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.
"BillM" fired this volley in news:SrFaj.8097 $7I.6072@trndny09:
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 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 $20k you mentioned, for a 5 x 10' machine with a 10-15HP spindle, tool changer and vacuum system. But then 20,000 to 30,000 pieces per year is a fair number.
You don't say what sort of plastic you are using, but lasers are popular for acrylic.
The machine was a Knongsberg sample maker (about 0k, you don't want one), the sales people called it a CNC router, but it was really a fancy plotter that had an engraving spindle on it, was a pretty nice spindle though, a Kavo 60krpm brushless unit, but only 1kw and a 6mm collet, If we had had a 10hp spindle holding a 1/2 bit I suspect hold down would be even more of a problem
Been doing a little Googling and there appear to be an infinite number of CNC router manufacturers. At least I haven't found the end of the list yet!
The bottom of the line C.R. Onsrud looks like a dream---maybe if the project takes off and we go to a multiple machine line, but the bucks aren't there now unless I can find a good used one. Probably a better machine used than half of the cheaper ones brand new.
Vacuum---Part of the business is rotary thermoforming. I have 2 10hp vac pumps available. Was figuring on using one or both for the vac table. The current project will use 4'x8' and 5'x10' sheets of plastic, so I'm probably OK on vacuum. Plastic is probably going to be LDPE sheet in the .050"-.065" range. Probably not something a laser would work well on.
"BillM" fired this volley in news:pzQaj.72$we6.43 @trndny09:
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 E. Sponenburgh" wrote in message news:Xns9A0D68FF03546lloydspmindspringcom@216.168.3.70...
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.
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(
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, 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.
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.
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