Re: Rope turnings in wood.

this thread got buried in my spam folder.
yes it did come off a little terse. my question was about electronics and stepper drives. I have been in the woodworking business for all of my life starting out in my fathers shop picking bobbers out of mounds of sawdust as they were being produced. I am aware and familiar with the forces, techniques and equipment. I have done twisted turnings with a router mounted on the cross feed and also with a shaper spindle mounted on the cross feed. I also mount a skill saw on the cross feed for gross removal on large turnings. here is a couple links to some vids of one of my lathes.

http://i1.ytimg.com/vi/xp39LBNmKZ4/default.jpg

and

http://i3.ytimg.com/vi/Z1sf00vxB3M/default.jpg

I have done "ropes" in the past with a mechanical linkage from the saddle(carriage, apron) to the spindle(headstock) using a shaper spindle mounted on the cross feed and angled to the turning at the proper pitch. This system doesnt work with tapered or columns of varying diameters because the architectural ratios are lost. The grooves are the same width but the space between them varies. I have a solution to this but it goes part and parcel with my original question. mechanically this was time consuming and took a great deal of hardware in comparison to what I think would be needed for using a linked system of steppers.

Hope this helps.

Roger

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Roland Jollivet <Roland.Jollivet@...> wrote:
>
> I must say, this does sound confusing to me too. You need to use the correct
> terms for the axes. Lathe spindle or router spindle. Is there a router?
>
> Are you saying you want to turn the wood Slowly.. in the lathe chuck, and do
> a cut? And so you need a high power motor?
>
> That's crazy.(if I understand it correctly) because the cutter will simply
> bite and the finish will be terrible.
>
> Always use a router at 90deg to the Z axis. Now you could feed it with a
> smallish stepper.
> If the Z and X are stepper driven, a G01 X100 Z5000, which is a 'straight
> line' will give you a spiral.
>
> I apologise if it all sounds like an insult. I'm just describing different
> scenarios trying to figure it out.
> Also, if you are using a router, the forces involved are so small that it
> may be better to knock up your own machine instead of dusting up the metal
> lathe.
>
> Regards
> Roland
>
>
>
> On 20 January 2010 03:19, oreos40 <oreos40@...> wrote:
>
> >
> >
> > I am new to this group. Some here may have seen me post this question in
> > other groups.
> >
> > I want to do "rope" turnings in wood on a metal lathe. I plan to use shaper
> > blades on a spindle to do the cutting. The foundation of what I want to do
> > is to couple an encoder and a stepper. the encoder will be on the spindle
> > and the stepper will be on the longitudinal(carriage) to drive them in sync.
> > I need a user adjustable ratio to vary the pitch of the twist. yes its a lot
> > like threading but the ELS wont work. it requires a minimum rpm and relies
> > on a count once per rev of the spindle. it becomes less accurate the more
> > coarse the twist of the "rope"(thread) becomes. The second problem I have is
> > one of power. all of the DIY drivers i have been able to find are for less
> > than 7-8. I have a motor rated at 9 amps 2.5 v per phase 900oz/in I figure I
> > will need at least 600oz/ins unless I want to get wild on the reduction side
> > of the drive and then I will have trouble fitting it under the cover on the
> > headstock. I would really rather not go outboard with a drive.I have been to
> > the commercial sites and know I can buy a driver for the motor but that's
> > not why I am here. I have been told to run the motor with reduced power. I
> > need the power that's why I have the motor!
> >
> > Anyone got a handle on the electronic side of this? coupling actually two
> > steppers with a handwheel input and being able to input a ratio between the
> > two outputs for the drivers.
> >
> >
> >
> >
>
>
> [Non-text portions of this message have been removed]
>