Ping Morris Dovey re CNC wood Lathe

Stay in touch with your progress.

TomNie
> I'm my own worst influence! I made a few drawings and think I'll need
> to build a scaled-down version of one of these things. A three-axis
> (x,r,theta) machine for turning not only round parts; but also for
> routing things like wood forms for watercraft hull and aircraft
> (fuselage and wing) molds...
>
> --
> Morris Dovey
> DeSoto Solar
> DeSoto, Iowa USA
> http://www.iedu.com/DeSoto/JBot.html
>
>

Morris Dovey (in [email protected]) said:

| CW (in [email protected]) said:
|
|| The process you have just described is known as hemstitching.
|| Commonly done on CNC mills.
|
| I'd really like to see this. I struck out on my web searches. Can
| you point you point me at any photos?

Oops! It's making the separately machined edges match up. I've done
that with CNC routing but never knew it had a name.

Thanks!

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto

The process you have just described is known as hemstitching. Commonly done
on CNC mills.

"Morris Dovey" <[email protected]> wrote in message
news:_%[email protected]...
> Morris Dovey (in [email protected]) said:
>
> | Like I said, an interesting project. :-)
>
> I couldn't leave it alone. Last night I got to thinking more about
> this. The more I thought about it, the more the problem became one of
> dealing with the size and mass of the workpiece; and that the best
> solution would be one that required (precision) moving of the least
> mass.
>
> By the time I was ready to call it a day, it appeared to me that the
> best solution would be to position the workpiece inside the machine
> and tell the machine where the "centers" were. A machine capable of
> rotating an x- and z-axis could use trig to displace all cut surfaces
> from the line connecting the those centers.
>
> If an additional reference point were established at each end, the
> workpiece could be turned approximately 180 degrees and the second
> half machined with only a pair of "V" supports - and it would work for
> asymetrical and helical/spiral cutting as well!
>
> The machine would then only need to be "beefy" enough to support
> itself and withstand cutting forces - a very different situation from
> trying to spin a heavy piece of wood at lathe turning speed; and a
> considerable improvement over turning a heavy workpiece even slowly
> with steppers.
>
> The only workpiece movement needed could be done with a fork lift!
>
> --
> Morris Dovey
> DeSoto Solar
> DeSoto, Iowa USA
> http://www.iedu.com/DeSoto
>
>

CW (in [email protected]) said:

| The process you have just described is known as hemstitching.
| Commonly done on CNC mills.

I'd really like to see this. I struck out on my web searches. Can you
point you point me at any photos?

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto

Morris Dovey (in _%[email protected]) said:

|| Like I said, an interesting project. :-)
|
| I couldn't leave it alone.

I'm my own worst influence! I made a few drawings and think I'll need
to build a scaled-down version of one of these things. A three-axis
(x,r,theta) machine for turning not only round parts; but also for
routing things like wood forms for watercraft hull and aircraft
(fuselage and wing) molds...

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto/JBot.html

CW (in [email protected]) said:

| No, actually I can't. Never really looked. If you're in the Seattle
| area, I could arrange a live demonstration.
| Been running some parts for the last three weeks that a major
| feature on it is hemstitched.

I'm halfway across the country from you - my loss. If I ever get out
that way, I'll give you plenty of warning! :-)

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto

Morris Dovey (in [email protected]) said:

| Like I said, an interesting project. :-)

I couldn't leave it alone. Last night I got to thinking more about
this. The more I thought about it, the more the problem became one of
dealing with the size and mass of the workpiece; and that the best
solution would be one that required (precision) moving of the least
mass.

By the time I was ready to call it a day, it appeared to me that the
best solution would be to position the workpiece inside the machine
and tell the machine where the "centers" were. A machine capable of
rotating an x- and z-axis could use trig to displace all cut surfaces
from the line connecting the those centers.

If an additional reference point were established at each end, the
workpiece could be turned approximately 180 degrees and the second
half machined with only a pair of "V" supports - and it would work for
asymetrical and helical/spiral cutting as well!

The machine would then only need to be "beefy" enough to support
itself and withstand cutting forces - a very different situation from
trying to spin a heavy piece of wood at lathe turning speed; and a
considerable improvement over turning a heavy workpiece even slowly
with steppers.

The only workpiece movement needed could be done with a fork lift!

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto

Art Ransom (in [email protected]) said:

| Told that you were involved in CNC. I am close to building a CNC
| wood lathe with 24" swing and 10' between centers.

You're a braver man than I! The CNC part doesn't strike me as being
anywhere near as difficult as meeting the structural requirements for
spinning a chunk of wood that size.

If I needed to build a machine to "turn" something that large, I think
I'd opt to do the turning part with a gang of stepper motors and do
longitudinal CNC routing - an approach that would allow for features
like mortising, fluting (both straight and helical), and production of
non-circular cross sections...

Sounds like an interesting project!

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto

No, actually I can't. Never really looked. If you're in the Seattle area, I
could arrange a live demonstration.
Been running some parts for the last three weeks that a major feature on it
is hemstitched.

"Morris Dovey" <[email protected]> wrote in message
news:[email protected]...
> CW (in [email protected]) said:
>
> | The process you have just described is known as hemstitching.
> | Commonly done on CNC mills.
>
> I'd really like to see this. I struck out on my web searches. Can you
> point you point me at any photos?
>
> --
> Morris Dovey
> DeSoto Solar
> DeSoto, Iowa USA
> http://www.iedu.com/DeSoto
>
>

On Fri, 10 Mar 2006 06:42:19 -0600, "Morris Dovey" <[email protected]> wrote:

>Art Ransom (in [email protected]) said:
>
>| Told that you were involved in CNC. I am close to building a CNC
>| wood lathe with 24" swing and 10' between centers.
>
>You're a braver man than I! The CNC part doesn't strike me as being
>anywhere near as difficult as meeting the structural requirements for
>spinning a chunk of wood that size.
>
>If I needed to build a machine to "turn" something that large, I think
>I'd opt to do the turning part with a gang of stepper motors and do
>longitudinal CNC routing - an approach that would allow for features
>like mortising, fluting (both straight and helical), and production of
>non-circular cross sections...
>
>Sounds like an interesting project!

Good point, Morris...
Maybe a CNC version of that Legacy Milling Machine Bill Grumbine uses?

http://www.enter.net/~ultradad/legacy.html

Mac

https://home.comcast.net/~mac.davis
https://home.comcast.net/~mac.davis/wood_stuff.htm

mac davis (in [email protected]) said:

| Maybe a CNC version of that Legacy Milling Machine Bill Grumbine
| uses?
|
| http://www.enter.net/~ultradad/legacy.html

That comes fairly close. The legacy appears to be an x-y machine, with
the y-axis at a fixed height, which might be a bit restrictive for an
application like Art's.

Keep the long x-axis, dispose of the y-axis altogether, and add a
(vertical) z-axis with just over a foot of travel. Replace the hand
wheels and indexer mechanism with PC-controlled stepper motors; and
you'll have something closer to what I'd imagined.

I think I'd weld up the machine from 4" square steel tubing - the
Legacy's aluminum rails just aren't "beefy" enough to hold that much
mass. The same (80/20?) rails and slides could probably be used if
they were secured to the steel structure - but I'm not sure if they're
available in 10+foot lengths. The ball-type lead screw could be used
if precision isn't a significant factor, or a finer pitch Acme lead
screw could be used if it is.

The challenge would be in arriving at a good balance of torque and
precision to rotate that much mass. An "easy-button" solution would be
a large ring gear driven by however many steppers it'd take (the
larger the ring gear, the greater the available precision).

Like I said, an interesting project. :-)

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto