--- In
Homebrew_PCBs@yahoogroups.com, "mikezcnc" <eemikez@c...> wrote:
> Jan, Dave, thanks for commenting.
>
> Dave, I re-read your post five times and to me it was a very
dramatic
> story.
>
> I know from your posts that you are exceptionally qualified on the
> subject. Since you have done so much work, have you considered
> writing down plans and selling them.
I have thought about it, but there is one preresuiquite, and that is
to actually build the thing. For about 5 years, our office was a few
blocks away from an owner run, one-man machine shop. I would stop by
every couple months to get some part or another made and would get
pulled into some sort of project or another. I wired the phones, ran
a computer network for his CNC, upgraded his PC for the CNC, repaired
the contactors on his lathe, hung a cabinet, leveled his large
mill... you know the type of work. need an extra hand and it gets
done. He offered me free run of the shop for the last 6 months
before he retried. I moved and got married, so I was out of luck on
the machining side of things.
I was able to make a couple Z axis for a different drilling machine
so I did get some benifits from the exchange.
> I used to have a T-tech that I should have kept for drilling. Now I
> have a Sherline 5000 that has a very long (7") X but very short Y
> (3"). That is way to short for boards I have in mind. I am looking
> into moving a Z-column behind the base. I posted that message on
CNC
> SHerline butit did not post it- I don't know why. Does it make
sense
> to place that Sherline on a thick and larger base and relocate the
> base of Z behind the original base? That would gain another 3 " and
> overall would work for me. Maybe you heard of that kind of
> modification. Sherline is an unusually rigid machine and I can feel
> it would be great for PCBs. Mike
I am not familiar with the Sherline, but mechanical stability of a
machine is far worse than you might imagine. Put a dia indicator on
your column and chuck up a 1/16 drill bit and drill a small aluminum
part. you will be amazed at how much movement there is on that dial
indicator.
Moving the column back, or the spindle forward will put considderably
more mechanical advantage (or disadvantage) on your column. It would
need some sort of reinforcement. But, that is not a bad thing, nor
hard to do. Almost any type of additional support will add a huge
amount of support and stability.
A quick look at the model 2000 shows that they have a method of
offering a much deeper throat. Considder mounting your mill on a 1/4
steel plate that extends those many inches behind your table. Then
bolt in a couple uprights that are relativly short, but high enough
to allow you to add two 1/4 inch rods to the top of your column on a
45 degree angle. That would offer full table movement and a
considderabley more stable head.
If I was to need a small hobby mill, I'd considder one of those
$199.99 cast iron units from Homier called a drill/mill. or that $699
Mill Drill that is like a Rong-Fu bench mill. I think you could put
your Sherline in a vice on that sucker.
It would offer the ability to do heavy milling, but lacks any Z axis
feed. A CNC converson would be simple to do, but would need heavy
motors to make it work.
Thinking about it, buying one of those 600 pound monsters would allow
me to do the kit plans for a pretty large CNC PCB machine. One
problem is that Homier road shows are few and far between and it is
rare they have the big mills.
Now, if I can only find the time.....
Dave
>
>
>
>
> --- In Homebrew_PCBs@yahoogroups.com, "Dave Mucha"
<dave_mucha@y...>
> wrote:
> > --- In Homebrew_PCBs@yahoogroups.com, "mikezcnc" <eemikez@c...>
> wrote:
> > > Dave, thank you for commenting. Have a look at this:
> > > www.easgmbh.de/images/Bgs60.jpg I think it was about 1200 euro.
> > >
> > > How hard would it be to make something like that? Parts seem to
> be
> > > mostly from a catalog. I don't see the Y-axis motor, maybe it's
> > > hidden behind the Z... ALso, how to contact Ballendo off list
so
> I
> > > don't irritate Stefan for the n-th time? (is dollar sunken so
> LOW?)
> > >
> > > Mike
> > >
> >
> > Hi Mike,
> >
> > I know and use G-code so an X/Y would be much faster for me to
get
> up
> > to speed with.
> >
> > I just ran thru a design for a 12 x 12 x 2" work envelope
machine.
> > it would use $150.00 worth of mechanical parts in the form of
> > aluminum and ground shaft and such. I figure another $100 for
the
> > electronics, so before I look at steppers and lead screws, I'm up
> to
> > $250.00.
> >
> > Using all-thread and surplus steppers would up the cost to around
> > $300.00 for a unit that is pretty good. Using ACME screws would
> not
> > all too much to the cost, but the big factor would be the machine
> > time to drill and tap all the holes to make the unit stable in
all
> > directions.
> >
> > Since I don't have a milling machine, it would cost me a couple
> > hundred $$ to have all the holes drilled and tapped to get that
> good
> > alignment that would be needed to eliminate poor fits.
> >
> > Then assembly of the unit would be a few more hours.
> >
> > IF (really big IF) all the motions went perfectly and I got a
great
> > deal on the machining and all the parts fit flawlessly I still
> would
> > be over $500.00 for the machine.
> >
> > The head on the Z axis is still a question. There are more than
a
> > few ways to actuate that, but since I'm mostly concerned with
> > drilling, it is of little importance.
> >
> > I did a design recently for a proposal and used ballscrews and
> linear
> > rails and the cost was close to $2,000.00 for a 12 x 18 x 4 work
> > envelope.
> >
> > If I had access to a milling machine, I would be done already,
but
> my
> > access retired last year and moved on to those things old
> machinests
> > do when they retire.
> >
> > I had thought of trying to barter with someone who has a mill for
a
> > machine, but that is hard to do. Most people who have a mill
don't
> > need PCB's and already to the machining.
> >
> > My Neighbor has a Bridgeport but it is in stoarage as he has no
> place
> > to put it. When that gets mounted, then I will make my machine
as
> I
> > can trade machining time for use. He's an auto mechanic and I
> spent
> > 5 years working in a machine shop.
> >
> > Dave