"Ignoramus15775" wrote in message
...
Got a 1/2 HP single phase motor today (totaly enclosed) for $2. 5/8"
shaft. I would like to make a grinder out of it, but I am not sure how
1750 RPM works out for 8" wheels. I would buy wheels at Harbor
Freight. Is 1750 RPM about right for these wheels? Is 1/2HP a sensible
horsepower?

thanks

i

No, too slow. It's quite common for a 7" wheel to be able to be run @
3,600 RPM, and some 8" wheels are so marked as well. Power-wise, 1/2
horse is fine for sharpening toolbits, but would be a slight compromise for
heavier grinding. You could get by with it by taking it easy, though.
If you really want to use it, you'd have to run larger wheels, say 12".

Wheels should be run at their recommended speeds so they behave as they're
intended. Slowing wheels down makes them behave as if they're softer than
they are- which means that speeding them up makes them behave as if they're
harder than they are. I'm sure you understand that the abrasive doesn't
change--it's the way the bonding agent behaves.

Almost all grinding wheels will be marked with a recommended maximum speed.
Try to run as closely to that speed as you can without going over.
Exploding wheels are very unforgiving, generally leading to death. If you
don't know about ringing a wheel before putting it to use, get the concept
down pat, for it can be the difference between life and death for you.
Simply place the wheel on something that won't dampen vibration (screwdriver
blade, for example), and tap it *lightly* with a slightly hard object, like
a screwdriver handle. The wheel should ring like a bell. If it makes a
dull thunk kind of sound, it's most likely cracked, and cracked wheels
explode when spooled up. The best thing to do with the wheel like that is
break it so it can't be used by some unsuspecting fool.

Be certain to match the abrasive of the wheel to the work you're doing. If
you're grinding steel, use aluminum oxide. Other materials, including cast
iron, silicon carbide is a better choice. There's lots to know about
grinding, so you'll do well to ask questions along the way, which I've
noticed is your style, anyway. That way you can pick up on important things
as they become a problem for you. There's a few of us with grinding
experience that will keep watch over you.

Harold

"Ignoramus15775" wrote in message
...
Got a 1/2 HP single phase motor today (totaly enclosed) for $2. 5/8"
shaft. I would like to make a grinder out of it, but I am not sure how
1750 RPM works out for 8" wheels. I would buy wheels at Harbor
Freight. Is 1750 RPM about right for these wheels? Is 1/2HP a sensible
horsepower?

thanks

i

Don't put a whole lot of eggs in this basket. My 10" is powered a little on
the lite side at 5 hp. I forget the speed but is belt driven faster than
the motor. What do you want to do, sharpen your golf tees? However, a 6"
wheel on a belt driven arbor with 1/2 hp is a workhorse.

there are situations where a slow speed grinder is very helpful - many wood
turners prefer 1750 because you sharpen very frequently and you don't need
to remove very much metal. maybe you should offer to trade on the wood
turning NG
"Ignoramus15775" wrote in message
...
Got a 1/2 HP single phase motor today (totaly enclosed) for $2. 5/8"
shaft. I would like to make a grinder out of it, but I am not sure how
1750 RPM works out for 8" wheels. I would buy wheels at Harbor
Freight. Is 1750 RPM about right for these wheels? Is 1/2HP a sensible
horsepower?

thanks

i

--

"william_b_noble" wrote in message
news:1124638990.9850a5f60841db0a48086ee075fb0b73@t eranews...
there are situations where a slow speed grinder is very helpful - many
wood
turners prefer 1750 because you sharpen very frequently and you don't need
to remove very much metal. maybe you should offer to trade on the wood
turning NG

That's an interesting approach. The wheel running slower than advised will
cut much cooler, due in part to it behaving much softer and sloughing off
easier. It's hard on wheel life, but that shouldn't be a problem for
touch-up. If one was roughing HSS blanks, that would be a serious mistake,
though. The blank starts acting like a dressing stick.

Harold

"Ignoramus15893" wrote in message
.. .
On Sun, 21 Aug 2005 14:42:06 GMT, Tom Gardner wrote:

"Ignoramus15775" wrote in message
...
Got a 1/2 HP single phase motor today (totaly enclosed) for $2. 5/8"
shaft. I would like to make a grinder out of it, but I am not sure how
1750 RPM works out for 8" wheels. I would buy wheels at Harbor
Freight. Is 1750 RPM about right for these wheels? Is 1/2HP a sensible
horsepower?

thanks

i

Don't put a whole lot of eggs in this basket. My 10" is powered a little
on
the lite side at 5 hp. I forget the speed but is belt driven faster than
the motor. What do you want to do, sharpen your golf tees? However, a
6"
wheel on a belt driven arbor with 1/2 hp is a workhorse.

Thanks... I will check things out. I am very confused about how I can
make a higher HP grinder (say 2 HP). Basically, I cannot find shaft
adapters. I do not want to make one myself for safety reasons, I would
rather buy one from a company that has been making them for years and
knows all the gotchas.

i


If you want a working powerful grinder, buy or make a belt-driven arbor,
forget the adaptors or go to http://www.clesco.com/ (one of my customers)

The other thing is heat. Don't want a lot of heat generated to change the
temper of the tool steel. Water grind is best. Most don't have or think
of it. They use fracturing stones that stay sharp and shatter not burn.
Martin

william_b_noble wrote:

there are situations where a slow speed grinder is very helpful - many wood
turners prefer 1750 because you sharpen very frequently and you don't need
to remove very much metal. maybe you should offer to trade on the wood
turning NG
"Ignoramus15775" wrote in message
...

Got a 1/2 HP single phase motor today (totaly enclosed) for $2. 5/8"
shaft. I would like to make a grinder out of it, but I am not sure how
1750 RPM works out for 8" wheels. I would buy wheels at Harbor
Freight. Is 1750 RPM about right for these wheels? Is 1/2HP a sensible
horsepower?

thanks

i

--






--
Martin Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
NRA LOH, NRA Life
NRA Second Amendment Task Force Charter Founder

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On Mon, 22 Aug 2005 02:03:22 GMT, Ignoramus15893
wrote:

On Sun, 21 Aug 2005 14:42:06 GMT, Tom Gardner wrote:

"Ignoramus15775" wrote in message
...
Got a 1/2 HP single phase motor today (totaly enclosed) for $2. 5/8"
shaft. I would like to make a grinder out of it, but I am not sure how
1750 RPM works out for 8" wheels. I would buy wheels at Harbor
Freight. Is 1750 RPM about right for these wheels? Is 1/2HP a sensible
horsepower?

thanks

i

Don't put a whole lot of eggs in this basket. My 10" is powered a little on
the lite side at 5 hp. I forget the speed but is belt driven faster than
the motor. What do you want to do, sharpen your golf tees? However, a 6"
wheel on a belt driven arbor with 1/2 hp is a workhorse.

Thanks... I will check things out. I am very confused about how I can
make a higher HP grinder (say 2 HP). Basically, I cannot find shaft
adapters. I do not want to make one myself for safety reasons, I would
rather buy one from a company that has been making them for years and
knows all the gotchas.


Ok First off don't let the guys safety ranting scare you away. I've
watched you enough to know that you learn from what ever advise you
get and making the arbor is not beyond your capability or tooling (you
do still have the lathe right) just your knowledge. Well that's easily
correctable right here. I feel this is a perfect learning project for
someone to make on a lathe. It covers all the basic operations you
need to know for proper lathe operations.

Second I still go with the belt recommendation from earlier but if
you insist on a straight arbor then let's go through the steps of
making one.

First things first. Since you're wanting to mount such a big wheel
on this arbor start with at least a piece of 1 1/4" stock 1 3/8" or
even 1 1/2" would be better. I like to see a minimum of 1/4" wall on a
socket like this with more being better but be sure to at least have
3/16" wall.

You need to drill and BORE the socket that slips over the shaft of
the motor. Just drilling will not give you the size and straightness
you need for this hole. Look at this step as a good piece to learn
this process. If you want you can use pieces of scrap pipe to practice
boring to size. You will need to know how to do this if you're going
to many projects on a lathe so it's time to learn it. If you have any
questions there's more than enough people on this forum willing to
answer them. In fact the real problem is that the variety of answers
can be overwhelming to a beginner.

The main things I'm concerned about on this part is to make the hole
at least 2 times the diameter deep with 3 times being a better figure.

Be sure the stock is running true when you do the boring and if it
isn't then take a light cut across the outside of the socket area till
it is running true. This is so that you can be sure you're running
true with the socket when you turn it around for the other operations.

Make the socket size to maybe 0.002" oversize of the shaft. Size is
better but you can get by with a slight bit of oversize before the
shaft doesn't run true enough to use without vibration.

Put 4 setscrews in the socket when you get to that part of the
operation. Two inline with the keyway and two more 90deg around from
the first two. Put one about 1/2" from the end of the bore and another
about 1/2" from the outside end of the socket. Repeat with the other
two.

The next lathe operation is the turning of the shaft for the
grinding wheel. You need to turn this to size or a little under. Again
here size is better but 0.002" or even 0.003" under isn't going to
kill you. You'll have to true the wheel after getting it mounted
anyway. You need to be sure and leave at least 1/4" and I'd prefer
more like 1/2" - 3/4" of the adapter full size between the bottom of
the bore and the socket and the square shoulder you'll leave at the
end of turning the shaft down. If you get to close to the socket then
there won't be enough metal to be strong enough for safety. Be sure
that the shoulder you leave is faced square and straight since this
will be what makes the wheel run true. I'd recommend you make this 1"
dia since that's the standard size for most grinding wheels without
the use of bushings. It needs to be long enough for the width grinding
wheel you intend to use plus two washers, and a nut. Add at least 1/2"
to this figure for future expansion.

Now we get to the slightly tricky part. You need to thread the arbor
for the nut. The best way to do this is to cut the threads on the
lathe. Again this is something you can and should practice. It will
turn into a valuable skill later on. Don't thread all the way to the
shoulder. Figure out the thinnest grinding wheel you'll likely use and
add the thickness of one washer to figure out what length should be
left unthreaded. I'd make them right hand for easier access to nuts.
Just be sure to mount the motor so that the arbor is sticking out the
right hand side as you're looking at it to make sure the nut won't
unscrew when you use it.

Now you need to make the washers. These are important as was brought
up before. They need to be sized to the size grinding wheel you intend
to use. Probably around 3"-4" dia in this case. I'd start with at
least 3/8" thickness. You need to face one side flat. Then you can
mount them one at a time in the arbor itself with a piece of pipe
that's been faced square on both ends between the nut and the washer.
You can then face the other side straight as far as you can before
hitting the pipe. If you want you can also under cut the inner portion
leaving about a 1/4"-3/8" wide portion to contact the wheel at this
time. Once that's done to both you'll need to chuck the washers backup
to face off the tit in the middle that was left because of the pipe.
Doing it this way will make sure that the washers run true to the
arbor.

If you want you can taper the outside of the washers while they're
on the arbor. At the very least you should round the corner that's
away from the wheel.

This should get you started anyway. I'm sure there will be many
people chiming in with good advise and or horror stories. Don't let
the horror stories scare you away. They're good advise as well about
what not to do.



Wayne Cook
Shamrock, TX
http://members.dslextreme.com/users/waynecook/index.htm

On Mon, 22 Aug 2005 03:56:36 GMT, Ignoramus15893
wrote:

Thanks Wayne, your post makes sense 100%. I saved it and will print it
out if I ever get to this point. Meanwhile, I will also explore belt
drive as a possibility. Here, I can buy appropriate pipe or threaded
rod and be quite safe and happy. All I will need is pillow block
bearings and shaft and pulleys. That could be a better long term
solution, although possibly more expensive and time consuming.


It would be more expensive but more useful in the long run. Threaded
rod is ok but not the best. Just be sure and double nut the left hand
wheel if you use threaded rod. I built one that way a long time ago
before I ever had a lathe. Again 1" is a good size though 3/4" would
cost less and be good enough.

Actually I think it's the wheel guards that are going to be more of
a problem for you without welding capability.

Wayne Cook
Shamrock, TX
http://members.dslextreme.com/users/waynecook/index.htm

Skip the Harbor Freight wheels. They are crap.

I bought a Norton 60 grit wheel for one side of my 2HP
Harbor Freight grinder and a 10" buffing wheel for the other
side.

Night and day difference in quality of grind and how much
material was being taken off. Needed a lot less pressure to
do the same amount of grinding.

I have two HF wheels I'll sell you. I keep them on a shelf
in case I somehow destroy the Norton and need an immediate
spare.

Bart D. Hull

Tempe, Arizona

Check http://www.inficad.com/~bdhull/engine.html
for my Subaru Engine Conversion
Check http://www.inficad.com/~bdhull/fuselage.html
for Tango II I'm building.

Remove -nospam to reply via email.

Ignoramus15893 wrote:
On Sun, 21 Aug 2005 14:42:06 GMT, Tom Gardner wrote:

"Ignoramus15775" wrote in message
. ..

Got a 1/2 HP single phase motor today (totaly enclosed) for $2. 5/8"
shaft. I would like to make a grinder out of it, but I am not sure how
1750 RPM works out for 8" wheels. I would buy wheels at Harbor
Freight. Is 1750 RPM about right for these wheels? Is 1/2HP a sensible
horsepower?

thanks

i

Don't put a whole lot of eggs in this basket. My 10" is powered a little on
the lite side at 5 hp. I forget the speed but is belt driven faster than
the motor. What do you want to do, sharpen your golf tees? However, a 6"
wheel on a belt driven arbor with 1/2 hp is a workhorse.


Thanks... I will check things out. I am very confused about how I can
make a higher HP grinder (say 2 HP). Basically, I cannot find shaft
adapters. I do not want to make one myself for safety reasons, I would
rather buy one from a company that has been making them for years and
knows all the gotchas.

i