Old B&G speed dial: advice?

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jsl

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This is a thirty-year-old analogue dial. The needle has become a bit sticky, and reluctant to respond to low speeds. It reacts to a gentle tap on the glass. Is there anything I can do to free it? I am aware that it is very delicate, with a very light hairspring, so I guess that oil is not the answer.
 
jsl said:
This is a thirty-year-old analogue dial. The needle has become a bit sticky, and reluctant to respond to low speeds. It reacts to a gentle tap on the glass. Is there anything I can do to free it? I am aware that it is very delicate, with a very light hairspring, so I guess that oil is not the answer.
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I would tend to suggest the contrary of oiling. Clean the delicate bearings, which are similar to the ones of a watch, with a very thin and volatile solvent: pure alcohol or something alike that will not melt other things around.

Daniel
 
Lighter fuel, not meths. Use a hypodermic syringe to squirt the LF. When clean allow time to evaporate.
Then use the syringe again this time using a watch oil if you can get it. If not, use 3 in 1 oil.
I do not suggest you dimantle it because the hairspring is very delicate and if you b#gg#r it up you've had it. Handling delicate instuments like these is a professional occupation.
Another alternative is for you to consult a skilled watchmaker / clockmaker first, probably the wisest option.
 
The Tinsleys in Lymington can clean and reset these, if they're not actually dammaged, however, the dessicant tubes are no longer available and my old ones don't work any more. There's nothing that can be done about that and you need to be careful to seal the units if you are going to dive into them.
 
Thanks

Phoenix of Hamble said:
What style is it?

I've got two rotary style ones on my boat that i'll be removing over the winter, and if they're of any use, they're yours for a small donation to the RNLI.
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This is a good offer. How do I define the style? Black face, white numbers and needle. Anything else I can describe?
 
Very helpful

VO5 said:
Lighter fuel, not meths. Use a hypodermic syringe to squirt the LF. When clean allow time to evaporate.
Then use the syringe again this time using a watch oil if you can get it. If not, use 3 in 1 oil.
I do not suggest you dimantle it because the hairspring is very delicate and if you b#gg#r it up you've had it. Handling delicate instuments like these is a professional occupation.
Another alternative is for you to consult a skilled watchmaker / clockmaker first, probably the wisest option.
Click to expand...

I might try this scarey operation when I have taken up Phoenix's offer of a spare one.
 
Ah!

Tradewinds said:
Some dials go up to 10kts, some up to 12. Might make a difference but I don't know for sure. I'd try & match like for like.
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And I can't actually remember, since that end of the dial does not get visited very often. Five knots is at the 12 o'clock position, so I guess max will be 10. I know! I'll have a look in the photo album. Remember those things? Like books? With pictures in?
 
Check the electrical connections whilst under way - if the thin wires are going into crimps then it is possible that a connection is not all it should be, that tap on the glass to make the needle move might just be improving the connection as opposed to easing a sticking needle. Had a similar issue with a B&G wind speed indicator which was under reading
 
Meters

The meter movement is usually a moving coil small current meter. Here a tiny coil is mounted on jewel bearings and held at zero by coiled hair springs. The coil moved inside a magnet and pole pieces in a small gap. The pivots give very little trouble. More often metal filings can get into the magnet gap or the needle gets bent to hit the glass or scale. All of these will be obvious with gentle push or blow to move the needle.
Unless of course as said it is an electrical problem. good luck olewill
 
I'm more and more impressed

William_H said:
The meter movement is usually a moving coil small current meter. Here a tiny coil is mounted on jewel bearings and held at zero by coiled hair springs. The coil moved inside a magnet and pole pieces in a small gap. The pivots give very little trouble. More often metal filings can get into the magnet gap or the needle gets bent to hit the glass or scale. All of these will be obvious with gentle push or blow to move the needle.
Unless of course as said it is an electrical problem. good luck olewill
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...impressed with the quality and detail of these responses. A gentle blow will indeed move the needle, which is definitely not bent. So if it moves, you are suggesting that poor electrical connection is more likely than slight stickiness? If there are filings in the gap, how would I detect them?
 
Meter

Yes movement will be impared with any obstruction. So it is probably OK. Perhaps an electrical fault. If it has been sealed of course flings are unlikely. If seen they can be removed with selotape tape sticky side out. (AKA Durex in oz) slipped into the gap. good luck
 
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