Your going to need a beefy machine to do 19mm in one pass at 6m. I wouldn't fancy doing that with 6mm tool either! Cut quality would be shite with all the chatter and that's if it didn't snap. 10mm would be where I'd want to be at really.
OK, so that was a bad thing for me to mention as a requirement to the supplier, I'm correcting that now.
I have some 6mm wide grooves, and 19mm wide grooves, both about 6mm deep. I was hoping to cut the whole thing with one cutter but swapping is no biggy either.
What do you recommend if I had 3kW spindle and 6000mm/min ?
The whole job with 6mm cutter and DOC= 6mm?
or 6mm cutter for narrow grooves, 10mm for wide grooves and multi-pass for cutting the profile?
Multipass rough cut the profile, then a full depth finish pass with compression cutter?
I will be hot glue edgebanding the cut edge, and I've got a choice of chipboard or mdf for the core of the melamine board.
Last edited by jimbo_cnc; 05-03-2015 at 03:50 PM.
If you need both the top and bottom edges clean, then you want to cut the profile with a compression bit.
If you can, I'd try to go up to a 4-5Kw spindle, which should let you cut the profile in one pass with a 10mm compression bit. Machine rigidity will dictate how fast you can go, but I've cut 19mm board in one pass at ~17m/min with a 10mm compression bit.
If your limited to 3Kw, then I'd probably try using a 1/4" compression bit for everything. Cut the profiles slightly oversize in 3 passes, with a final cleanup pass at full depth, removing about .5mm.
Thanks for that.
I'm not limited to anything. I'm just looking for the most economic way to cut 200 boards per year.
It might be close if they were all the same, but say I have 10 model options. That would mean liasing and travelling to the cnc shop everytime someone orders one. That's $50 of my time IF it all goes well, plus the $100 machining fee x 50 visits = $7500 per year.
If I damage a panel later in the build process the costs and delay are horrendous if I can't just run another one off myself.
Obviously there are also many other advantages to having my own machine too, outside of the main 200 board requirement.
I'm listening and using the advice I get.
I'm not hell bent on that machine, but no one has suggested any alternative yet. That's not a criticism, just a
And it appears to meet my needs. Even if it doesn't meet your idea of how fast I should cut wood. (I'm up to about 6000mm/min now, just in case you think I'm still at 3500)
As to ballscrew size, I've asked for 2 proposals from the seller, 25mm ballscrew and 32mm ballscrew, with details of motors and drivers. When I get that info, I will try to analyse the overall performance of the options. Apart from acceleration, what else is there to consider?
Last edited by jimbo_cnc; 05-03-2015 at 09:58 PM. Reason: added 6000mm/min
as anticipated, next question is acceleration.
I've got some specs:
Motor: 85BHX450B current：4.0A resistance: 0.5Ω, inductance：3.0mH, torque：6 Nm
can't find that on google, but I can just use the values given.
Driver: Leadshine MA860H
I've plugged the values, along with some guesses on gantry weight into the motorcalc spreadsheet, and for 25mm ballscrew it all looks good.
I deconstructed the spreadsheet so I can see the acceleration being used is based on time to achieve feed rate. This results in 0.57g requirement for my cutting.
Is that an appropriate value for this machine?
I'd also like to use this machine for my small plastic parts. I haven't paid any attention to acceleration settings on my 6040, although I might have followed some advice without remembering it. I'm going to run some of my cutting jobs in Mach3 with different motor tuning to see what difference it makes.
When I plug in the 32mm ballscrew, it's clear the ballscrew dominates. I can get about 0.3g from the motor above. Or I can ask for a larger motor. I was quoted +$100 for 32mm ballscrew, but wasn't given a price for a bigger stepper.
It's a Classic mistake often made thinking bigger is better when reality is it's often the worst thing to do. Bigger motors spin slower and require much more power and those drives won't handle larger steppers and give great performance from them.
You Get the performance thru correctly matching screws and motors to rest of machine. Just going LARGE only leads to COSTLY under performing Mistake.!!
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