X/Y Axis movement
December 12, 2013 11:46PM
Hi Guys
This might be a Stupid Question. But I need to know.
According to PrintRun (Proterface) my x and Y axis seems to be reversed.
I know I can change the wires 180° to reverse the direction
Now for the Dumb Question.
What is really the "front" of the printer.
1. With the control board Bottom left - Y forward/back x- left right
2. Control Board Left back, and you can see the RS logo? or y left/right, x forward back?

I try to figure out my home position

Thanks again
Cheers
Danie
Re: X/Y Axis movement
December 13, 2013 01:10AM
Hi Danie,

The "Front" may be the wrong question. X- and Y-Home are near the Duet board housing. If you look from the Y-axis motor it's on the left.
X -Home means the X-carriage is near the Z-axis extrusion and Y-home means the heated bed is the furthest away from the Y-axis motor.
From this position every X+-command puts the carriage to the right and every Y+ pushes the heated bed towards the Y-Axis motor.

Markus


XBee & electronics blog: [lookmanowire.blogspot.com]
Re: X/Y Axis movement
December 13, 2013 02:03AM
Thanks Markus
Hope I have it right now.
See attached Image

Cheers
Danie
Attachments:
open | download - ormerod_axis.jpg (131.6 KB)
Re: X/Y Axis movement
December 13, 2013 04:36AM
Daniedb

It depends what you are describing moving. The Y axis + and - in your picture shows the nozzle movement relative to the bed, rather than the actual movement of the axis, which is the other way! The motor end is the homing position of both X, Y and Z axis. At 0,0,0 the nozzle should be over the back right hand corner of the bed, just touching the surface.

Ian
RepRapPro tech support
Re: X/Y Axis movement
December 13, 2013 04:48AM
Ian
According to the Picture,
This is the directions my
Y + / - Board moves
X + / - Nozzle Moves
Z + / - Nozzle up/down
when pressing those buttons in PrintRun

what need to be reversed?

Cheers
Danie
Re: X/Y Axis movement
December 13, 2013 05:00AM
Quote
reprappro
Daniedb

It depends what you are describing moving. The Y axis + and - in your picture shows the nozzle movement relative to the bed, rather than the actual movement of the axis, which is the other way! The motor end is the homing position of both X, Y and Z axis. At 0,0,0 the nozzle should be over the back right hand corner of the bed, just touching the surface.

Ian
RepRapPro tech support

I hope you mean the back left of the bed for home - homing Y on mine winds the bed initially toward the Y motor until it hits the switch, it then winds away from the motor until it comes to rest with its left hand edge under the nozzle (ie the end of the bed closest to the motor is home, when the bed is at its furthest from the motor, and not the right hand edge of the bed when the bed is closest to the motor)...
Re: X/Y Axis movement
December 13, 2013 05:37AM
Sorry, my mistake...

The Y axis homing switch is a MAX endstop. ie it triggers at the maximum positive point. So when the Y axis homes, it finds it's Y=200 point. Then it can move back to 0, at the other end of the axis. Without this, due to the orientation of the Y axis, any part printed would be mirrored.
The other two axes are MIN endstops; they trigger at 0 for X and Y.

Also, orientate the machine correctly when looking at it. Face the machine with the Y axis motor closest to you. The X axis moves left-right, the Y axis forward-back. The nozzle should home front-left on the bed! It's just we get used to looking at the machine with the bed (Y axis) left-right, which is atually 90 degrees out...

Sorry if that confuses everyone!

Ian
RepRapPro tech support
Re: X/Y Axis movement
December 16, 2013 01:51PM
I actually have an intermittent problem with my homing. Though it could be my error fault, so if so please feel free.

Sometime when I hit HOME Y in the web interface instead of moving towards the Y motor hitting the Y stop and then moving away to home (as described earlier) it just moved the bed away from the motor resulting in the inevitable grinding noise as it hits the end of the Y axis travel. I'd rather avoid this happening at all as I don't want to wear things out.

It does also sometimes happen with homing z as well. When using the IR it gets close to the bed and then instead of slowing down it starts reversing rapidly.

(N.B. As I write this I've just seen the Y stop is disconnected and I've reconnected it...)
Re: X/Y Axis movement
December 16, 2013 04:06PM
@Carnivalus

I have the same problem when sometimes homing the Y-axis (in Pronterface) instead of running to the Y-endstop and then homing it runs the other way and hits the end of the Y-axis travel.
I also have some intermittent Z-axis homing problems. As I can't use the Webinterface (my Duet board is one of those that has no functioning network) both happens in Pronterface.
The proximity sensor also seems to be very unstable if the light conditions change (e.g. sunlight).

Markus


XBee & electronics blog: [lookmanowire.blogspot.com]
Re: X/Y Axis movement
December 16, 2013 04:31PM
@Ian - re the sensitivity to ambient light, have you considered toggling the power to the LED then subtracting the "dark" signal from the "on" signal? You might already be doing this ("chopping" like this is a common trick), but if not it should yield better signal to noise .

@Markbee- remember to shield the snowmen from the sunlight! ;p

Edited 1 time(s). Last edit at 12/16/2013 04:36PM by rayhicks.
Re: X/Y Axis movement
December 16, 2013 05:56PM
Well I created another axis set to check my calibration, then pottered out. When I got back I found that when it had gotten halfway through making the x and y axis parts the y axis slipped maybe? As the next layers were all shifted by 1cm towards the y motor. Looks pretty cool (and I'm impressed that it could print such an overhang so well) but useless to lose. The belts seem taught still...
Re: X/Y Axis movement
December 16, 2013 06:28PM
@Carnivalius - the Y axis belt, where the two belts interlock, needs to be tightly held in the y-rib. To check it is, hold the Y axis motor pulley and try to move the Y carriage. I had to slip a small piece of paper, folded, below the two belts where they interlock, or it slipped in one direction. I have added this to the build instructions (last step) [www.reprappro.com]
We're looking at altering this a little for the next set of printers, to improve the belt location.

@rayhicks - good idea! I'll suggest it to Adrian Bowyer.

Y axis homing - I'll check tomorrow. I don't think M119 (check endstop status) is enabled in the RRP Firmware. Generally, I would expect this to be a connection problem. If the axis moves away from the endstop, it thinks the endstop is activated already, and tries to move until it is no longer activated. Unfortunately, it never gets to that state if the endstop is disconnected. Movement away should, perhaps, be limited to 10 or 20mm, then throws an error.

Ian
RepRapPro tech support
Re: X/Y Axis movement
December 17, 2013 04:09PM
I did have a slipping Y belt before, so I actually cable tied the two belt ends together. I can grip the bed and it doesn't shuffle. This y axis slip happened post cable tying
Re: X/Y Axis movement
December 17, 2013 04:23PM
Further observations of the 'home' procedure and a problem I experienced.

When I home X it homes reliably to the silver foil on the tab.
When I home Y the plate stops with the extruder nozzle about 5mm or so off the plate edge.

But to home Z, I then need to move X about +55mm to get the sensor centralised with the reflective film and then move Y 10mm to allow the sensor to be over the reflective tape and allow the Z axis to be homed.
The above is not a problem, but can I set this X,Y,Z location as the reference point?

I created my first layer file using slic-3r..... and this has a 'home all axis' command near the beginning:
Quote

.....
M104 S185 ; set temperature
G28 ; home all axes
G1 Z5 F5000 ; lift nozzle
M109 S185 ; wait for temperature to be reached
......

This 'home all axis' command appears to take the head off the plate and tries to home over the z axis drive gears.
It then crashes into the plate and rips the Kapton tape....... sad smiley
Prior to this, I had the nozzle nicely set at a good X,Y point and had set the Z axis.
Should I remove 'home' commands?

I have not yet examined the lift nozzle G code, but that did not do enough, the temperatures were all up to the set point at this stage so there was not any follow up 'wait for temperature'.

I think this has been mentioned elsewhere, but the sensor position does not have to be the 'home' position (as is nicely demonstrated by the X axis), so would it not be better if home all axis, raised Z a fixed amount, moved to the X sensor and then centralised itself in line with the foil area which then becomes Home X.
Similarly Y goes to its sensor and then positions itself over the foil for the Home Y location.
Finally Z is homed which is now safely over the foil.
This sequence would make 'home all axis' work safely, rather than what appears to happen.

If I have missed a setting in PronterFace or the Slicer program please let me know.
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