Lathe Cross Slide Problem

[EdK]

Not good news. There doesn't appear to be a way to make this work. Just plain not enough room. I obviously screwed up some measurement because I remember measuring the depth of the trough prior to making the drawing for the nut.

The saddle is only 3/8" thick at the trough so not enough meat there to remove some to allow the nut to fit. I can't remove enough material from the nut to get it to fit either. At this point I think my only option is to work with the original nut and make the mounting surface flat and then shim it to the center-line of the lead screw.

Sorry to have wasted your time Ken.

Ed

       

[Highpower]

(06-30-2014, 12:17 PM)EdK Wrote: I can't remove enough material from the nut to get it to fit either.

Ed

Maybe I'm missing something, but it looks like there is an awful lot of material that could be milled off the top of the nut. Splain please...

[EdK]

(06-30-2014, 12:43 PM)Highpower Wrote:

(06-30-2014, 12:17 PM)EdK Wrote: I can't remove enough material from the nut to get it to fit either.

Ed

Maybe I'm missing something, but it looks like there is an awful lot of material that could be milled off the top of the nut. Splain please...

Willie,

The surface that would need to be milled down is the surface that is sitting in the trough, not the top surface seen in the picture. That top surface sets the distance from the nut center-line to the lead screw center-line so it can't be changed.

Ed

[EdK]

There still may be some hope left for this project. Taking some more dimensions of the cross slide features, the nut dimension could be changed to clear the trough if the slit for adjusting the backlash doesn't need to go all of the way through the threads but could be 2/3rds or 3/4ths of the way. That might leave enough meat left to hold the two halves together allowing the nut height to be lowered. See attached sketch. Current nut on the left and proposed new nut on the right. The green being the nut and the brownish being the trough.

Ed

   

[PixMan]

Go ahead and modify the nut, nothing to lose.

I can make you a new nut PDQ as I have the tap I used for the one you've got. I can leave cutting the slit up to you if you want, though the cutter I have would probably go about that deep. You can measure the one I sent to see the max depth I can get, as it's easy to see where I stopped milling and went further with a bandsaw.

[EdK]

(06-30-2014, 03:32 PM)PixMan Wrote: Go ahead and modify the nut, nothing to lose.

I can make you a new nut PDQ as I have the tap I used for the one you've got. I can leave cutting the slit up to you if you want, though the cutter I have would probably go about that deep. You can measure the one I sent to see the max depth I can get, as it's easy to see where I stopped milling and went further with a bandsaw.

Ken,

I can't modify the current nut because if I take enough off to clear the trough I cut into the slit and I end up with two halves instead of a whole nut. If you could make me a new nut that would be wonderful, although I hate to have to ask you to do that.
I'm going to mock up the redesigned nut in aluminum without the acme thread. I'll make it a slip-fit over the acme thread just to test for clearances with the trough. I don't want to screw this up again. If all goes well with the mock-up, then I'll create a new drawing with the updated dimensions.

Sorry to put you through this and I'm eternally grateful.

Ed

[stevec]

Ed, just how much material (if any) would be left beyond the thread depth if you removed enough material from the rounded end of the nut? I would think you would not need much and the less material the easier for the setscrew(?) to distort the nut in order to take up for thread wear?
I'm remembering you changed the leadscrew Dia. from .5" to .625" as per Ken's 5/8" acme tap so that ate some material right?
Lastly what would be the problem with Ken just making a solid nut? It would seem to me that the new materials would be superior to the orig. and we're not talking about a 2 or three shift operation of the lathe. I'd bet a solid nut and maybe a back up spare would last longer than you.
Just my take.

[EdK]

(07-01-2014, 11:59 AM)stevec Wrote: Ed, just how much material (if any) would be left beyond the thread depth if you removed enough material from the rounded end of the nut? I would think you would not need much and the less material the easier for the setscrew(?) to distort the nut in order to take up for thread wear?

Steve,

Per post #136 "I can't modify the current nut because if I take enough off to clear the trough I cut into the slit and I end up with two halves instead of a whole nut"

(07-01-2014, 11:59 AM)stevec Wrote: I'm remembering you changed the leadscrew Dia. from .5" to .625" as per Ken's 5/8" acme tap so that ate some material right?

Correct.

(07-01-2014, 11:59 AM)stevec Wrote: Lastly what would be the problem with Ken just making a solid nut? It would seem to me that the new materials would be superior to the orig. and we're not talking about a 2 or three shift operation of the lathe. I'd bet a solid nut and maybe a back up spare would last longer than you.
Just my take.

Actually, I will have Ken make a solid nut if this is going to work out. He doesn't have a slitting saw large enough to make the slit so I'm going to put the slit in since I have a 4" slitting blade. But that's a good thought. Leave the slit out for now and see how it works out. I could always add a slit later on if it became necessary.

Thanks for the thoughts Steve.

Ed

[f350ca]

There looks to be plenty of material on either side of the slot. Could you drill and tap the two sides, mill it down to make two separate nuts and TRY it. The set screw should still spread them to remove backlash. They can't turn with the lead screw through them.

[EdK]

(07-01-2014, 12:39 PM)f350ca Wrote: There looks to be plenty of material on either side of the slot. Could you drill and tap the two sides, mill it down to make two separate nuts and TRY it. The set screw should still spread them to remove backlash. They can't turn with the lead screw through them.

Hmmm, that might be worth a try.

I'll have to think about that.

Thanks,
Ed