I made a couple of small pulleys in Al over the weekend on my mini-
lathe. 1" OD, 1/8" x 1/2" bosses on either end, 1/4" belt bed
recessed 3/32" with 1/16" walls to hold the belt in place. They work
ok, but I can't help thinking it took too long and made too much
noise!

How would you sequence the various cuts to make such an item? What
tools would you use? I used a regular LH cutting tool to facing,
skimming and cutting the first boss, then a combination of grooving
and parting tools for the rest.

TIA,
Chris

On Feb 17, 10:40*am, wrote:
I made a couple of small pulleys in Al over the weekend on my mini-
lathe. 1" OD, 1/8" x 1/2" bosses on either end, 1/4" belt bed
recessed 3/32" with 1/16" walls to hold the belt in place. They work
ok, but I can't help thinking it took too long and made too much
noise!

How would you sequence the various cuts to make such an item? What
tools would you use? I used a regular LH cutting tool to facing,
skimming and cutting the first boss, then a combination of grooving
and parting tools for the rest.

TIA,
Chris

For that size I'd drill and bore the hole, cut the groove and face one
end of the bar, and part it off. When the set was done I'd reverse the
chuck top jaws and face the other sides. (Actually I'd use a 1"
collet).

I drill deep but bore only a little past the width of each blank
because a long, thin boring bar deflects easily. I use a rule and a
magnifier for low-accuracy jobs like pulleys rather than tediously
setting the parting tool accurate to 0.001".

If I need accurate thickness I trim them on the mandrel. Take a light
cut, measure, move the 29 degree compound twice the excess. Sin 30 =
0.5.

Pulleys too large to chuck are harder. If possible I drill extra holes
and drive from a faceplate. They are easiest to remove to reverse or
check when they are pressed onto a mandrel, most solid when screwed to
the faceplate. A compromise is to screw the blank on, rough the OD and
bore the ID, then press it onto a mandrel for the finishing cuts.

If you don't have a mandrel the right size, you can tighten a coupling
nut or a stack of hex nuts onto a full-thread bolt and turn to fit.
Clamp the blank between the head and a nut, with some tubing or a
socket as a spacer if necessary.

Jim Wilkins

Too much noise? Seems you were running the parting tool too fast. I
just made one 1 1/2" dia and parted the groove using the parting tool
to the bottom depth. I swung the tool post to 20 deg and cut the right
side face with the parting tool to bottom of the groove. Then swung
the tool post over to the other side to 20 deg and finished the groove
on the left side.
I made a 1 1/2" pulley with a 9/16" hole all in one setup. The groove
I cut was 1/2 wide for an A belt. I bored the hole last. Took me about
an hour and a half.
I used a 16" South Bend lathe. Probably makes a big difference.
Dan


On Tue, 17 Feb 2009 07:40:35 -0800 (PST), wrote:

I made a couple of small pulleys in Al over the weekend on my mini-
lathe. 1" OD, 1/8" x 1/2" bosses on either end, 1/4" belt bed
recessed 3/32" with 1/16" walls to hold the belt in place. They work
ok, but I can't help thinking it took too long and made too much
noise!

How would you sequence the various cuts to make such an item? What
tools would you use? I used a regular LH cutting tool to facing,
skimming and cutting the first boss, then a combination of grooving
and parting tools for the rest.

TIA,
Chris

On 2009-02-17, wrote:
I made a couple of small pulleys in Al over the weekend on my mini-
lathe. 1" OD, 1/8" x 1/2" bosses on either end, 1/4" belt bed
recessed 3/32" with 1/16" walls to hold the belt in place.

Hmm ... this sounds as though you are making a pulley for flat
belts, not V-belts. Is this the case?

If so -- the more common way to hold the belts centered is to
skip the flanges entirely, and to simply crown the areas which you
probably left flat. It would look something like this (within the
limits of ASCII graphics):
_ __ _
_____| | | |_____
(_____ | | _____)
|_|__|_|

With two hubs. The parens are the closest that I can come to
representing a crown.

The crown causes the belt to walk toward the highest spot.
You'll find similar techniques used to keep a belt on a belt sander.

They work
ok, but I can't help thinking it took too long and made too much
noise!

:-)

How would you sequence the various cuts to make such an item? What
tools would you use? I used a regular LH cutting tool

O.K. What are you calling a LH cutting tool? One which cuts on
the left side of the tool, or one designed for cutting on the left side
of the workpiece? The latter is the standard usage, FWIW, so a LH tool
cuts on its own right.

to facing,
skimming and cutting the first boss, then a combination of grooving
and parting tools for the rest.

Well ... first off -- I would go for a crown instead of a square
groove with flanges. It provides less wear on the edges of the belt.

Now -- I would face and shape the first hub and bore with the
stock held in the chuck. Part it off and turn it over to face and
produce the hub on that side.

I would then mount it between centers on a very shallow taper
arbor (I think about 0.002"/foot), and turn the OD and form the crown.
I would probably use a file to form the crown, unless I had a radii
turning fixture. If you have some radius gauges, aim for something like
a 5/16" or 3/8" radius for a 1/4" wide belt which should give plenty of
crown. You might be able to live with a larger radius.

Turning and filing the crown on an arbor between centers assures
tha the pulley's OD is concentric with the bore.

If you're expecting to spin at high speeds, you probably want to
true up the hubs and the facing while it is on the arbor, because there
could be a bit of off-center from when you flipped it and gripped it in
the chuck after parting.

Now to see what others have suggested.

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On Feb 17, 11:02*pm, "DoN. Nichols" wrote:
giant snip

Changed my security setting, lost my ability to post!

Yes, flat belts. I've seen/heard of the crowned pulleys (leather
belts and overhead shafts, right?), didn't occur to me to use them.

Yep, I'm wrong about the LH tool. I checked in my book and I am using
a RH tool.

The application is the link between the windshaft and alternator on a
v. small wind turbine. Shouldn't get really high speeds unless the
wind picks up something awful.

Thanks for all the advice. I'll apply it on the next one!

Chris

On Feb 18, 6:32*pm, wrote:
On Feb 17, 11:02*pm, "DoN. Nichols" wrote:

giant snip

Changed my security setting, lost my ability to post!

Yes, flat belts. *I've seen/heard of the crowned pulleys (leather
belts and overhead shafts, right?), didn't occur to me to use them.

Yep, I'm wrong about the LH tool. *I checked in my book and I am using
a RH tool.

The application is the link between the windshaft and alternator on a
v. small wind turbine. *Shouldn't get really high speeds unless the
wind picks up something awful.

Thanks for all the advice. *I'll apply it on the next one!

Chris

You could try bicycle sprockets and plated chain, too.

This photo shows one mounted on a simple hub:
http://picasaweb.google.com/KB1DAL/H...33382447691698

Jim Wilkins