Re: suggestions for router lead

Hi Ballendo,

nice to see you here again. Where have you been hiding ??
I remeber that you were doing some designing, any sites to show your
work ?


About Grahams situation and leadscrews. I would recommend
considdering a belt drive with a 3:1 on the leadscrew. and go for
slower table speed. that would offer a 2:1 for faster speed and
possibly 1:1 for high speed.

Figure 0.0005 or better resolution on high speed and everything
should be in the right ranges.

one thing about leadscrews, the smaller may be able to pull, but on
the push, the flex may be too great. I had to tension my screw to
compensate for this problem.

Dave



--- In CAD_CAM_EDM_DRO@yahoogroups.com, "ballendo <ballendo@y...>"
<ballendo@y...> wrote:

> Graham,
>
> I have used 1/2 or 3/8 diameter, 10tpi, 2 start for machines of

this

> type. Using a 297/298 type bipolar chopper driver and a 34vDC power
> supply, the top speed is about 100IPM. Using 1/2 stepping drivers,
> the resolution is .0005, which is adequate for most tasks, and

until

> fairly recently was the single most common resolution for cnc

systems.

>
> The steppers were in the 150 oz./in. range: I have used both size

23

> and 34 motors with this setup and gotten similar results. The

spindle

> tool was a woodworking laminate trimmer.
>
> The nuts were Turcite, which is a brand of acetal plastic.
>
> I have used both Ball Screws and Actuators, and Kerk, as suppliers
> with good success. IME, the Kerk nut design is better; but the BSA
> nut is more "available" on short notice. I have described how to
> make "do-it-yourself" anti-backlash nuts in messages in the archive
> of this group.
>
> Hope this helps,
>
> Ballendo
>
> P.S. Your message suggests that you may be considering the axis

which

> moves the table to be a Y axis, when it is properly called the X

axis

> in a bridge design as you have described. Several internet websites
> continue to mislabel machine axes, with resulting confusion for
> everyone.
>
> P.P.S. One such site is the super-tech site, which may be of

interest

> as their minirobo design may be similar to what you have in mind.
> Have a look, but beware of their axis labeling<G>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Graham Stabler

<eexgs@n...>"

> <eexgs@n...> wrote:
> > I am trying to design a small CNC router based around a Dremel or
> > similar. I have decided upon a fixed bridge design with Y axis

on

> > the bed and X,Z on the bridge. I thought that this would give me

a

> > nice stiff machine and maximise the force available from the Y
> > stepper.
> >
> > Anyway, I'm looking into leadscrews. I am considering acme

screws

> > with Delrin nuts but am having a hard time deciding on the lead I
> > should go for. Obviously more lead gives greater speed but
> > resolution suffers.
> >
> > I want a reasonable swift machine that will do some basic pcb
> > milling, ply part cutting and mould making. The design is based

on

> > an A4 paper sized bed and is designed to be sturdy as I intend to
> use
> > quite a lot of 1/2" ali in the construction. Steppers a 200 step
> > bipolars.
> >
> > Cheers,
> >
> > Graham Stabler
> > Nottingham, England.