# Thread: 7' X 4' Combi

1. Originally Posted by Ricardoco
ive set steps per to 20 Velocity to 3000 accl to 200, Oh im using metric, now when you type in X1000 the gantry travels 1M so that much is correct but im not sure it is the only way to do it the drivers are on the lowest setting which is 200 per rev.
200mm/s^2 for the acelleration is very low. You should be able to get around 1 to 2 m/s^2.
The motion will be a lot 'smoother' if you use microstepping. I reckon you'll get around 8m/min, so that's 133mm/s. 200 step/rev is 20 step/mm, so 25000/(133*20)=9.4. So you can have anything up to 9.4 times the number of step/rev ... so try 1/8th microstepping.

Originally Posted by Ricardoco
with four people sitting on the gantry it dosnt evn know you are there..
The overall mass of the gantry doesn't make much difference to the feedrate you can get, it mainly affects the acceleration obtainable (Newton's 2nd law). Increase the acceleration and it will 'notice' plus the people will probably fall off which is an added bonus.

2. Originally Posted by Jonathan
200mm/s^2 for the acelleration is very low. You should be able to get around 1 to 2 m/s^2.
The motion will be a lot 'smoother' if you use microstepping. I reckon you'll get around 8m/min, so that's 133mm/s. 200 step/rev is 20 step/mm, so 25000/(133*20)=9.4. So you can have anything up to 9.4 times the number of step/rev ... so try 1/8th microstepping..
I set the accelleration slow while i was setting things up as i was affraid of missing steps in one of the twin steppers and it all getting out of shape but as you suggest i will speed that up, Ok so how do i set it up to use microstepping then, (I thought i was LOL)

Originally Posted by Jonathan
The overall mass of the gantry doesn't make much difference to the feedrate you can get, it mainly affects the acceleration obtainable (Newton's 2nd law). Increase the acceleration and it will 'notice' plus the people will probably fall off which is an added bonus.
LOL that would be funny, if not for the fact i was one of them...

Was it good to see your ballnuts working then? and where are these extra points you said i could have.

Rick
Last edited by Ricardoco; 18-03-2013 at 10:46 PM.

3. Originally Posted by Ricardoco
...... Ok so how do i set it up to use microstepping then, (I thought i was LOL)
Rick

Ok i think i have got itLOL

To get 1/8 microstepping.

I have 200 full steps per full revolution of motor as it is a 1.8deg motor.
360degrees (1 full revolution of motor)/200steps=1.8degrees per step
8 Microsteps per full step (1/8 microstep)
200x8=1600 steps per rev (1600 set on the driver)
10mm travel on gantry for 1 revolution of the stepper,
1600 steps/10mm=160 Microsteps per mm set in "steps per" in motor tuning
1mm/160microsteps=.00625mm gantry travel per microstep given 1:1 gear ratio motor to screw.

YES??

Rick

4. Originally Posted by Ricardoco
8 Microsteps per full step (1/8 microstep)
200x8=1600 steps per rev (1600 set on the driver)
10mm travel on gantry for 1 revolution of the stepper,
1600 steps/10mm=160 Microsteps per mm set in "steps per" in motor tuning
1mm/160microsteps=.00625mm gantry travel per microstep given 1:1 gear ratio motor to screw.
Perfect :)

Originally Posted by Ricardoco
where are these extra points you said i could have.

5. Originally Posted by Ricardoco
Ok finaly Purchased the Rails for the Y Axis.
Attachment 8469 Attachment 8470

Ive got 2x GL20TF + Rails at 1300mm, (when they arrive that is)

Rick
Well this just goes to show how fast things can arrive. The rails arrived this morning thats 4 days including the weekend, and this is the second time this has happened with this seller and all the way from Korea. Well hats off to them thats all i can say, they are listed as used on the add and to be fair they are immaculate. Magic

less than £200 and free postage as well.

GL20TF+1300mm Used Linear Bearing NB-Nippon Bearing SR20W THK NSK LM Guide CNC | eBay

Rick

6. Nice one Rick but Jonathan better watch out, somebody has been stealing his designs

Rotary Nut BLR1616+BLK1616+930mm Used THK Rolled Ball Screw Support BK12+BF12 | eBay

7. Originally Posted by Swarfing
Nice one Rick but Jonathan better watch out, somebody has been stealing his designs

Rotary Nut BLR1616+BLK1616+930mm Used THK Rolled Ball Screw Support BK12+BF12 | eBay
LOL Naaa Jonathans are better than that and considerably better priced.
Mind you, if he wants to get some Uni spending money perhaps he should be selling them on Ebay as well..

Rick

8. Only if he supplies the ballscrew and nut at the same time?

9. Them ebay jobbies look abit shit IMO

Them ebay jobbies look abit shit IMO
I must say they do. Jonathans are sturdy, well machined and constructed. I just wacked the motors and ballscrews/Nuts on and away..

Rick

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