Further to my wanting to put fluting around the edges of shelving,
(and the answer is "Pin Router", thanks for that great tip), is it
cost effective to get expensive router bits slightly modified?
The fluting bit I have gives five beads at the one pass, but at each
side of the beads, is a flat that is really in the way.
Has anyone gotten something like this removed by professional
sharpeners? Was it cheap? Was it satisfactory?
I am loathe to grind the bastards off myself cos of balance problems,
but what about spinning the bit in the router and judiciously grinding
the little carbide flats of with a suitable corundum stone?
That should keep the balance right, No?
I would not recommend modifying carbide bits and carbide needs either
diamond wheels or else very soft 'green' stones. I believe your suggestion
of spinning the bit in the router is a recipe for disaster. As a machinist
the stationary tool is invariably offered to the grinding wheel, the feed
mechanism is graduated in 1/10 of thou and better.
For your application I would suggest you look for suitable high speed steel
bits and if the profile is not exactly what you need those can be ground
with a Dremel or similar. Providing the diamater is quite small the out of
balance component will be almost negligable.
On Thu, 13 May 2004 00:22:15 -0500, "Bernard Randall"
Thanks Bernard. I sort of suspected so.
Just out of interest, what are "very soft 'green' stones"?
Out of curiosity, what is likely to go wrong with spinning the
half-inch-shank bit in the large router, well secured in the router
table, and applying the stone judiciously to it?
I remember years ago on the metalwork lathe sharpening the carbide
tipped tool by hand on the carborundum grind wheel. Worked a treat
For one thing, if you're not _very_ careful you'll find that the carbide
cuts the stone very nicely if it doen't hurl it across the room in pieces,
hopefully lodging in the wall and not in your gizzard. When you were
sharpening that tool on the lathe, you were turning the stone, not the
cutter, were you not? And did you just jam the point of the cutter into it
or did you sneak up on it from beneath?
If you're going to do this, do not try to use the router to spin the tool
(if you need to use it as a positioning aid that's another story but be
careful about getting it full of filings), and make up a jig that lets you
repeat the same motion on all flutes so you end up with a consistent cut
and good balance. At 20,000 RPM it doesn't take much unbalance to cause
things to come apart, and I've seen a chunk of carbide hurled by a rotating
machine go right through a Navy landing craft (there's a reason it's used
in armor-piercing ammunition).
As someone else pointed out, you'd do better to start with a steel tool than
carbide--machining carbide is a specialized art. Unless you're going to be
doing an awful lot of this or are working with a very abrasive wood the
steel tool (assuming it's good quality and not consumer-grade crap) should
hold up just fine and if it's properly sharpened may even give you a little
bit cleaner cut.
Reply to jclarke at ae tee tee global dot net
In general, hard materials should be ground on a relatively soft wheel, and
vice-versa. The first letter on a grinding wheel designation is the type of
abrasive: A for aluminum oxide, C for silicon carbide, GC green silicon
carbide. On the occasions I've run 'green' stones there's dust
If you run a carbide bit into a stationary stone you'll cut the profile in
it. If you had both the router and grinder running you stand every
possibility of the router biting off a large enough chunk of the wheel to
jam the wheel and it will litteraly explode - extremely dangerous.
The problems you face running the router and applying the stone to it are 1)
a carbide tool will profile the stone not vice-versa 2) the grinding dust
will get everywhere, possibly also into your router 3) any profile you do
get will be normal to the tool, i.e. no cutting angle, so those portions of
the tool will burn your surface, not cut it.
When machinists do off-hand grinding it's always with part of the tool
resting against a solid tool rest becase the action of the grinder is to
pull the tool into the wheel. The gap between the tool rest and wheel is
kept very small to prevent anything jamming the wheel, exploding wheels are
a very real danger, and experienced machinists always tap wheels before
mounting them to ensure they 'ring true'.
On Thu, 13 May 2004 11:06:27 -0500, "Bernard Randall"
Thanks, I didn't know that -- sort of counter-intuitive.
Thanks for that. I've just found a full key to this code and find my
two grinder wheels are Alumina.
Thanks, good warning :)
Thanks again. I had no intention of poking a stone at my spinning
router bit. I would have had both elements securely clamped and offer
the stone to the bit via the fine height feed of the router.
This bit is cylindrical with the profile longitudinally down the long
edges of the cylinder.
I would not want to touch the profile other than the two small flats
at each end of it. I was intending to grind away the top of the
cylinder (2mm) until the beading profile was reached, and then
judiciously remove carbide from the bottom of the cylinder (ajacent to
the shank) until the small 2mm flat is removed.
Good warning -- thanks
As I explained above, this won't apply. The carbide I would be
removing would not then touch any work piece. I'm trying to leave the
profile section intact while removing the small flats at each end that
will be in the way.
Thanks once again. I was always taught to stand to the side of any
wheel being powered up.
Anyhow, after all the good advice I've received here, I think I will
price the mods I want at the local saw doctor (Carbide sharpener).
Thanks to everyone :)
Once upon a time (mid '70's), in high school auto shop, a kid in my class
asked the teacher, "Can I make my own camshaft?" The teacher thought about
it for a moment, and said, "Well, sure. Just get a big chunk of steel, and
cut away everything that doesn't look like a camshaft."
I've modified a few carbide bits. I try to use HSS if I'm going to
modify even if it does require resharpening more often. The way I've
made the modification is to chuck the bit in a 6 inch Atlas lathe and
engage the back gear for slowest speed. I then mount a Moto Tool on the
cross slide with a diamond stone mounted in the Moto Tool. I then grind
by eyeball (nothing scientific about this part) to a pencil line I've
drawn on the carbide of my desired contour. Results in no problems with
p.s. I think you'll be disappointed in trying to do it with carborundum.
The stone will grind away almost as fast as the carbide - maybe faster.
Jerry Shaw wrote:
What size of diamond wheels are you using? Are they reasonably priced? Do
your dry grind or use some form of lubricant.
I got a large diamond wheel for a grinder at auction, but generally prices
have put me off, but I'd like smaller sizes for the Quorn T&C grinder I'm
the thought of taking a spinning router bit and :"judiciously grinding
by a cutter.
I think that tryingt o midifya router bit like that is different from
working something on a grinder - on the grinder, the spinning surface is a
surface - once the piece is in contact, it'll stay in contact. When the
router bit is spinning, the only part that you'll be touching is the edges
of the bit - kind of like the difference between touching the surface of a
spinning bicycle wheel and a propellor...... Sounds like a recipe for a
trashed stone at best.....
It has been explained in previous post that this will likely result in a
pulverized stone (which IS highly likely) and, if it did work. would result
in NO cutter relief causing the tool to cut badly or not at all. If you need
this done, take it to a professional tool grinder. One that does
metalworking tools. Take them the bit, tell them what you want and they will
tell you if it is feasible with that cutter or not. They have the equipment
and know how to do this kind of work.
Instead of grinding a new bit, is there any other option? Like gluing
a strip of cheap pine to hardwood, with thick brown paper (from a
Shopping bag) in between. Then remove the strip.
Or else do the routing in more than one pass.
I'm not an expert. But I see what patterns can be made with multiple
passes from router bits, and it always impresses me.
Sending unsolicited commercial e-mail to this account incurs a fee of
$500 per message, and acknowledges the legality of this contract.
Any machine shop can do a simple modification like that for you in just a
few minutes. It will be cheap IF you find the right guy in the right shop.
If this is your typical fluting bit, an inch or less in diameter, balance
won't be a big deal if you take even a little bit of care. I would grind it
myself by hand, but it would be at work, not on my home grinder.
We have an extensive machine shop at work, with wheels specifically for
carbide, and would use that if doing it freehand. We also have endmill
sharpening equipment and if I wanted a perfect job would use that. None of
this is equipment that I would have at home or any woodworking shop.
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