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Author Topic: South Bend Fourteen Lathe conversion  (Read 26517 times)

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Offline Telco

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Re: South Bend Fourteen Lathe conversion
« Reply #20 on: April 11, 2013, 11:30:18 AM »
For you  "fourteen" owners, The aluminium tool holder "shelf"  hanging on the front of the machine consists of the two pieces of aluminum flat bar that hang onto edge, two pieces of alum angle drilled and tapped  for the flat bar to attach to,   and the back of the aluminum plate rests against the side..I'm going to finish it out with 1"x 1/2" tube around the edge to perty it up a bit. It will lift off with all the tools on it and is plenty stiff as is, although the tube will make it rigid...No welder required. Has worked out great so far.

Offline jeep534

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Re: South Bend Fourteen Lathe conversion
« Reply #21 on: April 11, 2013, 11:33:43 AM »
I think you may end up putting a trigger directly on the spindle there is "play" in this desighn  "hood" on this message board could probably help with this problem you might send him a private message.

Offline jeep534

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Re: South Bend Fourteen Lathe conversion
« Reply #22 on: April 11, 2013, 11:36:24 AM »
For you  "fourteen" owners, The aluminium tool holder "shelf"  hanging on the front of the machine consists of the two pieces of aluminum flat bar that hang onto edge, two pieces of alum angle drilled and tapped  for the flat bar to attach to,   and the back of the aluminum plate rests against the side..I'm going to finish it out with 1"x 1/2" tube around the edge to perty it up a bit. It will lift off with all the tools on it and is plenty stiff as is, although the tube will make it rigid...No welder required. Has worked out great so far.
   actually the toolholders will hang on the front of the chip pan with no modifications   which is kind of funny we end up with tons of tool holders

Offline Telco

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Re: South Bend Fourteen Lathe conversion
« Reply #23 on: April 11, 2013, 11:55:16 AM »
The lower "apron" I suppose its called, is now dead weight.. only held o by a few bolts, from what i can tell its only job is an attachment point for the half nut..I have some 1" Alcoa plate ( 7075 ) , and was debating replacing the apron with this..and possibly adding another half nut or machining a bronze nut for minimizing backlash. Would this be a mistake?

Offline Telco

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Re: South Bend Fourteen Lathe conversion
« Reply #24 on: April 11, 2013, 11:55:58 AM »
Pic

Offline Telco

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Re: South Bend Fourteen Lathe conversion
« Reply #25 on: April 11, 2013, 01:02:45 PM »
 thank you very much jeep, I will message hood about this, but there is virtually no play in the system i can feel. The only detectable play is in the spindle itself, which I suspect is virtually the same as it was 20 yrs ago. the only wait to feel it is to turn the spindle back and forth and you can you feel a tiny amount of play. I just opened up the cover under the original electronic control to ensure the spindle bearings were being lubricated properly, and all the gears look good as new.  I'll take a video and post a link to it in a few minutes. this is what I need though.. there has to be something I've overlooked somewhere.

Offline Hood

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Re: South Bend Fourteen Lathe conversion
« Reply #26 on: April 12, 2013, 02:42:41 PM »
Looks like a nice project and always good to see another lathe using Mach :)
Regarding the encoder, I am not sure if that will work or not. I think the kit you bought uses the parallel port and unless the breakout board sretches the index pulse then it will almost certainle be too fast for the parallel port to see.
Hood

Offline jeep534

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Re: South Bend Fourteen Lathe conversion
« Reply #27 on: April 12, 2013, 04:28:52 PM »
The lower "apron" I suppose its called, is now dead weight.. only held o by a few bolts, from what i can tell its only job is an attachment point for the half nut..I have some 1" Alcoa plate ( 7075 ) , and was debating replacing the apron with this..and possibly adding another half nut or machining a bronze nut for minimizing backlash. Would this be a mistake?
I would be looking here or similar
http://rockfordballscrew.com/

Offline Telco

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Re: South Bend Fourteen Lathe conversion
« Reply #28 on: April 13, 2013, 01:57:41 AM »
Thanks hood, the motion control and encoder both came from machmotion, so I assumed they would play nice together. But I have thought that this may be a problem..my biggest concern at this point is to get this thing threading properly. It cuts beautiful threads, but the pitch is larger than commanded. In a threading cycle, the true s dro will jump to 600 if it is command is 500, the higher the speed, the greater the jump..Im stumped on this one..thanks for the link jeep, i will be adding balls screws, just need to get the thing running right first...

Offline Hood

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Re: South Bend Fourteen Lathe conversion
« Reply #29 on: April 13, 2013, 05:44:38 AM »
Ok the breakout you have must be widening the Index pulse of the encoder :)

The spindle not doing as commanded should not be a problem as far as threading is concerned as long as your feedback is reporting the RPM correctly. It sounds like it may not be however. The pitch being larger seems to confirm  this as what it sounds like is Mach is seeing the spindle faster than it actually is so is moving the Z axis at a speed to correspond to this faster RPM and thus if your spindle is actually rotating slower then your pitch will be larger.
 One thing that may be causing the RPM to read higher than actual is you may have a ratio set up in spindle pulleys, another is your encoder is not connected 1:1 to the spindle.
Hood