Joining two motors

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12 Aug 2020 23:18 #178060 by phillc54
Replied by phillc54 on topic 2 motors on one axis
Yes, and the soft limits need to be inside the hard limits.

linuxcnc.org/docs/2.8/html/config/ini-ho...witch_example_layout

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13 Aug 2020 07:12 - 13 Aug 2020 07:12 #178074 by Aldenflorio
Replied by Aldenflorio on topic 2 motors on one axis
Is it the same information for 2.9?
Last edit: 13 Aug 2020 07:12 by Aldenflorio.

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13 Aug 2020 07:25 #178078 by tommylight
Replied by tommylight on topic 2 motors on one axis

Aldenflorio wrote: Is it the same information for 2.9?

Yes, 2.8 and 2.9 or Master have the same homing procedure.
If you insist on being able to jog "joints" before homing a tandem machine, have this added to the ini file in the traj section
[KINS]
JOINTS = 4
KINEMATICS = trivkins coordinates=XYYZ [color=red]kinstype=BOTH[/color]
Only the part in red.
Beware that the jog buttons on the keyboard will not be as usual while the machine is in "joint mode", and lower the jog velocity slider to some low value to prevent from racking the gantry.
After setting it up it is advisable to remove the part in red from the ini file to prevent accidentally messing up the gantry.
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13 Aug 2020 12:16 #178095 by dgarrett
Replied by dgarrett on topic 2 motors on one axis

have this added to the ini file in the traj section...


The cited method is not sufficient.

The provision that disallows joint jogging of
synchronized joints is controlled by ini file settings
for [JOINT_n]HOME_SEQUENCE with negative values as
described here:

linuxcnc.org/docs/2.8/html/config/ini-ho....html#_home_sequence

A method to allow joint jogging prior to homing (for machines using
synchronized joints) is documented here:
linuxcnc.org/docs/2.8/html/config/ini-ho...l#_inhibiting_homing

and demonstrated in the sim config sim/axis/gantry/gantry_jjog.ini:

github.com/LinuxCNC/linuxcnc/blob/master...ntry/gantry_jjog.txt
github.com/LinuxCNC/linuxcnc/blob/master...ntry/gantry_jjog.ini

Using trivkins with kinstype=Both is useful to clarify
the joint number (0,1,2,...) and axis coordinate letter
(x,y,z,a,b,c,...) distinctions in gui displays

Use of kinstype=B is described in the manpage:
linuxcnc.org/docs/2.8/html/man/man9/trivkins.9.html
The following user(s) said Thank You: phillc54, tommylight, rodw, Aldenflorio

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14 Aug 2020 04:28 - 14 Aug 2020 04:28 #178151 by Aldenflorio
Replied by Aldenflorio on topic 2 motors on one axis
Thank you for all that info it truly was helpful. I read all of the homing page and I think I have an alright understanding. In my understanding it doesn’t seem like it’s too hard of a thing to do. It seems the main things are these. Find out when you want them to home (ex: x first then y). Then you figure out how fast you want them to travel when looking for the home. Then you find out how far you want it to move away from the limit switches when it hits them and how fast it does that. That point is then home. The soft limits tell the machine to slow down and that it’s getting close to the limit switches. I suppose I’m still trying to understand how to implement soft limits though. Since I’m using a floating head and a proma 150 thc then the z doesn’t need to be homed and should just be left alone during this sequence. Maybe I understood it wrong though but hopefully not. I don’t need to move the axis before the machine is homed. But I would like to manually be able to move them once they are homed. Also I have another question (below is a simple drawing of my machine red:limit switches, yellow:soft limits for reference) since I’m using two motors on one axis then they two switches both have a Max and both have a min. Will I have to make a distinction or will it be made by itself?
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Last edit: 14 Aug 2020 04:28 by Aldenflorio.

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14 Aug 2020 23:08 - 14 Aug 2020 23:08 #178211 by Aldenflorio
Replied by Aldenflorio on topic 2 motors on one axis
Home search velocity: how fast it searches for home

Home latch velocity: I’m not sure: possibly how fast it goes after reaching soft limits to fond the hard limits

Home final velocity: how fast it goes to home offset

Home ignore limits: whether or not it listens to hard limits and soft limits

Home use index: I don’t understand what it’s saying

Home offset: how far it moves away from the hard limits once it hits them

Home: final position - home I’m going to set it same as the offset

Home is shared: I don’t fully understand this one

Home absolute encoder: I doing understand this one either

Home sequence: the order in which they joints home

Volatile home: is the machine might move after power off

Locking indexer: I’m not sure

Immediate home: if you don’t have hard or soft limits so where it stands it considers home

Inhibiting homing: not sure but it seems important to what I’m doing
Last edit: 14 Aug 2020 23:08 by Aldenflorio.

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15 Aug 2020 06:15 #178235 by Clive S
Replied by Clive S on topic 2 motors on one axis

Aldenflorio wrote: Home search velocity: how fast it searches for home

Home latch velocity: I’m not sure: possibly how fast it goes after reaching soft limits to fond the hard limits

Home final velocity: how fast it goes to home offset

Home ignore limits: whether or not it listens to hard limits and soft limits

Home use index: I don’t understand what it’s saying

Home offset: how far it moves away from the hard limits once it hits them

Home: final position - home I’m going to set it same as the offset

Home is shared: I don’t fully understand this one

Home absolute encoder: I doing understand this one either

Home sequence: the order in which they joints home

Volatile home: is the machine might move after power off

Locking indexer: I’m not sure

Immediate home: if you don’t have hard or soft limits so where it stands it considers home

Inhibiting homing: not sure but it seems important to what I’m doing


]Home search velocity: how fast it searches for homeYes . But the direction it searches is determined by the sign in front of the number ie. -10 or just 10 etc.

Home latch velocity: The same as above the sign will denote the direction to back off the switch. When we are talking about the home switch ( there is confusion about the home switch and the limit switch as you can use the same switch for both) This is where the the word sharing come in to play ie. home switch is shared.

Home final velocity: how fast it goes to home offset No. This is the speed it goes to the final home position and it should be a little bit (at least) be away from the home switch to stop false triggering and can be any where you like.

Home ignore limits: whether or not it listens to hard limits and soft limits No. When using just one switch for home and limit
it is saying that when homing ignore the switch as a limit when it is homing but then make it a limit switch when it is finished homing.
It is nothing to do with soft limits.


Home use index: I don’t understand what it’s saying You can forget this

Home offset: how far it moves away from the hard limits once it hits themThis is usually a very small number and with dual axis it is used to square the gantry for instance if the gantry is 1mm out of square then you would put in 1mm then that would drive the gantry 1mm mor on one side than the other.

Home: final position - home I’m going to set it same as the offset This is where you want the final home position to be . I would leave the offset at zero until you want to square the gantry then put in the amount the gantry is out of square.

Home is shared: I don’t fully understand this one This means you are sharing a switch as a home and limit using just one switch

Home absolute encoder: I doing understand this one either You can forget this.

Home sequence: the order in which they joints home Yes that is correect BUT for gantry homing this must have -ve sequence number ie -2 and both side of the gantry HAVE to have the same sequence number (also you cannot miss out any numbers ie. 0,1,-2,-2 ---- 0 move the first joint usually Z then X or Y ...

Volatile home: is the machine might move after power off You can forget this

Locking indexer: I’m not sure Forget

Immediate home: if you don’t have hard or soft limits so where it stands it considers homeIf you don't have home switches

Hard limits are like rubber blocks at each end to stop it running off the rails. Limits switches are in case of emergency to shut the machine down in case of errors.. At one end you can use the same switch as a home and limit.

Soft limits are setup so that the machine under normal circumstances will never hit the limits and de-accelerate before them. So these are set up to be inside all switches..... The final home position has to be inside the soft limits .

Hope this helps. Please feel free to correct me if any errors in the above,

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15 Aug 2020 07:13 - 15 Aug 2020 07:13 #178239 by Aldenflorio
Replied by Aldenflorio on topic 2 motors on one axis
Sorry I wrote this kinda weird. I started from the bottom so it might make more sense to read from the bottom up.

Home search velocity: ok, thank you

Home latch velocity: ok so this sounds like what I though offset was. If I read it right then this tells it the direction and speed that it travels once it hits the switch

Home final velocity: understood, thank you

Home ignore limits: So does that mean that it won’t stop if it trips the switches? I guess this one still confuses me

Home offset: ok I’m moving from the bottom up so I addressed this farther down. I thought I was using my switches to home the machine and then this would tell it to move a bit away once it trips the switches. But from what you wrote it sounds like this is only to square an out of square gantry.

Home: ok, thank you

Home is shared: I’m not sure if I’m properly addressing what you said but hopefully I am. I have 7 limit switches total (or whatever they are called, they’re linked below) four for the y axis, two for the x axis, and one for the floating head on the z axis. I thought I was going to have it home based one when it tripped those switches bc in my mind that’s more accurate. I think this pertains to that.

Home sequence: ok so I want z first, then x, then y. Y is two motors so I would have z=0, x=1, y=2, yt=-2 (or is that 2 again?)

Immediate home: ok I have what I believe are switches linked bellow.


usa.banggood.com/5pcs-AC-250V-5A-Adjusta...der&cur_warehouse=CN

www.amazon.com/gp/product/B07BL33XXT/ref...07_s01?ie=UTF8&psc=1

Thank you very much for the much needed clarifications. Also I apologize for my ignorance in this subject.
Last edit: 15 Aug 2020 07:13 by Aldenflorio.

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15 Aug 2020 07:56 #178243 by cmorley
Replied by cmorley on topic 2 motors on one axis
homing use two speeds;
home search velocity is the 'course' speed used to find the rough position of the switch.
latch velocity is the 'fine' speed for precision latching of of the switch position.

home offset is the distance of the home switch to the origin.

This explained in detail here:
linuxcnc.org/docs/2.8/html/config/ini-homing.html

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15 Aug 2020 07:58 - 15 Aug 2020 08:14 #178245 by Clive S
Replied by Clive S on topic 2 motors on one axis
Ok

Home ignore limits: So does that mean that it won’t stop if it trips the switches? I guess this one still confuses me


Ok Home and limit switches are two different things. The above means that when it is in the homing state the switches will be treated as a home switch but when IT IS homed then it becomes a limit switch. The idea is that you don't need a limit switch at this end.

If you want to have a separate limit switch then you would not set the home switch as shared.

thHome is shared: I’m not sure if I’m properly addressing what you said but hopefully I am. I have 7 limit switches total (or whatever they are called, they’re linked below) four for the y axis, two for the x axis, and one for the floating head on the z axis. I thought I was going to have it home based one when it tripped those switches bc in my mind that’s more accurate. I think this pertains toat.


The ONLY switches that are used when homing are the home switches ie. one at the top of Z . One of the X and two on the Y .The floating head etc are not use for this purpose

Home sequence: ok so I want z first, then x, then y. Y is two motors so I would have z=0, x=1, y=2, yt=-2 (or is that 2 again?)


The Y tandem axis HAS TO HAVE the same -ve number ie Y1=-2 Y2=-2
Last edit: 15 Aug 2020 08:14 by Clive S.

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