Re: [CAD_CAM_EDM_DRO] Rotary to linear translation - an interesting idea.

Jon, I would agree with Bertho. If you take a piece of .010 shim stock and
bend it into a circle, the distance around the circumference will obviously
be greater on the outside than the inside because the inside diameter is
.020 smaller than the O.D. Yet laying the shim flat will produce two equal
lengths. This change in effective diameter will be seen if the shim stock
is partially wrapped around a cylinder(the encoder shaft).

All IMHO

Ward M.

ward@...

----- Original Message -----
From: "Jon Anderson" <janders@...>
To: <CAD_CAM_EDM_DRO@egroups.com>
Sent: Monday, April 10, 2000 1:55 PM
Subject: Re: [CAD_CAM_EDM_DRO] Rotary to linear translation - an interesting
idea.


> Bertho Boman wrote:
> >
> > If the ribbon is wrapped around part of the wheel, that is not true
> > any longer. The inside of the ribbon will compress and outside will
> > stretch to be able to bend. Then presumably, the center line will be
> > what stays the same.
>
> The wheel is going to rotate based upon that part of it that is in
> direct contact with whatever it's rolling against. Wrapping that surface
> partway around the roller is not going to change the diameter of the
> roller. Only changing the radius/diameter is going to alter the
> relationship.
> I once had plans for a home made DRO. It used two disks machined with 45
> degree bevels at the rim. These were held apart by a spacer, with the
> bevels facing each other. This rolled against a round rod. The system
> was calibrated by altering the spacer thickness, moving the disk closer
> or further apart, thus altering the diameter at the point of contact.
> Travdial does the same thing by crowning the edge of the wheel and
> tipping the unit to alter the contact dia.
>
> Jon
>
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