Tid-Bit 19 - Restoring Clock Pivots
Published in the March 2013 NAWCC Bulletin, starting on page 187.
My goals in restoring clock and watch mechanisms are:
1. Restore the mechanism to as close to original condition as possible,
2. Reduce friction in the gear trains, and
3. Minimize the potential for additional wear and tear.
This article focuses on the work I do in restoring the clock pivots. Specifically I cover the use of stones - to remove imperfections in the pivot - and burnishers - to produce an extremely smooth and hard finish.
Which reminds me of a question that I often hear: Do I use the same techniques on all of the clocks I work on? Typically, this is a question asked by someone who works mostly on American spring-driven mechanisms, like those found in kitchen clocks. To which I can honestly say yes, I use the same techniques. Granted, I mostly work on Vienna Regulators, but I use the same techniques on all the mechanisms I restore.
A case in point – I have a British long-case clock from the late 1800’s. I do not believe the pivots were originally burnished, based on my observations when initially reviewing the mechanism – looking at the pivots under a 10 power microscope and focusing on areas that had not seen apparent wear. This particular mechanism strikes the quarters on a nest of 8 bells – the quarter-strike train was originally driven with a 32 pound weight.
I had the mechanism restored by a gentleman noted for his work on English mechanisms. When done the mechanism ran perfectly - with a 32 pound weight for the quarter-strike train.
I later went through the mechanism myself – after noting black deposits around several of the pivots. I found the pivots to be only marginally burnished. My restoration included stoning the pivot-surfaces (to remove grooves and to “flatten” the circumference of the pivot) and then burnishing each pivot. The quarter-strike train now operates with a 14 pound weight and has been running, as my shop clock, for the past 4 years.
Were the pivots originally (as in back in the 1800’s) properly burnished? I don’t think so. In point of fact, I have worked on perhaps 60 British long-case clocks. I have only found one maker whose pivots reflected effective burnishing.
Which raises a bit of a controversy – is it appropriate to burnish pivots that were not originally burnished – thus going against the first goal listed above? My answer is yes – the reduction in wear, with a focus on preserving the mechanism for future generations - is my justification. In terms of my shop clock – after 4 years I am not seeing black residue around the pivots, and it should be self-evident that a gear train that is being driven by a 14 pound weight is not going to see as much wear as if driven by a 32 pound weight.
Equipment
This Tid-Bit is meant to sum up and draw on several previous Tid-Bits covering tools that I use to restore pivots.
Tid-Bit 1 - “Got Stones”, published in the October 2009 Bulletin, starting on page 580. This Tid-Bit explains the type of stones I use for working pivots and how I prepare the stones for use.
Tid-Bit 5 – “Power Pegging”, published in the 6/2010 NAWCC Bulletin, page 314. While this Tid-Bit is not specifically on restoring pivots, it goes hand in hand with this subject since even a perfectly restored pivot will not perform well in a pivot hole that is not properly cleaned.
Tid-Bit 11 – “Making a Burnisher”, published in the October 2011 Bulletin, starting on page 538. The burnishers I use have 3 out of 4 edges rounded and are sized to be appropriate for the different sized pivots that I restore.
Tid-Bit 14 – “To See or Not To See”, Published in the June 2012 NAWCC Bulletin, starting on page 297. I find that the minimum magnification needed to do pivot restorations is 5 power (5X), provided the person doing the restoration is experienced enough to really know what they are doing. Otherwise 10X is more appropriate. And please understand that I am referring to magnification, not diopter – as discussed in Tid-Bit 14. The numbers one sees on reading glasses and Optivisors refer to their diopter – a diopter of 10 is only 3.5X.
Tid-Bit 16 – “Gear-Holding Techniques”, published in the October 2012 Bulletin starting on page 525. It is important to realize that the gear/arbor must be mounted in the lathe such that the pivot spins with little wobble when being restored.
Tid-Bit 17 – “6-Jaw ‘Bezel’ Chucks”,published in the December, 2012 NAWCC Bulletin, starting on page 637. These chucks make it possible to hold some gears that are not amenable to other techniques.
Pivot Files – as the youth of today say – “Not so much”. I only use pivot files when the damage they do to the pivot (because of their very coarse nature) is less than the damage being repaired (due to wear and tear on the pivot). While I rarely reach for a pivot file, I do have a number of them to choose from.
Lubricant. There was a time I used rubbing alcohol for my stoning and burnishing work – it is very effective – and tends to keep things very clean. I also used it to lubricate my carbide gravers, where it was not so effective. When I switched to using automatic transmission fluid for my gravers I also switched for my pivot work – it works very well.
Light Source. You can’t do great work if you can’t see what you are doing.
With that introduction, let’s talk a bit about safety. As with any thing we do on a lathe, there are risks involved in restoring pivots - risks to ourselves, as well as risks to gears, pivots, and tools.
Safety
While it might seem unlikely that we could end up with something in our eye, anytime one is working around a lathe one needs to be wearing some form of eye protection. I use microscopes for all of my watchmaking lathe work - which is handy because it gets my eyes about a foot from the action. Every one that uses a lathe needs to give thought to how they can keep their eyes safe while using the lathe.
Having used a 5X loupe I can say that one must be very careful not to get ones nose involved in ones lathe work. This is doubly so with the 10X loupes I used at one time to do pivot work. One must be especially careful when using 3 or 6 jaw chucks, or faceplates to hold the workpiece. Even the gear itself can pose risks when holding the arbor in a collet – the teeth can snag anything that gets near them (a good reason not to wear long-sleeve shirts with the cuffs undone or loose long-sleeved sweatshirts. I am especially aware of the risk every time I work a pivot with a gear that has pins sticking out of the side – these pins love to drag a stone or burnisher – either breaking the stone, throwing the stone/burnisher, breaking off the pivot, or breaking off the pin. And, of course, if one is not careful, the pins can very quickly cut an errant finger that gets in their spinning way.
In addition to the pins in the sides of gears, it is a good idea to watch out for the short pieces of metal on winding drums that are meant to guide the second round of line being wound onto the drum so the line doesn’t end up on top of the first round of line. These little pins are often sharpened, making them more effective for deflecting line and cutting miss-placed fingers.
The force applied to stones or burnishers is likely the source of the greatest risk for breaking pivots. It just doesn’t take much force to break or bend a pivot as small as some we find in the nicer clocks. And, besides, the more force one applies the deeper the scratches will be when stoning and the more risk of galling the pivot when burnishing.
Why do I stone pivots – to get the pivots as perfect as possible before burnishing. Which raises another point. I am lucky enough to get to work on clocks that have often spent many many years “under the roof”, a quaint way of saying “in the attic”. My primary focus is Vienna Regulators, with a penchant for long duration pieces. While working on such clocks, some of which have had very little wear or maintenance since new. I have seen a number of clocks with pivots that were tapered when they were originally made. Do I make these “coned” pivots into perfect cylinders – thereby likely necessitating bushing the plates?
I think each and every restorer has to come to grips with their own philosophy for restoring mechanisms. I have previously discussed my concerns with bushing Viennese mechanisms – see “To Bush or Not to Bush - A Very Important Question Indeed!” in the December, 2006 Bulletin, starting on page 698. I only bush when it is clearly necessary. And, having worked on year-duration weight-driven mechanisms that operate on as little as 10 pounds with tapered pivots – I do not focus on making perfectly cylindrical pivots – I follow the original makers lead.
Likewise, when presented with scored pivots – my focus is to remove enough of the problem to give the arbor an effective wear surface. When stoning a pivot I will not attempt to remove every imperfection – I often talk about a 99% solution – or one in which I remove at least 99% of the grooves, but don’t go after the last one or two grooves - perhaps the last one percent - if it will require significant pivot diameter reduction.
Don’t get me wrong – if a pivot can be made absolutely perfect with a light stoning – I go for perfect. But, if I will be removing enough pivot material that I will likely have to bush the pivot hole – I give it some thought.
Given that I will sometimes leave small imperfections in my finished pivots I think it is also important to point out that when burnishing I pay extra attention to imperfections, using the rounded edges of my burnisher to round the edges of any circular grooves or other imperfections in the finished pivot. In this way I minimize the impact of these residual imperfections in the pivots operation. Of course, working under 10X magnification, the imperfections I am talking about are just not likely to be visible to the naked eye or even under a 2 power loupe.
Stoning a Pivot
My first rule of thumb when starting to restore a mechanism is to start with the largest pivots first. This gives me time to get my touch sensitized before going to the finer pivots.
My second rule of thumb would likely be that I use the finest abrasive that I can, based on my initial inspection of the pivot. My choices for initial work are pivot files, and the 3 different faces on the hard Arkansas slips that I use for pivot work (discussed earlier in the “Equipment” section.
Rarely do I use pivot files – the damage they do to the pivots is excessive due to their relatively coarse nature. Brings to mind a discussion I was having with a British restorer who was used to working on British long-case mechanisms. He was fairly sure that one should always start with a pivot file. Until he worked on his first Vienna Regulator mechanism and looked under his new 10 power microscope at the file next to the pivot. Only then did he realize how really coarse pivots files are.
Usually I will start with the number 2 face on my hard Arkansas slips (prepared with 220 grit sand paper) and see if it will remove imperfections in a timely manner. If the pivot is in decent shape I will start with the number 3 face (prepared with 600 grit sandpaper) – or I may go directly to burnishing if the pivot is in excellent condition.
The grits I refer to are the grades of sandpaper I used to prepare the faces. The equivalent “grit” of the faces of the hard Arkansas stones are much finer – the number 3 face gives a finish comparable to a very worn 2000 grit or finer Emory paper. But, unlike the Emory paper, the stone does not conform to the shape of the pivot – so the stone can show where the pivot is not perfectly flattened.
I find that the effort necessary to remove the coarser scratches left by pivot files or the number 1 face (prepared with 100 grit sandpaper) is much greater than just taking a bit more time with a finer face initially.
Over the years I have had a number of questions about the impact of pivot restoration work on the shoulders adjacent to the pivots. Some are concerned that burnishing the pivot will also result in significant metal removal from the shoulder. This concern was coupled with the belief that burnishing was a metal removal process. Reality is that burnishing is not meant to be a metal removal process – it is a metal working process – and has negligible impact on the dimensional stability of the shoulder. Stoning on the other hand can result in metal removal from the shoulder of the pivot. While this was not a concern in the videos I shot for this article (because they show the steps in making a pivot for a pulley, and the shoulder needed to be cleaned up anyway), it is important when working pivots on existing arbors.
The primary way I keep from impacting the shoulders is to focus the pressure from my fingers on stoning the pivot, and not letting the stone press against the shoulder. While the stone often rests against the shoulder, there is very little pressure in that direction.
The secondary way I keep from impacting the shoulder has to do with the way I prepare my stones, and how I use them. My stones have three different faces:
Coarse face (perhaps the equivalent of 600 grit sandpaper), marked with a single dot,
Medium face (perhaps the equivalent of 1200 grit sandpaper), marked with two dots,
Fine face (think of very worn 2000 grit sandpaper), marked with 3 dots.
There is one coarse face, and, on the opposite side of the stone there is a fine face. The other two sides (the sides adjacent to the coarse and fine faces) are medium faces. When I stone a pivot with a coarse face the adjacent face, or the face touching the shoulder, is a medium face – which is much less aggressive than the coarse face. Likewise, if I orient the stone correctly, the face touching the shoulder when stoning the pivot with the medium face is the fine face. And, when using the fine face on the pivot a medium face is touching the shoulder. But, in this last case I am using the lightest possible pressure on the stone and focus on not working the shoulder.
Then, when I burnish I consciously burnish both the shoulder and the pivot.
In my years of working on Vienna Regulators there have been several occasions when I knew I had individual gears in a mechanism that did not have enough end-shake. I have found that the techniques discussed in this tid-bit did not alleviate this problem – in fact I could not see any impact to the endshake when I worked the pivots. I had to either cut back the shoulder with a graver or create a small depression in the plate to give the necessary end-shake.
My first Tid-Bit discusses making two slips – one with ¼ inch faces, the other with 1/8 inch faces. These are pretty much the only two slips I use – a point I want to emphasize – you don’t need a wide array of slips to do pivot work – these two slips will cover most of the work you do on pretty much all the clocks you work on – unless you get into tower clocks – at which point you might need a ½ inch slip. The only exception is that I will sometimes get out a coarser hard Arkansas stone – when the pivot wants a bit more taken off, but not enough to merit having to clean up the mess a pivot file makes. Oh, and sometimes I will get out a 1/16 inch wide ruby slip that I have prepared by flattening the different faces on diamond plates of different grits. It is very handy on really small pivots.
Figures 1 and 2 show how I hold slips when stoning a pivot.
Read MoreMy goals in restoring clock and watch mechanisms are:
1. Restore the mechanism to as close to original condition as possible,
2. Reduce friction in the gear trains, and
3. Minimize the potential for additional wear and tear.
This article focuses on the work I do in restoring the clock pivots. Specifically I cover the use of stones - to remove imperfections in the pivot - and burnishers - to produce an extremely smooth and hard finish.
Which reminds me of a question that I often hear: Do I use the same techniques on all of the clocks I work on? Typically, this is a question asked by someone who works mostly on American spring-driven mechanisms, like those found in kitchen clocks. To which I can honestly say yes, I use the same techniques. Granted, I mostly work on Vienna Regulators, but I use the same techniques on all the mechanisms I restore.
A case in point – I have a British long-case clock from the late 1800’s. I do not believe the pivots were originally burnished, based on my observations when initially reviewing the mechanism – looking at the pivots under a 10 power microscope and focusing on areas that had not seen apparent wear. This particular mechanism strikes the quarters on a nest of 8 bells – the quarter-strike train was originally driven with a 32 pound weight.
I had the mechanism restored by a gentleman noted for his work on English mechanisms. When done the mechanism ran perfectly - with a 32 pound weight for the quarter-strike train.
I later went through the mechanism myself – after noting black deposits around several of the pivots. I found the pivots to be only marginally burnished. My restoration included stoning the pivot-surfaces (to remove grooves and to “flatten” the circumference of the pivot) and then burnishing each pivot. The quarter-strike train now operates with a 14 pound weight and has been running, as my shop clock, for the past 4 years.
Were the pivots originally (as in back in the 1800’s) properly burnished? I don’t think so. In point of fact, I have worked on perhaps 60 British long-case clocks. I have only found one maker whose pivots reflected effective burnishing.
Which raises a bit of a controversy – is it appropriate to burnish pivots that were not originally burnished – thus going against the first goal listed above? My answer is yes – the reduction in wear, with a focus on preserving the mechanism for future generations - is my justification. In terms of my shop clock – after 4 years I am not seeing black residue around the pivots, and it should be self-evident that a gear train that is being driven by a 14 pound weight is not going to see as much wear as if driven by a 32 pound weight.
Equipment
This Tid-Bit is meant to sum up and draw on several previous Tid-Bits covering tools that I use to restore pivots.
Tid-Bit 1 - “Got Stones”, published in the October 2009 Bulletin, starting on page 580. This Tid-Bit explains the type of stones I use for working pivots and how I prepare the stones for use.
Tid-Bit 5 – “Power Pegging”, published in the 6/2010 NAWCC Bulletin, page 314. While this Tid-Bit is not specifically on restoring pivots, it goes hand in hand with this subject since even a perfectly restored pivot will not perform well in a pivot hole that is not properly cleaned.
Tid-Bit 11 – “Making a Burnisher”, published in the October 2011 Bulletin, starting on page 538. The burnishers I use have 3 out of 4 edges rounded and are sized to be appropriate for the different sized pivots that I restore.
Tid-Bit 14 – “To See or Not To See”, Published in the June 2012 NAWCC Bulletin, starting on page 297. I find that the minimum magnification needed to do pivot restorations is 5 power (5X), provided the person doing the restoration is experienced enough to really know what they are doing. Otherwise 10X is more appropriate. And please understand that I am referring to magnification, not diopter – as discussed in Tid-Bit 14. The numbers one sees on reading glasses and Optivisors refer to their diopter – a diopter of 10 is only 3.5X.
Tid-Bit 16 – “Gear-Holding Techniques”, published in the October 2012 Bulletin starting on page 525. It is important to realize that the gear/arbor must be mounted in the lathe such that the pivot spins with little wobble when being restored.
Tid-Bit 17 – “6-Jaw ‘Bezel’ Chucks”,published in the December, 2012 NAWCC Bulletin, starting on page 637. These chucks make it possible to hold some gears that are not amenable to other techniques.
Pivot Files – as the youth of today say – “Not so much”. I only use pivot files when the damage they do to the pivot (because of their very coarse nature) is less than the damage being repaired (due to wear and tear on the pivot). While I rarely reach for a pivot file, I do have a number of them to choose from.
Lubricant. There was a time I used rubbing alcohol for my stoning and burnishing work – it is very effective – and tends to keep things very clean. I also used it to lubricate my carbide gravers, where it was not so effective. When I switched to using automatic transmission fluid for my gravers I also switched for my pivot work – it works very well.
Light Source. You can’t do great work if you can’t see what you are doing.
With that introduction, let’s talk a bit about safety. As with any thing we do on a lathe, there are risks involved in restoring pivots - risks to ourselves, as well as risks to gears, pivots, and tools.
Safety
While it might seem unlikely that we could end up with something in our eye, anytime one is working around a lathe one needs to be wearing some form of eye protection. I use microscopes for all of my watchmaking lathe work - which is handy because it gets my eyes about a foot from the action. Every one that uses a lathe needs to give thought to how they can keep their eyes safe while using the lathe.
Having used a 5X loupe I can say that one must be very careful not to get ones nose involved in ones lathe work. This is doubly so with the 10X loupes I used at one time to do pivot work. One must be especially careful when using 3 or 6 jaw chucks, or faceplates to hold the workpiece. Even the gear itself can pose risks when holding the arbor in a collet – the teeth can snag anything that gets near them (a good reason not to wear long-sleeve shirts with the cuffs undone or loose long-sleeved sweatshirts. I am especially aware of the risk every time I work a pivot with a gear that has pins sticking out of the side – these pins love to drag a stone or burnisher – either breaking the stone, throwing the stone/burnisher, breaking off the pivot, or breaking off the pin. And, of course, if one is not careful, the pins can very quickly cut an errant finger that gets in their spinning way.
In addition to the pins in the sides of gears, it is a good idea to watch out for the short pieces of metal on winding drums that are meant to guide the second round of line being wound onto the drum so the line doesn’t end up on top of the first round of line. These little pins are often sharpened, making them more effective for deflecting line and cutting miss-placed fingers.
The force applied to stones or burnishers is likely the source of the greatest risk for breaking pivots. It just doesn’t take much force to break or bend a pivot as small as some we find in the nicer clocks. And, besides, the more force one applies the deeper the scratches will be when stoning and the more risk of galling the pivot when burnishing.
Why do I stone pivots – to get the pivots as perfect as possible before burnishing. Which raises another point. I am lucky enough to get to work on clocks that have often spent many many years “under the roof”, a quaint way of saying “in the attic”. My primary focus is Vienna Regulators, with a penchant for long duration pieces. While working on such clocks, some of which have had very little wear or maintenance since new. I have seen a number of clocks with pivots that were tapered when they were originally made. Do I make these “coned” pivots into perfect cylinders – thereby likely necessitating bushing the plates?
I think each and every restorer has to come to grips with their own philosophy for restoring mechanisms. I have previously discussed my concerns with bushing Viennese mechanisms – see “To Bush or Not to Bush - A Very Important Question Indeed!” in the December, 2006 Bulletin, starting on page 698. I only bush when it is clearly necessary. And, having worked on year-duration weight-driven mechanisms that operate on as little as 10 pounds with tapered pivots – I do not focus on making perfectly cylindrical pivots – I follow the original makers lead.
Likewise, when presented with scored pivots – my focus is to remove enough of the problem to give the arbor an effective wear surface. When stoning a pivot I will not attempt to remove every imperfection – I often talk about a 99% solution – or one in which I remove at least 99% of the grooves, but don’t go after the last one or two grooves - perhaps the last one percent - if it will require significant pivot diameter reduction.
Don’t get me wrong – if a pivot can be made absolutely perfect with a light stoning – I go for perfect. But, if I will be removing enough pivot material that I will likely have to bush the pivot hole – I give it some thought.
Given that I will sometimes leave small imperfections in my finished pivots I think it is also important to point out that when burnishing I pay extra attention to imperfections, using the rounded edges of my burnisher to round the edges of any circular grooves or other imperfections in the finished pivot. In this way I minimize the impact of these residual imperfections in the pivots operation. Of course, working under 10X magnification, the imperfections I am talking about are just not likely to be visible to the naked eye or even under a 2 power loupe.
Stoning a Pivot
My first rule of thumb when starting to restore a mechanism is to start with the largest pivots first. This gives me time to get my touch sensitized before going to the finer pivots.
My second rule of thumb would likely be that I use the finest abrasive that I can, based on my initial inspection of the pivot. My choices for initial work are pivot files, and the 3 different faces on the hard Arkansas slips that I use for pivot work (discussed earlier in the “Equipment” section.
Rarely do I use pivot files – the damage they do to the pivots is excessive due to their relatively coarse nature. Brings to mind a discussion I was having with a British restorer who was used to working on British long-case mechanisms. He was fairly sure that one should always start with a pivot file. Until he worked on his first Vienna Regulator mechanism and looked under his new 10 power microscope at the file next to the pivot. Only then did he realize how really coarse pivots files are.
Usually I will start with the number 2 face on my hard Arkansas slips (prepared with 220 grit sand paper) and see if it will remove imperfections in a timely manner. If the pivot is in decent shape I will start with the number 3 face (prepared with 600 grit sandpaper) – or I may go directly to burnishing if the pivot is in excellent condition.
The grits I refer to are the grades of sandpaper I used to prepare the faces. The equivalent “grit” of the faces of the hard Arkansas stones are much finer – the number 3 face gives a finish comparable to a very worn 2000 grit or finer Emory paper. But, unlike the Emory paper, the stone does not conform to the shape of the pivot – so the stone can show where the pivot is not perfectly flattened.
I find that the effort necessary to remove the coarser scratches left by pivot files or the number 1 face (prepared with 100 grit sandpaper) is much greater than just taking a bit more time with a finer face initially.
Over the years I have had a number of questions about the impact of pivot restoration work on the shoulders adjacent to the pivots. Some are concerned that burnishing the pivot will also result in significant metal removal from the shoulder. This concern was coupled with the belief that burnishing was a metal removal process. Reality is that burnishing is not meant to be a metal removal process – it is a metal working process – and has negligible impact on the dimensional stability of the shoulder. Stoning on the other hand can result in metal removal from the shoulder of the pivot. While this was not a concern in the videos I shot for this article (because they show the steps in making a pivot for a pulley, and the shoulder needed to be cleaned up anyway), it is important when working pivots on existing arbors.
The primary way I keep from impacting the shoulders is to focus the pressure from my fingers on stoning the pivot, and not letting the stone press against the shoulder. While the stone often rests against the shoulder, there is very little pressure in that direction.
The secondary way I keep from impacting the shoulder has to do with the way I prepare my stones, and how I use them. My stones have three different faces:
Coarse face (perhaps the equivalent of 600 grit sandpaper), marked with a single dot,
Medium face (perhaps the equivalent of 1200 grit sandpaper), marked with two dots,
Fine face (think of very worn 2000 grit sandpaper), marked with 3 dots.
There is one coarse face, and, on the opposite side of the stone there is a fine face. The other two sides (the sides adjacent to the coarse and fine faces) are medium faces. When I stone a pivot with a coarse face the adjacent face, or the face touching the shoulder, is a medium face – which is much less aggressive than the coarse face. Likewise, if I orient the stone correctly, the face touching the shoulder when stoning the pivot with the medium face is the fine face. And, when using the fine face on the pivot a medium face is touching the shoulder. But, in this last case I am using the lightest possible pressure on the stone and focus on not working the shoulder.
Then, when I burnish I consciously burnish both the shoulder and the pivot.
In my years of working on Vienna Regulators there have been several occasions when I knew I had individual gears in a mechanism that did not have enough end-shake. I have found that the techniques discussed in this tid-bit did not alleviate this problem – in fact I could not see any impact to the endshake when I worked the pivots. I had to either cut back the shoulder with a graver or create a small depression in the plate to give the necessary end-shake.
My first Tid-Bit discusses making two slips – one with ¼ inch faces, the other with 1/8 inch faces. These are pretty much the only two slips I use – a point I want to emphasize – you don’t need a wide array of slips to do pivot work – these two slips will cover most of the work you do on pretty much all the clocks you work on – unless you get into tower clocks – at which point you might need a ½ inch slip. The only exception is that I will sometimes get out a coarser hard Arkansas stone – when the pivot wants a bit more taken off, but not enough to merit having to clean up the mess a pivot file makes. Oh, and sometimes I will get out a 1/16 inch wide ruby slip that I have prepared by flattening the different faces on diamond plates of different grits. It is very handy on really small pivots.
Figures 1 and 2 show how I hold slips when stoning a pivot.
