Is there any reason I couldn’t or shouldn’t use a proper 1/2" router with nice quiet operation and the muscle to git 'er done with this rig?
I have some lovely soft-start 2hp spindles wieghing in at 5 pounds with a bit, just begging to get off the bench.
I understand a remix of the spindle holder holder would be required, making that slightly heavier as well.
It hangs off the front, but I don’t have a LR3 So i can’t say if it would be enough to bring the tool off perpendicular from the table.
I’m confident the steppers and screws could handle it, but I think it’s overkill. The 611 doesn’t usually get pushed hard enough to bog down, so I can’t imagine where you’d need the extra power.
Maybe someone else can bring a little more insight into potential problems, but I’ve seen a 2.2kw spindle on a MPCNC (and also an angle grinder and a CO2 laser tube).
Might be one of those things you do just to do it? You can always get a smaller router later😊
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As long as you dont try and actually use the full 2 hp, shouldnt be a problem. Opens up some tooling options as well for facing operations. Otherwise you are looking at going to nema 23’s that are 1+Nm on X/Y and going to a 15mm belt and/or switching to 3mm pitch. No clue if it will fit on the LR3 though. I will say even an 800w spindle motor has the power for some solid work while staying quiet.
F=m*a… You may not be able to make use of the force available on such a thing, but that extra weight isn’t going to hurt as long as it doesn’t tweak your gantry bad. Doubling the mass of your spindle will make it move a lot less when the bit tries to bully it around. Bigger collet may open up more insteresting options too, like shapers etc.
Hi guys.
Interested in learning more about not being able to utilise the extra power.
I am not an engineer, and i tried to learn more about f=n*a, but google has let me down.
Omg. I cant wait for my new glasses to come in.
Got results for f=m*a.
Will study.
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The other point I would make is that the router already has enough to git er done. It is a balance. More weight means more force is needed to start and stop the movement (that’s where F=m*A comes in). More weight also means more sag. More force means more flex, and more likely to skip steps (the stepper motors slipping, especially at high speeds).
In my opinion, there isn’t much to gain and there is a lot to lose.
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To be clear, i would mainly be using a 1/4" compression bit.
But the option to use my existing 1/2" shaping bits would be super, not to mention my existing spindles.
I dont mind getting bigger steppers and beefier belts.
I dont mind adding a third rail on the x axis to counter against torque on the y. I literally don’t care how heavy this thing is.
Hell, i will swap the whole gantry for a 100 x 100 aluminum extrusion, which makes more sense to me anyway.
I was definitely simplifying the larger scope of all the forces involved on a mill while cutting, and to be sure my experience WRT gantry flex etc is with the primo, not the LR. My primo has enough chops to deal with a 1500W router, but not sure on the LR. Sounds to me from what Jeff said the LR may not be a good choice for the big stuff. Router power will rarely ever be a limiting factor, even if you have a small POS trim router. I put up some decent times in the CNC drag race with a small Bosch Colt for example.
Also, what I said about forces was perhaps oversimplified. There are many forces to be concerned with in cnc… gravity, acceleration of the gantry, shear loading on the bit, and even vibration due to balance issues in the spindle. They all are there, and which particular force ruins your cut will depend on everything, lol… especially your machine and how it’s built. Do be aware though, that all of these forces are what add up to make errors in cuts… it’s up to the user to determine what/where the causes are. On top of F=m*a, it’s also super helpful to understand a little about stress and strain (F=k * X, simple enough lol). You are definitely doing yourself a huge service by reading up on basic physics as part of your early cnc experience.
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Just to confirm: you guys are cutting 5/8" melamine in a single pass with 1/4" routers?
Good edges both sides, etc.?
Both sides single pass… that implies a 1/4" compression bit. I haven’t seen many folks rocking compressions on their cnc’s, but not a bad goal to shoot for if you want to do lots of melamine or veneers. Dead reckoning, I’d say yeah the 1/4" routers commonly used on these things have enough power to get it done without burning bits. That’s just a guess though… only time I’ve done melamine on cnc is with my primo, 1/4 up cut, money side down, 2 passes to avoid chatter on the money pass.
This is my worry. Sometimes both sides count.
Feed and acceleration rates are not so important as getting a smooth, no chatter finish on the parts i lay out on the sheet.
Slowing down the feed rate at a certain point will ensure the bit doesn’t chatter and you get clean edges, but that has to be tempered with the capabilities of the spindle. Most common mpcnc spindles are higher speed routers. To keep the chip loads high enough to make a bit last, those higher rpm demand higher feed rates. If your router is torqy enough to spin a compression bit slower such that the same chip load is maintained at a lower feed rate, you may find it easy to do. Otoh if the router can’t go slow enough, reducing feed rate will make the bit wear faster.
So if bit wear is not a big concern, then just slowing feed rate will get you by fine. I think the main point would be how much production it will do… if this is just for an occasional one off in melamine then no worries… if it is doing melamine compression cuts 24/7, bit costs might become prohibitive. Compression bits aren’t cheap either.
I am aware of the too-slow thing but with a 9.5a machine i don’t forsee a problem with that.
I think the other guys are worried about acceleration rate.
Isn’t all sodftware eguipped to tweak that? Even the free stuff?
Yes, all firmwares have a max acceleration that can be configured. You can set a max acceleration in firmware, which most folks set to be safe for each machine. Afterwards, gcode can be used to further limit acceleration.