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Hi all,
I used to own a 4x8 PRS Standard. Thinking about getting back into CNC with a desktop max and 1 kw spindle — but only if I am confident it can handle through cutting hardwoods up to 1.5” thick with a reasonable pass depth. It can do this, right? Tried searching the forum and didn’t find much that was recent.
Thanks!
Brian
Hi Brian,
Only ever stalled the Desktop w 1hp, by user errors(Don't try to cut Teak with 1.25" bit at 3IPS when you skip a decimal and it's a .5" pass...not a .05" pass....
And do NOT try cutting Teak with your collet nut/collet on the same "Bad" day!) :)
Not sure what "reasonable" is, but never had a problem with pass of 1/2 to 3/4 bit diameter at up to 2.6IPS...lots of torque!
Never heard it bog down or even change rpm, except for that user error "Bad" day.
Rugged little Beastie! :)
Don't have any pics right now of deep cutouts, but to give you an idea...
I Do surface a lot of Sugar Maple/Walnut branches and both W Oak and Sugar Maple Burls with a 1.25" Whiteside morticing bit at 2-3IPS,
and first several roughing passes are anywhere between .1-.2" depending on jigging stability with no problem before I get to a nice depth, and go shallower for finish passes.
May give you an idea, as you're already experienced.
Thanks Scott! Seems like your Desktop gets some heavy use! By “reasonable” pass depth I mean .15”ish for ordinary hardwoods (not teak!). On my full size machine with the 2.2kw spindle I would typically profile cut 3/4” ply in 3 passes and ash in 5 passes. As a hobbyist now I don’t mind a somewhat slower workflow…up to a point.
I'd think deflection would be the limiting factor on the smaller machines, right?
I personally think it's the opposite John.
Shorter gantry(33.125" outer supports(measured outside/outside)), and then on the two 2013&"14s we owned,
the welded frame/machined rail surface/linear rails and precision bearing blocks on all axis makes it very Rigid.
Now granted, I have not ever personally seen/run a modern Desktop, or run a 4X8' machine, But had "Pappy" Baynes up for a morning after he sold his full size...
And after an hour or so of cutting(and asking), he yarded on the spindle and uprights with the machine on...
and said "This thing is built like a TANK!!"
And then a guy and his wife from Boston drove up to spend a day with his bits/material(Sugar Maple)/and cut examples, and we cut all day.
He'd only had his brand new PRS Alpha for 6 months, and cut quality wasn't what he wanted. (he also yarded on the Desktop and was impressed).
I tweaked his file for his material/bits and he walked away very impressed with the cuts and machine...
He got home and ran the same exact file on his machine with my cut example to compare...and it wasn't as good:(
We emailed back and forth with pics and suggestions, and him tweaking his machine ala Shopbot Tech suggestions, but he said his never came out as good as Desktop's.
Brian,
I rarely cutout on sheet goods(full sheets and wheelchairs don't mix well) or thick hardwood with a .25" bit.
I tend to cutout BB ply/up to .9" hardwood/etc. with a .125" EM (Kyocera for Carveright) because I nest close to reduce waste when I do.
BUT I was a Total Newbie, and listened closely to Brady and others for tweaking my bits for the "Sweet Spot".
"Start at 150IPS at 1/2" bit diameter passes...and then tweak up and down from there for hardwoods"
And I never had a problem...so a .15"ish pass depth instead of my .125"(always about the finish of the cut for me) seems entirely doable.
I don't have many pics of cutouts on ply, but back then it was all 1/2D passes and 40% stepovers and some bits were run at 10K and 2-2.6IPS to run cool.
(I can see my .5" Centurion FEM downshear in my Big Leaf Maple "computer shelf", and that would be running at 10K,.25" pass,40% stepover, with Fluting toolpaths running up to 3/4" deep
cutter depth after initial cut was made as it was only cutting the stepover)
So I can't directly answer your question except in other contexts.
DO know that the 1hp HSD seems to be in the 2.2hp Chinese spindle range judging by cuts/comments on the Vectric forum.
99.9 % sure it won't disappoint you, but perhaps you can find someone with a Desktop close to you to visit to satisfy you??
Sorry I can't be more direct help Brian.
scott
Oh...1 .25" bit I have likes to run at 2.6IPS and 9K, but I wouldn't use a larger bit at that rpm without shallow passes....
9K is Really getting at the bottom end of the HSD's torque range(10-12K is Great).
Scott - Great to know. I figured they'd be flimsy. At some point in the future, I'll have to downsize to a desktop machine. Not looking forward to the day but I can't see being without a CNC machine. Too darn useful.
NOT flimsy John:)
I'd only had first Desktop for about 4 months before we got a FeinII HEPA for dedicated DC(with a DustDeputy...it's perfect for a Desktop combo),
and was in Rockler shopping for for hose/blastgates/etc.
They had a cutting Shark setup, and customer was saying;
"Oh...I'm Not cutting too fast...when I cut and see the router mount distort....I slow down!"
STILL makes me cringe to think we were considering one!!
(Now Those are flimsy! But people still manage to show decent stuff on the Vectric Forum)
Never for a minute did we regret going 2 Desktops! :)
The positional accuracy and cut repeatability has repeatedly shown me that my wood movement(and MDF spoilboard) move...Not my machine in multi-day 3Ds. :)
Lots of people downsize once they're not cutting sheet goods and big slabs...No body seems to get stronger and healthier with more energy as they age..You Adapt. :)