Aluminium Profile Type Router - Initial questions

[CNCRY]

For anyone's reference in future this is the setting:


Initially I set the spindle min to 5000, max 24000 which I assumed meant it would just not allow a command below S5000, but figured out that meant 5000rpm = 0v, so when I set 10000rpm I would get 7500ish instead! So set min to 1, max 24000 and all good (to the nearest few hundred anyway).

Playing around in UCCNC reminded me of a couple of other things
- is it worth setting max velocity and acceleration at this point, set to 2000 units, so 20m/m which I expect is faster then it will go.
- Is there any worthwhile tuning of steppers needed - these are the hybrid steppers so slightly less common. I see there are 4 switches which can be used to set pulse/rev but no idea if these are worth changing?
Or maybe I'm just thinking up ideas while waiting on parts:) Feels like I'm on the home stretch now, just need to figure out my workholding and spoil-board which doesn't eat up the Z distance.
I also couldn't find an obvious answer on this - can I use normal 1/2" router bits in the spindle or does everyone use endmills? Obviously something like a Lock Mitre bit would be a bad idea, but the simple 2 flute straight bits, chamfer etc..

[JAZZCNC]

Playing around in UCCNC reminded me of a couple of other things
- is it worth setting max velocity and acceleration at this point, set to 2000 units, so 20m/m which I expect is faster then it will go.

2000 is the units ie: mm or inch value so if you want 20m/m it needs to be 20,000 not 2000. Read below and it will make more sense, if not just ask.

The velocity and acceleration are very important and you can't just womp them up and leave it at that because you'll just get stalling motors.
This is the bit that you'll see mentioned as motor tuning and it's a balance between velocity and acceleration, If you increase one it will affect the other at some point and you'll have to decrease one of them.

Every machine is different when it comes to tuning the motors because of friction and mass, voltages etc, so it's very much feel way your way thru and lots of little tweaks.
Start low on both at say 4000mm/min on velocity and 500 on acceleration. Then adjust just the velocity until the motors stall, then reduce the amount by 25%, then do the same with acceleration. This will give you a base line and nice stable machine, you can tweak it up from there but again only adjust one at a time and test.

- Is there any worthwhile tuning of steppers needed - these are the hybrid steppers so slightly less common. I see there are 4 switches which can be used to set pulse/rev but no idea if these are worth changing?

Well first hybrid steppers are common as muck, probably the most common stepper on the market and it means NOTHING. I see this a lot that people get blinded by jargon and think that the word Hybrid means they are something special when all it means is they can be wired in several ways making them an Hybrid of several types of steppers.

Again these switches are very important as they set the micro steps, infact THE most important bit because if you don't know this setting then you can't possibly set the correct Steps Per unit value in UCCNC and you won't get the correct amount of movement. It also affects the motor tuning because the higher these settings then the motor acts differently, going too high can give negative results as they are very close relationship with motor tuning and the system as a whole.

There will be a chart on the stepper case that gives different micro step options and will tell you the positions those switches need to be set for each micro step amount.
Set them up to give 1600 micro steps. There is no need to go higher as it starts to give negative results.
Now you take this figure and do a calculation for the steps per unit value that you enter into UCCNC. Divide 1600 by the ball-screw pitch and any ratio you may have. So if it's direct drive with 10mm pitch then 1600/10=160 for the steps per.

This will give the correct movement, the Steps Per setting is a none negotiable setting and you can't just use a random number, it must be calculated from the Drive settings. ball-screw pitch and any ratios applied to it.

-I also couldn't find an obvious answer on this - can I use normal 1/2" router bits in the spindle or does everyone use endmills? Obviously something like a Lock Mitre bit would be a bad idea, but the simple 2 flute straight bits, chamfer etc..

You can use what ever you like, stick a pencil up it if you like. Also no reason why couldn't use a Lock mitre bit provide it's not like 6" and 3kg in weight. I regularly use a 70mm surfacing bit which is bigger than a lock mitre bit.

I often use my old worn out end mils that I've used on aluminium for cutting wood as they are still more than good enough for hogging out wood and often I've only worn the first 4-5mm out and I cut much deeper in wood. I then use a decent end mill for the finish passes.

[Neale]

I also couldn't find an obvious answer on this - can I use normal 1/2" router bits in the spindle or does everyone use endmills? Obviously something like a Lock Mitre bit would be a bad idea, but the simple 2 flute straight bits, chamfer etc..

One way to look at this is, "Would I use this cutter in a handheld 1/2" router at 26000RPM?" Or even a 1/4" router. If the answer is yes, then go ahead with it in a more powerful spindle with much better control!