Re: [CAD_CAM_EDM_DRO] not stiff enough!

Don't need to read it again. Just thought I'd "point out" that you little
deflection program isn't much good unless it took into consideration a LOT
of other factors...which I was fully aware of after 30 years in the machine
design business.

Incidently, over at another egroups site we already hashed out those
weld/don't weld and can you /can't you drill and tap those hardened and
ground shaftings.

Yes, you can weld them. Yes, it takes a lot of skill to do it properly
withouot turning them into junk. Yes, you can drill and tap them fairly
easily. To do that you need to do is use a carbide cutter (or a grinder) to
machine down below the surface hardness. After that, you can drill and tap
using ordinary tools because the shafts are soft on the inside.

Another way to splice the shafts would be to machine a hole in one end,
machine the end of the other piece to fit the hole and and join the parts
with a suitable dowel pin.

>Read the post again. :^)
>
>Yes, geometry and materials matter a lot with deflection.

Incidently....I've got a machine designed that's been on the back burner for
sometime.for some time. This machine has two 3/4" diameter rails nearly
eight feet long supported only at the ends. An assembly riding on tewo
other 3/4" diameter shaft running crosswise rides on these shafts. Yes they
will probably deflect under the loads that will be resting on them. How
much I have no idea but since the amount of deflection is irrelevant due to
the machines operating characteristics, I'm not going to bother calculating
them. However, once I get the machine off the back burner and finish
building it, I think I'll measure the actual deflection just out of
curiosity.

>Just trying to find a way for the guy not to have to rebuild his
>machine. Or to try to weld case 60 shaft which would turn it
>into instant junk.
>
>Oh that reminds me.... you can drill a hole in the middle of hardened

case60

>shaft with a carbide spade drill. I do it
>a good bit. One support bolt in the center hooking the shaft
>to a stiff support will reduce deflection four times. Combine
>that with fixed end support and I think the system stiffness
>will be very satisfactory.
>
>Leslie Watts
>L M Watts Furniture