Think prop spinner for a model airplane (is this sounding familiar?)

Assuming that I'm not turning from solid (oh, it sure is!), how hard is
this going to be on a Smithy-sized lathe (7" swing over the ways, cheap
Chinese construction). I'm thinking that I'd use soft aluminum, no
thicker than 50 mil and probably more like 30 or 40.

I've never spun metal before, but I've seen videos so I know I'll be
able to do it with hand-made tools, like a pro, the very first time.

While we're on the subject -- how do you spin a piece that's rounded on
the end? Make a dimple in your sheet, then spin down from there?
You've got to have some surface area on the tail stock, don't you?

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html

On Wed, 15 Jun 2011 11:15:56 -0700, Tim Wescott
wrote:

Think prop spinner for a model airplane (is this sounding familiar?)

Assuming that I'm not turning from solid (oh, it sure is!), how hard is
this going to be on a Smithy-sized lathe (7" swing over the ways, cheap
Chinese construction). I'm thinking that I'd use soft aluminum, no
thicker than 50 mil and probably more like 30 or 40.

I've never spun metal before, but I've seen videos so I know I'll be
able to do it with hand-made tools, like a pro, the very first time.

While we're on the subject -- how do you spin a piece that's rounded on
the end? Make a dimple in your sheet, then spin down from there?
You've got to have some surface area on the tail stock, don't you?
Tim-
You're gonna have to first turn the spud that supports your piece to
the inside shape. Then hold the piece to to the spud with a hardwood
pusher. Push on this pusher with a live center of course. Once the
pusher is spinning cut away enough of it to get enough clearance for
your spinning tools. BTW, pieces that are long in relation to their
diameter are hard to spin. You will probably need to anneal the piece
a couple times. Good Luck.
Eric

wrote in message
...
On Wed, 15 Jun 2011 11:15:56 -0700, Tim Wescott
wrote:

Think prop spinner for a model airplane (is this sounding familiar?)

Assuming that I'm not turning from solid (oh, it sure is!), how hard is
this going to be on a Smithy-sized lathe (7" swing over the ways, cheap
Chinese construction). I'm thinking that I'd use soft aluminum, no
thicker than 50 mil and probably more like 30 or 40.

I've never spun metal before, but I've seen videos so I know I'll be
able to do it with hand-made tools, like a pro, the very first time.

While we're on the subject -- how do you spin a piece that's rounded on
the end? Make a dimple in your sheet, then spin down from there?
You've got to have some surface area on the tail stock, don't you?
Tim-
You're gonna have to first turn the spud that supports your piece to
the inside shape. Then hold the piece to to the spud with a hardwood
pusher. Push on this pusher with a live center of course. Once the
pusher is spinning cut away enough of it to get enough clearance for
your spinning tools. BTW, pieces that are long in relation to their
diameter are hard to spin. You will probably need to anneal the piece
a couple times. Good Luck.
Eric

Full disclosu I've never done this, but I've watched.

A piece like that likely would be much easier to spin if you start with a
tube, and work it down over a steel mandrel. Use a lot of pressure on the
tool (you may need a wheel-type) to shrink it down uniformly as you progress
toward the point.

--
Ed Huntress

On Wed, 15 Jun 2011 15:05:10 -0400, "Ed Huntress"
wrote:


wrote in message
.. .
On Wed, 15 Jun 2011 11:15:56 -0700, Tim Wescott
wrote:

Think prop spinner for a model airplane (is this sounding familiar?)

Assuming that I'm not turning from solid (oh, it sure is!), how hard is
this going to be on a Smithy-sized lathe (7" swing over the ways, cheap
Chinese construction). I'm thinking that I'd use soft aluminum, no
thicker than 50 mil and probably more like 30 or 40.

I've never spun metal before, but I've seen videos so I know I'll be
able to do it with hand-made tools, like a pro, the very first time.

While we're on the subject -- how do you spin a piece that's rounded on
the end? Make a dimple in your sheet, then spin down from there?
You've got to have some surface area on the tail stock, don't you?
Tim-
You're gonna have to first turn the spud that supports your piece to
the inside shape. Then hold the piece to to the spud with a hardwood
pusher. Push on this pusher with a live center of course. Once the
pusher is spinning cut away enough of it to get enough clearance for
your spinning tools. BTW, pieces that are long in relation to their
diameter are hard to spin. You will probably need to anneal the piece
a couple times. Good Luck.
Eric

Full disclosu I've never done this, but I've watched.

A piece like that likely would be much easier to spin if you start with a
tube, and work it down over a steel mandrel. Use a lot of pressure on the
tool (you may need a wheel-type) to shrink it down uniformly as you progress
toward the point.
That would work unless you wanted a closed end, like a prop spinner.
The first time I tried to make a long narrow piece it started to
wrinkle and I was unable to get the wrinkled edge shrunk back down
enough so I ended up cutting the piece short. So instead of a silver
cup about 1 inch dia at the bottom, 1 1/4 at the top, 1 3/4 long, it
ended up about 1 1/4 long. Still made a nice shot cup, just holds a
little less tequila.
Eric

On 6/15/2011 10:15 AM, Tim Wescott wrote:

While we're on the subject -- how do you spin a piece that's rounded on
the end? Make a dimple in your sheet, then spin down from there? You've
got to have some surface area on the tail stock, don't you?

Years ago I watched a metal spinner making teardrop headlight shells for
high quality reproduction pedal cars. It was formed almost completely in
one setup. Now I wasn't close enough to see any real detail, but I did
see a small dimple in the shell when he was done, the pressure pad and
form being shaped to form this dimple when the disk was clamped. The
clamping pad was fairly well relieved to allow tool access. He spent
what seemed like a long time getting the metal started forming, then all
of a sudden, he zipped along and got 80+% of the shaping done in
seconds! Some back and forth work to smooth out the ridges, then the
pressure pad was pulled back. At this point, there was sufficient
friction between the shell and the form to hold it, and he finished off
the shaping in the region near the end that he couldn't really reach at
the beginning. The owner of the shop explained the dimple was pressed
out in secondary operation.

Be careful about going too thin on material, it often tends to thin out
as you form it.

Another trick I just recalled, he used the main roller tool and a back
tool to form a small and shallow upturned edge on the blanks as a first
step after clamping. Upturned being away from the spindle, toward the
tailstock. What this does is strengthen the rim and helps prevent the
edge of the disk from buckling.

I have no idea if the disks were annealed or not. But I suspect getting
it done as fast as possible helps avoid work hardening the material.

Hope this helps some.


Jon

On Jun 15, 2:15*pm, Tim Wescott wrote:
Think prop spinner for a model airplane (is this sounding familiar?)


Tim Wescott
Wescott Design Serviceshttp://www.wescottdesign.com


How many are you planning on making? It seems to me that you could
make a die set fairly easily to form them. I have no experience with
aluminum, but just used hardwood to make a die set for copper. For
aluminum I expect you would have to use steel.

Dan

On Wed, 15 Jun 2011 11:15:56 -0700, Tim Wescott
wrote:

Think prop spinner for a model airplane (is this sounding familiar?)

Assuming that I'm not turning from solid (oh, it sure is!), how hard is
this going to be on a Smithy-sized lathe (7" swing over the ways, cheap
Chinese construction). I'm thinking that I'd use soft aluminum, no
thicker than 50 mil and probably more like 30 or 40.

I've never spun metal before, but I've seen videos so I know I'll be
able to do it with hand-made tools, like a pro, the very first time.

While we're on the subject -- how do you spin a piece that's rounded on
the end? Make a dimple in your sheet, then spin down from there?
You've got to have some surface area on the tail stock, don't you?


We build spinning machines for all sorts of applications.
What you are attempting will take lots of trail and error for sure.
Here is a link of a spinning machine we retrofitted.
http://s32.photobucket.com/albums/d1...nt=Spinvid.mp4

If I can be of help get in touch

db

Tim Wescott wrote:
Think prop spinner for a model airplane (is this sounding familiar?)

Assuming that I'm not turning from solid (oh, it sure is!), how hard
is this going to be on a Smithy-sized lathe (7" swing over the ways,
cheap Chinese construction). I'm thinking that I'd use soft aluminum,
no thicker than 50 mil and probably more like 30 or 40.

I've never spun metal before, but I've seen videos so I know I'll be
able to do it with hand-made tools, like a pro, the very first time.

While we're on the subject -- how do you spin a piece that's rounded
on the end? Make a dimple in your sheet, then spin down from there?
You've got to have some surface area on the tail stock, don't you?

How big is the part?. What you're proposing is quite doable and if
you're willing to have a go can be learned without too much trouble.
When I taught myself to spin, about 1997, there was not that much
information on the internet but quite a bit more now. I started with a
prop spinner shaped part, I wouldn't now as there are much easier forms
to start with, but I persevered after destroying my initial couple of
blanks and managed to get a complete part by number 6. The main thing
with a part with a small initial clamping area is to get the metal laid
down properly to support the blank or it'll fatigue and break near the
clamping piece. The laying down of the material onto the spinning chuck
is done on the pass back towards the tailstock. A couple of pieces I've
done of this nature are here
http://www.metal-arts.co.uk/temp/Spinning/spin1.jpg and
http://www.metal-arts.co.uk/temp/Spinning/spin2.jpg . The aluminium one
is easy as that was 1050 and doesn't really seem to work harden, the
brass one was probably 10% spinning and 90% annealing between spinning.