Aluminum profile and alu plate 1500mm x 600mm x 150mm working area, first cnc.

[pierantoine]

last version with 80x120 aluminium profile.


I have shorten the long axis to improve acceleration / whipping

i've read the forum and it seems that for 1500mm rm1610 could be a better choice than 2010 for acceleration reasons. do you agree ?

[JAZZCNC]

i've read the forum and it seems that for 1500mm rm1610 could be a better choice than 2010 for acceleration reasons. do you agree ?

Yes for acceleration reasons but at that length your still high chance of whip with 16mm screw. And why would you need Higher acceleration than 20mm could provide.?
At this length 20mm is better suited and to improve things more go with 20mm pitch and use 2:1 ratio on the pulleys. Also have Fixed bearings at both ends.
This gives the advantage of lower screw speed and higher torque. The Fixed bearings make everything that little bit stiffer.

[pierantoine]

Hello Dean ! thanks for your answer, yes both fixed and 2:1 with htd5 15mm was planned with ali pulleys 2 grubscrews and i've seen that you also advises that using Angular Contact Bearing from Fred worth the price so i'll do like that..

[JAZZCNC]

Hello Dean ! thanks for your answer, yes both fixed and 2:1 with htd5 15mm was planned with ali pulleys 2 grubscrews and i've seen that you also advises that using Angular Contact Bearing from Fred worth the price so i'll do like that..

Would only use 2:1 ratio with 20mm pitch. If done with 10mm pitch the speed will be too low for router.

[Boyan Silyavski]

Those green bars at front and back are not necessary. Dont worry about them. Its better to be open frame.

[pierantoine]

Would only use 2:1 ratio with 20mm pitch. If done with 10mm pitch the speed will be too low for router.

for info i have nema 24 4nm steppers from cnc4u,
This is my first router it will be used for multicut materials (aluminium, wood, polycarbonate, etc...) and i'm looking for the best resolution before speed, but on the other end i understand that for some materials.. a fast feedrate could be need, so maybe an rm2010 could be an intermediate solution...

1 - we always see Z axis with rm1605, i assume with 1:1 or another ratio ?
2 - For my long axis to get a 1400mm travel i could use a 1550mm rm2010 with an 1:1 ratio but will it work correctly ? (whipping...)
if it wont work wich length would you use maximum ?
3 - If using RM2020 for cutting aluminium do you think i can have a good resolution with a pulley change to something like 4:1

Many thanks for your help..

[Boyan Silyavski]

200 steps per revolution will move the axis 10mm if using screw xx20 and if 1:2 as Dean suggested. so for 1mm -20 steps. But as you will use 1/8 microstepping, then 160 steps per mm. So 1/160=0.00625 resolution.

[pierantoine]

Hello !
okay that's clear thanks..

[JAZZCNC]

200 steps per revolution will move the axis 10mm if using screw xx20 and if 1:2 as Dean suggested. so for 1mm -20 steps. But as you will use 1/8 microstepping, then 160 steps per mm. So 1/160=0.00625 resolution.

Boyan is correct that what I suggested gives same 10 movement per rev like 10mm pitch because of the ratio but don't be fooled by the micro step numbers because they are unrealistic in real world use.
Micro stepping is best thought of as way to increase smoothness not resolution. Yes the resolution is increased to some degree but not anything like the numbers suggested.

If you take it that Full step 200 is the minimum resolution then it's safer bet. What you actually get will be better but how much does depend on several factors like motor quality etc. If you work on calcualting using half the micro step used this will probably be more realistic figure.

Now if your going to use 2:1 ratio on the RM1610 ( I didn't realise you was doing this!) then whip won't be problem because the same apply's. Your screw will be spinning at half the speed than if 1:1 which is when whip occurs on 10mm pitch. Down side is that Max speed is halfed and with 10mm pitch this means for materials that require higher feeds you could struggle.

There are other factors that come into play which will dictate which way is best for you. The relation ship between Motors, drives, psu and Controller will greatly affect the kind of performance you'll get from machine.
Just saying I'm using 4nm motors (even if low inductance) isn't enough to determine overall performance.

For instance same 10mm pitch with 4nm High inductance motors with only 45v using Analog drives controlled by the parallel port with 25khz will perform much much slower than same size motors with Low inductance using 65v with Digital drives and Ethernet controller at 125khz. Upto half the speed.!!
Even if motors are low inductance the remaining factors still play big part in overall performance.

So this relationship between components affects how you go about it.

However I can safely tell you that on machine like yours if using 4nm motors with 65v with 80v digital drives and good motion controller, ideally Ethernet based that you will, provided build quality is to decent standard with good alignment of rails ballscrews etc with 2:1 ratio on 10mm pitch achieve 7500mm/min without too much trouble.


If using 2:1 on 10mm pitch gives what you require in speed terms then I'd go with 16mm.