On Wed, 18 Feb 2009 13:45:16 -0600, Tim Wescott
wrote:
Of late when I need a cutter I rough it out of an appropriate HSS blank
with a Makita hand grinder, then finish it on a bench grinder.
The reason for this is because the bench grinder is very slow, and
shaping convex profiles (as you find on the shoulders of a cutoff tool)
erodes the hell out of the corners of my grinding wheels. Since I want
to get things done, and I want to do it without dulling the corners on my
bench grinder, I use the hand grinder.
This works fine, but it's ugly as hell.
Is there a "more right" way to do this? The tools that I have at my
disposal are the afore-mentioned hand- and bench grinder, a truely
ancient Dremel tool (for which I have cutoff wheels, and can afford a few
odds and ends), and some stones for finishing things off nice and sharp.
I vaguely remember trying to cut off a corner of a 1/4" tool blank with
the Dremel cut-off tool and thinking that it's a dandy way to turn cut-
off wheels into powder.
If you just couldn't stand the thought of doing it with the above tools,
what one tool would you make me buy, and how would you tell me to use it?
==============
4 X 36 belt sander with 6 inch disk. Use zarconia [blue] belts
to rough grind and a fine grade disk to finish grind. With a
fine grit on the disk you can get a literal mirror finish.
example of sander
http://www.use-enco.com/CGI/INSRIT?P...PARTPG=INLMK32
example of zarconia belts [scroll to bottom of page]
http://www.use-enco.com/CGI/INPDFF?P...PARTPG=INLMK32
example of disks
http://www.use-enco.com/CGI/INPDFF?P...PARTPG=INLMK32
Most car parts places that have painting supplies will have even
finer ones down to 2000 grit for a super finish.
The protractor on the fence/table is OK for wood working, but an
improved holder and accurate guide will give you better and more
repeatable results.
for my solution see
http://mcduffee-associates.us/machining/tabanggg.htm
and
http://mcduffee-associates.us/machining/thfnce.htm
Also get one of the machining textbooks that discusses lathe tool
geometry and nomenclature. Moltrecht vol one is good.
[get both volumes when you order.] Frequently on sale from Enco
and Amazon
http://new.industrialpress.com/machi...ition-volume-i
also the reprints from Lindsay books are very good and are priced
very reasonably.
http://lindsaybks.com/
most any of these lathe books will be very helpful.
Just make the tools look like the pictures to start.
http://lindsaybks.com/bks/lathebk/index.html
These angles have been developed over 100 years are more. After
you get this down, you can vary to see what works best with your
machine and way of working. Be sure to keep a notebook and
sketch what you do for easy reference.
A tip -- regular M2 is both easier to grind and cheaper than 5 or
10% cobalt, and will be more than adequate for your initial
projects. Also for the typical hobby/home shop lathe, rake at
the high side of the recommended range, or even above can be
helpful as this reduces the cutting forces. The trade-off is
shorter tool life, but this is not a major consideration for
home/hobby shop use.
Unka' George [George McDuffee]
-------------------------------------------
He that will not apply new remedies,
must expect new evils:
for Time is the greatest innovator: and
if Time, of course, alter things to the worse,
and wisdom and counsel shall not alter them to the better,
what shall be the end?
Francis Bacon (1561-1626), English philosopher, essayist, statesman.
Essays, "Of Innovations" (1597-1625).