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Hole shape when using a Seitz jewel-setting-tool reamer?


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Hello All;

When I had to ream quite a few holes (from 1.0mm to 1.09mm and some from 1.09mm to 1.19mm) for my jeweled pivot gauge (https://www.watchrepairtalk.com/topic/26650-diy-seitz-jeweled-pivot-gauge/#comment-221428 ) I noticed that the copper-plate moved radial in sync with the rotation of the reamer.

These jewel-set reamers do have only one cutting edge when rotating in one direction. The other side of the reamer, opposite to the rotational direction cutting edge, leans against the side of the hole.

Hand-holding the copper-plate and hand-driving the reamer, I could obviously prevent the plate from rotation, but I couldn't stop the slight radial movement of the plate. In the end, the top cylindrical part of the reamer goes through the reamed hole, assuming that the reamer has created a nice cylindrical hole.

But noticing this radial movement, I started wonder whether the hole shape ends up being that nicely cylindrical ? Or perhaps slightly oval, triangular or what?

Anybody any thoughts?

 

Edited by Endeavor
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  • Endeavor changed the title to Hole shape when using a Seitz jewel-setting-tool reamer?

I've never used my reamers, but I saw a video where the hole was gradually reamed out selecting a larger and larger reamer. Very little material was removed with each reamer. It could also be that you need to use a bit of oil to smooth the process. Well, not even sure I understand the problem, but thought my reply at least wouldn't be harmful!?

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1 hour ago, VWatchie said:

I've never used my reamers, but I saw a video where the hole was gradually reamed out selecting a larger and larger reamer. Very little material was removed with each reamer. It could also be that you need to use a bit of oil to smooth the process. Well, not even sure I understand the problem, but thought my reply at least wouldn't be harmful!?

Sounds like the reamers are wandering off center slightly, they're not balanced like a drill bit.  🤔 , seems like an odd design shape. I cant say i understand the geometry of how they cut , i just suppose they should work .

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If a hole is out of round (ovalled), then using a Seitz or Horia reamer will not bring it back to round, even if half the hole is a good shape, as the reamer will always wander, therefore the hole won't be in the correct position and in the case of a barrel bridge or mainplate, it only needs to be out by 0.01 mm and the barrel will rub on the bridge and mainplate, so you can see how critical it is to getting the hole central. I have found the only way that really works every time is using a centring microscope on the lathe. I use a Skoal centring microscope from Korea (Costs about £300). This is able to find the hole centre and bore it out using a micro carbide boring bar. The hole is now totally circular, now you can use the Seitz or Horia reamers to open up the hole to 0.01 smaller than the bush or jewel. How the centring microscope works is by finding the exact trajectory of the outside of the hole. See the video in this link. It shows a Rolex oscillating weight that needs bushing, but the principle is the same: https://www.instagram.com/p/CszBfc7LPL4/

Clocks don't have this problem, as the tolerances aren't so fine as a watch movement

Edited by Jon
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7 hours ago, Jon said:

If a hole is out of round (ovalled), then using a Seitz or Horia reamer will not bring it back to round, even if half the hole is a good shape, as the reamer will always wander,

The holes were made with a normal HSS drill and I've no idea how cylindrical the holes were before reaming? But at least a HSS-drill has two opposite cutting edges, whereas a Seitz reamer hasn't. Well, it has, but only one side cuts.

In my observation above, it may well be that the holes were oval to start with and that is what caused the radial movement of the plate?

But, if we assume that the to be reamed hole is perfectly cylindrical, what concerns me is that those Seitz reamers do have only one side which cuts, namely the one in the direction of the rotation. The reamer gets "supported" against the borehole by the other side of the reamer (the non-working cutting edge). Since it cuts with only one cutting edge, I still try to get my head around it whether the reamer stays centered or cuts an asymmetrical hole. And if it cuts an asymmetrical hole, does that than gets corrected by the very end of the reamer where the reamers cutting edges go over into the cylindrical part of the reamer? 🤔

 

 

Edited by Endeavor
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4 hours ago, Endeavor said:

And if it cuts an asymmetrical hole, does that than gets corrected by the very end of the reamer where the reamers cutting edges go over into the cylindrical part of the reamer? 🤔

I believe I heard someone say that the cylindrical part of the reamer should always go into the hole as well. I can't remember the rationale for it though, or if any was given. I understand that you are trying to understand the principles but as far as your jewelled pivot gauge is concerned it shouldn't really matter what the holes look like or where they are on the plate as long as the jewel sits securely and reasonably flat.

10 hours ago, Jon said:

If a hole is out of round (ovalled), then using a Seitz or Horia reamer will not bring it back to round, even if half the hole is a good shape, as the reamer will always wander, therefore the hole won't be in the correct position

So what you're saying is that we can't repair a damaged jewel hole by just using a Seitz jewelling tool, right? All we can do is open up a non-damaged hole when we don't have the correct size jewel 🤔 That's valuable information to avoid going from worse to worse.

Edited by VWatchie
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32 minutes ago, VWatchie said:

I believe I heard someone say that the cylindrical part of the reamer should always go into the hole as well.

I don’t have any reamers yet to verify so this is something of a guess. I suspect the the reamers are tapered to give a gradual cut and the top portion that is cyndrical finishes off to give a taper free clean hole.  Which could still be out of round if the taper section has created a wide enough oval. There is a jewelling faceplate that can clamp this might minimise the effect of the wander

32 minutes ago, VWatchie said:

So what you're saying is that we can't repair a damaged jewel hole by just using a Seitz jewelling tool, right? All we can do is open up a non-damaged hole when we don't have the correct size jewel 🤔 That's valuable information to avoid going from worse to worse.

Sounds feasible unless the part being reamed can be held completely rigid and the reamer and its spindle had no slop whatsoever.  The tolerances on the tool and accessories would need to super minimal, in reality i bet far from the accuracy of a lathe. So like jon said the reamer is going to follow the shape of the hole, i would say through the tolerances of the tooling. Time to buy a lathe watchie, come on you know you want one 😆

Edited by Neverenoughwatches
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1 hour ago, Neverenoughwatches said:

Time to buy a lathe watchie, come on you know you want one 😆

Hmm... One should really be getting one while they're still affordable. My impression is that all other quality tools have increased in price significantly in recent years while lathes still feel somewhat reasonably priced. Anyway, I still have a long way to go to get the most out of my current tool collection.

1 hour ago, Neverenoughwatches said:

I suspect the the reamers are tapered to give a gradual cut and the top portion that is cyndrical finishes off to give a taper free clean hole.

Yes, they're tapered, and I would suspect you're 100 per cent right.

1 hour ago, Neverenoughwatches said:

There is a jewelling faceplate that can clamp

Is that an accessory for the Seitz jewelling tool?

EDIT: Found the "face plate" in the Seitz jewelling manual, which is used to hold small parts, such as the pallet cock, when reaming.

 

 

Edited by VWatchie
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I tend to agree with Jon that the only real way to know your hole is on location and round is to use a faceplate in the lathe. But, many, many watchmakers have reamed holes for jewels with their Seitz or Chatons SA or Favorite or Horia etc. tools successfully as well.

It's one thing if you're opening up a hole 0.10mm, another if you're opening say a hole for a barrel arbor pivot a full mm to fit a bushing. As has been observed, the reamers don't necessarily turn concentrically with the spindle of the tool; this can lead to the reamer cutting oversize if the part being reamed is held rigidly. If the part is allowed to float, as Endeavor did, the reamer will probably follow the original hole and cut to size. The reamer will make a round hole, and should be run right up to the cylindrical part (and some oil used). But if working on an oval hole, the location will almost certainly be an average of the original hole center and the new center of the oval.  This will be an improvement of the prior state, but not ideal.

 

To add to all the confusion, there are different types of reamers used by different manufacturers. Favorite uses 5 sided tapered reamers, look like short little cutting broaches, that end at a cylinder of the correct size. Seitz and Chatons SA use single lip reamers. Horia offers both, calling the 5 sided ones cutting broaches and the single lip ones smoothing broaches. I've used them all, and found that the single lip ones from Chatons SA cut the best, and run quite true in the spindle. I still let the part float so the reamer follows the hole as well as it can.

 

But most of the time, I do the work in the lathe. I have a rather large (for watchmakers) lathe set up permanently for faceplate work, and use optical centering like Jon mentions. It really takes just a moment to center up and open up a hole! And I bore it right to size, but I have plug gages that make checking very simple.

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Two facts were confused here, I am afraid:
- a hole not staying/getting round
- a hole wandering out of center, though round.

It will get/ stay round, not oval, if you ream fully to the end (and was smaller before reaming).

But it can wander from its true center
- if it was oval, sidewards worn before
- if you press more to one direction while reaming. You will produce bigger  shavings in that direction and move the center then.

One cutting edge is is used for canon drills, too, to produce long, accurate holes.

The item moving with the reamer is normal, due to tolerances of the tool combination. It will do no harm if you let it move. Clamping the item would throw the produced hole out of size.

Frank

PS written before 2 new posts above 😉

Edited by praezis
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For the jeweled pivot gauge the shape of the holes aren't that important, but the radial movement of the plate observation was to me.

My main reason for placing this question is that I'm investigating if it would be possible, in a safe way that is, to enlarge a worn-out arbor hole in the barrel / train bridge of a 1975 Omega 861 to insert a jewel / bushing?

As some of you know, that hole has two different diameter and the arbor runs in (and wears out) the bottom (lager) diameter, leaving the top (smaller) part of the hole untouched. Therefor the smaller top diameter should still be in a factory-made perfect cylindrical shape and in center.

However, in order to insert a jewel (or a bushing) the complete hole, obviously starting from the smaller factory-made cylindrical hole, has to be enlarged quite a bit.

If these Seitz reamers (the only ones I have) are delivering an "iffy" hole shape, than the DIY jewel / bushing-idea with those Seitz reamer is for sure out of the window. As @nickelsilver says, opening a hole from 1mm to 1.09mm is one thing, opening up a hole from say 1mm to 3mm is another.

Any thoughts on that one?

Edited by Endeavor
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I know a fellow who does a lot of Omega work, and does top notch work, and he regularly opens the barrel hole in the bridge for a bushing, just using the Seitz reamers. He says he's had no problems with the hole wandering off center. I think if you're very careful and let the part move with the reamer it should be ok... but I personally would still do it in the lathe.

 

I'm not sure where he gets his bushings or what sizes are available (I make all my bushings), but if you open it to the smallest OD possible for a bushing, and find that the barrel now sits tilted, the hole can still be rectified in the lathe and a slightly larger bushing fitted.

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18 minutes ago, nickelsilver said:

but I personally would still do it in the lathe.

And so would I, but sadly that's not an option. If it can be done with those Seitz reamers, that would for me be infinitive easier and cheaper.

I think in one of your previous post you hinted to that person. I found and contacted him, but never got a reply...... So far, the Omega movement is in parts, awaiting for a save and solid solution. One of those "time will bring the answer(s)" and don't hurry watches 😉

Edited by Endeavor
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On 6/5/2023 at 2:13 PM, VWatchie said:

I saw a video where the hole was gradually reamed out selecting a larger and larger reamer

That's what I was going to recommend start small and gradually go up in size do not try to go to the finished hole. Then despite somebody insisting that their precision we made and that you can go all the way to smooth particle be absolute perfect oftentimes I find the whole is now too big. So I finally get almost to the end and I try the jewel but be careful not the forced the jewel they will break. The whole really does have to be the right size to avoid complications.

 

 

 

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18 hours ago, nickelsilver said:

I have a rather large (for watchmakers) lathe set up permanently for faceplate work, and use optical centering like Jon mentions.

I have seen @nickelsilver mention using an optical centering microscope in several posts.

I did a web search and can only find optical centering microscopes for larger lathes. What does a watchmaker's optical centering microscope look like?

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On 6/6/2023 at 12:16 PM, nickelsilver said:

this can lead to the reamer cutting oversize if the part being reamed is held rigidly. If the part is allowed to float, as Endeavor did, the reamer will probably follow the original hole and cut to size.

On 6/6/2023 at 1:29 PM, nickelsilver said:

I think if you're very careful and let the part move with the reamer it should be ok...

Please bear with me. I'm sure the answer to the following question is obvious to most people with a somewhat decent mechanical understanding, but if I don't ask I won't get a reply... 😳

What exactly does "let the part move with the reamer" and "If the part is allowed to float" mean? In my mind, if the plate or bridge isn't being held rigidly it will just "spin around" and no cutting will take place. I still haven't had any use for my reamers as I'm doing so little work, but the day will (hopefully) come when I will need them.

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7 hours ago, HectorLooi said:

I have seen @nickelsilver mention using an optical centering microscope in several posts.

I did a web search and can only find optical centering microscopes for larger lathes. What does a watchmaker's optical centering microscope look like?

Here's some pics of my scope. It's a simple setup with a B8 shank that fits the tailstock. Ideally it would be adjustable in one axis, so the cross hair can be brought over to the hole edge, but as long as the hole fits the field of view it works.

20230607_133557.jpg

20230607_133702.jpg

I rarely use that one though. When I do faceplate work (which is frequently) I have a dedicated Schaublin 102 short bed lathe that takes a removeable spindle in the headstock. The spindle also fits the table holder of a Hauser M1 jig boring machine (gotta love the Swiss!); so, part goes in faceplate on the Hauser, which has a scope that interchanges with the live spindle in its head, scope is used to center the part, then the whole faceplate spindle goes to the Schaublin. Sounds like a lot of steps, but it's really really fast and really really accurate. It's much more convenient tapping the part in center with the spindle vertical.

 

 

IMG_0034.JPG

IMG_0036.JPG

IMG_0037.JPG

IMG_0038.JPG

 

Then, if needed I have another scope that fits the tailstock of the Schaublin 102 (it can be fitted with a taper to fit their 70 too). It's adjustable and has built in illumination, very nice scope. But it too hasn't been used in years, just too easy to use the other setup.

20230607_133827.jpg

But bottom line, any scope with at least one cross hair can be used, and it doesn't have to fit the tailstock, you could set it on a wooden block on the lathe bed. All that matters is that you can see the hole, and reference it to some line in the scope's optics. A magnification of 35x will allow you to center up within microns very easily.

 

8 minutes ago, VWatchie said:

Please bear with me. I'm sure the answer to the following question is obvious to most people with a somewhat decent mechanical understanding, but if I don't ask I won't get a reply... 😳

What exactly does "let the part move with the reamer" and "If the part is allowed to float" mean? In my mind, if the plate or bridge isn't being held rigidly it will just "spin around" and no cutting will take place. I still haven't had any use for my reamers as I'm doing so little work, but the day will (hopefully) come when I will need them.

You will need to hold the part down on the table of the jeweling tool and prevent it from turning, but as you turn the reamer, if it wants to move the part radially you should let it move- just not spin, or lift up from the table.

Edited by nickelsilver
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48 minutes ago, VWatchie said:

the following question is obvious to most people with a somewhat decent mechanical understanding

No, it's not, hence my question.

 

48 minutes ago, VWatchie said:

In my mind, if the plate or bridge isn't being held rigidly it will just "spin around" and no cutting will take place

If you read my initial question, it is stated that I hand-held the plate to prevent rotation of the plate, but I couldn't prevent the small radial movement of the plate while turning the reamer.

It took me a while and having read all the answers, I think (I "think"!) that I understand now what's going on.

The reamer is ridged and stays in the center-line of the ridged Seitz jeweling tool (ignoring the play of the shaft in the jeweling tool). Since the reamer cuts only in the direction of ration, it cuts an asymmetrical hole while the reamer itself stays in the central-line (symmetrical). You can't have both, so something has to "give", in our case the plate. This asymmetrical cutting action continues until the very end (the top) of the reamer, where the cutting edge goes over into the cylindrical part of the reamer. If you have a close look at one of the Seitz reamers, the cutting edge "tapers off" toward the cylindrical part, therefor the cutting action become less and less asymmetrical towards the end. This, as I understand it now from @praezis, where he mention other examples, should give a cylindrical hole. That's also the reason why you should continue to ream until the reamer is fully down, including the cylindrical part of the reamer.

This in my current understanding of how it works. Please correct me if I'm wrong 😉

 

 

Edited by Endeavor
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I tried this. I cannot see why it would lead to a too big hole. You just have to be very careful with the last reamer. If the reamer gets stuck and you have to wiggle it off you end up with a bigger hole. The only real problem is centering the plate. I've centered the plate to stump (through train bridge jewel)  in Horia and then transferred the stump to Seitz. I guess it works if the stump fits tightly in both tool bases. Next time I'll try doing everything in the Seitz tool.

image.thumb.png.dad8a80cd02afcdca278ac176117ec04.png

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2 hours ago, VWatchie said:

Please bear with me. I'm sure the answer to the following question is obvious to most people with a somewhat decent mechanical understanding, but if I don't ask I won't get a reply... 😳

What exactly does "let the part move with the reamer" and "If the part is allowed to float" mean? In my mind, if the plate or bridge isn't being held rigidly it will just "spin around" and no cutting will take place. I still haven't had any use for my reamers as I'm doing so little work, but the day will (hopefully) come when I will need them.

Eyup watchie tbh i was under the assumption that the part would need to be held rigid but also in conjunction with no side tolerance of the tooling. So something like a slow moving version of a lathe. But thinking about what frank and Nicklesilver have said it kinda makes sense not to fight against where the reamer wants to ream,( well kinda makes sense and will probably make more sense when i actually have a go myself ). As regards to the floating, i think the part still needs to be held ( by hand if large enough ) but only enough to allow the cutting to take place so not clamped in position. Floating as on water but still able to bob around and have some movement . This sounds like it only applies to a hole that has ovalated (as opposed to holes in respect to ovulated, which is  completely different to anything watch related ) otherwise that would make the Seitz clamping accessory pointless.

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On 6/6/2023 at 4:29 AM, nickelsilver said:

He says he's had no problems with the hole wandering off center. I think if you're very careful and let the part move with the reamer it should be ok... but I personally would still do it in the lathe.

This is one of those interesting things in life not just watch repair. Everyone has different experiences everyone hopefully remembers their bad experiences and tries not to do that again. But everyone still can have different methods of doing the same thing their method works fine for them and your method doesn't and they won't even try it.

Then didn't see that anyone posted the users manual for the tool yet. So I've attached that maybe that will offer is some insight in the using the tool

Seitz book.pdf

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91902462_Screenshot2023-06-07at18_45_08.png.b74eca1fe6879c9dcc8c3d7a0500db4e.png

Thanks for that John, now the have the Seitz side of the story, which corresponds with what already has been said.

I was trying to get my head around as to the why the reamer creates the movement, does my theory above makes any sense?

 

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1 hour ago, Endeavor said:

does my theory above makes any sense?

I think: yes. It may wobble by the thickness of the shavings.

Never spent thoughts about it, but wondered how a Swiss tool can be so out of round…

Frank

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1 hour ago, praezis said:

Never spent thoughts about it, but wondered how a Swiss tool can be so out of round…

That's why I try to get to the source. Once the basic principle is understood, the rest is a logical consequence.

If the theory is correct, than Indeed, the amount of wobble will be the thickness of the shaving = amount of asymmetric.

The logical consequence would be that the to be reamed hole has to have the freedom to float by the amount of asymmetrically and can not be clamped fixed in relation to the reamer.

It's a bit difficult to explain in a non-native language, but I do hope that you get the drift of what I'm trying to explain 😉

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