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GraemeVW
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I thought the jaws on this 3 jaw looked a little worn.
Ok, this isn't a test bar, but at one point in its life it was ground to the dimension it is now. All 3 jaws are the same you can see they are worn towards the ends.
Maybe I need both sets of jaws, maybe I'd be better off replacing the chuck, maybe I should try and grind them. May not be able to make a perfect job of it, but pretty sure I could get them better than that!
Ok, this isn't a test bar, but at one point in its life it was ground to the dimension it is now. All 3 jaws are the same you can see they are worn towards the ends.
Maybe I need both sets of jaws, maybe I'd be better off replacing the chuck, maybe I should try and grind them. May not be able to make a perfect job of it, but pretty sure I could get them better than that!
God mode restorations
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As said above by pete. Chuck bell-mouthed. Jaws normally wear towards the back
GraemeVW
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That is the perfect term for it.
Would that have been done on purpose then?
It doesn't close down when you tighten the chuck down.
Either way, it's not much use to me I don't think.
But if I clamp something right at the back of the jaws to load them, and mount a grinding stone on my dremmel in the tool post, I should be able to grind them to be loads better than that.
If then have to clearance the back section of jaws that didn't get ground.
Edit...
This looks easier!
Would that have been done on purpose then?
It doesn't close down when you tighten the chuck down.
Either way, it's not much use to me I don't think.
But if I clamp something right at the back of the jaws to load them, and mount a grinding stone on my dremmel in the tool post, I should be able to grind them to be loads better than that.
If then have to clearance the back section of jaws that didn't get ground.
Edit...
This looks easier!
GraemeVW
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Ignoring chuck jaw issues, the grub screws and nuts for the cross slide gib turned up today. Cut the grub screws down and pointed them to match the 2 originals that were remaining. Replaced all 4 though.
This site pleases me more than it should. Something about the red, with oil blacked hardware and silver nuts.
A new feed nut is on its way too. I'll have to make a holder for it, but that should sort 95% of the wear in the cross slide.
Now I can adjust the gib I can tell there is very little wear in the cross slide ways either.
This site pleases me more than it should. Something about the red, with oil blacked hardware and silver nuts.
A new feed nut is on its way too. I'll have to make a holder for it, but that should sort 95% of the wear in the cross slide.
Now I can adjust the gib I can tell there is very little wear in the cross slide ways either.
GraemeVW
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Had a quick Google, using the term bellmouthed, is that assuming the jaws are like this due to either wear inside the chuck, bending, or wear in the jaw slides?
The chuck doesn't seem to have any wear as such in any other area, it's just the clamping surface of the jaws that, as you can see, are tapered for whatever reason.
The jaws don't move in any way when clamping, they don't pull away from the scroll on the inner end.
I think I'm reading the intention of you both right? You were suggesting it's bot an issue that could be remedied by grinding the jaws as the problem is elsewhere?
It seems this chuck has just worn in the opposite way to normal (or been modified to hold a slight taper!)
Pete.
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No it's not worn, the chuck has been clamped down tight on a part held only on the end of the jaws and it's bent the guides for the jaws. There is no way in hell anyone is going to bend steel jaws with a thin cast iron chuck face, it's the iron that gives. I had a chuck that was exactly like this. I took the 'bent' jaws and put them in another Pratt chuck, and it was perfect.
GraemeVW
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A little more investigating.
The wear on the jaws. It looks like they have been reground, badly. You can see the taper in the contact patch. It's also concave side to side and convex end to end.
Hold them to a square and you can see. I checked the square with a brand new jaw from another chuck.
I measured the body too. Not to the scroll, but to the inner body.
I measured from the top of the guide rail so if they are bending out, I'd see.
I managed to measure between 0.03 and 0.05mm bigger gap at the center if the chuck than at the outer.
Seems a little bit of everything is causing this.
Majority seems to be in the bad jaws though. I wonder if they were worn and someone did a bad job of grinding them. Probably worn from years of over tightening that's caused 0.04mm of bend (or wear?) In the body.
I'm probably still try and grind the jaws, worth a go.
Edit...
Scratch that, 0.02mm is the most difference I can measure.
GraemeVW
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Yep.
I'm reasonably sure I can make them better. I doubt I can make them worse!
It's not really usable as is anyway, except with the other end of the work supported too.
Those fans usually come off very easily. I normally use a couple of flat wrecking bars, with care.
GraemeVW
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This one needed alot of pulling!
Fan wpuld ha e broken before it moved. Interestingly, the splined shaft it mounts on was covered in factory grey paint. Might be why it was so tight.
If you do break one it might be worth knowing they are cheap enough to buy on AliXpress. Most of the sizes are available, but the search system doesn't help.
Nice job.
I've done the same in the past - changed just about every nut, screw and bolt just to make it look nice. Ended up spending more than I should on imperial fixings. Ended up selling the machine and buying something else instead. It won't be long before you feel the urge to upgrade...
GraemeVW
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I've not had to replace many fixings, most I've oil blacked or burnished back to as new.
As for upgrading, I don't know, would be a while. I only really need to swing 12", which this will, although bigger lathes will give better tool positioning for actually working on 12" jobs.
But, I bought this lathe as it's light enough not to be an issue. I can break it down into bits I can carry. Means if/when I move, it's alot less stress. I wouldn't buy bigger unless I was in my final home.
If I did go bigger, I'd need a smaller lathe too anyway. Even this will be too big for some of the stuff I end up doing.
My main urge at the moment is a mill, been on my mind for 10 years, bit the lathe upgrade beat it to some garage space.
GraemeVW
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I will, at some point, still have a go at regrinding the jaws, but sometimes it's easier to just throw money at the problem.
Pratt 7.5" with both sets of jaws. A bit of damage to the end of the internal jaws, but other than that it looks in really good condition.
Pratt 7.5" with both sets of jaws. A bit of damage to the end of the internal jaws, but other than that it looks in really good condition.
GraemeVW
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Diy motor pulley kit arrived today, thanks to @indy4x.
If I get that right, I will have low range and high speed range.
The Chinese reversing switch also turned up. I don't know how good this will be, but I'm also using it to send power to the on/off buttons so the switch can never switch on under load.
Quick lash up to check that I've got the wiring right, and it all works.
The buttons won't activate the contactor unless the motor switch is in forward, or reverse. If the motor switch goes to off, everything is dead. Means the only way to start the motor running is with the contactor.
I'll make a decent handle for the switch.
If I get that right, I will have low range and high speed range.
The Chinese reversing switch also turned up. I don't know how good this will be, but I'm also using it to send power to the on/off buttons so the switch can never switch on under load.
Quick lash up to check that I've got the wiring right, and it all works.
The buttons won't activate the contactor unless the motor switch is in forward, or reverse. If the motor switch goes to off, everything is dead. Means the only way to start the motor running is with the contactor.
I'll make a decent handle for the switch.
GraemeVW
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Started looking at the electrics.
Mounted the new switch where the old one was, but made a new handle for it.
The contactor is mounted at the rear and mains cable fitted. For some reason I couldn't get past the thought the contactor should be on wood. I justified it as in case a wire comes out? I dunno, I'm not an electrician. Just felt like the right thing to do
I can you t the on/off switches now I know how long the reversing switch handle is, and then wire it all up.
Also, while getting the box steel to make a rear splash guard and shelf set up, I picked up a 320x25mm steel disc to make a face plate.
Mounted the new switch where the old one was, but made a new handle for it.
The contactor is mounted at the rear and mains cable fitted. For some reason I couldn't get past the thought the contactor should be on wood. I justified it as in case a wire comes out? I dunno, I'm not an electrician. Just felt like the right thing to do
I can you t the on/off switches now I know how long the reversing switch handle is, and then wire it all up.
Also, while getting the box steel to make a rear splash guard and shelf set up, I picked up a 320x25mm steel disc to make a face plate.
