[tomfish]

Hi,

I am specifying an ATC router for job-shop / medium production runs. My main material will be birch plwood. I see spindle power on non-hobby machines is listed anywhere from 3kW to 7kW (4 to 9 HP).

Where in this power range should I be looking, and what are the deciding factors? I don't want to spend money on a spec I will never use, but equally I want to be a little future-proof.
Can anyone chime in with their experience?

[ger21]

What type of machine is this, as the machine must be capable of utilizing a large spindle?

I'd recommend the 9HP. A larger spindle will not only allow faster cutting, but it will also tend to have a longer lifespan. When spindle rebuilds can cost $2500, that's an important factor.

[tomfish]

It'll be an imported servo-driven, helical rack 1325 (8x4ft) router with vacuum bed. Many are specced with 9HP spindles, but I'm not sure if I would be under-driving it in plywood. The lifespan benefit is a fair point.

[ihavenofish]

dont just look at rated power, look at the toque curves. mine is for example 3.8kw (5hp), 4.5kw 30 min rating, from 12000rpm to 24000rpm. some spindles will also be 3.8kw, but only at 18000rpm or 24000rpm, meaning they have much less torque at lower speeds.

i expect anything over 3.8kw at 12000rpm (the smallest "standard" sized HSD ES915 ATC router spindle that everyone copies) should be more than adequate for plywood or hardwood with large cutters. the big HP spindles tend to be useful for swiniging huge shaper heads around. not needed so much for 1/2" and smaller cutters youd use in plywood.

[ger21]

That depends on how fast you're going.
And what type of plywood you're cutting.

[ihavenofish]

yes, but im assuming his typical chinese 1325 router is the same as most of the ones i see online. they dont cut *that* fast.

[tomfish]

Thanks both,

Ihavenofish is right, it will not be a huge machine. Something along the lines of https://www.youtube.com/watch?v=4s4hLC-Fn_4 (although I suspect that one isn't running at full speed in the video).
IHNF, have you found any limits with your 3.8kW spindle? For example where you've had to reduce feed to keep RPM where it should be?

I anticipate the majority of my work will be done with 3/8" and 1/2" compression bits. The rest will be larger diameter roundover and chamfer bits, but all consistent with the typical cutting you'd do in max 1" plywood. The other limit may be the toolholder (ISO30 ER32). There must be a max torque you can put through an ER32 holder before it risks slipping, but I can't find any numbers.

[ihavenofish]

Thanks both,

Ihavenofish is right, it will not be a huge machine. Something along the lines of https://www.youtube.com/watch?v=4s4hLC-Fn_4 (although I suspect that one isn't running at full speed in the video).
IHNF, have you found any limits with your 3.8kW spindle? For example where you've had to reduce feed to keep RPM where it should be?

I anticipate the majority of my work will be done with 3/8" and 1/2" compression bits. The rest will be larger diameter roundover and chamfer bits, but all consistent with the typical cutting you'd do in max 1" plywood. The other limit may be the toolholder (ISO30 ER32). There must be a max torque you can put through an ER32 holder before it risks slipping, but I can't find any numbers.

mine has not cut yet. the machine is not fully built yet. ive cut plywood and hardwood on my other machines though so i have a good handle on how it should perform.

the actual speeds and feeds you use, and thus the resultant power required is a math thing. most carbide tools recommend 3000ish sfm in plywoods and hardwoods, slower for mdf. on a half inch tool, that is near 24000rpm. youll fine tune from there, based on weather the tool is burning the wood or vibrating alot. feed rate you go by the tool. a 2 flute carbide bit might suggest 0.01 inch per tooth in plywood for example, which works out to 480ipm, probably right in the range your machine can run.

so power, well, we need to estimate the power it takes to cut the wood. 4-6 on the brinell hardness scale is a good ballpark to start with. so, punching all that into my calculator, i get 22900rpm, 458ipm, 3/4" depth, 1/2" with, 0.86hp.

so you dont really need an overkill spindle, though you do need an honest one. beware sellers that advertise the peak instantaneous power - which is totally useless.

[ger21]

I cut 3/4" plywood at 750-800ipm and 16,000 rpm, which needs considerably more power than your example.

But I use a bigger machine.

[ihavenofish]

yup, but what tool? im using in my example a generic carbide 2 flute. some tool makers will recommend higher or lower feeds and speeds.

[ger21]

1/2" 2 flute compression spiral from Vortex. If I use a 3/8", I up the rpm's to 17,000.
I've used various compression spirals from different manufacturer's at the same rpm and feedrate.

[ihavenofish]

so basically, your experience says, lower sfm, and a higher feed per tooth - on your industrial machine.

so, the question will be if his machine can handle that speed and force. in a straight line, i expect it probably can.

with a sharp tool though, thats still only 2.5hp.


all that exta HP is really for stuff like this:

[ger21]

I don't believe that a 2.2KW spindle can handle what I'm doing. (2.5HP)

[ihavenofish]

a 2.2kw spindle can i think. a chinese watercooled "2.2kw" spindle, not likely, as those are only 2.2kw at 24000rpm for the 1 second just before they burst into flames. they are also very lightly built and would nto handle the actual force applied without vibrating to death i dont think.

do any pro routers have power meters like VMC's do? it would actually be nice to have real life some number references.

[ger21]

None that I've seen.

[Boltz]

I cut 3/4" plywood at 750-800ipm and 16,000 rpm, which needs considerably more power than your example.

But I use a bigger machine.

Those sound like pretty conservative settings for your equipment. Are you short on vacuum?

[tomfish]

But I use a bigger machine.

Gerry, what type of machine are you using? This discussion is really interesting, thanks for the input.

[ihavenofish]

Those sound like pretty conservative settings for your equipment. Are you short on vacuum?

you have to strike a balance. just cause the machine can push, doesnt mean the work piece or the tool or the fixture will enjoy it.

[Boltz]

Gerry, what type of machine are you using? This discussion is really interesting, thanks for the input.

He used to run a Morbidelli, I think, which is a good, solid medium weight machine.

[ihavenofish]

He used to run a Morbidelli, I think, which is a good, solid medium weight machine.

yes. but its going to be the tool as the limiting factor i think.

maybe im wrong though. i have machines with that kind of power and rigidity, but not with that kind of speed (my new one does, but its not ready). id just expect the tool to snap if you pushed any harder.