I have just purchased a Boxford Lathe

[123hotchef]

Is it not just a tapped hole through the backplate and a brass slugs to protect the spindle thread

I'm assuming it's to stop the Chuck unscrewing

yes just to stop the chuck unscrewing when it is in reverse

 

[123hotchef]

yes just to stop the chuck unscrewing when it is in reverse

That is a nice job thanks @Seadog have you done this mod to your Boxford?

 

[Seadog]

It's on the "to-do" list, Lee

 

[123hotchef]

It's on the "to-do" list, Lee

Make 2 then please sir!

 

[123hotchef]

After cleanning the 4 jaw I found each jar adjuster to have cracks so do I repairs

it or bin it

 

[Seadog]

They're heat-treated. Any repair will soften them. Often that type of breakage is caused by hitting the chuck to unscrew the chuck. Always use a spanner on one of the jaws.

 

[123hotchef]

They're heat-treated. Any repair will soften them. Often that type of breakage is caused by hitting the chuck to unscrew the chuck. Always use a spanner on one of the jaws.

That is a good idea I tried to remove the chuck the other day but you need 3 hands!

 

[Dcal]

I had the same problem with my 4 jaw
See link below of how I fixed it.
It's been fine since.

Sorry for not getting back to you sooner, been at the Edinburgh Fringe.

Dave H, thanks for the advice, I'll get a look at the Glanze stuff.
I've had much better luck with the HSS tools and as you said found real issues trying to sharpen the brazed carbide tools.

I'll keep playing with the HSS for now as I have a few and it will be good practice to learn to sharpen the tools.

Seadog, do you know what size BXA holder I need to get or a good (I mean cheap) supplier?

I tried re-centering the lower die in the 4 jaw to deepen the dish and followed the instructions on doubleboost's youtube video to good effect, until i tried to give a jaw a good tighten to get it bang on and promptly broke the adjusting grub screw.
Great videos by doubleboost and really useful for a beginner like me.

View attachment 149348

The 4 jaw is the only chuck I have on a back plate so I was a bit stuck
I was able to get 1/2 whit grub screws but didn't know how to hold them to machine the slot for the chuck jaw.
Also I didn't have a functioning chuck

I decided to attempt a temporary repair to the broken grub screw.
I brazed in a m6 bolt in to the missing bit and filled it up with braze. I then ground off the excess and ran a tap down it.

View attachment 149349

I then ran a 1/2 inch whit tap down a 12mm coupler and M12 nut and made a half nut.

View attachment 149350

I was then able to use the "repaired" grub screw to hold the coupler in the chuck, thread on a new grub screw and lock it in place with the half nut to allow me to machine the slot.

View attachment 149351


By turning the tool post I was able to machine both shoulders of the slot with the same HSS tool.

View attachment 149352

View attachment 149353


Really pleased with the results and I have a fully functioning 4 jaw again.
I need to make 3 more grub screws as there are cracks on some of the old ones, but I now know how to hold them.

 

[slimjim]

I had the same problem with my 4 jaw
See link below of how I fixed it.
It's been fine since.

I have a 4 jaw Bernard 6 inch chuck with the same problem, and I plan on doing the similar as you did, you can buy new, but they are serious money for a fairly simple but rare screw, I will maybe just cut a bit of square tool steel and braze in, in no rush, as I bought a pre owned chuck, with perfect screws.

 

[123hotchef]

my grub screws are not so bad in comparison they just have cracks down the sides, I do have a bigger 4 jaw chuck I can use anyway, I may just try tigging the cracks up nothing to loose

 

[slimjim]

my grub screws are not so bad in comparison they just have cracks down the sides, I do have a bigger 4 jaw chuck I can use anyway, I may just try tigging the cracks up nothing to loose

Mine just has cracks, I wouldn’t tig it,

It’s probably due to an ill fitting key, or just tightening it to much, when entering work than using the key to unscrew the chuck,

 

[123hotchef]

why would you not tig it?

 

[Dcal]

Mine only had a crack until it let go.
It will probably let you down when you need it but if you've another chuck it's not much of a problem.

If you tig it you will take the temper out of the screw, brazing is a lower temperature process, so less heat input.

Also if it's anything like mine the screw can be screwed fully into the chuck when you are holding small parts so you need to be sure you don't weld the threads (or repair the thread after)

 

[123hotchef]

I have never brazed I have braised! lol soldered plenty of copper pipe though, if I tig it it would only be a quick spot on the broken corners, do you think that is more heat than braising?

 

[Dcal]

Yes
You need to melt the steel to weld it, you only need to melt the brass when brazing.

 

[123hotchef]

Yes
You need to melt the steel to weld it, you only need to melt the brass when brazing.

but you surley need to heat the screw up to make the brass pull in and stick?

 

[Dcal]

but you surley need to heat the screw up to make the brass pull in and stick?

Yes but only to the melting point of brass which is about 500 degrees less than steel.
It is very easy to overheat it though.

Why not fix it properly.
You have a lathe, the screws are cheap, it's a nice wee project and you will end up with a better job.

 

[123hotchef]

Yes but only to the melting point of brass which is about 500 degrees less than steel.
It is very easy to overheat it though.

Why not fix it properly.
You have a lathe, the screws are cheap, it's a nice wee project and you will end up with a better job.

are the screws available to purchase?
I have a bigger 4 jaw anyway so did not want to throw money at it.
The tig is there I reakon a quick blast with the tig one dab and it wold be fine nothing to loose really. I have a torch just need brazing flux and rods if i was to braze

 

[Dcal]

Mine were 1/2 inch whitworth and just shy of 1 and 1/4 long, £4.35 on evil bay doesn't seem too bad.

https://www.googleadservices.com/pa...hUKEwjV6rf_q87jAhXKAmMBHbDMAacQ9aACCGU&adurl=

 

[123hotchef]

Mine were 1/2 inch whitworth and just shy of 1 and 1/4 long, £4.35 on evil bay doesn't seem too bad.

https://www.googleadservices.com/pa...hUKEwjV6rf_q87jAhXKAmMBHbDMAacQ9aACCGU&adurl=

Did you grade them in the hole. They are not a direct replacment