Bushing a plate bearing for barrel arbors

[Neverenoughwatches]

Hiya watch people ........Surprisingly enough this is the first one i have had to do, i usually manage to close arbor holes with ' hammer time ' unfortunately not the case with the movement I'm currently working on. The original bearing had a thin walled shoulder added to it from the inside...which i knew would crumple when trying to reduce the hole size....and it did. So I'm left with the option of bushing a  .5 hole to 2mm ( 2mm is the smallest i have with a near enough arbor hole that i need )  Thought a little practice would benefit the outcome. Seems very straightforward but any input that might include something i miss....could be helpful....thanks fellas.

So far so good with the practice piece..... but I need to recreate that same crumpled shoulder on the bush.....just less crumpled . Looking for other options before i ream out the plate

Take off the damaged shoulder completely from the original plate....leave the hole and add a free floating ring ?

Nope...the shoulder formed part of the bearing....so that wont work....ideas anyone ?

[caseback]

You do have a lathe, right? 

[Neverenoughwatches]

17 minutes ago, caseback said:

You do have a lathe, right? 

yeahhhhhh...but i dont like where this is going

It just heard me mentioning its name.....its now currently shaking in it's draw

Shhhhh it's ok.....caseback was only joking.

So here's the plan I've come up with.....i tell you want i need making and give you my address and we'll just take it from there .

[caseback]

No, no, no...no more excuses 

[Neverenoughwatches]

2 minutes ago, caseback said:

No, no, no...no more excuses 

I have no idea what you're talking about caseback.......it was a bloody good plan

Sigh....okaayyy....

I do have other watches that i could work on, much friendlier than this one

[caseback]

27 minutes ago, Neverenoughwatches said:

I do have other watches that i could work on, much friendlier than this one

Oh, that's grand!  Getting the little one's hope up, and then putting it back in the projects drawer? Are you really that cruel? 

[Neverenoughwatches]

17 minutes ago, caseback said:

Oh, that's grand!  Getting the little one's hope up, and then putting it back in the projects drawer? Are you really that cruel? 

No i can't bring myself to do that, it's "who dares wins" time again....I'll go get a crow bar to prise my distressed lathe out of its sleeping quarters

[Neverenoughwatches]

Chucked up and ready to go . A quick touch up to graver and we're off

Absolutely no way i can do this under a loupe....not today anyway...this difficulty proves to me the shear skill of anyone that can work on pieces dimensionally under 2mm using only a loupe.

The added complication that the bush needs a finishing height of 0.3 is not helping.....why would it...

ridiculously stupid barrel arbor bearing design with an insanely thin shoulder.....not happy.....not happy at all.....

I need a different plan, the maximum diameter of the bush has to 1mm and even that risks breaking out of the side of the plate...think I'm pretty much stuck just now. 

At least the lathe got an airing

[Neverenoughwatches]

After drawing on some inspiration provided by Caseback I will make another more solid attempt at making  this tiny bush. Tbh i think I'm actually pushing my luck at bushing this area of the plate and at the thickness it is....but without it I dont think I can progress and would need another undamaged plate.

[tomh207]

10 minutes ago, Neverenoughwatches said:

After drawing on some inspiration provided by Caseback I will make another more solid attempt at making  this tiny bush. Tbh i think I'm actually pushing my luck at bushing this area of the plate and at the thickness it is....but without it I dont think I can progress and would need another undamaged plate.

I’m no expert as you know Rich but what little I do know is that the order of operations is the key to any machining. Here is what I have come up with during my extreme caffeinating regime this morning ️

 

1) face off the end of your brass bar

2) dimple the centre of the faced end of the bar with the smallest and sharpest graver you have

3) drill the centre of the bar deeper than the thickness of the bearing and a good bit smaller than the required arbor hole

4) turn down an over length piece of the bar to the lip diameter 

5) mark over length the unshouldered part of the bush and turn that to diameter

6) face off the end of the bush until the small end is the correct thickness

7) mark off the overall thickness of the bush to have the lip you require

8 ) part off the bush to that line

9) clean off and debur on an Arkansas stone

10) fit the bush to the main plate 

11) using incremental sized reamers bring the bearing whole to size with you Seitz tool

 

long winded, not like me at all hopefully one of the real experts like @nickelsilver or @nevenbekriev can give us a leg up telling me where I got it wrong.

 

Tom

[nevenbekriev]

OK, let me see what we have to do here.

Rich, I need to see all the pieces. The main plate, the barrel with it's arbor and the ratchet wheel that I guess stays under the bridge. We need to know what is this thin shoulder needed for.

[Neverenoughwatches]

7 hours ago, nevenbekriev said:

OK, let me see what we have to do here.

Rich, I need to see all the pieces. The main plate, the barrel with it's arbor and the ratchet wheel that I guess stays under the bridge. We need to know what is this thin shoulder needed for.

Will do Nev, the short thin shoulder/hub fits into the recess below the ratchet wheel. Below the ratchet wheel is another separate small one that drives the hour wheel. I assume the shoulder is to prevent this wheel rubbing on the main plate. 

[AndyGSi]

What diameter is the outside of the shoulder?

Would a piece of brass tube work better?

[Neverenoughwatches]

10 hours ago, tomh207 said:

I’m no expert as you know Rich but what little I do know is that the order of operations is the key to any machining. Here is what I have come up with during my extreme caffeinating regime this morning ️

 

1) face off the end of your brass bar

2) dimple the centre of the faced end of the bar with the smallest and sharpest graver you have

3) drill the centre of the bar deeper than the thickness of the bearing and a good bit smaller than the required arbor hole

4) turn down an over length piece of the bar to the lip diameter 

5) mark over length the unshouldered part of the bush and turn that to diameter

6) face off the end of the bush until the small end is the correct thickness

7) mark off the overall thickness of the bush to have the lip you require

8 ) part off the bush to that line

9) clean off and debur on an Arkansas stone

10) fit the bush to the main plate 

11) using incremental sized reamers bring the bearing whole to size with you Seitz tool

 

long winded, not like me at all hopefully one of the real experts like @nickelsilver or @nevenbekriev can give us a leg up telling me where I got it wrong.

 

Tom

Thanks Tom , sounds like a good order to me. I think the smallest Seitz reamer is 0.69mm . I would drill the arbor hole to 0.4 then broach to fit. I'd really like to do this another way if possible. 

6 minutes ago, AndyGSi said:

What diameter is the outside of the shoulder?

Would a piece of brass tube work better?

The recess in the drive wheel is 0.8mm.... so 0.7mm max for the bush /tube. The arbor shaft is only 0.46 at this end. 

[caseback]

9 minutes ago, AndyGSi said:

What diameter is the outside of the shoulder?

Would a piece of brass tube work better?

 

[Neverenoughwatches]

5 minutes ago, Neverenoughwatches said:

Thanks Tom , sounds like a good order to me. I think the smallest Seitz reamer is 0.69mm . I would drill the arbor hole to 0.4 then broach to fit. I'd really like to do this another way if possible. 

The recess in the drive wheel is 0.8mm.... so 0.7mm max for the bush /tube. The arbor shaft is only 0.46 at this end. 

 

6 minutes ago, Neverenoughwatches said:

Thanks Tom , sounds like a good order to me. I think the smallest Seitz reamer is 0.69mm . I would drill the arbor hole to 0.4 then broach to fit. I'd really like to do this another way if possible. 

The recess in the drive wheel is 0.8mm.... so 0.7mm max for the bush /tube. The arbor shaft is only 0.46 at this end. 

maybe 1mm max for the recess. 

[AndyGSi]

So would this 0.7mm O/D & 0.5mm I/D tube not work?

[Neverenoughwatches]

56 minutes ago, AndyGSi said:

So would this 0.7mm O/D & 0.5mm I/D tube not work?

Thanks Andy , the hole is a little over what's required. What I'm worried about is the fact that this is a high torque bearing...a 0.7mm bush/sleeve is going to subject to a lot of pressure and the plate is so thin for a friction fit. Once I've opened up the hole for a bush fitting....I'm then committed.

[nevenbekriev]

Hi Rich,

OK, now it is pretty much clear to me what it is - a Roskopf type movement where the minute wheel is part of the barrel and it is friction fitted there to enable hands setting.

I guess that this shoulder on the bearing actually doesn't get IN the hole of the minute wheel where the arbor goes, am I right? This is important to know, as different solutions will be needed in this case than in the other.

[Neverenoughwatches]

1 hour ago, nevenbekriev said:

Hi Rich,

OK, now it is pretty much clear to me what it is - a Roskopf type movement where the minute wheel is part of the barrel and it is friction fitted there to enable hands setting.

I guess that this shoulder on the bearing actually doesn't get IN the hole of the minute wheel where the arbor goes, am I right? This is important to know, as different solutions will be needed in this case than in the other.

Thats correct Nev a Roskopf pin pallet movement, in private messages with Caseback i did call this small wheel a direct drive minute wheel but i wasn't entirely sure of it's exact name. The shoulder on the plate or maybe more accurately in description the hub Does get inside the hole of the minute wheell. The arbor at this end aslo has a shoulder set back into the hole, the plate hub and arbor shoulder connect to serve keeping the minute wheel from rubbing on the plate. I will add a picture of the arbor sat in the hub. I thought about grinding back the damaged hub and have a free ring in its place.

[nevenbekriev]

I see. This is the worst case...

Another question: Is dial thick enough as to allow grinding on it's back side of about 0.2mm? I mean, no standard bushing will help here, the bush has to be riveted or at least soldered. It will be easier if part of it protrudes above the plate and it will lift the dial this way, but if the dial can be thinned in the area above the bush, this will be good.

[caseback]

Hi Nev. My last suggestion in the pm's to Rich was to make a bush like this because he suggested that a bush could probably protude out of the top end of the plate by about 0.2mm without interfering with anything.

One could consider using some loctite. If part of the wider shoulder protudes out into the plates cutout, that could be trimmed off. Do you think that would work?

 

Edited November 18, 2024 by caseback

[nevenbekriev]

I would suggest almost the same, with the addition to solder it in place with led solder

The diameter of the base of the bush - may be 3-4mm. The base thus will protrude above the cut place for the hour wheel and must be filed there to the plate shape after soldering.

[caseback]

7 minutes ago, nevenbekriev said:

I would suggest almost the same, with the addition to solder it in place with led solder.

To limit the amount of heat needed as opposed to silver solder. Good one. 

Time to give your lathe another airing Rich!

[Neverenoughwatches]

Thanks for the ideas fellas, this sounds like a good plan that I feel comfortable with. I'll  need to get in some practice sessions with making the bush ( very small compared to anything I've turned up before....i may be a little while with that....maybe a week or so...as I'm back in school till next summer...along with work and taking care of mum some days, makes my time limited at the moment. But that idea of the back plate added to bush from you both sounds like a solid plan .

1 hour ago, caseback said:

To limit the amount of heat needed as opposed to silver solder. Good one. 

Time to give your lathe another airing Rich!

I've used bismuth low melt solder in the past a few times to repair dial feet, its fairly solid stuff .