Desktop Speeds

[PNast]

I have a PRSALPHA 96x48 and my sign business is getting very busy. I am thinking of adding a Desktop w/spindle. I cut mostly pocket text using speeds of 3-4 ips. Can the Desktop handle these speeds? I have been told it does not support the software controlling the rpm, how do you set the rpm? Can it run 8-10 hrs. a day?

Thanks,
Paul

[tlempicke]

The desktop is much more precise than the big machine and will do engraving with no problem. Very well built with a good stiff frame. Should be no problem running a full day every day. You set the speeds on the VFD, which is mounted on the left side of the gantry.. There is a numerical display that tells you the frequency and that in turn tells you the speed of the router.

[scottp55]

Paul, Mainly cutting hardwoods here so wouldn't use those speeds, but pocketing hard maple at 2.6IPS @.25" depth with 1/2" ballnose and FEM for hours doesn't seem to phase it. Like wise surfacing hardwoods with a 3/4" straight at 4IPS at .03-.1" depth 40% step. Have cut 12-14 hours numerous days and she doesn't ever get hot or bog. But like I said all hardwoods and for the most part protos, but getting close to production levels and after 6 months of seeing it work I have few worries she can take it. Good machine-very tight. Our more normal use is 1/8 and 1/4" inch bits at 1.1-1.6IPS for VCarving so we need the cleanest pass.

[PNast]

Thanks Tom and Scott, I cut .15 deep using Poplar. I use Gary Beckwith's new 1/4” Chipbreaker Finisher for the pocket clean out at 2.5 ips. It sounds like the Desktop will handle these signs no problem and take up a lot less real estate.
-Paul

[scottp55]

Paul, I was looking into the chipbreaker/finishers in 1/2" but the price spooked me, so tried a .5" FEM down and got good results, but still curious about the bit. On poplar are you cutting in one pass, or leaving a skin and a cleanup. What's your stepover and how good is the pocket finish? Always looking for the cleanest pocket--Do you have pics before sanding? Is yours an upcut and if so any tearout? Need a clean top edge for 50% of my cut in hard maple/cherry/black walnut. Thanks

[PNast]

Hi Scott,
I cut in one pass, this sign I did at 2 ips. feed 1 ips. plunge and 18% stepover and 15000 rpm. I can do faster speeds as long as I keep the chipload at .005 and still get a very clean cut. I am using Beckwith Decor Products BDP015 Two flute, Solid Carbide Downcut Chipbreaker Finisher With a 1” LOC, 1/4” shank and 2.5” OAL. They are $24.90, you cant go wrong for that price and they last a long time. I usually just hit the pocket quick with a 180 grit sanding mop. - Paul

[scottp55]

Thanks for the pics Paul, Always nice to see it close up. We'd be getting the .5" and it was hard justifying without actually seeing the finish. Our pockets are .4" deep and business card sized for our current project and were a PITA to hand sand. We just bought a Fein oscillating but haven't made a pocket adapter for it yet. Thanks for the feeds and speeds as now I can plug a .5" in the database and compare what I'm getting with the Centurion .5 FEM down. BTW love the Centurion and got the .25" at the same time.

[PNast]

No problem. I forgot to say I cut it using the conventional cut direction. The downcut bit will tear chunks off in the climb cut direction. I am sure you know this, I figured I would put it here in case anyone is thinking of pocket cutting with a downcut bit for the first time.

[scottp55]

Paul, Don't assume anything:) I was only using conventional for a finish skin pass. Does it hurt the bit to use climb cut when roughing or final cut out? I want to get the best mileage out of my downcuts. Seemed to be getting acceptable chips at a good speed and 50% stepover. Thanks

[PNast]

I would only cut conventional with a downcut bit and only climb with an upcut but I could be wrong. I didn't know about this when I first started using the downcut bits and ripped the tops of my letters off. I use the .25 downcut for pocket cleanout and a 1/16th ball nose to get in the area's the .25 cant get into (same toolpath). On occasion I forget to change the 1/16th ball nose to climb and it shreds my letters always when it ramps around the curves. Maybe some of the experts can clarify this.