and the South Bend "How to Run a lathe " book.
Took yonks of practice to get a clean grind (smooth face on all surfaces) and the angles right. Probably about 20 hours all up, standing in front of a 8 inch grinding wheel. Most of it was on bits of mild steel, the final test was when they gave you a piece of tool steel and said "do it" - I did, then chucked up a piece of scrap in the lathe and it did a nice job - cut well, smooth finish. Then put a nose radius on it (another craft skill, took a while to master) and it got even better.
I can now grind my own lathe tools with a reasonable degree of accuracy.
So, thanks to those who replied - it would be nice to have a tool grinder that I could just dial up the angles, but I have deliberately set out to do a trades course and learn the basics. (I think its a bit like learning Morse Code - takes ages, little progress, then it all starts to make sense.....and you have a new skill)
And greatful thanks to Harold Vordos - his dissertions on freehand grinding are a wonderful source of "how to do it, properly...)
I don't have links to lathe tool images with specific grinding angles, and only recently have gotten a book that has some illustrations of different turning tools with recommended angles and sizes/locations of chip breakers. "Shop Reference for Students and Apprentices", includes lots of machining info and specs from Machinery's Handbook (same publisher, Industrial Press Inc).
Here's an angle-adjustable holder for grinding lathe cutting tools, that greatly simplifies roughing-to-shape grinding and eliminates burnt fingertips.
I made my first holder on a small lathe, using a bar holder in the compound turret to hold the round stock, while using endmills held in a 3-jaw chuck.. not really a sophisticated setup, but it worked well enough to create the first holder.