Colour Printing - the next step:

To follow on from the basic twin extruder test in the last blog, here we have the results of my first test using support material

The machine is loaded with two colours of ABS, mainly for convenience at this stage, Black for the object and Yellow for the support material.

The file chosen is a bearing cap, printed from the bearing axis up, this has a semi-circular void that runs front to rear of the part. Actually this file prints very well without support material but it is a small part suitable for testing the head change.

Small it may be, but it still contains a fair number of layers and therefore lots of head swapping!

The first test was done with a hand edited file, I added several new lines of G_Code to manage an orderly change over from one head to the other. On more complex parts, it would not be practical, the new codes need to be added by Skienforge.

Skienforge already deals with support material by issuing a temperature change to flag the start and end, I need several other codes inserting at this point. To do this I have made a simple modification to Skienforge to pick out the support material, then insert my new codes as required.



The image shows the first complete part made by running the file from Skienforge.
Finish on the part is crude as the G_Code has been generated with 0.4mm layer thickness, this ensures a relatively quick build and gives a manageable file size.



The print is far from perfect, but I have to say I am encouraged by the results.

Colour Printing!

First attempt at two colour printing, not the most astonishing object but you can see the potential.
The print has been done on a V3 machine fitted with twin extruders. The two single colour objects were printed together from one file, the two colour object by swapping heads through the build, changes triggered by G_Code.
You can see the potential for running support material along with the main print, swapping seamlessly back and fourth between the two.

The wall is single filament thickness so alignment has to be reasonably good between the heads. The object is far from perfect as its only the third print of a new machine fitted out with the twin head.
More to follow on this.

More Skienforge

Important Settings:

At first glance, it may not seem very obvious what values to use in the myriad of Skienforge's boxes, needless to say, get it wrong and you will almost certainly finish up with an inaccurate print and possibly poor print quality.

I hope the following notes will help establish the correct values for your set-up and hopefully take out some of the guesswork.

What I will say at the outset is most of the option variables can be left at default so the problem is somewhat simplified.

In addition to the material profile, we need only concern ourselves with are the following:
Head speed
Extrusion Rate
Layer thickness

Get these right and the rest are only for fine tuning.

The first thing to decide is what resolution you require in the printed part. Bear in mind the fact that the higher you want the resolution then the longer it will take to process and print the part.

The fineness of print quality mainly depends on, the nozzle size, the speed of print and layer thickness.

If we take the standard machine we have little control over the nozzle diameter, it is drilled at *0.5mm, however, speed and layer thickness can be changed.

When you download a new copy of Skienforge on to a “fresh” PC, the layer thickness will be set at default 0.4mm. (If the install is over a previous Skienforge release, the value will be as you last set it.) This is a practical value to work with the standard nozzle, it gives a reasonable quality coupled with fast build times. Other values can be used, larger will produce a more course finish and smaller values put more layers into the object giving a finer surface finish.

If the standard setting of 0.4 is put through Skienforge correctly then the effect is to take the 0.5mm filament from the nozzle and stretch it out to reduce the section to 0.4mm, i.e. the head travels a little faster than the extrusion rate.

If Skienforge simply set one filament on top of another, the contact area would be very small as the two circular sections touch only on the circumference. The result would be a very weak object with poor layer adhesion. To overcome this, Skienforge squashes the new layer into the preceding one to give a larger contact area and hence a stronger object. Two Skienforge parameters are used to control this;
Extrusion width over thickness (ratio) : default value 1.5
Perimeter width over thickness (ratio) : default value 1.8

In this way Skienforge extrudes more plastic into the perimeter of each layer making the outer shell of the final print more robust. Internally the fill will be at 1.5 x layer thickness.
In either case the filament is printed as an elliptical section that has its major/minor diameter = the ratio.

With the machine set correctly:
0.4mm thickness x 1.5 gives Extrusion width = 0.6mm.
0.4mm thickness x 1.8 gives the Perimeter width = 0.72mm

To calibrate the machine we need to ensure this relationship holds true.

The only way to verify this setting is to print a single filament wall and measure it.

Calibration:
In Skienforge
Enter a value for:
layer thickness.
The desired head speed.
Look up the appropriate extruder RPM for the above settings.(See Table)



The selection table is compiled from theoretical values, many of the options have been tested but use them as a guideline for starting your test, then make adjustments to your machine to ensure it produces the correct perimeter wall thickness.

Now run a test object and see what you have.

Measure the wall thickness with a vernier gauge, take a few readings round the object.
With 0.4mm thickness the perimeter wall should be 0.72mm wide.
If the wall is too thick then reduce the extruder RPM. Wall too thin then increase the rpm.

Within a couple of tests you should be able to get the wall spot on or within 0.01mm of the target value.

That's it!

The above calibration will be required for each material type used with the machine and care will be needed the further you deviate from the nozzle diameter.

Other tweaks: on my machine, the infill pattern on the base, was not right up to the perimeter(using ABS). To correct this and force Skienforge to run closer to the edge, I changed a value in “Inset” The default value is 0.1, reduce this and the gap gets wider, increase this and the overlap is larger. My value finished up at 0.3 to give a nice clean join up to the perimeter.

Other settings of interest that do not alter the accuracy of the part are:
The fill density depending on how robust the part needs to be, Values 0.1 to 0.99 are all good.
0.1 to 0.4 Light duty
0.4or 0.5 Normal duty
0.5 to 0.9 Heavy duty

Interface layers in the raft:
I use 1 not the default 2 layers, this is quicker and still caters for a slight run out or warp in the bed material.

Finally, in raft I do not use the cooling cycle and I have quite a few of the other options switched off. The complete set-up mentioned here is cut back to the minimum requirement, from this point you can experiment with other options from a known base point.

The easiest thing for me to do is post a version of Skienforge along with my preferences and the latest version of the firmware. Everybody trying this will then be exactly the same and I have a sporting chance of helping anybody who has problems with the print.

That's just about it, with the machine set as above you will be able to move through the full range of print quality by making only two changes to Skienforge namely layer thickness and extruder RPM



The image shows the complete range of practical values for layer thickness. On the left 0.55mm through to 0.25mm in 0.05mm steps. All the cylinders are printed single filament wall.
ABS
16mm/sec head speed.

*There are plans to create a range of nozzle sizes for use with the machine.

Machine/Firmware manual

RapMan O&M Manual

Machine Geometry.
Table Coordinates
It might be easier to view the print table as a a sheet of graph paper, and therefore, that each point of the table has an X,Y coordinate we can send the tool head to. The axes are set such that the centre of the table is the origin at X=0,Y=0.

Looking down on the table with (0,0) at the centre, a positive(+ve) move in X would be a move to the right of centre. A +ve move in Y is from the centre to the rear of the machine, exactly as the standard graph representation drawn on paper.

e.g.
If we pass the machine an instruction to go to point X50,Y50 if starting from the origin, the tool will be sent 50mm to the right in X and 50mm to the rear in Y

X-50,Y-50 would do the opposite and send the tool 50mm to the left in X and 50mm forward of centre in Y.

The four quadrants as follows.
X+,Y+ Rear, right hand 12 – 3 O clock
X+, Y- Front, right hand 3 – 6 O clock
X-,Y- Front left hand 6 – 9 O clock
X-, Y+ Rear left hand 9 – 12 O clock

We are also able to move the Machine in the Z axis, this being a straight line through the origin perpendicular to X and Y. For the RapMan we have defined Z = 0mm when the tool is just touching the top of the table (or work piece). A 10mm +ve move in Z will move the table down giving the tool an elevation of +10mm above the table. A -ve move in Z would move the tool into the table or work piece.

If we mount a 5mm thick work piece on the table and set Z=0 on top of it, this will enable us to use -ve Z values and machine down into the 5mm thick work piece.

On top of the table the maximum work area is:
X -135 to 130
Y -100 to 100
And in Z a range:
Z 0 to 230
Giving a maximum potential size of object at 265 x 200 x 230mm

When designing for Rapid prototyping we should aim to create an object that is equally spaced about the origin, in this way when it is printed on the RapMan the object is neatly printed in the centre of the table.

Stepper Motors
The RapMan uses stepper motors to move in each of the three axes, this is critical to the operation of the machine as these motors can be made to move in a very controlled manor.
Unlike other DC and AC motors that rotate when power is applied, the stepper motor is only able to move in discrete steps in either direction. The motors we use have 200 full steps per revolution, ie, issue the motor controller a single step and it turns the motor 1/200 of a revolution. The important thing to realise is the motor is held in each new position and while energised it does not move again unless it gets another step pulse.

It gets a little more complicated in that the stepper controllers are able to take the basic step resolution and deliver 1/16th step output, thus giving us the ability to move the motor in 200x16=3200 steps every revolution.

To turn the motor 180 degrees, we send it 1800 steps, if the diameter of the motor drive pulley is known, it is possible to calculate exactly how far this will be. The motor can be run at constant RPM by sending it a continuous stream of pulses at a fixed frequency, if the steps are counted it is possible to calculate exactly how many revs the motor has turned.

Knowing the circumference of the motor pulley and the number of pulses per revolution in X and Y we can show it requires 87.575steps/mm
In Z we have 2560steps/mm since we are turning a threaded rod with a small pitch.

Following on from the graph analogy the RapMan table is divided up into squares equating to a 1/16th step, this is the smallest discrete unit we can address.

87.575 steps in a mm this will give us 0.011mm resolution in X&Y with 0.0004mm in Z
These are theoretical maximums for the machine, realistic maximum is 0.1mm XY&Z.
Mainly due to restrictions of materials used.

Home
To ensure that we know where the tool is at any time, the machine is initialised to a known reference point, we call this the Home position.

The first action of the machine is always to confirm the position of the Home coordinate. It does this by running up to limit switches then moving back out very slowly until the switch resets. As each axes sets then re-sets the switch, it updates the processor with values defined for the back left hand corner of the machine.Home on the RapMan is at coordinate X = -135mm, Y = 100mm, Z = 0mm
The origin of the machine in the centre of the table is at coordinate 0,0 Measured from Home this is a "step" move of 135*steps/mm in X and -100*steps/mm in YRest Position.
At the front right hand side of the table there is another hole cut in the table, this is designated as a rest position. This is placed at the front of the machine to make access to the tool easier.
The rest position is at table coordinate X130, Y-100, Z is at the current height.

Electronics.
The electronics offer a basic UI to control the machine. This is achieved by use of push buttons and a small OLED screen to display updates of machine status.
The control board also contains the interface for an SD Card and an array of four stepper motor driver chips.

Along the top of the board we have motor connection terminals Fan and AUX header.
On the left we have the tool header, on the right our power and USB ports.
Alongside the screen you will find the PICKit2 programming header.
At the heart of the board is the main processor the Microchip PIC32 running at 80MHz. This is one of the latest high performance 32bit devices and it controls all aspects of the RapMan.
Details of the connections to the board are covered by the build manual. Please use this to ensure it is connected exactly as stated.

Tool Header
The RapMan identifies the type of tool fitted by checking the voltage dropped across a reference resistor, values as follows:

Description Resistor A/D
976 Ohm resistor for PEN 1K (90)
4.7K Ohm resistor for Extruder 4K7 (320)
9.9K Ohm resistor for Extruder2 10K (500)
22K Ohm resistor for Not Defined 22K (700)
47K to 100K Ohm resistor for Router 47K to 100K (840 to 920)
1M Ohm resistor for No Tool 1M to open circuit(1010 to 1024)

At Ver1.0.5 the Extruder, Pen and Router have been defined in firmware.

AUX header.
Top left of the board is a two way screw terminal used to power any auxiliary equipment fitted to the RapMan. This port is driven by a FET feeding 12VDC to the terminals. Power is limited only by the size of the PSU supplied with the RapMan. If you need several Amps from this port then please change the main PSU and add in the extra capacity.

The RapMan uses 12V 5Amp supply.

SD Card
The control board has an indicator LED for card detect, no card the LED is OFF, card correctly installed the LED is ON.

The RapMan uses an SD or MMC card up to Maximum 2GB
The card should be formatted to FAT16 or 32
Files on the card should reside in the root directory and be in the form of G-Code text files as generated by Skienforge. File size is not limited and can run to several Megabytes.
Valid file extensions are *.gco and *.bfb any other file extension is rejected as invalid

Firmware
V1.0.5
On power up the firmware offers the following Menu
1)Run File
2)Manual Move
3)Tool Setup
4)Home Tool head

Move up or down through the menu items using the Y+ and Y- buttons, press X+ to select the option

1)Run File
This checks to see the tool type fitted and enables you to choose the file you want to run.
The file offered as the first choice is the last one added to the card.
At this time use the Y+ button to move to the previous file and Y- to go to the next file.

You can see confirmation of the file number at the bottom of the screen.
Selection of the file is made by pressing the X+ button on the right.
If you wish to return back to the start menu press “Esc” button at the bottom left of the screen.
Once the file has been selected the machine confirms the home coordinate and proceeds to run the file.

During the print it is possible to pause the process by pressing the Esc button. In this event the machine halts at the end of the current instruction and runs over to the rest position where the heater and extruder motor are turned off.

The message on the screen reflects the status of the machine and offers return to print by pressing the escape button again.

It is possible to make adjustment to the machine settings during a print.
The axis buttons are all redefined to change the three main parameters.
X buttons change extruder speed up and down
Y buttons change the temperature up and down
Z buttons change the tool speed up and down.

Note the changes are made at the end of the current g_code instruction to prevent corruption of the print.
At the end of the print you are given option to return to the main menu.

Screen output:
You should always be able to see the Firmware version number at the top of the screen.
Below this is confirmation of the file name that is open.

The current G_Code line number
The Tool Head speed in mm/s
The Extrusion rate in mm/s

The next two lines are status indicators.
Top is the print progress, this runs left to right and is updated regularly throughout the print.
The print is complete when the solid bar reaches the right hand side of the screen.

The next line of the screen shows the status of the step buffer. This is another progress bar running left to right. No indication is buffer empty, a full bar across the screen is buffer full.
The status is reported at the end of each G-code instruction, after the following line has been read in and is ready to go. If there is content left in the buffer at the end of each line of code then we have no segment pausing. It is normal for this line to be very animated.

The bottom line of the screen reflects the extruder status.
The first number on the left is the target temperature setting for the extruder.
The asterisk shows heater status, when showing the heater is on, not showing the heater is off.
Immediately to the right of this is the current temperature of the extruder, this number shows the temperature reported by the thermistor on the heater barrel, the value fluctuates as the heater is switched in and out.

If the temperature drops 5C or more from the set value then the fan is turned off, if the temperature drops 10C or more the motor is turned off for protection.

2)Manual Move
Select this option to move the machine manually. The information on the screen reflects the current position in XY and Z. This function is most useful to move the machine round during setup, especially in finding the home position for Z.

3)Tool Setup
The machine moves over to the rest position for this mode. In this way any extrudate can discharge through the hole provided in the table.

Below the firmware version number, the screen shows the tool attached to the RapMan.
In the case of a Pen this screen is redundant as there is no set up to be done.

In the case of the extruder the screen gives a message at the top if the temperature is lower than 100 DegC. This is just a reminder that the motor will not run if the temperature is too low. As soon as the temperature is above this figure the message is removed.

On the next line is the current setting for the extrusion rate in mm/s, when you first enter the screen this value shows 0.7mm/s as the Extruder is set at 1rpm. The extruder minimum value is 1, below this is off, above 1 starts the motor (if Temp >100C)

The next line is the heater status On or off.
The bottom line of the screen reflects the extruder status.
The first number on the left is the target temperature setting for the extruder.
The asterisk shows heater status, when showing the heater is on, not showing the heater is off.
Immediately to the right of this is the current temperature of the extruder, this number shows the temperature reported by the thermistor on the heater barrel, the value fluctuates as the heater is switched in and out.

X+/- adjust the extrusion rate up and down
Y+/- adjust the temperature setting up and down
Z+/- do not have any effect.

This mode is most useful in setting the machine to run new materials and in when checking the extruder function.

4)Home Tool head
Does only as it suggests. Re confirms the home position from any point on the table.
Use in conjunction with the manual moves to set Z=0.

G-Code instruction
In addition to the control offered by the menu we also have special instruction codes that can be put into the G-Code, these items are Modal commands for switching in or out machine functions.
Listing of all special commands follows,

M_Code_M101 Turn extruder on.
M_Code_M103 Turn extruder off.
These two codes frequently work together in the G-Code to flag when the extruder is, or is not, required. This usually occurs at the end of a printed thread while the tool moves to the start of the next thread. The RapMan default is to continue to run the extruder during this time and use the M103 flag to initiate a rapid move then return to normal print speed after M101.
If you require the motor to stop during these moves then you can use the M225 command below, this flag stops the motor during rapid moves. M224 returns the system to default.

M_Code_M104 M104 S145.0 Set temperature to 145.0 C.
Used to make a change in temperature. The machine is instructed over to the rest position while the change takes place, after this it returns to the print and continues.

M_Code_M106 M106 Turn fan on.
M_Code_M107 Turn fan off.
M106 and 7 set a flag to enable or disable fan control.
M_Code_M108 M108 S210 Set extruder speed to 21.0RPM

BFB codes
M_Code_M220 Turn off AUX
M_Code_M221 Turn on AUX
M220 and 221 directly switch the Aux port on or off

M_Code_M222 M122 S500 Set speed of fast XY moves
M_Code_M223 M123 S500 Set speed of fast Z moves
500fast – 2000slow
M222 and 223 set the speeds used for the fast moves initiated by M103, Machine default is set at 500
Settings up to 1000 all work well, the larger the number the slower the speed and as a consequence the hairs get thicker. The benefit of slower speeds is that it is very much kinder to the machine.
(I use 768 for both values)

M_Code_M224 Enable extruder motor during fast move
M_Code_M225 Disable extruder motor during fast move
These flags set and re-set the extruder enable during fast moves. Enabled you run the motor during the move.

G_Codes

G_Code section included for reference:

RapMan special codes
G0 Rapid Motion Implemented - supports X, Y, and Z axes.
G1 Coordinated Motion Implemented - supports X, Y, and Z axes.
G2 Arc – Clockwise Not used by Skienforge
G3 Arc - Counter Clockwise Not used by Skienforge
G4 Dwell Implemented.
G20 Inches as units Implemented.
G21 Millimetres as units Implemented.
G28 Go Home Implemented.
G90 Absolute Positioning Implemented. V1.0.5
G92 Set current as home Implemented V1.0.5

M101 Turn extruder on Forward.
M102 Turn extruder on Reverse. Still to add
M103 Turn extruder off.
M104 S145.0 Set target temperature to 145.0 C.
M105 Custom code for temperature reading. Not used
M106 Turn fan on.
M107 Turn fan off.
M108 S400 Set Extruder speed to S value/10 = 40rpm.

M codes that may be introduced for the RepRap
M120 Pgain PWM control values
M121 Igain “
M122 Dgain “
M123 Imax “
M124 Imin “

**********************
BFB codes
**********************
M220 Turn off AUX V1.0.5
M221 Turn on AUX V1.0.5
M222 Set speed of fast XY moves V1.0.5
M223 Set speed of fast Z moves V1.0.5

Typical File header produced by Skienforge:
G21 millimeter system selection
G90 absolute distance mode
G28 Return to home position
M222 S1024 Manually added to file M222 S500 Set speed of fast XY moves. Default value 500 -V1.0.5
M223 S768 Manually added to file M223 S500 Set speed of fast Z moves. Default value 500 -V1.0.5
M103 Turn extruder OFF.
M105 Custom code for temperature reading – not used by RapMan
M104 S247.0 Set temperature to 145.0 DegC.
G1 X0.0 Y0.0 Z0.0 F480.0 linear interpolation
M101 Turn extruder ON.
Main code follows


Tony.

Skienforge Settings

The Skienforge tool suite is well documented along with the download.
I would like to thank Enrique Perez for this remarkable body of work. It has settings for everything you are ever likely to want to tweak. I find the G_Code generated is capable of producing very nice prints.
I use the following basic settings and only usually change temperatures and speeds. I will point out any other settings that are specific to a particular print file.

Analyze -not used

Carve – numbers from the top
1.5
1.0
Check – correct mesh
Infill bridgewidth 1.5
Check – Infill in direction of bridges
Layer thickness 0.4
Layer thickness over precision 10.0
Clip – 0.15

Comb – Not active

Export –Check – Activate Export
Check - Delete Comments
Check – Delete M110 Gcode line
Uncheck - Binary 16 Byte
Check – Do Not Change output
Uncheck - Gcode Small
Uncheck – Gcode Step
File Extension - “bfb”

Fill - List of settings from the top
999
0
1
0
1
0.1
0.0
45.0
1
0.2
90.0
Infill Pattern – Grid Hexagonal
Interior infill density over exterior density ratio 0.9
Check – Outside Extruded first
Solid Surface thickness layers – 3

Fillet – Not Active
Hop – Not Active

Inset – Extrusion Perimeter width 1.8
Infill Perimeter 0.05
Check – Calculate overlap form Perimeter and infill
Check – Start at Home

Material – ABS
Multiply – Not Active
Oozebane – Not Active

Polyfile – Check - Execute file

Raft – Check – Activate Raft
Check – Add Raft
Numbers from the top
0.5
1.0
1
0.75
0.0
0.1
0.5
1.0
2
1.0
Next block
1.0
15.0
0.0
Check – No Support material
Bottom block of numbers
60.0
0.0
0.0
0.0
0.0
0.0
247.0 Use your temperature setting here!
247.0 Use your temperature setting here!
247.0 Use your temperature setting here!
247.0 Use your temperature setting here!
0
0
Speed – Activate Speed
Extrusion Dia over thickness ratio 1.25
FeedRate mm/s 16 – Use your speed setting here.
Uncheck – Do not add flow rate
Uncheck – Metric
Check – PWM Setting – we use this to set the extruder RPM
Bottom block of numbers
400.0 Extruder RPMx10
0.5
1.0
1.0

Stretch – Not Active
Tower – Not Active
Unpause – Not Active
Wipe – Not Active

Tony.

Print Problems

Potential print problems:


Too Cold
The filament looks like it is wiry with strands that pop up from the raft, inter layer adhesion is poor or non-existent.



Too Hot
This is harder to diagnose, you might find you can build the object completely especially if the object is small.
Generally speaking the characteristic of to high temperature is the layers melt into one another too much, fine detail in the shape is hard to maintain and the object is likely to exhibit more warping. The easiest way to diagnose this is to print a test object that has a fine stem, like the wine glass.

Print speed greater then Extrusion rate
This pulls the filament thinner, if you intend to run like this you must make allowance for it in Skienforge, set the layer thickness to a lower value in direct proportion.

Print speed less than Extrusion rate
This is used to good effect on the base layer of the raft, more material is pumped out thickening the filament. As above if you wish to maintain dimensional accuracy in the main body of the print you must make allowance for it in Skienforge, set the layer thickness to a higher value in direct proportion.



Warping
Running 16mm/s at 40rpm with ABS is good for small objects but starts to cause problems the larger the object gets. By the time any dimension is > 50mm warping is a significant effect.
I have done some experimentation recently and found warping can be reduced if the print speed is reduced. Try 8mm/sec at 20rpm, this has produced objects > 100mm long with minimal warping, the obvious down side is the build time is doubled.
Another option is to warm the print table or blow hot air round the print, both methods have been used to good effect.

Removal of the object
The easiest way is to slide a flat blade under the raft and work all the way round, chances are the object will pop off before you are finished. Alternatively if the object remains stubbornly fixed to the table. Push the blade as far as you can under one edge, then get a flat bladed screwdriver and use it to push the back of the blade. I have not failed with this method so far. If you do this please take care with the blade, I don't want any medical bills flying my way!
Tip: mark the X axis orientation on the print with a felt tip pen.

You now have your first minimug off the printer.

Ovality
Is the mug round or very slightly oval? You may need to run a large circular object to be sure of this. If there is any ovality it should be aligned with either the X or Y axis. Take the small diameter
and note the axis that is running undersized. Check the belt on that axis is tight enough.

The photo shows good prints top and bottom, left and right are slightly oval.

Material Feed fault
This otherwise good print was spoilt by the material feed, the plastic reel was too stiff on its axle, the extra drag was too much for the extruder and it slipped a few times during build.
The drum was remounted on bearings and the next print was fine.










Have a good look at the finished object. The minimug is quite strong, it should be very hard to break it. If it does fracture along the layers then try a slightly higher temperature.

Are the sides of the mug good quality, with no hanging filaments on the outside, it may have slight imperfections due to Z moves. Inside will have a few hairs, this is normal.

The minimug is a good starting point, but it will not allow the fine tuning required to run off some of the more demanding objects, so for now, try a series of minimugs, play with the settings and observe the results, you will soon start to get a feel for the machine and how the material behaves.

Continue until you can reliably produce a good mug.

Changes on the fly
With the new firmware release it is possible to change the extrusion rpm and the set temperature during a print run. We have utilised the four axis buttons (+X-X+Y-Y) to increase or decrease the settings as required.

X RPM Adjust the extruder RPM
Y Temperature Adjust the heater temperature

Once you start printing you can use the buttons to do any fine adjustment and immediately observe the result in the print. This is also a real help when testing new materials, it can save much card swapping. When you see the result you want, make a note of the settings and edit the G_Code file to suit.

I encourage you to have a play with the feature and learn what changes can be made to the print quality. Take care when you run down to the lower temperatures for the material.

Tony.