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Author Topic: Mach turn & tool change  (Read 8861 times)

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Offline jimpinder

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Re: Mach turn & tool change
« Reply #10 on: January 21, 2009, 04:20:07 AM »
I am getting into this a bit late on - but there are a few things I am puzzling about.

The first was the comment in the first post - "How to make Mach 3 turn an axis for which there is no DRO"
I cannot see why you do not just put a DRO on the screen for the turret - marked turret. It only needs to be one or at the most two digits long.

As far as turning the toolholder on a stepper, then if you set the steps per unit at the number of steps it needs to turn to from one tool to the next, then the commands are simple G0 A1.*********  -  G0 A1  where ********* in the fraction you need to overun, and A1 is the locked position of Tool1. The machine would then overrun the position and back up to lock the tool.  The DRO would then show the number of the tool in the holder.

I would make the home position the position of locked tool 0, but I cannot see why you need three indicators - one would do if you have the contrallability of steppers.The logic of choosing the tool numbers is fairly straight-forward, if the axis is continuous.

I know Hood has already done a lot on this - but am I anywhere near the right lines on this, I might start on a turret myself, soon.

Jim.


Not me driving the engine - I'm better looking.

Offline Hood

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Re: Mach turn & tool change
« Reply #11 on: January 21, 2009, 04:48:26 AM »
Jim yes thats more or less, as you say only one pulse is needed but seems that three are on this turret so never confused the issue :)
Probably best to set up the steps per unit to match your tools so if you had six tools work it out so T1 is 0, T2 IS 2 etc etc.

Not sure how the rotational axis works , ie whether 1 revolution is 1 unit or more likely 1 degree is 1 unit, so if you had a stepper that was 10 micro stepping that would be 2000 steps to do 360 units so 2000/360=5.5555  would be steps per degree so for 6 tools you need to move 60 degrees each tool  so set it to 5.555 x 60 =333.333steps per unit.

Hood

Offline jimpinder

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Re: Mach turn & tool change
« Reply #12 on: January 22, 2009, 04:49:02 AM »
You can make one unit be what you want. I dont know the gearing on this particulary turret, but I would make the steps per unit sufficiently high to move my turret round to the next tool (as you say 60 degrees). Lets call each unit a "toolturn" instead of an inch, or a foot, or a millimeter.

This, I thought, would make the logic side of the job a lot easier. You can still do fractions of a toolturn, in either direction to lock it in place. If you limited the DRO to a single digit readout it would show the tool number only as it passed the mark, and then got locked back into place.
Not me driving the engine - I'm better looking.
Re: Mach turn & tool change
« Reply #13 on: January 23, 2009, 12:13:18 AM »
Hi,
 I'm just wrapping up the wiring to this mess, as soon as I get to a point where I can start testing I will let everyone know.

 FYI, The 3 optical switches is the way this turret was built .I could tear it apart and make a new encoder wheel that just uses one to show home,but I have enough stuff around to make the 3 work.

 I am a machinist by trade and hoped that by getting this machine up to par that it will help me be more competitive with the bigger shops in my area. I threw in the PLC to help with adding a bar feeder as soon as the turret is working right.

Brian
Re: Mach turn & tool change
« Reply #14 on: February 01, 2009, 08:38:27 PM »
OK,
 Here is what I have going on. I set up the turret for rotational and it re-zero's after 360. I'm having problems controlling the direction of rotation, for instance I can make a G0A+25 and it will go to 25 degree's then if I give it a G0A+360 it wants to take the shortest way to 360 instead of going the right way all the way around

Brian

Offline Hood

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Re: Mach turn & tool change
« Reply #15 on: February 02, 2009, 02:59:00 AM »
Config menu the General Config, change the "Angle Short Rot on G0" to unchecked.
Hood
Re: Mach turn & tool change
« Reply #16 on: February 03, 2009, 08:52:02 AM »
Cool,
 Works good now,Thanks'

 The next problem I'm having is in the macro. I would like the turret to do a ref home before it moves to the tool. I've used the G28.1 A0 with mixed results. The turret will turn and then set and error when it see's the home switch (something like home switch is triggered, reset and try again).

Brian


Offline Hood

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Re: Mach turn & tool change
« Reply #17 on: February 03, 2009, 09:07:41 AM »
Sounds like your switches are a bit sensitive, you could do a few things,
You could  try increasing the debounce a bit so your switches are not quite so sensitive (probably not the best idea)
You could set a G28 position on Homing and limits page and when you call G28 from the macro it will go there, setting your G28 as just off your limits should avoid this problem.
You could do the move in absolute moves, you would need to probably call a G0 before you did the G53. Doing the G53 just short of machine zero should avoid hitting the limits.
Hood
Re: Mach turn & tool change
« Reply #18 on: December 18, 2011, 01:32:03 PM »
Hi All,
 I'm working on this tool changer again (after 2 1/2 years). I was having lot of trouble with the stepper losing counts after a couple of tool changes ,so I installed a 100w ac servo on the tool changer and that fixed some of the mess.
 I'm now trying to get the micro smart plc to talk with mach3 , I've read allot of the mod bus threads but still really can't tell what the code should be in the plc to allow it to "talk" to mach. any help would be more than appreciated.

Thanks' Brian  

Offline Hood

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Re: Mach turn & tool change
« Reply #19 on: December 20, 2011, 07:29:11 AM »
Any links for that PLC?
Hood