Re: 8" grinding wheels turning at 1750 RPM?
- From: Wayne Cook <wcnews@xxxxxxxxxxxxxx>
- Date: Sun, 21 Aug 2005 22:50:22 -0500
On Mon, 22 Aug 2005 02:03:22 GMT, Ignoramus15893
<ignoramus15893@xxxxxxxxxxxxxxxxxxxx> wrote:
>On Sun, 21 Aug 2005 14:42:06 GMT, Tom Gardner <tom@xxxxxxxxxxxxx> wrote:
>>
>> "Ignoramus15775" <ignoramus15775@xxxxxxxxxxxxxxxxxxxx> wrote in message
>> news:ZKUNe.81110$6N6.9832@xxxxxxxxxxxxxxxxxxxxxxxx
>>> 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
.
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- Re: 8" grinding wheels turning at 1750 RPM?
- From: Tom Gardner
- Re: 8" grinding wheels turning at 1750 RPM?
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