Base config

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14 Mar 2021 10:37 #202200 by samforsey12345
Base config was created by samforsey12345
First of all, thank you guys for this epic resource! I have got a lot further along with minimal difficulty than I thought I would

I am at the stage where mechanically and electronically I am ready to setup the base config. I have got all the home/ limit switches working as they should.

My initial question is about step scale. I have tuned my X axis to within a reasonable tolerance using a DRO. I then thought it would be a simple case of using the same step scale on the Y axis, however when doing so, it only moves precisely half the distance of the X axis. Is that to be expected? I have no experience with G code but would expect if I try to jog it 100mm, it would move 100mm.

I recently bought Gecko 201x drives to replace cheap chinese stepper drives I had. These are a great improvement. I have checked that the wiring is the same for both drives, and these are fixed at 10 microsteps (partly the appeal of these drives, I am trying to simplify things a bit)

The other question I have is my origin seems to be in the wrong place, I am homing with the X axis to the left rear and Y axis to the top left rear. Is this just a case of setting home offset to put the torch where axis is expecting it to be? or just accepting that I am looking at it from the rear view as opposed to the front view?

Again thanks a lot, I feel like I am fairly close to adding the plasmac layer and if I hadn't fried the plasma cutter (oops) I may have been up and running this weekend!

Sam
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14 Mar 2021 10:42 #202201 by thefabricator03
Replied by thefabricator03 on topic Base config
You need to calibrate your machines steps per unit,

Use the formula
(Commanded distance/actual distance) x current steps per unit
The following user(s) said Thank You: dvn4life1972

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14 Mar 2021 10:49 #202202 by samforsey12345
Replied by samforsey12345 on topic Base config
Hi fabricator, that was a quick response!
I have done this for the X axis using the DRO shown in the picture. I get 61.227 steps/mm.
I should have added to my initial post that both X and Y axis have the same timing belt setup and gearing, so theoretically should move the same distance per step.
My Y axis is moving half the distance that the X axis is, so if I put 122.454 steps/mm in it moves the correct distance and have verified that with a steel rule.
I was just wondering if there was something else going on which needs to be put right as I don't understand where the discrepancy comes from

Sam

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14 Mar 2021 10:53 #202203 by thefabricator03
Replied by thefabricator03 on topic Base config
Not quite sure why is would be 2x the step for the X axis if mechanically both are the same. Its hard to tell from the picture but are both belt gears set up the exact same?

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14 Mar 2021 11:15 #202205 by samforsey12345
Replied by samforsey12345 on topic Base config
For all intents and purposes they are the same. The drums which create the wrap around the drive pulley are different sizes but this shouldn't affect distance moved.

Your bewilderment makes me think it's probably not software related. The labels on the stepper motors are the same and I bought them as a kit from eBay, but perhaps one has been labelled incorrectly and one is only 200deg/rev and the others are 400deg/rev (as they should be).

Attached some pics for interest anyway! It's a bit rough and ready but doing this at home for fun!
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14 Mar 2021 11:43 - 14 Mar 2021 13:03 #202206 by samforsey12345
Replied by samforsey12345 on topic Base config
Just put Z axis motor on X axis. DRO still read correctly, then I thought to myself that doesn't look like 100mm of movement.

D'oh, I bought the DRO at an industrial auction and they must have set the X axis scale to 1/2 actual movement.

So correct step scale is now 122.454 which makes more sense as I'd calculated it to be 11.4285/mm and with 10x microstepping that makes it 114.285/mm

That answers that then.

So what gives with the home position? Is it inconsequential?

Thank you very much!

Here it is homing
photos.google.com/share/AF1QipNq8qPTxzUF...U2xQNVNNMlQ1WE55b25R
Last edit: 14 Mar 2021 13:03 by samforsey12345.

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16 Mar 2021 22:25 #202530 by andypugh
Replied by andypugh on topic Base config
You should be able to derive the step scale from the parts, not from experiment.

It is a simple calculation from microstepping, steps per rev, leadscrew pitch and gearing. That should give an exact answer.
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18 Mar 2021 12:18 - 18 Mar 2021 12:28 #202730 by samforsey12345
Replied by samforsey12345 on topic Base config
You are right, I had it in my brain that my primary pulley was a 15t, but looking at receipts it is a 14t. My secondary pulley is 30t , so I had assumed 2:1 for stepper revs to driving pulley revs

So my driving pulley drives the belt 70mm/ rev
(30/14) x 400(400steps/rev stepper motors) = steps per 70mm movement
857.14 / 70 = 12.2449 steps per mm
With 10 microsteps, that gives me 122.449 steps/mm

Thanks for the encouragement to check back over that initial calculation.

Sam
Last edit: 18 Mar 2021 12:28 by samforsey12345.

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11 Apr 2021 12:44 - 11 Apr 2021 12:57 #205633 by samforsey12345
Replied by samforsey12345 on topic Plasmac configured
Hi guys,
spring is here and things are looking up!

I have configured plasmac now. I am running an ArcOK signal from a reed switch with the ground wire wrapped around it. I tested this by manually firing the torch, and it shows as OK in the software.

I have used the conversational tab to attempt to cut a circle.

I am struggling with valid arc lost problem at the very start of the cut. I am running a pilot arc plasma cutter, and it seems as soon as it makes an attempt to switch to the primary arc, it throws me the error.

I am a simple man, so i was just trying it over and over again to see what would happen. And one time, as soon as the primary arc was lit, it cut a circle! Which was thrilling!

But which leaves me with the problem of it not working 99% of the time. So thanks again everyone but do you have any advice on this? I am wondering now whether I configured plasmac in mode 1 now (the user interface has ArcOK signal on it) but not sure how I can check this? Is there a variable to let the arc start before checking the ArcOk signal (cant seem to find anything in the files/ in software)?

Thanks
Sam
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Last edit: 11 Apr 2021 12:57 by samforsey12345.

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11 Apr 2021 13:42 #205637 by tommylight
Replied by tommylight on topic Plasmac configured
Version of PlasmaC ?
What error does LinuxCNC show when the arc is lost?
Where is the float switch located and is it wire with a fully shielded cable ?

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