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Author Topic: CNC'ing both quill and knee  (Read 15989 times)

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CNC'ing both quill and knee
« on: October 20, 2008, 07:12:06 AM »
Hi,  Have a Series II CNC machine that I am currently working on.
Not my first, but I want to make this my last mill.   :)

Quill unfortunately is a QC30 with 5" of travel.
The knee has huge box ways and is air assisted.

In most instances the quill is the better way to approach the
Z axis as long as you can get away with the 5" travel.  And yes,
I want to keep the quill as my Z axis.  But I would like to open
up the possibility of having more than 5" of Z travel using the knee.

My idea is to put a servo and drive on the knee and run the knee
under Mach control.  Technically it is the " W" axis-  because it is parallel to
the Z axis.

I don't know if it is possible to run these axis in concert with each other.
I guess if a job required more than 5" travel I could swap axis and
use the knee as the Z.  This swap could be done in the mach settings
I guess?   

Any input on my idea would be appreciated.

Thanks,
Scott


Edit:  I see looking at Mach's config screen that the only names for axis's are XYZ and ABC. 
I guess I would have to use B or C as the W axis. 







« Last Edit: October 20, 2008, 07:17:51 AM by polaraligned »

Offline Hood

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Re: CNC'ing both quill and knee
« Reply #1 on: October 20, 2008, 08:01:47 AM »
Brett is thinking about doing that on his Hurco and also I am thinking I may do it on the Beaver mill if I ever get it finished LOL
 What we are both  thinking of is using the Knee just for tool length offsets, how it will be done woukld probably have to be via a macropump but to be honest I havent put much thought into it yet.
 As for A B C or whatever I dont think it would really  matter as long as your CAM can put out the right letter for any code it will spit out and that should be easy enough to do in your CAMs Post Processor.

Hood
Re: CNC'ing both quill and knee
« Reply #2 on: October 21, 2008, 10:03:52 PM »
Brett is thinking about doing that on his Hurco and also I am thinking I may do it on the Beaver mill if I ever get it finished LOL
 What we are both thinking of is using the Knee just for tool length offsets, how it will be done woukld probably have to be via a macropump but to be honest I havent put much thought into it yet.
 As for A B C or whatever I dont think it would really matter as long as your CAM can put out the right letter for any code it will spit out and that should be easy enough to do in your CAMs Post Processor.

Hood

Ha!  That's exactly what I've always planned to do as well!  I've got the knee CNC'd right now, and honestly don't see any down-side to it - it was dead easy to do, only took one day - so I may not even bother doing the quill at all now...

Regards,
Ray L.
Regards,
Ray L.

Offline Chaoticone

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Re: CNC'ing both quill and knee
« Reply #3 on: October 21, 2008, 10:38:31 PM »
Yup, that is how I did my Bridgeport clone. Used the knee for Z and it was very simple to set up. I will be using the quill on the Hurco for the z and the knee for tool length offsets because I think it would stess the machine too much to throw the knee up and down at 800- 1200 IPM not to mention it would take a huge servo, drive, and most likely an air assist ball screw or counter weight for that. I think using both will give the best of both worlds. Fast rapids and feeds and full working height will allways be avaliable no matter how tall the work is or how long the tool is.

Brett 
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!
Re: CNC'ing both quill and knee
« Reply #4 on: October 21, 2008, 10:50:12 PM »
Yup, that is how I did my Bridgeport clone. Used the knee for Z and it was very simple to set up. I will be using the quill on the Hurco for the z and the knee for tool length offsets because I think it would stess the machine too much to throw the knee up and down at 800- 1200 IPM not to mention it would take a huge servo, drive, and most likely an air assist ball screw or counter weight for that. I think using both will give the best of both worlds. Fast rapids and feeds and full working height will allways be avaliable no matter how tall the work is or how long the tool is.

Brett 

Brett,

    Did you leave the leadscrew, or put a ballscrew on the knee on your BP?  I just have the leadscrew for now, and it works fine.  But, I figure in time it will wear, and I'll want a ballscrew eventually.

Regards,
Ray L.
Regards,
Ray L.

Offline Chaoticone

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Re: CNC'ing both quill and knee
« Reply #5 on: October 21, 2008, 10:55:23 PM »
Yes, I used a leadscrew. I replaced it with a new higher precision one but stuck with the screw so I wouldn't have to use a brake to keep the knee from drifting. I did add oilers to the gears and nut but it still works on it pretty good. I'm using 1850 oz in steppers and the final gearing is 6-1. I added gas springs and that helped my rapids some but 30 IPM is about all I can get out of it with this set up.

Brett
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!
Re: CNC'ing both quill and knee
« Reply #6 on: October 21, 2008, 11:28:22 PM »
Yes, I used a leadscrew. I replaced it with a new higher precision one but stuck with the screw so I wouldn't have to use a brake to keep the knee from drifting. I did add oilers to the gears and nut but it still works on it pretty good. I'm using 1850 oz in steppers and the final gearing is 6-1. I added gas springs and that helped my rapids some but 30 IPM is about all I can get out of it with this set up.

Brett

Brett,

    Interesting.  I'm using an 850 oz-in servo with 4.8:1 XL belt reducer, and can do better than 50 IPM, with no air springs (yet...  Just put the servo on about a week ago).  How much more it'll do, I don't know.  I know it would go 100IPM *most* of the time, but that is scary fast for me, so I just cut it in half.  I'm very happy with the way it works, but I do need to do something to provide positive lubrication. 
    One thing that surprised me - As I said, I used an XL belt for the reducer.  On the X and Y, I used GT2 belts.  The XL is MUCH noisier!

Regards,
Ray L.
Regards,
Ray L.
Re: CNC'ing both quill and knee
« Reply #7 on: February 10, 2009, 06:02:05 PM »
I am wanting to add a stepper to the knee on my bridgeport (Quill now used a Z) just for applying tool offsets.

Did anyone get this working?   How did you get mach to handle the extra motor and apply the tool offsets?

Thanks much!
Re: CNC'ing both quill and knee
« Reply #8 on: February 10, 2009, 06:20:29 PM »
I am wanting to add a stepper to the knee on my bridgeport (Quill now used a Z) just for applying tool offsets.

Did anyone get this working?   How did you get mach to handle the extra motor and apply the tool offsets?

Thanks much!

Mach supports up to six axes, so you'd just assign the knee to one of the "extras".  I think you'd then modify the M6End macro, to take the tool offset, and move the knee by the appropraite amount.  Should be pretty straight-forward.  I'll find out soon, as I've already servo'd my knee, and am about to servo the quil as well.

Regards,
Ray L.
Regards,
Ray L.
Re: CNC'ing both quill and knee
« Reply #9 on: February 10, 2009, 07:36:29 PM »
I am wanting to add a stepper to the knee on my bridgeport (Quill now used a Z) just for applying tool offsets.

Did anyone get this working?   How did you get mach to handle the extra motor and apply the tool offsets?

Thanks much!

Mach supports up to six axes, so you'd just assign the knee to one of the "extras".  I think you'd then modify the M6End macro, to take the tool offset, and move the knee by the appropraite amount.  Should be pretty straight-forward.  I'll find out soon, as I've already servo'd my knee, and am about to servo the quil as well.

Regards,
Ray L.
I am wanting to add a stepper to the knee on my bridgeport (Quill now used a Z) just for applying tool offsets.

Did anyone get this working?   How did you get mach to handle the extra motor and apply the tool offsets?

Thanks much!

Mach supports up to six axes, so you'd just assign the knee to one of the "extras".  I think you'd then modify the M6End macro, to take the tool offset, and move the knee by the appropraite amount.  Should be pretty straight-forward.  I'll find out soon, as I've already servo'd my knee, and am about to servo the quil as well.

Regards,
Ray L.

I am surprised this has not been hashed out in the past.   Hooking up the other motor and setting it up is very easy, its  "tweaking" mach to send the tool length offset to that new axis and not the Z that will be the trick.  I want to be sure it can be done before I buy and hook up the extra motor/axis.  The "normal" tool length offset has to be inhibited from acting on the z axis also, we don't want both axis applying the offset.