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Author Topic: Constant Surface Speed On The Lathe  (Read 13973 times)

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Constant Surface Speed On The Lathe
« on: December 07, 2009, 02:13:55 AM »
I am using the latest Lockdown 032 and have just tried using ccs

As i haven't got a spindle that revs to infinity i reach my maximum speed long before the x axis is at zero.

As soon as i reach my max speed the feed per rev progressively slows down as such it will never reach X Zero.

I then tried slowing the ccs speed down and running the code again.

At the diameter that i start, i am running too fast due to the minimum speed of my spindle at this point the feed per rev is showing double what is commanded the FPR slows as it reaches the commanded CCS then back to slowing as i max out at top speed

Is anyone successfully using CCS ?

Thanks
Phil
The Good Thing About Mach3, Is It's very Configurable

The Bad Thing About Mach3, Is It's Too Configurable

Offline Hood

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Re: Constant Surface Speed On The Lathe
« Reply #1 on: December 07, 2009, 03:33:31 AM »
 I have used CSS a couple of times and it worked fine for me, are you setting a max spindle speed?

Hood
Re: Constant Surface Speed On The Lathe
« Reply #2 on: December 07, 2009, 04:57:04 AM »
Only in the cam (ONEcnc)

The only lines produced apart from moves are

G95 F0.10
G96 S250

I will try removing the maximum speed in the cam to see if there is a difference

Phil
The Good Thing About Mach3, Is It's very Configurable

The Bad Thing About Mach3, Is It's Too Configurable

Offline Hood

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Re: Constant Surface Speed On The Lathe
« Reply #3 on: December 07, 2009, 05:33:20 AM »
Put a G48S**** and that will limit the speed that Mach will attempt to run the spindle at, so if you wanted a max of 1000 RPM you would put G48S1000 after your G96 line

Hood

Offline Dan13

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Re: Constant Surface Speed On The Lathe
« Reply #4 on: December 07, 2009, 06:00:02 AM »
Yes, and don't forget to program G97 S____ to cancel the CSS

I use CSS a lot on my lathe. Mainly for parting and grooving operations in metals. But I use it with G94, since I want the mm/min feedrate stay constant through the operation and not increase as the tool approaches the centre and RPM climbs. This helps to reduce stress from my little lathe.

Daniel
Re: Constant Surface Speed On The Lathe
« Reply #5 on: December 07, 2009, 06:26:50 AM »
Hood the G48 fixed the per per rev being too high at the beginning

So now at the beginning of the facing the CCS shows as being too high, the commanded feed per rev (.1mm) stays at 0.9 all the way to the point where the spindle runs out of speed to what is commanded before it ran double FPR .2mm

From this point the feed per rev progressively drops to 0.02mm per rev

Surely it should be better than that ?

Dan13

Thanks already done in the PP in cam  ;)

Phil
The Good Thing About Mach3, Is It's very Configurable

The Bad Thing About Mach3, Is It's Too Configurable
Re: Constant Surface Speed On The Lathe
« Reply #6 on: December 07, 2009, 06:32:56 AM »
Just a couple of further points i am using a SS

I can see the slowdown in the feed

Phil
The Good Thing About Mach3, Is It's very Configurable

The Bad Thing About Mach3, Is It's Too Configurable

Offline Dan13

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Re: Constant Surface Speed On The Lathe
« Reply #7 on: December 07, 2009, 07:10:07 AM »
Phil,

Try to use the CSS with G94. That's the only way I've been using it and have never had problems.

Also, where do you read the CSS rate from? I am not sure the display is correct... I have not paid attention to this one, but I do know for a fact that the Strue DRO shows nonsense in CSS mode.

Daniel

Offline Hood

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Re: Constant Surface Speed On The Lathe
« Reply #8 on: December 07, 2009, 09:11:58 AM »
Just tried on my lathe and the feed per rev does alter and it is well screwed in that if you feed from X low to X high it is fast and the other way it is excruciatingly slow.
 Now where does the problem lie? I had issues a while back with CSS and I asked around at the one or two that were using it with the PP and they said it worked fine, in later versions of the SS plugin I thought it was sorted but have only used it a couple of times and I was thinking it correct but obviously its not.
So as I said, where is the problem, SS or Mach?
Does anyone have a lathe on the PP that could test? I am SS, you are and also I think Daniel is.
Either way I think it will just have to be lived with for now or use the F/Min as Daniel has said, tested here and I get the same results as Daniel. Brian is going to be looking at Turn but when I dont know and I certainly wouldnt be holding my breath and Greg seems to be up to his ears as well so not looking like he will be having a look at it any time soon, sometimes its a bitch to be in a minority :(

Hood
Re: Constant Surface Speed On The Lathe
« Reply #9 on: December 07, 2009, 11:02:48 AM »
Hood Thanks for trying, at least i know it's not me this time.  ::)
 
Maybe it's Rich's fault he's been mucking about for ages with screwcutting/threading, why hasn't he sorted out CCS  ;D

So if you have a lathe and a SS and you want to use CCS, add your name here and maybe we could get a delegation over to Art/Brian's or Greggs to get it sorted ASAP. 8)

Those router boys can wait for a change. ;D ;D ;D

Dan13 Thanks for the suggestion but i want it all.

Phil

The Good Thing About Mach3, Is It's very Configurable

The Bad Thing About Mach3, Is It's Too Configurable