Micrometer

[Nucejoe]

Hi ya all. 

 Shopping for a Micrometer I came accross this,  a PWD brand, made in Poland, is anybody here familiar with this brand? are they any good?  I don't think I need top quality ones really. 

https://esam.ir/zoomItemN.aspx?img=e17qs968_171417-22143243!1.jpg&slide=1&IDi=22135287

 Appreciate your help. 

[Tony13]

I have something similar.

Different brand, have used it for my motorbikes while racing for years and now for watch work.

There from the communist era, since they could build great fighter planes with tools like that it would also suit us

 

[HectorLooi]

Why don't you get a digital one. Mitutoyo is a good brand. Even some digital ones from China are pretty good. 

I'm also thinking of upgrading to a digital version. It's getting a little tiring on the eyes, squinting and counting the divisions on the micrometer scale.

Maybe I should get my eyes checked for astigmatism. Wait a minute.... I remove my glasses when I'm working.... so they are not being corrected for astigmatism.... No wonder the lines seem to be all over the place!

[LittleWatchShop]

7 hours ago, Nucejoe said:

Hi ya all. 

 Shopping for a Micrometer I came accross this,  a PWD brand, made in Poland, is anybody here familiar with this brand? are they any good?  I don't think I need top quality ones really. 

https://esam.ir/zoomItemN.aspx?img=e17qs968_171417-22143243!1.jpg&slide=1&IDi=22135287

 Appreciate your help. 

I think it would do just fine.  Similar to this one which I use all the time even though I have a JKA and a digital Mutitoyo.

[Michael1962]

As long as you zero it in properly without applying too much tension to the knurled knob, it should be fine. I remember that the analog Mitutoyos I used in my apprenticeship had a really good temperature range that they were accurate in. Maybe some of the cheaper ones don’t have that? Though these days it hardly matters as I am not trying to measure something when the temperature is zero. 

[nickelsilver]

Pretty much all mics (all that I know of) are calibrated at 20 degrees C. In the practical world, if the mic and part are the same temperature it doesn't really matter if you are a few or more degrees off, it's only when measuring really small numbers like microns or ten thousandths of an inch that it can be a concern, especially if the part is a different metal than the mic.

 

I like to check my mics to gages, and since 99% of what I measure is small round stuff I use small plug gages. If the mic is decent quality, you can usually just go with cleaning the face of the spindle and anvil and check that it zeros correctly. There is always an adjustment, but it usually requires a little pin spanner wrench to do. I can see in Joe's pic the wrench is there, so that's good.

 

I know a fellow who bought a set of Polish mics some years back, and ran them through the calibration lab at his work, and they checked out great.

[Nucejoe]

 I have an assortment of staffs,  perhaps two thousand or more , just mixed with no way to ID most of them other than to measure dimensions, so need an accurate Micrometer to measure pivot diameter with. 

You gentleman are generous so to prove that I am not really a bad guy either, I best start sending members some staffs. 

Just to be on the safe side, I did put in a bid for a Mityotyo.

Regards

 

[nickelsilver]

I really strongly recommend not using a micrometer to measure balance staff pivots. By the time you can feel that the spindle and anvil are in contact, you have marked the pivot with a couple of tiny flat spots. I know some people say the spring loaded dial type tools like the JKA Feintaster won't mark pivots, but I don't trust that. For stuff under about 0.15mm you really need a jewel gage. I know they are hard to find and expensive, but those little flats will really mess up your timing.

[Nucejoe]

Hi Nickelsilver, many thanks for your advice. 

I got Jdrichard to blame for this, he said about using micrometer to measure staff, too bad he will never need any of my staffs. 

Regards

[Nucejoe]

On 1/9/2019 at 6:19 AM, SockMonkey72 said:

Hello Looking for a Seitz Pivot Gauge

 

Is this what you recommend.  

Have never come accross a new one for sale,   just used ones.

[jdm]

A good old Soviet mic is quite common in my part of the planet. Here is mine, I use it almost every day. 

[nickelsilver]

24 minutes ago, Nucejoe said:

Is this what you recommend.  

Have never come accross a new one for sale,   just used ones.

Yes. They can also be found in 0.005mm increments, which is nice. Also, the Seitz "balance pivot straightening tool", which isn't great for straightening pivots, has jewels from 0.07mm to 0.15mm in 0.0025mm increments- that's awesome for checking small balance pivots. Not cheap, but great.

[LittleWatchShop]

51 minutes ago, Nucejoe said:

Is this what you recommend.  

Have never come accross a new one for sale,   just used ones.

I have one of these.  Dad kept it in near mint condition--jewel 41 has a chip but is still functional.

[VWatchie]

On 2/15/2022 at 1:48 PM, nickelsilver said:

I know some people say the spring loaded dial type tools like the JKA Feintaster won't mark pivots, but I don't trust that.

I measured pivots down to 0.07mm in my JKA and looked long and hard at them in my stereo microscope at 40X magnification but couldn't see any deformations, dents, or damage. That doesn't mean there weren't any, but at least none that I could detect.

The Seitz jewel gauge, on the other hand, is perfectly safe and also makes it easier to select the right jewel holes as you can just try the pivot in the different jewel holes in the gauge until you find the perfect side shake. The only real disadvantage with the Seitz jewel gauge is the price. I believe I paid around $250 for mine and felt it to be insanely expensive at the time. Even so, the asking prices these days are twice that and more and they seem to become rarer by the day.

The JKA is a lot less expensive than the Seitz jewel gauge (nice!). However, I was under the impression that once you had measured the pivot in the JKA you could just add 0.02mm to the jewel hole, but that doesn't work (don't ask me how I know). I'm not sure, but I think adding about 25 % to 30 % of the pivot diameter to the jewel hole could be correct. For example, if the pivot diameter is 0.09 the jewel hole should be 0.12. If the pivot is 0.20mm the jewel hole should be 0.26. Again, I'm not sure my theory is correct so if anyone would like to comment on that it would be interesting. With the Seitz jewel gauge, there's no guessing!

I guess what I'm trying to say is that if the Seitz jewel gauge is out of reach, the JKA Feintaster could be an acceptable option.

[LittleWatchShop]

4 hours ago, VWatchie said:

I guess what I'm trying to say is that if the Seitz jewel gauge is out of reach, the JKA Feintaster could be an acceptable option.

Happily, my dad bequeathed both to me.

[nickelsilver]

The thing with indicator based "mics" is they won't reliably split hundredths as well as a screw mic simply due to their design (though good quality ones can repeat quite well). Also, on many mics, both handheld, table, or the JKA style, the faces of the spindle and anvil aren't particularly parallel. So, if you take a plug gage, and check in several places around the faces, you end up with different readings. This is actually the cheat to wring a good reading from one- check with a good plug gage approximately the diameter you will be measuring, at a given spot, and then check your part the same way.

 

I don't have a JKA but a colleague has one that appears to be a very recent model in new looking condition. Checking with a carbide CARY 0.51mm plug gage, depending on where I checked on the faces it ranged from spot-on, to a few microns under, to almost a whole 0.01mm over. My screw mic of similar design was much closer, spot-on overall, with it reading a few microns under at the very edges of the upper part of the faces.

 

It's a rather involved process to lap these faces correctly; it's really easy to end up with convex faces, so not recommended if you aren't used to it.

 

9 hours ago, VWatchie said:

I measured pivots down to 0.07mm in my JKA and looked long and hard at them in my stereo microscope at 40X magnification but couldn't see any deformations, dents, or damage. That doesn't mean there weren't any, but at least none that I could detect.

 

The JKA is a lot less expensive than the Seitz jewel gauge (nice!). However, I was under the impression that once you had measured the pivot in the JKA you could just add 0.02mm to the jewel hole, but that doesn't work (don't ask me how I know). I'm not sure, but I think adding about 25 % to 30 % of the pivot diameter to the jewel hole could be correct. For example, if the pivot diameter is 0.09 the jewel hole should be 0.12. If the pivot is 0.20mm the jewel hole should be 0.26. Again, I'm not sure my theory is correct so if anyone would like to comment on that it would be interesting. With the Seitz jewel gauge, there's no guessing!

 

I'd say it's tricky to have a hard rule on pivot to jewel clearance. In small sizes, 10% would work. That would mean a 0.10 pivot in a 0.11 jewel. But for a center wheel with a 0.80 pivot 0.08mm would be way too much. 0.02 would be fine. So the clearances become larger as the size gets smaller- this is one reason why movements tend to perform less well as the size goes down.

[VWatchie]

4 hours ago, nickelsilver said:

I'd say it's tricky to have a hard rule on pivot to jewel clearance. In small sizes, 10% would work. That would mean a 0.10 pivot in a 0.11 jewel. But for a center wheel with a 0.80 pivot 0.08mm would be way too much. 0.02 would be fine. So the clearances become larger as the size gets smaller- this is one reason why movements tend to perform less well as the size goes down.

Thanks for the info it makes a lot of sense! I figured out why I thought the clearance had to be a lot more. The train wheel bridge on the movement I'm currently working on doesn't fit very well on the main plate. It needs to be pushed down on one side with force (I've tried to lower the bridge down evenly but no matter how I try it refuses). To make sure I don't snap the pivots while forcing the bridge down I need to tilt the bridge slightly towards the pivots so that the pivots slightly reach into the jewel holes. Of course, to get the pivots into the jewel holes while the bridge is tilted the diameter of the holes needs to be larger than when the bridge is in its fixed position.

That bridge or the main plate likely has to be adjusted but I will have to have a closer look and get back to it perhaps in a new thread with pictures as I have no idea how that adjustment could or should be accomplished. BTW, it is the same movement as in the "Serviced ETA 2763 having erratic rate and amplitude" thread. As I took it apart I discovered that the escape wheel jewel hole in the bridge was way too large. When pushing the intermediate wheel (driven by the barrel) back and forth the escape wheel pivot jumped like crazy in the hole. When pushing the intermediate wheel in a single direction with constant speed the pivot would keep jumping vibrating like crazy. Don't know why I missed this the first time around. Perhaps I was trusting "Swiss quality" too much (I doubt it would have passed me by if it was a Russian movement). Perhaps someone fitted a jewel with a too-large hole because of the faulty bridge, and that is perhaps the main reason for the erratic rate and amplitude, or what do you think? 

Edited April 5 by VWatchie

[VWatchie]

21 hours ago, VWatchie said:

That bridge or the main plate likely has to be adjusted but I will have to have a closer look and get back to it

Having a close look at the two posts underneath the train wheel bridge the post on the side that needed to be pushed down with force was slightly taller than the other. It also lacked a chamfer. Not completely, but a lot less defined than in the other post.

To fix this I taped (Kapton tape) around the post and then carefully shaped it with the file part of my Vallorbe burnisher making it slightly shorter and enlarging the chamfer but not touching its diameter. Now when I press it down it feels the way I'm used to. That is, when applying pressure on top of the posts the bridge slides into the main plate with a slight resistance.

I realize it's a funny place to write about this in a thread about micrometres, but as is so often the case one thing leads to another. Anyway, apologies about that.