Working on a project that looks like it will require a CNC
router. 5'x10' table, x-y with plunge
z will work. Plastic sheet, around 40 ft. tool path,
20,000-30,000 pcs per year.

There are a LOT of CNC router tables out there!!!! A quick
search turns up Shop-bot,
Shop Sabre, Warthog, Multi-cam, and a bunch of others. All
of them seem to indicate
that they are the best.

Anybody have a favorite? Any of them to avoid like the
plague? Any sources for good used machines? We will go
new--looks like around 20K will be a good start---but a
couple of
solid 5-10K used machines sitting face-to-face has some
appeal.

Thanks,

Bill

--Check, too at makezine.com and instructables.com for folks who
have rolled their own and posted how-tos..

--
"Steamboat Ed" Haas : Whatever happened
Hacking the Trailing Edge! : to Tom Nelson?
www.nmpproducts.com
---Decks a-wash in a sea of words---

"BillM" fired this volley in news:SrFaj.8097
$7I.6072@trndny09:
Anybody have a favorite? Any of them to avoid like the
plague?


I won't call it a "favorite", because I've never used any other; but I
helped one of my vendors set up a 5x9 Shop Sabre.

The learning curve was a little steep for a couple of guys who'd never
done CNC routing before, but the machine is a rock, capable of high-speed
continuous work in a production environment.

About the only thing that was a shock to me was that the vacuum blower is
a 20HP unit, and they maintain that nothing smaller will do for that size
table. We had to have Tony's garage re-mained for 400amp service to
handle the shop sabre, two large radial-arm drill presses, and four 2HP
table saws (and still be able to run his house).

On the subject of that vacuum, though: It was highly interesting that
the way they work it, a waste sheet of low-density particle board becomes
a "filter" for the vacuum. It literally sucks enough air through a 1/2"
sheet of particle board to stick the work down HARD.

Not knowing any other machines, I cannot say if others are better, but
I'd bet a real business on the Shop Sabre.

A warning -- if you think you need an indexable head, order it up-front.
It's almost impossible - and costly - to re-fit a unit with an indexable
head after the fact. Tony needed to add a straight-cut saw to his
machine after he'd learned enough to know he needed it. It cost him $5K
for the parts and to send Shop Sabre techs to his place to do the work
on-site. It would have been only a $3K part, factory-installed.

LLoyd

On Dec 20, 6:22 pm, "BillM" wrote:
Working on a project that looks like it will require a CNC
router. 5'x10' table, x-y with plunge
z will work. Plastic sheet, around 40 ft. tool path,
20,000-30,000 pcs per year.
Snip ...
We will go
new--looks like around 20K will be a good start---
Snip...

LLoyd had a good point about the vacuum pump. If you are using a
universal spoil board, and are using the whole 5 x 10 table to nest a
number of relatively small parts, a suitable pump alone will cost a
large fraction of $20K. I used to run a CNC thing* that had a 5x10'
table and a 10hp side channel blower (ring compressor) and we could
rarely use the whole table, we usually had to mask off 3/4 or so of
it. If the individual parts are large it is less of an issue.

On the other hand if you are making the same part over and over, you
might used dedicated gasketed fixture that could work with a much
smaller pump.

I've never actually used one, but I'm fairly impressed by C.R.
Onsrude's machines, I lobbied constantly for one but it never did any
good, however, you'd probably be looking at 10 times the $20k you
mentioned, for a 5 x 10' machine with a 10-15HP spindle, tool changer
and vacuum system. But then 20,000 to 30,000 pieces per year is a fair
number.

You don't say what sort of plastic you are using, but lasers are
popular for acrylic.

* The machine was a Knongsberg sample maker (about $150k, you don't
want one), the sales people called it a CNC router, but it was really
a fancy plotter that had an engraving spindle on it, was a pretty nice
spindle though, a Kavo 60krpm brushless unit, but only 1kw and a 6mm
collet, If we had had a 10hp spindle holding a 1/2 bit I suspect hold
down would be even more of a problem

Jay

"Bob's my cat" wrote in message
...
On Dec 20, 6:22 pm, "BillM" wrote:
Working on a project that looks like it will require a
CNC
router. 5'x10' table, x-y with plunge
z will work. Plastic sheet, around 40 ft. tool path,
20,000-30,000 pcs per year.
Snip ...
We will go
new--looks like around 20K will be a good start---
Snip...

LLoyd had a good point about the vacuum pump. If you are
using a
universal spoil board, and are using the whole 5 x 10
table to nest a
number of relatively small parts, a suitable pump alone
will cost a
large fraction of $20K. I used to run a CNC thing* that
had a 5x10'
table and a 10hp side channel blower (ring compressor)
and we could
rarely use the whole table, we usually had to mask off 3/4
or so of
it. If the individual parts are large it is less of an
issue.

On the other hand if you are making the same part over and
over, you
might used dedicated gasketed fixture that could work with
a much
smaller pump.

I've never actually used one, but I'm fairly impressed by
C.R.
Onsrude's machines, I lobbied constantly for one but it
never did any
good, however, you'd probably be looking at 10 times the
$20k you
mentioned, for a 5 x 10' machine with a 10-15HP spindle,
tool changer
and vacuum system. But then 20,000 to 30,000 pieces per
year is a fair
number.

You don't say what sort of plastic you are using, but
lasers are
popular for acrylic.

* The machine was a Knongsberg sample maker (about $150k,
you don't
want one), the sales people called it a CNC router, but
it was really
a fancy plotter that had an engraving spindle on it, was a
pretty nice
spindle though, a Kavo 60krpm brushless unit, but only 1kw
and a 6mm
collet, If we had had a 10hp spindle holding a 1/2 bit I
suspect hold
down would be even more of a problem

Jay

Thanks Lloyd and Jay.

Been doing a little Googling and there appear to be an
infinite number of CNC
router manufacturers. At least I haven't found the end of
the list yet!

The bottom of the line C.R. Onsrud looks like a
dream---maybe if the project takes off
and we go to a multiple machine line, but the bucks aren't
there now unless I can
find a good used one. Probably a better machine used than
half of the cheaper ones
brand new.

Vacuum---Part of the business is rotary thermoforming. I
have 2 10hp vac pumps
available. Was figuring on using one or both for the vac
table. The current project
will use 4'x8' and 5'x10' sheets of plastic, so I'm probably
OK on vacuum. Plastic
is probably going to be LDPE sheet in the .050"-.065" range.
Probably not something
a laser would work well on.

"BillM" fired this volley in newszQaj.72$we6.43
@trndny09:
OK on vacuum. Plastic
is probably going to be LDPE sheet in the .050"-.065" range.
Probably not something
a laser would work well on.


WARNING, Will Robinson; WARNING!

LDPE and HDPE are _N_A_S_T_Y_ to route on the CNC machine! It can be
done with very special flighting on the bits, but it's a nightmare with
regular woodworking bits. The top edges flay and form burrs that cannot
be removed except manually or by a separate top-finishing pass (doubling
or tripling your route-path time).

If you have not yet tried these materials in such a rig, I'd suggest you
find someone else who's CNC'ing the material on a similar machine, first,
and get some pointers.

We tried it... Tony gave up before I would have, but I didn't blame him
much.

LLoyd

"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote
in message
. 3.70...
"BillM" fired this volley in
newszQaj.72$we6.43
@trndny09:
OK on vacuum. Plastic
is probably going to be LDPE sheet in the .050"-.065"
range.
Probably not something
a laser would work well on.


WARNING, Will Robinson; WARNING!

LDPE and HDPE are _N_A_S_T_Y_ to route on the CNC machine!
It can be
done with very special flighting on the bits, but it's a
nightmare with
regular woodworking bits. The top edges flay and form
burrs that cannot
be removed except manually or by a separate top-finishing
pass (doubling
or tripling your route-path time).

If you have not yet tried these materials in such a rig,
I'd suggest you
find someone else who's CNC'ing the material on a similar
machine, first,
and get some pointers.

We tried it... Tony gave up before I would have, but I
didn't blame him
much.

LLoyd

Well----we aren't totally locked in on the material yet!!!
This is kind of a disposable
part. Probably going cheap high re-grind sheet of some
sort. I hand cut a few
prototypes, got a check-off on the next step, so we are in
prototype CNC mode now.

You want to try routing something nasty? Try foam/ABS
laminate. Has kind of a leather
like appearance. Used in dental equipment. Onsrud single
flute spiral down cut carbide,
and a S-L-O-W feed rate. Drives my guys nuts---they don't
like to move that slow.

Bill

Plastic is probably going to be LDPE sheet in the .050"-.065" range.

I don't know what your part(s) look like or how many different ones
you have, but have you considered die cutting?

Maybe you do want a Kongsberg after all( http://www.esko.com/Web/site.aspx?p=579
), they are primarily knife cutters, the router spindle is sort of an
after though. We never cut LDPE on ours, but we did cut modified
styrene about that thick (even thicker with multiple passes) with a
knife blade The styrene is harder than LDPE, and was really a bit
much to knife cut, but the stuff had photographic prints laminated to
it and paper doesn't route well (but try telling the sales people
that)
An advantage to knife cutting is that there is virtually no kerf for
the vacuum to leak though and there is no place for parts to slide. On
the other hand small holes are a problem. The machines are expensive
though, but we had the "i-cut" version with an over priced optical
registration system (plus the router spindle was about a $20K
upgrade !), so a basic knife cutting machine would be a lot less than
the $150K I mentioned before.

"Bob's my cat" wrote in message
...
Plastic is probably going to be LDPE sheet in the
.050"-.065" range.

I don't know what your part(s) look like or how many
different ones
you have, but have you considered die cutting?

Yes, we did consider die cutting. We have a supplier
fairly close that does very nice
steel rule dies, and they would probably work fine. We have
5 different sizes of
product, and the possibility of using the router to do some
mold prototyping for the
thermoformers tipped the scale in favor of the router.

Bill