"Snag" wrote in message news:tmugmi$13efh$1@dont-email.me...
I've got a bunch that have chipped tips on the flutes , and I
guess it's time I learned to sharpen them instead of tossing them and buying more .I've poked around a little and found a design for a fixture
using 5C collets that I can build with tooling I have on hand . I do
have a question about using my mill to grind these . It doesn't spin as
fast a a real grinder , about 1800 RPM tops IIRC . I'm looking for suggestions what type of wheel I need . Probably a cup wheel since the
end mill will mount with the tip up .
Snag
---------------------
This type of fixture works well enough for me, on my ancient $100
surface grinder. https://www.grizzly.com/products/grizzly-end-mill-grinding-fixture/g9887
I have the Enco version with 24 click stops, no dial or lock screw. The
base was cut square and the relief angle is in the mounting hole for the
ring that retains the collet holder. If I'd tried to make it I might
have had trouble matching the collet taper, the rest is pretty simple
and the tilt angles shouldn't need to be exact, eyeball alignment in the collet and on the grinder mag chuck is good enough to make an endmill
cut well. I did machine another collet closer nut that accepts flanged bushings to center an S&D drill bit, etc.
It isn't obvious that the end cutting edges angle in slightly toward the center. If you are set on making your own I can measure the collet
holder's lengthwise and sideways tilt angles on mine.
In addition to sharpening the ends normally it can grind worn tips into
a 30 degree bevel to cut sideways without dulling the spiral edges. I
have one old 1/2" 4-flute that I grind that way and use for roughing, to
save the other endmills for finishing. Another scheme to preserve the
spiral edges is to rough with plunge cuts which dull only the end edges
that I can easily regrind.
I also have a fixture like this to sharpen the spiral edges: https://www.shars.com/end-mill-cutter-and-sharpener
It's quite fussy to set up and use, and it reduces the diameter which
can be useful to cut a slot to 0.500" (with multiple passes or another
new endmill) instead of slightly larger from deflection, but is
otherwise a nuisance since they look the same.
I made it more rigid by removing the tilt mechanism that would swing the endmill into or away from a cup wheel, since I grind on the top with a
normal 6" wheel.
"Jim Wilkins" wrote in message news:tmv9mu$157ci$1@dont-email.me...
...
In addition to sharpening the ends normally it can grind worn tips into
a 30
degree bevel to cut sideways without dulling the spiral edges.
...
----------------
If that isn't clear, the fixture is tilted onto the 25 degree (I
measured it) angled face and the chipped end mill tip is ground back at
that angle like the cutting edge of a drill bit. It will cut as long as
the least chipped corner has been sharpened, and eventually regrinding
may restore others. You can grind a badly chipped one back to square
with a bench or angle grinder and restore the cutting edge geometry with
the fixture. 4 flute endmills can be salvaged although they are unlikely
to remain center cutting, 2 flute ones are easier.
Based on my mill's somewhat limited rigidity I grind the dull point back about 0.025" or less lengthwise, leaving at least half the diameter
cutting flat, and alternate between regrinding it square or beveled.
Both edge faces wear from roughing by plunge cuts. The beveled cutting
edges seem much less vulnerable to chipping in mystery metal with hard
spots.
I would be extremely careful to keep grit off the exposed ways of a
mill. The ways of a surface grinder are shielded.
I've got a bunch that have chipped tips on the flutes , and I
guess it's time I learned to sharpen them instead of tossing them and buying more .I've poked around a little and found a design for a fixture
using 5C collets that I can build with tooling I have on hand . I do
have a question about using my mill to grind these . It doesn't spin as
fast a a real grinder , about 1800 RPM tops IIRC . I'm looking for suggestions what type of wheel I need . Probably a cup wheel since the
end mill will mount with the tip up .
Projects, projects, ...
AFAICT with limited equipment the collet tilt angles are 5 degrees
toward the beveled end and 2 degrees to the left with the bevel toward
you (or me). At least those angle blocks visually match it to a square.
I confirmed that the bevel is 25 degrees from the base.
"Snag" wrote in message news:tn07ss$1asq8$1@dont-email.me...
Thanks , those are pretty close to the numbers I expected . One more
good day on the neighbor's machine should see it back in running shape ,
the motor's ready to drop in now .
I originally told the neighbor that I would do his after I finished
the truck ... I relented and moved it up because his wife was making him miserable over it . She's one of those "corporate movers and shakers" .
I'm sure glad I married a "simple country girl" !
Snag
------------------- My day's project was lost to helping an elderly
neighbor too. Everything went wrong, and it's reassuring that in my mid
70's I can still diagnose and fix problems quickly.
On 12/10/2022 5:22 PM, Jim Wilkins wrote:
"Snag" wrote in message news:tn07ss$1asq8$1@dont-email.me...
Thanks , those are pretty close to the numbers I expected . One more
good day on the neighbor's machine should see it back in running shape ,
the motor's ready to drop in now .
I originally told the neighbor that I would do his after I finished
the truck ... I relented and moved it up because his wife was making him
miserable over it . She's one of those "corporate movers and shakers" .
I'm sure glad I married a "simple country girl" !
Snag
------------------- My day's project was lost to helping an elderly
neighbor too. Everything went wrong, and it's reassuring that in my
mid 70's I can still diagnose and fix problems quickly.
Kids now days , if they can't read the problem off a computer screen they're totally lost . Remember Gus from Popular Mechanics (IIRC) back
in the 50's-60's ? His column taught me to diagnose a burned exhaust
valve by sticking a strip of paper to the end of the exhaust pipe with bubblegum ...
On 12/10/2022 5:41 PM, Snag wrote:
On 12/10/2022 5:22 PM, Jim Wilkins wrote:
"Snag" wrote in message news:tn07ss$1asq8$1@dont-email.me...
Thanks , those are pretty close to the numbers I expected . One more
good day on the neighbor's machine should see it back in running shape , >>> the motor's ready to drop in now .
I originally told the neighbor that I would do his after I finished >>> the truck ... I relented and moved it up because his wife was making him >>> miserable over it . She's one of those "corporate movers and shakers" .
I'm sure glad I married a "simple country girl" !
Snag
------------------- My day's project was lost to helping an elderly
neighbor too. Everything went wrong, and it's reassuring that in my
mid 70's I can still diagnose and fix problems quickly.
Kids now days , if they can't read the problem off a computer
screen they're totally lost . Remember Gus from Popular Mechanics
(IIRC) back in the 50's-60's ? His column taught me to diagnose a
burned exhaust valve by sticking a strip of paper to the end of the
exhaust pipe with bubblegum ...
Speaking of off the computer screen. There is a YouTuber who uses his
mill fairly often as a grinder you might find interesting. Its not
typically a "grinding" video, but instead one part of a project. He did
a fair amount of grinding in a video about making a grinder vise
(screwless vise). In a more recent video he touched on mill grinding
when making a case hardened gear. He also does a bit of case hardening.
Artisan Makes
Aside: I currently use modified grinder vises as my primary fixturing attachment on 4 mills because they take up less space for their range
than a mill vise, and they are more flexible than a fixture plate. (I
Use fixture plates too. Some mount in the vises as needed.)
Back on topic: I suppose I should have put this out there sooner. There
are two answers that come to mind for me about your concerns for speed.
(1) A larger wheel gives more surface speed. (2) Grinding slower works fine. Its just slower. For example a Tormec knife grinder is an order
of magnitude slower than a bench grinder or most other machine shop
grinding machines.
"Snag" wrote in message news:tn5940$2098c$1@dont-email.me...
..
I've been pondering the base for the fixture to mount the end mills .
I think I'll make the bottom angles and have the sides and ends square
with them . Then put the 2° bevel on top with the thru hole
perpendicular to the top . Just seems like the easiest way to me .
Snag
---------------------
I set the end mill fixture on my mill with the collet upright, 1/2" rod
in the fixture and spindle collets, raised the table to contact with the
back right corner, then pushed a 1/4" thick bar into the wedge space underneath from the front (bevel) side. The bar intersects the left side 2.05" from the back and the right side 2.95" from the back. A squared rectangular base block could be clamped to a mill table or lathe
faceplate this way and bored straight in to get both 2 and 5 degree
angles easily.
I might attach the 1/4" angled spacer with countersunk screws to reduce fumbling and let the setup be accurately repeated later.
jsw
"Snag" wrote in message news:tn5940$2098c$1@dont-email.me...
..
I've been pondering the base for the fixture to mount the end mills .
I think I'll make the bottom angles and have the sides and ends square
with them . Then put the 2° bevel on top with the thru hole
perpendicular to the top . Just seems like the easiest way to me .
Snag
---------------------
I set the end mill fixture on my mill with the collet upright, 1/2" rod in the fixture and spindle collets, raised the table to contact with the back right corner, then pushed a 1/4" thick bar into the wedge space underneath from the front (bevel) side. The bar intersects the left side 2.05" from
the back and the right side 2.95" from the back. A squared rectangular
base block could be clamped to a mill table or lathe faceplate this way
and bored straight in to get both 2 and 5 degree angles easily.
I might attach the 1/4" angled spacer with countersunk screws to reduce fumbling and let the setup be accurately repeated later.
jsw
"Jim Wilkins" wrote in message news:tn77jp$27nid$1@dont-email.me...
I'm going to have to take a minute to digest that ... OK , if I'm understanding this correctly I'll only have to cut one angle on the
bottom , the other two will be produced by the way the hole for the
collet is bored in the block - 2° tilt to the rear , 5° to the right .
If I put a couple of degree angle on the left end I can set the fixture
up to do the gash with the end mill horizontal/angled slightly down .
Snag
-------------
I don't understand the last sentence.
"Snag" wrote in message news:tn7sid$29fcg$1@dont-email.me...
I was talking about cutting the end gash with the end mill held
horizontal and using the edge of the grinding wheel . I've got this
figured out now . I planned on making this with a screw lock and 12
dimples in the collet sleeve to lock the setting . For now though it's
on the back burner .
Snag
--------------
The screw lock style should be less demanding to machine, on mine the
three spring-loaded balls have to all engage the dimples equally, but I
can turn it with one hand that is on the far side of the fixture from
the spinning wheel, and count the clicks. With the single screw lock a
slight indexing error won't matter.
Actually you need only as many dimples as you have flutes to sharpen,
which for me is 8 on shell mills.
"Snag" wrote in message news:tnae60$2ij1f$1@dont-email.me...
I was thinking 12 since it's evenly divisible by both 3 and 4 and I
have 3 and 4 flute end mills - and a rotary table (7.5 turns per 30° at 90:1) . It's raining here again and I have no other projects ... except
the neighbor's SxS UTV , and I ain't working on it in the rain . So a
little while ago I started roughing stock for this project . Yesterday
it wasn't raining , but I wanted to watch the guys installing my new
septic tank . Concrete this time , the last one was steel and only
lasted about 18-19 years .
Snag
---------------------
Manual indexing is a tedious and error-prone task. You can double-check
by setting dividers to the spacing of the first two holes and using them
to confirm the next drilling location if you are interrupted. Any error should be large, a whole or half turn. My last dividing job was cutting
a 68 tooth gear and there were issues... The one before that was 13, to spline a shaft for a motorcycle drive sprocket.
That storm may be heavy snow or ice when it arrives here, 'tis the
season. I finished prepping for it an hour ago.
jsw
"Snag" wrote in message news:tnb0j2$2k0qo$1@dont-email.me...
One of these
days I'm going to pin that set of 37/47 (IIRC) metric transposing change
gears I cut a while back . Haven't needed to cut metric threads yet so
...
------------------
You would have needed them if you didn't make them.
Shortly after buying the lathe I bought a metric transposing set of 127
and 120 teeth, since 120 instead of 100 gave more of the fine metric
threads I expected to need for the laser optics work I was doing then.
Turns out the engineer decided to move on and take the idea with him. https://ieeexplore.ieee.org/document/9749702
At the time the gears cost around $40 each. I finally decided to make a custom banjo stud to fit the double-keyed bushing that connects the
gears, since its bore is smaller than the South Bend stud. The price of
the standard 100 tooth gear is now up around $150 on Amazon,
considerably more from the industrial dealers I called. Making your own
was a good call. https://www.amazon.com/Boston-Gear-GB100A-Lightening-Pressure/dp/B004N62UIC
"Snag" wrote in message news:tnbikt$2nsdj$1@dont-email.me...
I got the RT shortly after I got the mill 'cuz I just knew ... turns
out the first gears I made were to repair some 2:1 reduction pairs in
the qcgb on my lathe . Those alone have saved me more than the cost of
the RT and all the gear cutters I've got . Logan wants like 160 bucks
for those little darlin's .
Snag
----------------------------
Did you make or buy the gear cutters?
Jim Wilkins wrote:...They average about 12 bucks each which I found reasonable .
Did you make or buy the gear cutters?
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