Re: Why not use threaded rod leadscrews?

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Paul" <paul3507@b...> wrote:

>
> Stainless threaded rod is cheaply available in 1m (39in) lengths.

Stainless is not as slippery as steel. it will have slightly more
friction than a standard steel rod.

If you go this path, chase a die down the lenght. they make
adjustable dies, and you are NOT trying to cut, just verify that the
threads are not damaged.

Then, spin the rod and with a paper towel, use your thumb nail
and 'thread' your nail along the lenght while pressing paper towel
into the thread.

you will feel every irregularity. when you do, stop, look and file.
repeat for the whole lenght.

'leadscrew' is shipped protected. 'all-thread' is dragged on the
ground before being shipped.

Also, you can by different tollerances of taps. by taping your nut
undersized you can get a tigher fit.

AND... by using a pulley tap and a LONG nut you can drastically
reduce backlash.

One thing that always concerns me is heat from spinning too fast.
Since I use a plastic nut it remians a concern.

as for efficencies, I have seen all-thread in the 30% range
ACME in the 60% and ballscrews in the 90%. If you need to spend $$$
for a motor (and driver) that is 3 times larger to compensate for
cheap thread..... your call.

Dave

> I know the V thread profile is not square, not ideal for loads, not
> ideal friction wise, greater wear/backlash problems, not so
> linear.......blah, blah
>
> BUT I can save a *huge* amount of money on a 1mx1m wood router (3ft
> 6in x 3ft 6in). I've been quoted over £100 ($180) for a new 1 meter
> leadscrew which I think is OTT.
>
> Also is there a cost-effective source for rack and pinions? All the
> large 8ftx4ft pro routers use rack and pinions.
>
> -Paul