Speed/quality question for PRS users

[richards]

Now that the PRS-Standard and the PRS-Alpha machines have been in the workplace for a few months, what kind of speeds are you using? If you cut MDF, I would be interested in the move speed, the type of cutter, the cutter depth per pass, the router/spindle used and the 'quality' of the cut. The quality parameter is totally subjective, but when I try for a quality cut, I use the highest move speed that maintains the surface finish of slower speeds.

I just visited a shop that is very interested in the PRS machines, but they don't know which model to buy - and like any business, if the PRS-Standard does the job, they would buy it instead of the PRS-Alpha. But they need some data.

Please share your experience.

[coolhammerman]

Mike:
I purchased a low hour used machine vintage 2003 PRT 48x96 with PC 7518 Router about 1 year ago. It has 2 X, 2 Y and 1 Z motors with Alpha running gear (X, Y and Z Cars). I upgraded to the 4G Gecko drive earlier this year and the difference was dramatic.

I cut primarily BC 3/4" plywood with 1/4" two flute solid carbide (not spiral-straight) 22,000 rpm, but lately have been cutting MDF also. Before 4G upgrade, Jog was 4ips cut @ 2.5. Quality was ok for what I needed. Sign V carving in Corian was not great. In fact only ok for gifts. I never tried to sell any of these due to the roughness. (Part of that was me as a new Botter).

After 4G upgrade, in BC Jog is 8ips cut is very comfortable @ 4ips, but will also do pretty good at 5ips. However, sometimes loses a step @ 5ips so I usually go with 4ips.

MDF cutout @ 4ips, V-Carve at 3ips still jog @ 8ips. Detail is fabulous and cut quality is very good without a final pass allowance.

Cut depth is always ~.250" and I make 3 passes.

More important that a file finish running without losing a step so I probably run slower than possible, but finish successfully 99% of the time.
Examples of the type of work I do at these speeds:
BC Plywood finished product www.wildandwoody.com (http://www.wildandwoody.com)
MDF finished product www.coolhammers.com (http://www.coolhammers.com)

Good Luck,
Ron

[Gary Campbell]

Mike..
I really wish I could help you here, as I know I owe you! We dont cut any MDF in our shop, but I can give you plywood numbers from our limited experience. I feel we look at our cutting VERY conservatively as most of our materials are 5 to 10 times the sheet costs of MDF and quality of cut will always over ride production. 3/4" mtls with 1/4 or 3/8 bits = 8-10 ips one pass. 1/2" materials could be cut faster but we have had a few get slid around on our vac table as more cut grooves appear. I have a PRSalpha with a 4hp HSD spindle and havnt found anything that even causes the machine any sweat. Including a mistaken 12 ips jog 1" deep thru Paperstone @ 15,000 rpm.
Gary

[richards]

Ron and Gary, thanks for the input. I took a look at both of your web sites and I am impressed with your work!

If I can get about a dozen or so more responses, it will be easier to get the 'big picture' view of how the machines perform in different situations. This is not a request to see who's cutting the fastest or the deepest, it's just a simple request to see what settings some of you would typically use to do normal production.

[Gary Campbell]

Mike...
Our "normal production" would be cutting teak, walnut or other hardwood pieces that couldnt be cut on a saw or edge cut on a shaper. Most of these are done at slower speeds that the sheet cutting, as none of the sheet edges end up being exposed. The majority of these are curved with rabbets and dadoes that used to take forever, or were impossible using hand held tools. Our toolpathing is done with quality of cut as the priority.
Gary

[boet]

Mike for what it is worth. I did a job of cutting veneered panels 860x1604mm 13mm MDF 425 slots per panel in total we cut 250000 slots.
Used PRS with 4hp HSD spindle. The cutter we used is a O flute 8mm Onsrud (61-414) we did a single pass cut of 13mm (ramp in) Cutting speed 75mm/sec (3ips). We worked about 9-10 hour day (non stop) and could cut about 12 panels (5100 slots) per day. The PRS did not ever in this total of 250000 slots lost a single step.

7655

[dray]

I cut mdf at 600 ips at 19,000 rpms 2 passes in 3/4 mdf.. All day long. I could cut in one pass at 500 ips but I do not have a vacuum setup yet.

[fleinbach]

Danny,

600 ips! Is this the new SUPPERBOT?

[dray]

sorry IPM

lol

[henrik_o]

Mike,

We have just begun phasing our PRS Alpha into production and I haven’t been able to do the test runs in mdf I intend to do, do you have any target scenario/breakpoint in mind or is it more general? If you have a set target, I’d be happy to run some tests around that and document the result.

Setup is a PRS Alpha with a 5hp Colombo and a somewhat decent vacuum system.

---^*^---

Hey, a supperbot? Being a bachelor and all, sign me up for that one

[richards]

Henrik,
Thanks for your input. I'm just looking for 'general' run time parameters. I know that everyone uses the machine in a different way, and I'm hoping to collect a little data to see the 'general' trends of how the machine performs.

[steve4460]

So I was always under the impretion that cutting in IPS makes a cleaner cut then cutting in IPM with the shopbot arcs inch PP . So for those of you that know better , Whats the Best way ?.

Bot on
SV

[fleinbach]

Stephan,

If you are cutting at 5 ips you are also cutting at 300 ipm. There is no difference in quality of cut. It is just 2 different ways to indicate the speed you are cutting at. The Shopbot uses IPS for its move speeds. If you select a bit that has IPM as its indication of speed the post processor will automatically convert this to IPS when it makes the Shopbot cut file.