Prs29a crystal repair

[JimmyGood]

Good day all. I'm looking for some advice. I have the older version of the 29a with the acrylic crystal. It has a nasty scratch that is too deep for polywatch. My local jewellers are quoting £40-£70 to replace it. Is it worth doing this myself? I have a couple of acrylic watches so could it be worth buying the equipment. Or should I just try and find a more reasonable watch repairer? My grandfather was a watchmaker so I'm assuming I have sufficient skills in my genes! Thanks in advance.

[walkerwek1958]

Suggest you post a detailed pic to show how bad it is. In most cases it’s possible to polish the damage out but it gas to be done properly, especially if its fairly deep. I’ve posted several times about the technique I use, which involves a small flat rubbing block and various grades of wet and dry paper. If its deep I’d use 1500 grit initially, following up with 3000, 5000, 7000, metal polish and finally polywatch. Different grades of wet and dry are available from Cousins, and you might as well order 2000 grit too. Using a finer grade is slower but will give the same result, it just takes longer. Keep the paper wet with dilute soapy water or detergent. If it’s a deep scratch you have to work the whole area around it, orherwise you’ll end up with a polished groove.

A word of warning, it’ll look a lot worse before it looks better. Be sure to mask off the rest of the case before starting, I prefer working on crystals out of the watch but it isn’t always practical.

Also suggest you inspect the crystal for cracks with a strong magnifier before starting work, no point polishing it only to find its got a micro- crack in it!

Easiest way to learn is to order a cheap acrylic crystal from Cousins for a couple if £ to practice on, put a scratch on. Its not a difficult technique to learn.

[JimmyGood]

The scratch is way too deep. I have polished to the extent that there is now a noticeable indentation and the scratch is still there. If I try more polishing I think I will have a very weak crystal on the watch. Definitely needs replacing.

[walkerwek1958]

The scratch is way too deep. I have polished to the extent that there is now a noticeable indentation and the scratch is still there. If I try more polishing I think I will have a very weak crystal on the watch. Definitely needs replacing.

Suggest you contact Eddie and ask whether a replacement is available.

I don’t know how thick the acrylic is on these, but its likely to be substantial and it’ll take a fair amount of refinishing........provided its done properly using the techniques I described.

If the crystal really can’t be refinished, and a replacement isn’t available, the only option is to have a generic crystal fitted.

Edit: Just checked the spec on these, the crystal is described as 1.5mm thick........that’s a lot and it should be possible to refinish this without weakening it.

[Rev-O]

Is it an armoured crystal?

If so I'm sure Sternkreuz make one and Cousins will sell it

[walkerwek1958]

Some of the Timefactors watches use thick acrylic crystals that don't have a tension ring. Unfortunately there's no direct generic replacement but there are ways to work around the problem. Can`t remember what this one's like. I fixed a PRS 25 (40mm) recently.

As I`ve already said, if the crystal really is 1.5mm thick it can be refinished.

[TomasC]

Yes, it is armoured crystal. I am living in Germany and had mine replaced by a local jeweller with a generic armoured acrylic crystal, domed, costs were 30,- EUR work included.

[Redcoat]

Just recently had to replace mine because of a small crack on the side. Eddie was kind enough to give me the dimensions of the crystal (32.4mm diameter x 1.5mm thick) and they’re easy enough to source for not much money. A competent watchmaker ought to be able to fit it for less than you’ve already been quoted.

[Wimm]

I am in the same predicament, I have a new Sternkreuz ATC crystal on its way. Luckily I was given a crystal press for Christmas. What can go wrong.........

[walkerwek1958]

Knowing the correct dimension for the crystal helps a lot, usually I don`t have that info so I measure what comes out, but often end up ordering 2 or 3 to get the correct size. They're only approx. £3 each so it's no big problem. You also have to decide whether to order a normal or high-dome version, but with experience it's usually easy to tell what's needed. If the seconds hand is contacting the glass the trusty timegrapher will show the fall in amplitude, it's annoying but it happens with old watches and it has to be addressed.

A crystal press is a must, mine's a cheap one but it does the job. Sometimes they're reluctant to go in, just ensure it's lined up right, squeeze carefully. Sometimes one edge won't go in and no amount of squeezing will work, either line it up again or try a smaller size. Increasing the bevel on the leading edge helps, very fine wet and dry around a block will do this.

As the above poster said......what can go wrong? Like anything, experience helps and there's only way to get that. Chicken and egg?........maybe.

As a general rule I don`t favour fitting crystals with the movement in the watch. The exception (through necessity) is the monoblock case watches from the 60s/70s, they're a pain because the glass has to come out to regulate the damned things.

Top Tip: keep a clean piece of premium grade Rodico handy for getting traces of dust and fibres off the dial and inside of the glass. A blower and a brush also help, but I usually use Rodico around the inside of the case to get any foreign bodies out. Golden rule: be very careful with AR coatings on the inside of the glass, they're soft and easily marked, don`t be tempted to wipe with anything.

Good lighting and magnifiers are a must for any watch work, they don`t need to be expensive, just good enough to do the job.

[JimmyGood]

Knowing the correct dimension for the crystal helps a lot, usually I don`t have that info so I measure what comes out, but often end up ordering 2 or 3 to get the correct size. They're only approx. £3 each so it's no big problem. You also have to decide whether to order a normal or high-dome version, but with experience it's usually easy to tell what's needed. If the seconds hand is contacting the glass the trusty timegrapher will show the fall in amplitude, it's annoying but it happens with old watches and it has to be addressed.

A crystal press is a must, mine's a cheap one but it does the job. Sometimes they're reluctant to go in, just ensure it's lined up right, squeeze carefully. Sometimes one edge won't go in and no amount of squeezing will work, either line it up again or try a smaller size. Increasing the bevel on the leading edge helps, very fine wet and dry around a block will do this.

As the above poster said......what can go wrong? Like anything, experience helps and there's only way to get that. Chicken and egg?........maybe.

As a general rule I don`t favour fitting crystals with the movement in the watch. The exception (through necessity) is the monoblock case watches from the 60s/70s, they're a pain because the glass has to come out to regulate the damned things.

Top Tip: keep a clean piece of premium grade Rodico handy for getting traces of dust and fibres off the dial and inside of the glass. A blower and a brush also help, but I usually use Rodico around the inside of the case to get any foreign bodies out. Golden rule: be very careful with AR coatings on the inside of the glass, they're soft and easily marked, don`t be tempted to wipe with anything.

Good lighting and magnifiers are a must for any watch work, they don`t need to be expensive, just good enough to do the job.

Thanks for the excellent advice!