I would like to learn the deep dark mysteries of tool grinding. Not just the angles but tool materials and what they are best used for. Been using carbide for years because I did not want to have to grind my own tools but lately have been dissappointed with my results even with carbide. Where do you suggest I go to further my knowledge? Trade school is really not an option. Would like to find info on the web or on DVD to be able to study as I have time. Even better yet would be spend some saturdays with an old machinist but I do not know of any. Ideas?
Tool grinding is not all that much of a mystery. I did take an evening class on machining and as I remember the instructor spent about twenty minutes on tool grinding ( not counting the time used to show how to grind threading tools using a surface grinder ). He did it all free hand with a regular bench grinder.
So say where you are and there might be someone around that would spend a little time with you. Especially if you do something like clean the swarf out of his shop.
No mysteries. See in your mind what the tool needs to do and grind away only what you have to keep the tool robust and still have a bit of relief. Pick up some HSS blanks. When you make a tool and try it, the tool will tell you quickly what it needs to be improved with the chip shape and how the edge holds up...or breaks. A few hours and you will be an expert. Keep your tool from overheating! This applies to machining AND ladies!
================= Much of the information you want is available in chapter 7 of Karl Moltrecht's book "Machine Shop Practice - Vol I" ISBN 0-8311-1126-7 from Industrial Press. You can buy it directly from them or from most of the mail order tool supply houses at a discount.
I suggest buying both volume I and II, as thse are not expensive and have a wealth of machining information.
See (keep a firm grip on your charge card!!)
?PMAKA=205-1006&PMPXNO=947692&PARTPG=INLMK32these are also good
?PMAKA=505-3536&PMPXNO=947684&PARTPG=INLMK32 Note that for the person just starting to grind their own single point tools the biggest challange is being able to repeat a particular grind, or to just *S*L*I*G*H*T*L*Y* change a grind as it is not difficult to tell when you need a bit more rake or relief. The problem is how to get it.
Unless you are grinding threading tools the exact angle is not critical. You will (or should) have a gage to check the outline and tip. click on following to see examples. USS
The problem is then how to adjust or regrind to fit the gage. The experienced machinist has enough fine motor skills and practice to do this, but the beginner does not and becomes discouraged on their 10th or 12 try.
One solution is to rig up a guide for your existing grinder or belt/disk sander to allow accurate setting and repeatability.
Dave Gingery developed plans for the normal small grinder. to see and possibly order click on
An alternative if you already have a grinder or belt/disk sander with a table and slot is to adapt what our machining class developed.
To see click on
While a Baldor style carbide grinder (actually used for both HSS w/white rocks and carbide w/green rocks) is ideal for the commercial shop where time is money, you can also use a belt/disk sander with a table with guide slot and mortise gage. The very fine grit disks you can get for automotive paint work will put a polish on your tools. I don't know if this actually affects the finish but it sure looks nice. If you have two tables, one for the belt and one for the disk, you can use a corse belt to rough [I like the blue zarconium oxide belts] and a fine disk to finish.
One trick is to get a fine bristle abrasive brush and use this to "hone" the tool. It will better job than you can by hand. Just a swipe or two across the brush at low rpm is all that is required.
Use a plastic ammo box for the ground tools to prevent chipping the edges. I find that a 222/223 box is just the right size for
1/4 inch bits.
I suggest that you stick with the common M2 HSS to start. It is cheaper, and more easily ground.
After some experience, and only if your tools are wearing faster than you like, try some of the T15 and 5-10% cobalt tools. These being more abrasive resistant are harder to grind, cost more, and are harder and thus are more prone to chip and break than M2.
Unka' George [George McDuffee] ============ Merchants have no country. The mere spot they stand on does not constitute so strong an attachment as that from which they draw their gains.
Thomas Jefferson (1743-1826), U.S. president. Letter, 17 March 1814.