Build Thread - Emco 320

[Chaz]

Made good progress. Maths was a bit wrong, corrected most of it. Then, oddly, the turret only 'winds in' when moving positive, not negative. It used to 'wind in' when driving the servo negative. I dont know if there is something in the turret that's impacted pending which direction of travel it is used in (its bidrectional) but that's now messed up all my maths ...

Argh.

[Chaz]

I'm going to go back to a different way to manage the moment. I should be able to, change to incremental mode once I find the location based on the sensor, correct?

Could I therefore use logic that says to spin forward till you hit the 4 bit logic? Problem is, with position control, I would assume that it will move till the move is done and only check logic 'after'? Correct?

Thanks

[Chaz]

Like talking to myself ...

I think I might know why the detection didnt work quick enough in the first attempt which ultimately cost burning out the motor.

I've done a lot of testing today, driving the motor forward and backwards manually, writing down the timing of each sensor and when it activates, for how long etc.

What Ive worked out is that if you turn the turret clockwise (facing the spindle), it counts from 8, down to 7 etc down to 1 and then to 8. If you stop when the system sees '1' and you lock on the next locking place, it will lock on tool 1. If you do it anticlockwise and lock when you sell tool 1, its too late and it locks into tool 2's position. I need to watch the older vids that I took but it could be this.

I've seen vids where with the original control you can simply say 'next tool up' or 'next tool down' - in this case, its not commanding a specific tool, it just moves to the next one and almost doesnt care. But, to find a specific tool, you can only do this going clockwise, unless you code some form of reverse before locking.

So, as I've now mapped out all of the angles I need, I can pretty much hardcode them. So I could say 'If tool requested is tool 1' then goto line 150 and at 150, it basically has the exact coordinates for where tool 1 locks etc. The same for 2 etc.

The only thing I need is a reliable home for the A so that my angles are consistent. What I'm going to try and do is basically let tool 1 (in the locked position) be A0 and then reference everything from there so the machine will always park / stop with Tool 1 in position.

I did try to do an incremental move in my previous attempt and it didnt like a G91 in the M6 code, so abandoned this idea.

[Chaz]

OK. T1 works. However I've worked out an issue that's caused problems and explains why sometimes it works and sometimes it doesnt. Once you lock, if you dont unlock the correct direction the wheel goes out of sync with the encoder. They are not directly connected and it 'rolls over' a position. Hard to explain. So in one condition, CCW before the tool change works. In the other, it doesnt and CW works. So yes, need to remain in the same position.

Should I be able to run an incremental G91 command inside of the M6 Macro? I need to have the first move always just move 10 positions in the to the negative direction to unwind, Doing an incremental move would be useful but the last time I tried G91, it didnt like it.

The other option would be to read the Axis location and then just move the the amount 10 less. Let me check if I can do that instead.

**Edit, just found this in the macro guide, so it muse be possible, this was an example of a move when homing:

G91 Z .050 F25 ; move Z axis incrementally in the positive direction .050”

[Chaz]

Seems lathe doesnt like G91. So figured out how to do it by subtracting from the current position with the following

#Move Amount Variable = #5024 - 10
G53 #Move Amount Variable

This works. The only issue I'm having is that my turret's 4 bit encoder seems hyper sensitive to what direction I come in from as it has a part that reads, then doesnt read, then rolls over to the next number. I'm now landing on the right tool consistently but sometimes the encoder thinks Ive gone just too far. The 'fix' will either be to ensure that I always come in from a positive A direction or maybe messing with the turret alignment which I'm not keen on, so will fix via software.

Emco320CorrectTool.mp4

(7.1 MiB) Downloaded 15 times

[suntravel]

G91 is mill only
on a late use UVW instead of XYZ for incremental moves.

Uwe

[Chaz]

Thanks. Just back from a few days in Portugal. Time to look at this again shortly.

[cnckeith]

https://www.centroidcnc.com/centroid_di ... manual.pdf

[suntravel]

Some parts of the lathe manual are from the mill with G91...

Uwe

[Chaz]

Some parts of the lathe manual are from the mill with G91...

Uwe

Exactly. Its not like I havent read through the manuals, extensively. For example, if you search for Incremental, nowhere do you get UVW references.

I also wouldnt mind some feedback on questions posed earlier. I do recognise that its holiday etc, so not been too pushy - Ive done a LOT of work to understand and make this work. Currently not having a reliable A 'home' is a problem as the starting position is critical. I'd love to know if I can do a position move and look for the turret 'bits' to then interferre but I think the position moves have to be completed before the next step can be taken.

Thanks