Handwheels on a retrofit? Why!? was Re: software questions DRO

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Kim Lux <lux@d...> wrote:

> There are two ways to have handwheels on a CNC machine: mechanical,

ie

> connected directly to the ballscrew or electronic, ie encoder wheels
> that connect to the software. Of the two, the latter is highly,

highly

> desirable.
>
> The advantages of the encoder wheels over manual feedwheels are:
>
> a) The CNC software becomes a DRO and all the benefits that go along
> with that become available. No more watching the collars on the
> feedwheels and counting ticks !
>
> b) You've still got access to G code commands to move: G0 x2 y1,

etc.

> Precisely moving an axis to a specific point is VERY time

consuming.

> With electronic feedwheels, you get both manual and computer

movement

> options.
>
> c) You've still got access to G code commands to machine things: g1

x2

> f4, g78 z-1 i-0.1 f2, etc. g77 y2.0 z-1 i-0.025 f4, etc You can't
> imagine how handy this is.
>
> d) The servos hold the ballscrews steady while stationary.
>
> e) Selectable resolution on the handwheel. We are running 100

count per

> rev quadrature encoders from Digikey (Bourns, $50 ea), giving us 400
> "jogs" per rev. With a jog resolution of 0.001", we are moving .4
> inches per rev. At 0.0005", we are moving .2 inches per rev. At
> 0.0001", we are moving 40 thou per rev. This is great for setting

up

> tool offsets.
>
> f) The feedwheels are away from the lathe and mill and moveable if
> desired. When we are machining with heavy cuts, there is coolant

and

> metal chips flying everywhere. It is nice to be able to stand

aside,

> protected from the debris.
>
> If you use feedwheels, I recommend one wheel per axis as switching

back

> and forth between axes is cumbersome. (Some software allows only 1
> feedwheel for all the axes.) We've modified the TurboCNC source

code to

> allow 3 simultaneous axes and it works great.
>
>
>
> Kim
>

I do agree with what you have said there are however
other points of view depending on the circumstance.
Having worked with large cnc machinery I know the
remote pendant with the feedwheel is nice and even
nessesary to operate them.
On small compact machinery where everything is within
easy reach it is not required or as useful.
The retrofit of a smaller mill/drill I am doing now
will have the option of mounting the original handwheels
back on.
My reason for this is reliability if anything with
the cnc controller drivers or motors goes wrong I will
still be able to use the mill, cheap and simple.
Durring manual operation the none moving axes's will be
locked acme screws or not, anybody machining manualy
with a unlocked axes would take a chance of things moving
unintentionaly anyway.
So if you have the $$$$ go for the electronic feedwheels.
If your building on the cheap try to keep your options open.
Good Luck