Bunn special timing regulation

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  • #48529
    silevitch
    Participant
    • Topics Started: 3
    • Total Posts: 15

    I am a new member of the forum and am just getting my feet wet. I have a 21J 18 Size Bunn Special watch that is running slow (about 5 minutes per day). I intend to adjust the hairspring regulation micrometer to speed up the watch. How sensitive is this adjustment?

    Regards
    Michael

    #53096
    arutha
    Participant
    • Topics Started: 85
    • Total Posts: 1536

    Hi Michael and welcome,
    you would be very lucky to get 5 mins per day adjustment from the regulator. This amount of loss will be down to needing a clean and service. If the watch has been serviced recently then the hairspring needs to be shortened and the collet adjusted on the balance staff to get the watch back in beat. What do you know of the watches history, has it been serviced recently?
    Paul.

    #53097
    silevitch
    Participant
    • Topics Started: 3
    • Total Posts: 15

    Dear Paul

    Thanks for your reply. My understanding is that the watch was thought to have been recently serviced. Clearly this is not the same as a definitive statement. The movement looks bright and shiny but that could be deceptive. I don’t have any real experience with watch repair (hence my signing up for the course) and i don’t want to do anything that will make things worse.

    Regards
    Michael

    #53098
    arutha
    Participant
    • Topics Started: 85
    • Total Posts: 1536

    Michael,
    If it was me I would put that watch away until you get some tools together and a couple of cheap movements to practice on. You will not be the first or the last person to have bought a watch or clock from someone who claims it has been “recently” serviced. This is an amazing hobby and you will soon know when you feel ready to tackle that watch. Just as a quick check, look at the watch pivots through a 10x loupe (or any strong magnification) to see if the pivots and holes look clean and that they are not moving about in their holes too much.
    We will of course be on hand to help whenever we can.:)
    Paul.

    #53099
    silevitch
    Participant
    • Topics Started: 3
    • Total Posts: 15

    Thanks Paul, that’s good advice. I do have a loupe and a practice movement but I’ll take my time before doing something irreversible.

    Michael

    #53100
    david pierce
    Participant
    • Topics Started: 90
    • Total Posts: 1360

    Michael,
    Before jumping in and repairing watches there are some things that need to be studied to understand how the mechanism works. There are books on the subject that cover a lot of these principals. I think your timing problem has to do with the center of mass which is adjusted with the MERIDIAN SCREWS on the balance wheel. This is the same principal as moving the weight up and down on a clock pendulum. Bob covers this in his clock videos and you should watch it as a first step. Second step, get some books and study.
    david

    #53101
    silevitch
    Participant
    • Topics Started: 3
    • Total Posts: 15

    Dear David

    That’s good advice. Thank you.

    Michael

    #53102
    willofiam
    Moderator
    • Topics Started: 75
    • Total Posts: 1437

    Hey guys, not that I know much but I thought I would throw in a couple of pennies, David, I am under the impression that the meridian screws ought to be left as a last resort for adjustments and even then adjusted very carefully and accurately (who knows though what the previous smith has done) I would think if someone who did not know what those screws were would have most likely screwed them all the way in thinking they were loose, this would make the watch run faster, I would, although, look at all the other balance screws and make sure they are all the way in, also there can be like Paul said several other things possible, dirt and grime, is the hairspring inside the regulating pins and are the pins straight and adjusted proper, is it in beat, ect..ect.. good advice on getting some books, some books have a section where you can look up the issue and it will give a possible solution, hope everyone has a fantastic day. William

    #53103
    arutha
    Participant
    • Topics Started: 85
    • Total Posts: 1536

    Great advice William!
    David, I know you are trying to help but telling someone new to watch repair that they may need to adjust the balance wheel timing screws may not be the best advice. If the watch has underlying problems and you did manage to adjust the screws to get it to run correctly you would then cause the watch to wear at an accelerated rate. Before you make any adjustments to the balance the first thing to check is if the watch has been serviced. There are a number of things that should be checked that could make a watch run slowly.
    When you get a watch in for a service the first thing to do is assume that everything is as it should be. As you take the watch apart you may then begin to find problems which you know need to be sorted, rough pivots, over-size pivot holes, cracked jewels, dirt etc. These problems need to be sorted first so you know that the watch should run properly. If after the clean and service the watch does not run properly you then start looking at other issues that are not immediately apparent.
    A watch can run slowly because of;
    1. Dirt
    2. Pivot and hole wear
    3. A cracked jewel
    4. A cock that has been mishandled, i.e bent slightly and now there is not enough end shake and the pivot is running with too much pressure on the cap jewel.
    5. The hairspring has been pinned back in the wrong position making the effective length too long.
    6. A bent pivot
    7. The wrong or weak mainspring
    8. The wrong type of oil i.e too thick
    and I am sure there are other reasons, I recently bought a ladies cylinder pocket watch that had the lower pivot snapped off of the lever, to overcome this the previous jobber had glued a small piece of brass onto the bottom of the plate and drilled a larger hole in it so the arbor was acting like the pivot. Safe to say it didn’t run quite fast enough because of the excess friction this caused.

    Michael, as I stated before when you feel ready the first thing to do is strip and clean the watch. Please don’t adjust the screws on the balance just yet.
    As David stated get a couple of good books and watch Bobs videos until you feel comfortable enough to have a go at servicing the watch. (remember that you can ask as many questions as you like if you come across anything you don understand :) )
    Paul.

    #53104
    silevitch
    Participant
    • Topics Started: 3
    • Total Posts: 15

    Dear William and Paul

    Thanks to both of you for your willingness to help. Less is more. The first thing for me to do is study the situation, read and watch Bob’s videos and then see what makes sense.

    Any further advice would also be appreciated.

    Regards
    Michael

    #53105
    david pierce
    Participant
    • Topics Started: 90
    • Total Posts: 1360

    Please re-read the post that I wrote, I did not say start turning screws on the balance wheel any more than Paul said go ahead and cut the hairspring to make it shorter so it can run faster. What I said was I think the problem has to do with the center of mass of the balance wheel which is adjusted with the Meridian Screws. This is similar to moving the weight up and down on a clock pendulum. These are timing adjustment procedures and timing adjustments should always come after repair and cleaning procedures. A major reason for this is to help rule any other issues that may be causing timing problems. Another reason is a broken and/or dirty watch will probably not keep good time. These are concepts that are learned through study and practice. I also stated that Bob’s clock videos explain the thoery behind pendulum weight and weight placement and feel that it would be a good idea to watch these to help understand how this affects oscillation. My reason for bringing this up was most people who are interested in watch repair will probably ignore the videos on clock repair. These videos should also be watched.
    Everything Paul stated on his list is correct and is covered in books on watch repair; hence, the reason to get the books ,study and learn about the mechanisms and how they work. If you pull up some previous posts from Watch the Bear a similar problem arose and the balance wheel was replaced with a different size balance wheel which corrected the problem. The reason this corrected the problem is because the new balance wheel had the correct center of mass. The Meridian Screws are there for this reason (an adjustment procedure) and should not be used for poising (a repair procedure) and yes, their purpose and adjustment procedures are also listed in in many books on watch repair.

    #53106
    arutha
    Participant
    • Topics Started: 85
    • Total Posts: 1536

    @david pierce wrote:

    I think your timing problem has to do with the center of mass which is adjusted with the MERIDIAN SCREWS on the balance wheel.

    Hi David,
    what concerned me about your post was if you take it from the perspective of someone with little knowledge and they come on the forum to ask a question they are ready to take in whatever advice is offered as they consider us to have suitable knowledge. Just by stating you think the problem could be this could lead someone with inexperience to then try adjusting the balance screws. Without having the watch in front of you to inspect it how could you possibly make this assumption? If you had worded it differently and said the balance screws might have been adjusted by the previous owner or repairer so bear this in mind if the watch is still losing time once it has been serviced then that would have been better.
    Again this is the problem with text as it can be taken the wrong way as you seem to have taken mine the wrong way. I didnt mean any offence and if I have caused you any then I am sorry.
    Paul.

    #53107
    david pierce
    Participant
    • Topics Started: 90
    • Total Posts: 1360

    Paul.
    About 15 years ago I bought a nice railroad pocket watch off of the internet. It ran fast so I took it to a watch repair shop in Atlanta Georgia. Their rapair technician put the watch on his timing machine, adjusted the regualator pins and gave the watch back to me. Over the next few days, it was running fast again. I took it back and the technician went through the same procedure. I took it home and and it did the same thing. I put the watch in a safe years ago and forgot about it. I never knew what was actually wrong with the watch until Watch the Bear had a similar problem. Through study, practice and observing the problems others have on these forums, I learned what these four screws are for and how to adjust them.
    When I took my first watch course a few years ago the balance wheels that offered this adjustment were already phased out due to modern manufacturing methods and materials. The balance wheels made today are dynamically balanced and reweighted by cutting the wheels with lasers. This produces a balance wheel that is ustimately cheaper to manufacture and produces a better product. The problem with the process is the machines are incredibally expensive and are owned by companies like Eubache who make millions of watch movements. Since it is an automated process the factories get a tremendous cost reduction per watch.

    #53108
    silevitch
    Participant
    • Topics Started: 3
    • Total Posts: 15

    I am very impressed with the level of collegiality and depth of information that is being provided to me (a new member) on this topic. As an update, I purchased the watch on eBay and it was represented as having been cleaned and oiled. When i received the watch it indeed looked like it had been cleaned and oiled in terms of appearance (a beautiful two toned movement in a display case!) The regulator pointer was right in the middle of its range as expected. When I timed the watch it was clear that something was amiss in that it ran at least 15 minutes slow over a 24 hour period. After integrating the information that this forum provided I decided to return the watch to the seller today after informing him that the watch was not as represented. Perhaps that’s a cop out but I felt that the problem was one that was beyond my skill set at the present time and discretion was the better part of valor. The upshot is that I am now looking for another watch of the same ilk and am immersed in the videos from the course and other related materials (ie Henry Fried’s book).

    I don’t want to stop the conversation on the topic of regulation. Let me say that I don’t think the problem I described was related to cleaning. It could very well have its roots in the adjustment of the balance screws or some other flaw like a cracked jewel or broken pivot or incorrectly pinned hairspring. (There was no discernible wobbling of the balance or other pivots that I could observe with a loupe.) My sense is that normal operation of a railroad watch of the Bunn Special 21J variety should lose/gain no more than 30 seconds to a minute over a 24 hour period. Is this correct?

    Regards
    Michael

    #53109
    arutha
    Participant
    • Topics Started: 85
    • Total Posts: 1536

    Hi Michael,
    I am sorry that David and I seem to have hijacked your post somewhat.
    I think you did the right thing, that watch if it had been serviced definately had an issue somewhere. Something like that should maybe loose or gain around 30 seconds per week if in tip top condition. Frieds book is very good and I dont think you could have made a better choice to start with :)
    If you have a good watch to start with and then service it and it doesnt run afterwards then you know you have done something wrong. Starting out on a watch that does have a problem, although you will learn from it, can take longer and be quite frustrating. Get yourself a cheap pocket watch and jump in, its the best way to learn after watching the videos and reading so you feel you have a basic understanding of what each of the parts do. Use a digital camera as you strip the watch so if you do forget where something goes you can look back and see :)

    Hi David,
    I completely understand what you are saying and it is good that you have learnt what one of the reasons for not keeping time could be but as per my previous post we just need to be careful how we word things. I re-type countless posts in case they could be taken the wrong way. I just wanted to make sure that anyone reading that post that is inexperienced didnt start causing more problems on their watch when all that was needed was a service. I hope you understand that there was no intention of asking people to disregard your post but just to make sure the basics had been checked first.
    Paul. :)

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silevitchBunn special timing regulation