Rolex oyster service part 2 – replacing the balance staff
A quick review of what's been done so far. The watch was sent in for a routine service. In part 1 of this article, I fabricated a new top barrel bushing and during testing I found out that the balance staff was defective. This time round I hope to be able to get the movement up and running by replacing the staff.
Last time I discovered a defective balance staff on this Rolex 1030 movement. The staff is very tiny, measuring just under 3mm in total length, with pivots measuring 0.07mm in diameter. If you remember were we left off last time, I found out that the staff was damaged and that it needed to be replaced. Photo 1 shows the damage to the collet seat and the cause of my problems trying to remove the hairspring. Lets get started with the removal of the old staff from the balance wheel.
A quick review of what's been done so far. The watch was sent in for a routine service. In part 1 of this article, I fabricated a new top barrel bushing and during testing I found out that the balance staff was defective. This time round I hope to be able to get the movement up and running by replacing the staff.
Last time I discovered a defective balance staff on this Rolex 1030 movement. The staff is very tiny, measuring just under 3mm in total length, with pivots measuring 0.07mm in diameter. If you remember were we left off last time, I found out that the staff was damaged and that it needed to be replaced. Photo 1 shows the damage to the collet seat and the cause of my problems trying to remove the hairspring. Lets get started with the removal of the old staff from the balance wheel.
Balance staff removal
Removing a balance staff is challenging and risky. The challenge on this size of a balance and staff is the size, they are both very small and therefore very fragile. The risk is getting the old staff out, without damaging the balance wheel arm. The first issue simply requires that you are aware of the size of what you are working with, and use appropriate care and caution. The risk during removal of the old staff is simply something you have to accept, removal can never be risk free, once you accept that fact, all you can do is apply your skills and best effort.
Before you can remove the staff, you have to remove the hairspring and the roller table. If you remember last time I managed (after much difficulty) to remove the collet and hairspring, and the removal of the roller table was done on my Platax tool. You can see all three parts in Photo 2.
Staff's are made from hardened and tempered (blue) high carbon steel. Normally you can cut blued steel with your normal graver and certainly it will cut with a carbide graver. What I have discovered over the years is that Rolex staff's tend to be really hard, so hard in fact that they almost certainly can't be cut with a carbide graver without removing the temper first. I think there are two factors influencing this problem: the staff's are hard to start with, and the peening of the rivet case hardens the staff even more. So based on that experience, I don't even try cutting the rivet off, without heating the staff and softening it first. This is simple to do, take a brass rod, drill a hole slightly larger than the staff, place the staff inside the hole, hold the rod and apply a heat with a small torch to the brass rod. The brass quickly transfers the heat into the staff, and when you see the staff turning blue, it should be soft enough.
Removing a balance staff is challenging and risky. The challenge on this size of a balance and staff is the size, they are both very small and therefore very fragile. The risk is getting the old staff out, without damaging the balance wheel arm. The first issue simply requires that you are aware of the size of what you are working with, and use appropriate care and caution. The risk during removal of the old staff is simply something you have to accept, removal can never be risk free, once you accept that fact, all you can do is apply your skills and best effort.
Before you can remove the staff, you have to remove the hairspring and the roller table. If you remember last time I managed (after much difficulty) to remove the collet and hairspring, and the removal of the roller table was done on my Platax tool. You can see all three parts in Photo 2.
Staff's are made from hardened and tempered (blue) high carbon steel. Normally you can cut blued steel with your normal graver and certainly it will cut with a carbide graver. What I have discovered over the years is that Rolex staff's tend to be really hard, so hard in fact that they almost certainly can't be cut with a carbide graver without removing the temper first. I think there are two factors influencing this problem: the staff's are hard to start with, and the peening of the rivet case hardens the staff even more. So based on that experience, I don't even try cutting the rivet off, without heating the staff and softening it first. This is simple to do, take a brass rod, drill a hole slightly larger than the staff, place the staff inside the hole, hold the rod and apply a heat with a small torch to the brass rod. The brass quickly transfers the heat into the staff, and when you see the staff turning blue, it should be soft enough.
Cutting away the rivet
To be able to cut away the rivet on the staff, the balance assembly has to be secured in the lathe (photo 3) and spun round while you cut away with your graver. I don't know about you, but whenever I have a balance wheel (or any wheel for that matter) spinning round in the lathe I get nervous. There is something about approaching a spinning wheel, with either screws or gear teeth sticking out, with a graver that forces me to really pay attention. I have visions of the graver catching the screws or teeth and the resulting disaster. Here's some good advice: never flip down your tip over tool rest without making 100% sure it's placed properly, and keep your foot off the lathe motor throttle until everything is in place and you're ready with the graver.
With the rivet removed, the staff is driven out with my Platax removal tool, Photo's 4 and 5. If your not familiar with this tool, I plan on doing a short write up on it in the future. Now that the staff is out, I can install the new one. I picked up a replacement staff from my supplier. I am not against making staff's when you can't get a replacement, but in this case, you're much better off buying a replacement staff, instead of attempting to fabricate a new one. So that's what I did. The new staff was installed using the normal work procedures. With the roller installed, I next install temporarily install the balance assembly on the mainplate with the balance cock in place. Everything about the balance is critical, especially so the alignment of the roller table with the pallet arm. So before I get too carried away with the rest of the work that needs to be done, I check the alignment carefully. See the results in Photo 6, everything looks good. With that out of the way, the complete assembly was placed on the poising tool to check if the weight is evenly distributed around the outer circumference. Photo 7 shows the correct placement, the flat part of the pivots is placed on the edges, and in Photo 8 you can see my small brush used to gently rotate the balance round and check the poising.
To be able to cut away the rivet on the staff, the balance assembly has to be secured in the lathe (photo 3) and spun round while you cut away with your graver. I don't know about you, but whenever I have a balance wheel (or any wheel for that matter) spinning round in the lathe I get nervous. There is something about approaching a spinning wheel, with either screws or gear teeth sticking out, with a graver that forces me to really pay attention. I have visions of the graver catching the screws or teeth and the resulting disaster. Here's some good advice: never flip down your tip over tool rest without making 100% sure it's placed properly, and keep your foot off the lathe motor throttle until everything is in place and you're ready with the graver.
With the rivet removed, the staff is driven out with my Platax removal tool, Photo's 4 and 5. If your not familiar with this tool, I plan on doing a short write up on it in the future. Now that the staff is out, I can install the new one. I picked up a replacement staff from my supplier. I am not against making staff's when you can't get a replacement, but in this case, you're much better off buying a replacement staff, instead of attempting to fabricate a new one. So that's what I did. The new staff was installed using the normal work procedures. With the roller installed, I next install temporarily install the balance assembly on the mainplate with the balance cock in place. Everything about the balance is critical, especially so the alignment of the roller table with the pallet arm. So before I get too carried away with the rest of the work that needs to be done, I check the alignment carefully. See the results in Photo 6, everything looks good. With that out of the way, the complete assembly was placed on the poising tool to check if the weight is evenly distributed around the outer circumference. Photo 7 shows the correct placement, the flat part of the pivots is placed on the edges, and in Photo 8 you can see my small brush used to gently rotate the balance round and check the poising.
Poising the balance
Normally the balance “gently” rotates and if it's out of poise, it rocks slowly back and forth towards the heavy side. Well, this one was extremely out of poise and it slammed down towards the heavy side as soon as I placed in on the tool. There was no way that removal of material from a screw was going to even come close to achieving the results I needed. So I decided that the only solution was the addition of copper washers under the screws, until the balance was within a reasonable poise and I could fine adjust it with the screw head cutter. This was a wise decision, because I ended up placing 5 washers under the screw heads, that's a lot of weight, see Photo's 9, 10, and 11 for details of this procedure. Always be aware that these screws are small and only need a slight tension to keep them in place. Once I had the balance somewhere near being poised, I finished the fine adjustment with the screw head cutter, see Photo 12.
With the poising finished, next I install the hairspring and collet. This movement has a fixed stud and I always do an approximate position of the location of the stud with relation to the balance wheel before installation. You do this by installing the balance and positioning the pallet arm midway between the banking pins, then holding the balance in place, note the location of the fixed mounting for the stud in relation to the balance wheel. Remove the balance, and install the hairspring lining the stud up with the spot you located on the balance rim, see Photo 13.
With the work completed, the balance wheel was installed, the hairspring secured in the balance cock, and the movement fully wound (Photo 14). The real test of course is the timer readout, and after a slight rate adjustment, the rate in all positions was within 1 second. The amplitude was a healthy 270+ degrees, as compared to the 90 degrees I had following the servicing. The dial and hands were installed, the movement cased up, and the watch monitored for a week to ensure all was well. What started out as a normal typical servicing, ended up as a fairly major rework.
Normally the balance “gently” rotates and if it's out of poise, it rocks slowly back and forth towards the heavy side. Well, this one was extremely out of poise and it slammed down towards the heavy side as soon as I placed in on the tool. There was no way that removal of material from a screw was going to even come close to achieving the results I needed. So I decided that the only solution was the addition of copper washers under the screws, until the balance was within a reasonable poise and I could fine adjust it with the screw head cutter. This was a wise decision, because I ended up placing 5 washers under the screw heads, that's a lot of weight, see Photo's 9, 10, and 11 for details of this procedure. Always be aware that these screws are small and only need a slight tension to keep them in place. Once I had the balance somewhere near being poised, I finished the fine adjustment with the screw head cutter, see Photo 12.
With the poising finished, next I install the hairspring and collet. This movement has a fixed stud and I always do an approximate position of the location of the stud with relation to the balance wheel before installation. You do this by installing the balance and positioning the pallet arm midway between the banking pins, then holding the balance in place, note the location of the fixed mounting for the stud in relation to the balance wheel. Remove the balance, and install the hairspring lining the stud up with the spot you located on the balance rim, see Photo 13.
With the work completed, the balance wheel was installed, the hairspring secured in the balance cock, and the movement fully wound (Photo 14). The real test of course is the timer readout, and after a slight rate adjustment, the rate in all positions was within 1 second. The amplitude was a healthy 270+ degrees, as compared to the 90 degrees I had following the servicing. The dial and hands were installed, the movement cased up, and the watch monitored for a week to ensure all was well. What started out as a normal typical servicing, ended up as a fairly major rework.
