Illinois Bunn Special 161 Elinvar service question

[Vintage12]

Hi Folks,

A quick introduction since this is my first post, I'm Colton (Col) for short. Please excuse any errors.

I'm at the beginning of my journey in to the fascinating world of American railroad watches and picked up this Illinois pocket watch at the auctions with the intention of a complete overhaul (amateur level - maybe my tenth overhaul, first Illinois). I hope you can assist with a couple of questions to get me started.

First, can you confirm my ID is correct on the movement. It was listed as a Type 14 Bunn Special, however my research tells me this is a Type 15 IIE 161 movement so with the Elinvar hairspring which leads me to my next question.

Are there any sources to find a replacement hairspring or balance complete? My search tells me these are difficult to find, perhaps the Elinvar-Extra could be obtained although that would be for a later model year watch which is not preferable. I assume the period Hamilton 992 16S Elinvar hairsprings were not interchangeable?

So, if you have a moment take a peek at the hairspring for me and share your thoughts on whether it can be saved. My inspection under magnification showed some mangling of the hairspring between the regulator pins and the stud, also the outer rings are touching which shouldn't be too bad to fix. The regulator pins look to have been closed down on the hairspring at some point. Overall the movement is quite dirty and I can't wait to get in to it.

Lastly the watch is operating, quite badly at -382s/pd (DU) - room for improvement.

Thanks in advance.

 

[musicguy]

Moving thread to watch repair section.

Welcome to the NAWCC Forum!


Rob

 

[Vintage12]

Thank you Rob. C.

 

[musicguy]

I did a quick look at the Illinois database, and it does say Model 15 Bunn Special 161E
3250 Made from 13 different runs. Made 1931.



Rob

 

[Skutt50]

Welcome to the forum.

So, if you have a moment take a peek at the hairspring for me and share your thoughts on whether it can be saved

Yes. That hairspring can be fiexd. It does not look that bad and should not be hard to fix. The clinging coils can be because of the kink close to the stud but could also be caused by magnetism or some oil. Do a search on the forum and you will find plenty of threads on hairspring manipulation. You can also do a search on YouTube to find several films showing how to deal with it.

You are best off trying to fix the existing hairspring. If you change the hairspring the timing is likely to be off and that is a bigger job to correct.
If you replace with a balance complete you will get the timing correct BUT the balance wheel usually has the serial number inskribed and you do not want to fit a balance with the wrong serial number.

 

[Vintage12]

Welcome to the forum.



Yes. That hairspring can be fiexd. It does not look that bad and should not be hard to fix. The clinging coils can be because of the kink close to the stud but could also be caused by magnetism or some oil. Do a search on the forum and you will find plenty of threads on hairspring manipulation. You can also do a search on YouTube to find several films showing how to deal with it.

You are best off trying to fix the existing hairspring. If you change the hairspring the timing is likely to be off and that is a bigger job to correct.
If you replace with a balance complete you will get the timing correct BUT the balance wheel usually has the serial number inskribed and you do not want to fit a balance with the wrong serial number.

I appreciate the feedback Skutt50, will take you up on your advice and try to fix the hairspring. That whole section from the stud and through the regulating pins needs work in just about all directions. I'm conscious of wanting to get the correct breguet coil over shape and will research the design (unless somebody has a handy pic). I won't know until it's removed but I'm hoping the straight shot from regulator to stud is not because it's too short. One step at a time.

I did a quick look at the Illinois database, and it does say Model 15 Bunn Special 161E
3250 Made from 13 different runs. Made 1931.



Rob

Thanks again Rob. I had checked on "pocketwatchdatabase" and it stated this serial# was a mixed run of Type II and Type IIE (Model 14 and model 15) but suspected the later since the "Elinvar" was printed on the balance cock. Type IIE it is.

 

[Skutt50]

I'm conscious of wanting to get the correct breguet coil over shape

The damaged area is actually just an arc to allow the regulator pins to move without moving the center of the hairspring. If you remove the hairspring from the balance and fit it to the balance cock, the center collet should rest directly above the balance jewels at all times when you operate the regulator from "fast" to "slow".

 

[John Runciman]

Are there any sources to find a replacement hairspring or balance complete? My search tells me these are difficult to find, perhaps the Elinvar-Extra could be obtained although that would be for a later model year watch which is not preferable. I assume the period Hamilton 992 16S Elinvar hairsprings were not interchangeable?

So, if you have a moment take a peek at the hairspring for me and share your thoughts on whether it can be saved. My inspection under magnification showed some mangling of the hairspring between the regulator pins and the stud, also the outer rings are touching which shouldn't be too bad to fix. The regulator pins look to have been closed down on the hairspring at some point. Overall the movement is quite dirty and I can't wait to get in to it.

If this was modern watch repair balance complete no problem. Balance complete for this watch I don't suppose you have a time machine? Or basically balance complete is not practical or even obtainable. Hairspring they were available separately typically in a timely oven over coil hairspring hairsprings were separate. But sourcing one might be a challenge and as others have pointed out there is the timing problem. In modern watches hairsprings are vibrated to that balance wheel. Watches with over coils they hairspring is typically premade to get everything exactly where it's supposed to be for timing requirements. Then the balance wheel is matched the factory has a infinite supply of timing screws we do not.

Usually simplistically advantage repair it's always best to keep what you have and try to fix it. Another thing occurs on a pocket watch if you look at your balance wheel it should have the serial number scribed or at least partially scribed. Because especially on pocket watches things are fit including the balance wheel so swapping the balance wheel may introduce other issues

Then before you can really do anything with the hairspring as others have recommended it should be cleaned so we know that oil sticky oil isn't holding things together. Definitely demagnetized that can cause issues. Then take your time study the situation doesn't really look that bad at least in the pictures I'm seeing and if you're not careful it can look much worse.

 

[Vintage12]

All good advice, thank you. I've previously used the collet centering technique to address a hairspring with just a small kink on the outer coils. This one is much worse than that so I'm pleased to read your assessments that it's really not too bad - those Youtube videos are very helpful, I've ordered some #7 curved tweezers so I can do this under the microscope. For sure I'll be cleaning with one-dip before getting started and it is my intention to poise the balance, I have the under cutters and a limited supply of timing washers (so difficult to find for 16S/18S that I've been pulling them off my practice movements). I'll demagnetize although expecting the Elinvar to be somewhat resistant given this was one of it's main features. I also have a timing machine to check in all positions once the movement is fully serviced. Is it normal to be buying cool vintage tools every week for this hobby? A rhetorical question. Thanks again.

 

[Vintage12]

John, I smiled after re-reading your comments. Unfortunately my Weishi 1000 timing machine doesn't have a back button so I'll just have to work in current time mode. C

 

[Skutt50]

and it is my intention to poise the balance,

Normally you would not need to do this because of the hairspring fix. The balance should be as good as before the kink occured.

May I suggest you first try it on the timing machine and if not acceptable, do a dynamic poise. Don't try a static poise since it will probably screw up the poising done during the 6 position adjustments once made at the factory.

 

[Dave Haynes]

The watch is also a 60 hour watch which takes a special mainspring. I don't know if mainsprings are available. I have one left and it is for my future use. I had two but gave away the first one. They are definitely worth the time and expense to repair.

 

[Daniel Reuben]

Woah on the undercutters and timing washers. This is not a split balance so the quarter screws should take care of all timing needs (that's the good part). If you want practice with undercutting and washers try a Hamilton 940 which is adjusted to 5 positions but the early ones had no timing screws at all and the later ones only had two if I recall. I guarrantee 98% of those for sale will fail position timing at RR standards. I don't mean to be arrogant but I don't see many people adjusting them to that degree of accuracy especially when flipping watches for sale.
All good advice so far, make sure the hairspring is not oiled. Make sure it is not magnetized, then remove from balance and re-attach to find if the collet is centered (it wont be). I believe the chief problem is someone nudged it (flattened) the curve from the stud to the regulating fingers which is why it is expanding out the back towards the cock base.
One last question not answered: this is a different hairspring than a Hamilton 992e or 950e, at least with regards to the stud. Even if the same dimensions otherwise it will be horrendous trying to restud this and likely as the balance wheels are different the weight will be off and timing may require major changes to the screws as the timing screws may not bring it to time.
If you succeed (we hope so) keep in mind once you bring it to time with the regulator in the center and you progress to position timing, you need an amplitude of about 180 deg so you can't position time with the watch wound fully. At 220 degrees the positions cancel out. At above 220 the timing becomes a little backwards. There's books on this. good luck.
- Dan.

 

[Daniel Reuben]

One more thing, your cap jewel on the balance doesn't look right. Is there actually a cap (flat covered jewel) on top or is the pivot exposed? Also the color of the setting looks brass not gold. This may have been switched. Can anyone else confirm? I have an older Bunn Special and not one of these so don't want to jump to conclusions. If the cap jewel is missing you'll get horribly poor motion dial up....

 

[Vintage12]

Excellent feedback - thanks.

Dave, I was reticent to run the watch too much prior service but did one baseline test at 56.2 hours, I imagine the full 60 will be available should I keep this mainspring. I've been replacing mainsprings as a matter of course on all my previous projects.

Daniel, Thanks for pulling in the reins, I'm not used to such tech in these one piece balance wheels - I'm just finishing up on a 1800's Waltham and that needed washers so good to hear this one should not. I happen to have a Hamilton 992E in the queue, will inspect and compare but likely I won't go down that rabbit hole. Your point about position timing with amplitude at 180 deg is interesting and news to me - more reading required. Lastly, you have a good eye on that cap jewel, take a look at this photo - the screws are counter sunk and the pivot is clearly showing. Where can I find a cap jewel and should the pivot hole jewel also be in gold originally?

I'm wondering what other discoveries await me.

 

[gmorse]

Hi Col,

This document by Dewey Clark on the subject of dynamic poising is worth reading before doing anything to your balance, although with missing top jewels on the balance your scope for practical testing is very limited.

I think I can see a chip of broken jewel next to the right-hand screw in your latest picture, and where there's one there are often others. If it's suffered a shock severe enough to break the cap jewel, the staff pivot may not be healthy either.

Regards,

Graham

 

[Vintage12]

Thanks Graham. Interesting read, for sure I will go with dynamic poising. Just need to find that cap jewel to get started. Looks like the offending intruder was a shard of glass possibly from a crystal breakage, regardless it will get a full clean & check up.

 

[179]

Thanks Graham. Interesting read, for sure I will go with dynamic poising. Just need to find that cap jewel to get started. Looks like the offending intruder was a shard of glass possibly from a crystal breakage, regardless it will get a full clean & check up.

Balance hole jewels are 99.999% in composition settings, as they are not seen. The upper cap for this grade needs to be gold to be correct, the bottom cap composition. The biggest problem is the ( and i will put it plainly) butcher work done to the balance cock. Taking a countersink bit to the holes is an abomination . A correct, screw even if it fits the thread ( who knows what has been done to that ) will not look good. Even larger correct looking Flat head straight shoulder screws i n a proper counterbore will not look great. Hamilton did use their Elinvar hairsprings on these by using an Illinois stud.

 

[Vintage12]

That makes sense on the hole jewel, thanks for confirming.Also helpful to know about the Hamilton Elinvar hairspring.

It's disappointing to see this purposeful work on what was a fine timepiece in it's day. But, I'm not going to give up. My search for a gold cap jewel hasn't proved successful so I'm thinking a donor movement may be in my future - I have a feeling I'll need it for the next chapter in this book.

 

[179]

That makes sense on the hole jewel, thanks for confirming.Also helpful to know about the Hamilton Elinvar hairspring.

It's disappointing to see this purposeful work on what was a fine timepiece in it's day. But, I'm not going to give up. My search for a gold cap jewel hasn't proved successful so I'm thinking a donor movement may be in my future - I have a feeling I'll need it for the next chapter in this book.

Colton, this is a learning experience for you, we have all had them, maybe not as expensive as yours Your 1st. pic threw up a red flag for me, and the 3rd, pic stopped the train. Good luck with your project

 

[Vintage12]

A quick update for you. I decided to pull the balance complete and investigate some more. First the good news, the balance wheel is correct to the movement and the serial numbers match so we'll be keeping that for sure.

Next, it must have been an optical illusion because a cap jewel is indeed in place, just the wrong composition one and looks to be set upside down hence the sunk screws. They were caked in oil, so much so I had to clean my work surface afterwards.

I popped the hairspring off the balance staff and it's not terrible but needs work from the collet out - it was also covered in oil to the point it would stick to the balance cock, the collet centering is off as expected but I think we can get that centered ok. I feel more confident the hairspring can be saved.

But then, on the balance wheel I see that somebody has been drilling for gold! And we thought under cutters were butchers.

So here's my question. I could leave the balance wheel well alone, or is it a reasonable approach to recover gold screws from my donor movement, weigh as best I can and replace the offending articles? Bad idea? It's not that the drill holes are easily visible with the naked eye, they are not.

Some photos attached for your viewing pleasure.

 

[gmorse]

Hi Vintage12,

So here's my question. I could leave the balance wheel well alone, or is it a reasonable approach to recover gold screws from my donor movement, weigh as best I can and replace the offending articles? Bad idea? It's not that the drill holes are easily visible with the naked eye, they are not.

I wouldn't make any changes to the balance until you've cleaned everything properly and reassembled the movement, so that you can see if you can bring it to time as it is now. You have no way of knowing if those drilled screws are original or replacements.

Some of the centre coils of the balance spring are rather too close, but that may be resolved when you centre the collet.

At least with all that oil you shouldn't find any rust!

Regards,

Graham

 

[Vintage12]

Thanks Graham. I'm rather surprised those drilled screws could be original from the factory, but that is helpful to know. On the hairspring I thought oil might be sticking the coils together so cleaned it in one-dip and also demagnetized. My markup attached was for my own notes on where to start manipulating the hairspring, hopefully I am on the right track.

 

[gmorse]

Hi Vintage12,



Actually, you might find that doing the green correction first brings you very close to a fix.

Regards,

Graham

 

[Vintage12]

Super helpful Graham - thank you.

 

[179]

Having worked on hundreds of high-grade Illinois watches, I will say that no watch left the factory with those screw heads in that condition . In "butcher" hierarchy they are 1 step above filed heads. On to the spring, it appears to be a Elinvar dyed blue as I would expect on this watch. To by eye these springs are a Blue-green hue, rather than a deep royal blue steel spring. The spring is worth saving. I never did think it did not have an upper cap, just completely wrong. Depending on the color and transparency of the jewel it is easy to see the pivot through it.

 

[Vintage12]

I will say that no watch left the factory with those screw heads in that condition

This was my initial thought. My assumption was the factories had many thousands of screws available with different weights to set up the balance wheel correctly. I guess it's possible watches needing a factory service later on could have modifications, but this seems extreme... Perhaps we'll never know, my guess is the butcher of horrorology has been tinkering.

I think I'll strip down the rest of the movement and see if there are any more discoveries. Will ponder on the balance wheel and what, if anything, to do about it.

Any tips on where to get parts for these lovely Illinois watches? I haven't picked up a donor movement just yet - is that my best option at this point?

 

[gmorse]

Hi Vintage12,

Perhaps we'll never know, my guess is the butcher of horrorology has been tinkering.

Unfortunately, many books written in the past by very respectable horologists described the several ways that balance screws could be lightened, and sets of screw damagers ('undercutters') were sold by every tool and materials house. If the balance worked correctly when it left the factory, how come it always managed to gain some weight when the watch was serviced, or the staff was replaced, apparently necessitating this type of 'adjustment'?

Regards,

Graham

 

[179]

Hi Vintage12,


Unfortunately, many books written in the past by very respectable horologists described the several ways that balance screws could be lightened, and sets of screw damagers ('undercutters') were sold by every tool and materials house. If the balance worked correctly when it left the factory, how come it always managed to gain some weight when the watch was serviced, or the staff was replaced, apparently necessitating this type of 'adjustment'?

Regards,

Graham

I think rather than the balance gaining a little weight, I believe it was the mainsprings driving it. Years ago mainsprings were supplied in various strengths to suit different grades of watches. Higher grades required weaker springs, and when powered by say a 7 jewel grade spring, ergo too much zing add some washers or a pair of small screws. The reverse of this was take some weight off the balance, drilling, undercutters, screw removal and other methods. Most watches over their lifetime have had several if not more mainsprings installed, followed by balance staffs, which induce their OWN problems.

 

[Daniel Reuben]

I think you'll be ok. The amount of gold removed can probably be compensated with the quarter timing screws. Don't fret.
I agree with hairspring assessment a few posts back. All of the problem is in the first turn out of the collet and the terminal end, nothing further I don't believe. Increase the curve at the first thin red arrow very slightly to hug the collet better. Then curve it again more tightly at the fat green arrow to shift the second coil slightly further away (around 07:00 in the photo). Mount it (the collet) on a tack and manipulate carefully. You can turn the tack in your hand to rotate the whole thing. When doing so you'll have the hairspring spiral out (or in) but in essence you want to get a flavor of if it is expanding evenly. I would say if you can only fix the inner curve by another 50% of what it needs you'll probably still be ok. On a 16s there's enough space between the coils to accept some assymetry. It is hard to coach how to bend hairsprings. I sometimes have bad luck with two tweezers. Often I like to nudge or squeeze a coil into itself to increase a curve, or pull it away (like over-stretching a spring) to lessen but you need a lot of experience to know how far to move beyond the point needed so when you relax it the coil winds up where you want and not too far in a new position. Lastly if you absolutely have to pick I'd absolutely make sure the outer coil at stud is fixed perfectly so the collet is centered and not worry about the first turn out of the collet but obviously if you can do that too then all the better.
I can't say where to get a new cap jewel but seeing how you have one I'd use it and proceed. I have a Hamilton 991 with incorrect (brass) cap but the watch works and position timed to RR standards so right now it is just cosmetic. Hopefully the same for you.

 

[gmorse]

Hi Daniel,

Mount it (the collet) on a tack and manipulate carefully.

A tack is fine for just checking in the flat, but I think it's much more controllable and safer to manipulate in the round and the flat when the spring is supported on a smooth level surface. I use a piece of Perspex, (acrylic sheet), which allows the tools to slide and not dig in. I use one pair of tweezers and a sharpened brass 'needle' to stroke the spring into shape for trueing in the round, and two pairs for making corrections in the flat. If the spring still has the stud pinned to it, hanging the collet on a tack can be misleading as gravity will distort the appearance.

Regards,

Graham

 

[Daniel Reuben]

Hi Daniel,


A tack is fine for just checking in the flat, but I think it's much more controllable and safer to manipulate in the round and the flat when the spring is supported on a smooth level surface. I use a piece of Perspex, (acrylic sheet), which allows the tools to slide and not dig in. I use one pair of tweezers and a sharpened brass 'needle' to stroke the spring into shape for trueing in the round, and two pairs for making corrections in the flat. If the spring still has the stud pinned to it, hanging the collet on a tack can be misleading as gravity will distort the appearance.

Regards,

Graham


...very good points. I was thinking there was probably no horizontal or coplanar distortion and didn't want to confuse but your assessment is quite valid. I do like the tack only in that in manipulating on a flat surface sometimes it gets away from you and occasionally the need to get the tweezers farther trough a loop (e.g. to lightly squeeze and flatten or gently release a tight curve where the very tips are too narrow to do). Actually the point about weight makes even eyeing the mounted hairspring in the cock difficult. When holding upright the collet will drop a little below the balance jewel on a large 16s or 18s hairspring. The same occurs when holding the cock vertical in other positions. If holding horizontal gravity drops the collet on the underside of the cock bridge but not necessarily where it would be in a relaxed position. I also hold it over my head and look up at it with a ceiling light shining down through the jewel but the collet is hanging far from the jewel and parallax along with the spiral nature doesn't necessarily allow for an accurate asessment - so it is somewhat of an average of all measurements to get the job done. As an aside on a non-Breguet hairspring it can actually be advantagous to have the collet slightly non-centered and to allow friction and the coil to preferentially unwind towards one side but that is not applicable here.....Lastly, Hamilton's stud attachment solves this perfectly as this is the only American attachment whereby if you mount the balance complete into the watch and screw down the cock bridge one can just rotate the balance and the stud is coaxed across the regulator arm and into position at the bridge. The stud will find its neutral position in the bridge and then the two stud screws can be screwed down. Thus the hairspring is always centered concentrically (unless wildly bent). All other companies the stud must be located exacty so one never knows if there is a loss of concentricity, technically speaking.

 

[Vintage12]

I'm just starting the full disassembly of the Bunn Special 161. For those of you familiar with the movement, can you tell me if the crown wheel screw is reverse thread or regular? It's not marked as reverse but I'm having great difficulty loosening it. Have put about 90% effort in to it in both directions but before I go further would like to know for sure. Also, any tips on undoing very difficult screws? I think I will sharpen up my largest screwdriver to get more torque on it, if it were my car I'd be breaking out the WD40, Heat, and impact driver next..

Aside from the discoveries with the balance, the rest looks good so far except for the copious amounts of oil - it's everywhere.

 

[Vintage12]

Belay that. A video I just reviewed on Youtube showed regular for the Bunn Special, but in fact this one is reverse thread. My largest sharpened screwdriver saved the day this time. Onwards.

 

[terry hall]

fyi

 

[Vintage12]

Thanks Terry. That is quite timely as I was inspecting my tear down and this confirms that I am missing the top jewel in the motor barrel amongst other things.

So after complete inspection, here's my assessment of where we are at.

1. Hairspring - needs reworking, likely repairable per group feedback
2. Balance Cap Jewel - wrong cap jewel, needs replacement
3. Dial - badly chipped and cracked, have NOS dial replacement
4. Motor Barrel - missing top jewel, 3 screws are wrong type and need replacing w/ possible damage to cap plate
5. Mainspring - is damaged, will replace with 60 hour spring
6. Center Wheel jewel - cracked, will need replacing (see pic)

I secured a couple of parts but unlike my Waltham and a recent Hamilton project, these Illinois Bunn Specials seem limited in parts availability. In the end I decided to pick up a donor movement, just waiting on that to start the rebuild process.

The good news is that all parts on the watch have matching numbers including the balance wheel.

 

[Vintage12]

Correction. I think. The 161 variant wouldn't have a motor barrel jewel pair, that would be the 163 correct?

 

[179]

Correction. I think. The 161 variant wouldn't have a motor barrel jewel pair, that would be the 163 correct?

Correct.

 

[Vintage12]

I've hit a snag.

First, my donor movement came in and I've successfully replaced the lower center wheel jewel, however, when it came to replace the upper end stone cap jewel in the balance cock, wrong size jewel setting! My donor is a 16S Bunn Special from 1927 and the gold endstone setting diameter is circa 2.06mm while the 1931 161 is more like 2.39mm - a big difference.

So, can someone confirm that Illinois/Hamilton changed these between these dates? or did someone ream out my jewel setting in the cock to fit those odd jewels we found?

Assuming the cock is original and I need the larger setting then it seems impractical to find a donor 161/161A/163A. So, where can I find a gold cap jewel with setting? I've looked everywhere I can but no luck so far.

 

[Daniel Reuben]

I have 2.45 mm on my spare Circa 1920 or so Hamilton balance cock gold cap jewel setting (The jewel cracked which is why I replaced it). I'll let Illinois experts weigh in but potentially as Hamilton purchased Illinois by then the cap jewel size may have adopted the prior Hamilton size (although we're still 0.06 off). It's hard to find spare gold jewel settings on the online auctions. It may be worth asking those who sell parts here or online for advice. I agree spare Hamilton parts seem easier to find than those for Illinois.

 

[Vintage12]

Daniel, Thanks for checking in to that. I re-measured both the hole jewel and cap jewel and they come in at 2.38-2.39mm, of course we know the cap jewel is wrong so that might be a bad reference even though it seems to fit in the cock. I used my jeweling set and found a 2.43mm pusher would not fit. The indication here is that Hamilton and Illinois used different sizes at least during the early part of their merger. I posted for a jewel in the WTB section here but nothing just yet. I'll rebuild the rest of the watch and hopefully somebody finds one in a secret draw.

 

[Vintage12]

Here's a comparison photo of those two balance cocks. They are different under scrutiny, also correct to their respective movements with matching serial numbers.

 

[Skutt50]

Looks like you have a damaged regulator arm on the 1927 movement. Good thing it is the donor movement.

 

[Vintage12]

Yes, indeed. Although aside from this and a broken balance staff the donor movement is not in too bad a shape. I almost feel it would be a shame to consign it to the parts bin so I ordered a replacement balance staff for it.

 

[179]

Yes, indeed. Although aside from this and a broken balance staff the donor movement is not in too bad a shape. I almost feel it would be a shame to consign it to the parts bin so I ordered a replacement balance staff for it.

Sounds like a good plan.

 

[Vintage12]

In my quest to find the correct endstone jewel I've been scrutinizing the Bunn Special movements through 1929 and they all have the smaller jewel and balance cock design. Then I stumbled on an early 1940's model with the correct endstone for sale by a coin store, it was advertised as a complete Bunn Special that was working but not tested and for a reasonable price. One thing missing in the description though... "161A".

Yep, now I have another Bunn Special - it's becoming a habit. This one is far too nice for parts either, in fact it is running near RR standards and, at first glance, is in better shape than my other two watches. At least I can use this one as a reference for correct parts although I'm not precisely sure what the difference is between 161 and 161A except for dameskeen finishing perhaps?

The 161 endstone search continues.

 

[179]

In my quest to find the correct endstone jewel I've been scrutinizing the Bunn Special movements through 1929 and they all have the smaller jewel and balance cock design. Then I stumbled on an early 1940's model with the correct endstone for sale by a coin store, it was advertised as a complete Bunn Special that was working but not tested and for a reasonable price. One thing missing in the description though... "161A".

Yep, now I have another Bunn Special - it's becoming a habit. This one is far too nice for parts either, in fact it is running near RR standards and, at first glance, is in better shape than my other two watches. At least I can use this one as a reference for correct parts although I'm not precisely sure what the difference is between 161 and 161A except for dameskeen finishing perhaps?

The 161 endstone search continues.

View attachment 748668 View attachment 748669

This is how it STARTS, be careful, it could morph into terminal.

 

[Vintage12]

Back to normal service. I've been manipulating that hairspring on the 161 back in to shape. The most difficult part was the first coil from the collet, I ended up filing down to almost nothing a pair of tweezers to get in to the tight gap and then stroking out that first bend - not perfect but a little better. Anyway, appreciate your gentle feedback on where this is at, hopefully acceptable. Not sure I can go too much further with my current skill level.

 

[Skutt50]

I ended up filing down to almost nothing a pair of tweezers to get in to the tight gap and then stroking out that first bend

I would put these tweezers aside and use ONLY for hairsprings.

Anyway, appreciate your gentle feedback on where this is at, hopefully acceptable.

You are getting there. Good job.
There are still some small improvements that could be made but if I were you I would try it in the movement.

Install the hairspring in the balance cock and move the regulator along its arc, checking that the center collet stays centered.
If so, install it on the balanse and see what happens..........

 

[Vintage12]

Good idea - I've reserved those tweezers for just hairsprings, also I filed down a bunch of needles and polished the ends. All for future use.

When I was adjusting the hairspring I used the regulator arm to check no collet movement, also found the regulator pins to be a useful lever for fine adjustments. I still think a few tweaks on that arm sweep may be needed to avoid touch points on the pins.

It's looking more like I will just have to use the old endstone jewel for now. At least I can check the watch out and get it running again (hopefully).