Initial design advise wanted

**Clive S** · 29-10-2016

2x65v dc diy toroidal
1x24v dc din rail
1x5 v dc ?!? Samsung smartphone USB charger hahaha

Waterpump for spindle.

A 50v 0 50v AC toroidal when rectified will give you about 72Vdc if you are using AM822 drives that would be good.

A 24Vdc din rail PS something like this;- https://www.aliexpress.com/item/DR-3...08.4.22.RcR90i

water pump https://www.aliexpress.com/item/Prac...2-37daba8373ea

motion controller needs to be at the top of your list some have the bob built in.

Don't buy any powers supplies until you know what controller you are getting as some run on 5v others need 12v or 24 v.

In fact leave all the electronics until the frame is built.

**JAZZCNC** · 29-10-2016

With 70Kg + Gantry then I'd advise you go with servos if you want very best performance. Setup isn't so much an issue these days modern servo drives are much more forgiving. The Main downside is cost.?
With servos it's not just the Motor/Drive cost you have to factor in the that to get the very best out of them you'll need Motion controller that can provide the required Pulse frequency. Most of the cheaper USB Controllers like UCCNC etc cannot provide the required pulse rate to get the full speed and resolution out servos. Electronic gearing is required and this comes at the cost of resolution. However for most routers this is sacrifice that can be made without affecting machine performance. It just defeats the point of one main advantage of servos.

If your going with belts then 8Nm Stepper motor will be minimum and best run on Mains voltage drive to get best from it and give decent speed.
I've just built two Routers with 1250 length cut that runs Belt drive twin 2010 screws with 4.5Nm 34 motors running 72Vdc AM882 drives with Gantry aprox 45Kg giving 700mm width cut and they will happily run at 10,000 mm/min with acceleration 1200s/s.

Now with bigger 8nm motor you won't get those speeds with only 72Vdc but with Mains voltage drive then you will and probably more. Obviously the higher weight and inertia of the Gantry will play bigger part in lowering performance but still you'll get at least 8000mm/min with 10mm pitch screw which is more than enough for most routers at this level/size.

Like Clive mentions Don't cut corners on the Motion controller. Avoid USB it's too twitchy. Ethernet is by far more stable.
There are several suppliers of Ethernet Motion controllers depending on what control software your thinking to use. My prefered choice and only controller I'll use with Mach3 is from Cslabs. However the new Ethernet card and UCCNC Software from CncDrive are very serious challenge to Mach3 so worth close look. Not used this Combo yet so can't comment properly but I'm hearing good things from People who know there stuff and who's opinion I trust. I Will be testing shortly along with the Cheaper Stand alone controller.

Then you have the stand alone controllers like may have seen mentioned lately on Forum (but I don't advise you take Boyans lead and connect two drives to one Signal Output.) Not sure if the 4 axis version will allow Slaving but if your using belts this won't matter and could use 3 axis version.
Again Can't comment or give an informed opinion but I will shortly have one to torture so will post something at some point.

hope this helps.

**driftspin** · 30-04-2017

So i have been reading a lot in the meanwhile.

I found this calculator for critical speed.

https://www.zappautomation.co.uk/ind...culators.html#
And for comparison
http://www.thomsonbsa.com/pdf/bsa_en...og_section.pdf

With about 1500 mm between the bearings, (long axis),
And about 900 mm between the bearings, (short axis),

SFU 1610 @ +/- 1500 mm (+/- 10mm core dia* = +/- 500RPM max * 10mm pitch) = 5 mtr/min
SFU 2010 @ +/- 1500 mm (+/- 15mm core dia* = +/- 800RPM max * 10mm pitch) = 8 mtr/min

SFU 1610 @ +/- 900 mm (+/- 10mm core dia* = +/- 1400RPM * 10mm pitch) = 14 mtr/min

It looks like 2010 is a good investment for the Long axis

I made a redisign of the frame to trade off some stiffness and complexity of the gantry vs frame.

Ill post soon since steel is on the way :-)

**fifa** · 18-09-2017

Drive should be defined based of the performance.

Gantry mass play role, however if acceleration is 1200steps/second assuming 200 steps/rev this means 6 rev/s, acceleration of the gantry will be 60mm/s2, assuming gantry's mass is 100 kg - results 6N inertia force ... Correct designed drive can run additional load of human body (100kg) without problem - I am testing drive in this way.

For better understanding: side force of 6mm mill can not exceed 40N, typically it is bellow 25N.

For hobby machines main inertia forces (torques) are defined with spindle diameter. Relation between Spindle Inertia and its diameter is power of 4 (double diameter requires 16 time higher torque), same rule is applying for pulleys and gears. All others relations are linear.

Do not expect stepper motor to run more than 10m/min. It is hobby machine. 10m/min means 1000rpm (assuming 10mm pitch), which is ca 7kHz with half step mode. Not an issue for cheap drivers. For 2 motors you need ca 40kHz cheap Arduino type breakboards can do the job (96kHz).
However they are not good enough if controller need to do also micro-stepping.

Motor performance depends on motor inertia. Therefore motor rotor inertia shall be as big as possible (rotor accumulates an energy). With servo you can afford ratio up to 4 with stepper it shall be always less than one (to avoid risk of loosing steps)

Start designing from "top" , do not go too much in details.

2kW main spindle is quiet (no cooling fan), it is strong enough to continuously cut oak with 10 mm dia 8 mm deep speed aprox 4m/min.

I am assuming you have in mind cheap Chinese spindles. Front bearings are small (15mm dia), consequently bearings are loaded "eccentrically" - not all the balls take a load, some of them are unloaded. If ball is unloaded it start skitting (due to friction between ball and lubricant), consequently bearings worn out relatively quick.

Regarding noise: Whatever you will do, most likely workshop has a window, which will work like horn. The best way is to "absorb" as much noise as possible (for example carpets on the wall - but then walls becomes also dust collectors...). Machine housing (envelope) will do the job.

regards

**driftspin** · 17-10-2017

Originally Posted by fifa

Drive should be defined based of the performance.

Gantry mass play role, however if acceleration is 1200steps/second assuming 200 steps/rev this means 6 rev/s, acceleration of the gantry will be 60mm/s2, assuming gantry's mass is 100 kg - results 6N inertia force ... Correct designed drive can run additional load of human body (100kg) without problem - I am testing drive in this way.

For better understanding: side force of 6mm mill can not exceed 40N, typically it is bellow 25N.

For hobby machines main inertia forces (torques) are defined with spindle diameter. Relation between Spindle Inertia and its diameter is power of 4 (double diameter requires 16 time higher torque), same rule is applying for pulleys and gears. All others relations are linear.

Do not expect stepper motor to run more than 10m/min. It is hobby machine. 10m/min means 1000rpm (assuming 10mm pitch), which is ca 7kHz with half step mode. Not an issue for cheap drivers. For 2 motors you need ca 40kHz cheap Arduino type breakboards can do the job (96kHz).
However they are not good enough if controller need to do also micro-stepping.

Motor performance depends on motor inertia. Therefore motor rotor inertia shall be as big as possible (rotor accumulates an energy). With servo you can afford ratio up to 4 with stepper it shall be always less than one (to avoid risk of loosing steps)

Start designing from "top" , do not go too much in details.

2kW main spindle is quiet (no cooling fan), it is strong enough to continuously cut oak with 10 mm dia 8 mm deep speed aprox 4m/min.

I am assuming you have in mind cheap Chinese spindles. Front bearings are small (15mm dia), consequently bearings are loaded "eccentrically" - not all the balls take a load, some of them are unloaded. If ball is unloaded it start skitting (due to friction between ball and lubricant), consequently bearings worn out relatively quick.

Regarding noise: Whatever you will do, most likely workshop has a window, which will work like horn. The best way is to "absorb" as much noise as possible (for example carpets on the wall - but then walls becomes also dust collectors...). Machine housing (envelope) will do the job.

regards

Dear fifa,

I have kinda refined the ballscrew selection.

Next station would be steppers and so on.

looks like its gonna be steppers for economical reasons, or servos if i decide to go on a spending spree

I am eyeballing the uccnc controller.

I hope mechanical stuff is done by end of this year.

ESo electronics in 2018 !

Grtz. Bert.

Verstuurd vanaf mijn SM-A320FL met Tapatalk