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Author Topic: Just got a lathe to retrofit  (Read 146166 times)

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Hood

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Just got a lathe to retrofit
« on: August 27, 2006, 03:05:54 PM »
This is going to take me a while to do but eventually I want to run this lathe (see below) with GRex and Mach.
 The Lathe is pretty big (490mm swing) and is approx 1981 vintage but came out of a University where it was used to test carbide, CBN and PCD tips machining Titanium. By the looks of it its done hardly any thing, beds dont have a scratch and everything looks to be like the day it was delivered from Churchill.
 I am not sure about the servos but they have resolvers so I dont they will work with modern drives so will have to look out for encoders. Anyway heres the pic of the lathe, will be a week or two before I get it and probably a year or so before I finish it.
Hood

Re: Just got a lathe to retrofit
« Reply #1 on: August 27, 2006, 04:27:03 PM »
Well Hood that is a nice looking lathe! I am in hopes to get one like that some day!
Fixing problems one post at a time ;)

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Re: Just got a lathe to retrofit
« Reply #2 on: August 27, 2006, 04:30:49 PM »
Are you retrofiting it to keep or do you resell it whan your done? Seems kind of big for average turning.

Hood

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Re: Just got a lathe to retrofit
« Reply #3 on: August 27, 2006, 04:52:07 PM »
Thanks Brian, I just couldnt resist buying it, got it for just above scrap prices :)

JDolecki
 I will be keeping it, its a perfect size for the kind of stuff I do.

Hood

Hood

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Re: Just got a lathe to retrofit
« Reply #4 on: August 27, 2006, 04:54:01 PM »
Oh Brian forgot to ask, I dont have a clue about servos and I think you have some experience, I was wondering what type and count encoders I should look out for?

Hood

Offline fdos

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Re: Just got a lathe to retrofit
« Reply #5 on: August 27, 2006, 06:11:08 PM »
Oh Brian forgot to ask, I dont have a clue about servos and I think you have some experience, I was wondering what type and count encoders I should look out for?


Hood. You need to work out what speed/resolution  you want.  They tend to fight each other when the pulse rate is limited ;-)

My Hardinge uses 2500 cpr encoders mounted on 5mm pitch ballscrews.  This with the original control gave half a micron resolution and 5metres/min rapids.

With the printer port this speed is not possible unless I throw some resolution away by using the drives step multipliers.

I think you should work out the minimum step you need and then work from there. 

Wayne....

Hood

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Re: Just got a lathe to retrofit
« Reply #6 on: August 27, 2006, 06:27:41 PM »
Thanks fdos
 I plan on using the G100 (GRex) so printer port/pulse rate wont be an issue (I hope).
 I dont have a clue what the speeds of this lathe are I dont know what the ballscrew pitch is but from the quick look I had I would say about 5mm, I believe the motors are on 90v at the moment but the current I am unsure of, there is a plate in the cabinet beside the drives which suggests the power supply is 40Amps, will this be what each motor is running at?
 I have a friend that is trying to find out info about the servos for me so hopefully i will have a clearer picture soon.
 Talking of pictures ;) heres one of the plate on the servos, its all double dutch to me but maybe you or someone will be able to tell me whether the motors will be good enough etc. For a larger picture have a look here http://mysite.wanadoo-members.co.uk/hoodsmachiningpages/ServoMotorPlate2.jpg

Hood

Offline fdos

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Re: Just got a lathe to retrofit
« Reply #7 on: August 27, 2006, 06:48:26 PM »
Hood

Kind of hard to read.   But what is the peak current?  I see 2.66A or 26.6A not sure.

How big are these motors?  Look fairly chunky to me LOL...

Wayne...

Hood

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Re: Just got a lathe to retrofit
« Reply #8 on: August 27, 2006, 07:01:24 PM »
Wayne
  dont really know what the peak current is and I dont see 2.66A or 26.6A on the motor plate. Is it the bit that says " Max prqd" that you are reading? if so then I think it says 288 but I dont see a point anywhere but presume its 28.8A. I dont have the lathe here and these are just some pics I took yesterday.
 The motors are big, probably about 7 or 8 inch  Diameter and acording to the nameplate they weigh 38kg.

Hood
Re: Just got a lathe to retrofit
« Reply #9 on: August 27, 2006, 07:12:55 PM »
If it was me I would think about getting new brushless servo motors :)
Fixing problems one post at a time ;)

www.newfangledsolutions.com
www.machsupport.com