Modern adhesives used in Horology
The British Horological Institute has archived and edited the following from e-mails sent to the Clock/Clockers mailing lists on the Internet. The information here does not necessarily indicate a method approved by the BHI, we are only publishing this digest so that others can decide for themselves whether the methods listed below will suit them.
From:
Joop Beem, Steven Berger, Dewey Clark, James R. Edwards, David Eiman, Tony Gray, Alan Heldman, Eliot Isaacs, Richard Karasik, Michael Kinney, Mike May, Robert Olson, Thomas Roma, David J. Smith, W. R. Smith, David Stephens, Tim Sweet, Dennis Truxal, Dennis J. Warner
The use of modern adhesives caused quite a collection of e-mail. I have tried to provide a summary of the suggestions and thoughts expressed.
Modern Adhesives have their place in watch and clock making especially in the area of machining of parts in preference to the use of substances such as shellac, but just be careful and use it as an aid to construction and repairs and don't use it as a substitute to skilled workmanship.
The reversibility in heat well above what they would ever experience in use but easily obtainable in the workshop) means that they also meet the requirements for appropriate use in restoration of old work.
All trade names are recognised
Loctite
For permanent bonding, Loctite is the finest thing available. It is resistant to water, diesel fuel, gasoline, antifreeze, hydraulic fluids, motor oil and transmission fluids and major shop fluids.
For an on-line Loctite Product Guide check out http://www.Loctite.com.au/products.htm
According to "Loctite adhesive/sealant product selector." The technical features are:-
#609 [product no. 60931] (601 in UK)
- for retaining bearings, bushings, and sleeves.
- Green colour.
- Viscosity cP 100-150;
- gap filling ability w/o primer, 0.005 inch;
- sheer strength 3,000 psi;
- temperature range -65 to 300 degrees F.;
- full cure w/o primer 6 hrs; full cure w/ primer 1 hr. (to mount a component on a shaft they indicate that it will work with anything from a "press fit" to a slip fit of two to four thou)
#680 [product no. 68035] for retaining gears, pulleys, shafts.
- Green colour.
- Viscosity cP1250;
- gap filling ability w/o primer 0.015 inch.
- Sheer strength 4,000 psi;
- partial cure 10 minutes; full cure 8 hrs; no primer required. (for heavier duty than the above; slip fit of two thou for maximum strength with primer)
"Quickmetal" (product No. 66040)
- Silver colour.
- Gap filling ability 0.020 inch;
- sheer strength 3,000 psi. (for heavy duty; slip fit of two thou).
#620
- (good to 450 degrees F);
- green;
- 7,000 cP viscosity;
- 15 thou gap filling.
(The familiar red-coloured products: 262 and 277, are specified as intended for locking and sealing nuts and bolts and studs).
Loctite works well in quite arduous situations, such as holding a fusee on to its arbor - but the surfaces must be scrupulously clean (use the Loctite special cleaner) and the clearance must be just right. I find about 0.001" (one thou) is OK for an arbor 5/16" diameter. Too close a fit and it 'goes off' too soon, before you have a chance to position the work correctly; too slack, and it doesn't reach full strength.
Thread Lock (Loctite 242)
- Dial screws in the ESA 9154 watch movement is a different story. If the cell wasn't dead, then one of those silly screws was stuck to the balance wheel magnet.
- Holding buttons onto watch stems
Loctite 601 (later replaced with 609) or Loctite 640
- bonding wheel collets
- bushings to arbors
- lantern and cut pinions to arbors
- In restoration work, if one is faced with a hopelessly worn pinion, instead of replacing the whole original arbor it is less destructive of the original work to grind the worn-out pinion off to a smooth radial surface and then slip on a new pinion with a dab of Loctite, without disturbing the original arbor at all, and often without having to disturb the wheel mounting at all. lantern pinion pins to their spools (though there are disagreements as to whether lantern pins should rotate or not)
- anchors to pallet arbors
- barrels to end caps
- gathering pallets to their arbors.
- affix the dial feet to the dial
- really holds the dial feet in place without having to drill holes in the dial
- repair of French spelter clock cases -
- To repair this I drilled a small hole in to the larger portion and also in the small portion that had broken off. Then took a steel taper pin etc. Placing the Loctite inside the holes and none outside, make the repair totally unnoticeable. If the job is finished off with some carefully matched gilding paste this sort of repair is pretty well invisible. In fact I can't think of any other suitable method of repairing spelter, especially if it's gilded.
- pivots
- loose bushings
Loctite Weld
You use it to seal in lantern pinions. It state that it has a shear strength of 3000 psi after 16 hours. If will fill gaps and is resistant to most shop fluids. It easy to apply, can be filed without losing is strength and therefore doesn't look as bad as a large glob of solder.
When replacing a lantern pinion: I take a hand drill ( I use a drill bit in a pin vice) and make several turns on the hole that the leaf was originally inserted through. This removes the brass that was "meshed over" (my term) the hole to help keep in the leaf. With a few extra turns the hole is large enough to allow the leaf to drop out. Once out, I mic. it and cut the proper size. I' m now ready to place it back in the lantern by inserting it into the original hole.
This is where the Loctite comes in. The original hole is larger, due to the hand drilling that was done to get the broken leaf out. I have three choices to keep the new leaf in place. 1. remesh the brass around the hole 2. put a glob of solder 3. place some Loctite on it. I don't do #1 because of the well known law of Murphy (if something can go wrong it will) I don't use solder because I have less control with a soldering iron/gun then I do with a tooth pick and solder is a pain to clean off.
I use Loctite and a tooth pick. If only one leaf is done I can place a small amount of Loctite over that hole and it will fill the gaps and is strong enough to hold up under pressure. This makes for a less unsightly repair. (I've about ten clocks in for repair that have had huge globs of solder, that just look bad) If I drop to much on the spot I can wipe it off before it dries or file it down afterwards.
Loctite Adhesive 290
In doing high-grade watch repairs that need to be water tight 290 is a necessity. A while back I was testing a case for water leaks and found a very slow leak around the crown. The case tube was down tight in the case frame and all the gaskets were new and lubricated with silicone. It still leaked. By removing the case tube and placing the Loctite down in the threads of the tube, replacing it and letting it set for 30 minutes, I found a case that did not leak. I now use the Loctite on all case tubes, friction or threaded. I also now secure all crowns to the stems with Loctite on at least three threads of the stem, do wipe clean any excess that you can see. A little Loctite goes a long way.
Super Glue
For bonding parts while machining, super glue is one of the finest things available for the clock repairer. Super glue is very brittle and should be considered a temporary bonding agent, such as for bonding parts for turning or mounting parts on stub arbors. The bond can then be broken with heat and the residual super glue dissolved with acetone. Since acetone will dissolve super glue, it would not make much sense to use super glue to bond a replacement pivot in place.
Double sided sticky tape
This comes in a range of styles, but I use a 'high tack' variety. It will hold thin brass plates to an old-fashioned 'wax chuck' perfectly safely. The secret is to use plenty of pressure in fixing the work to the chuck - I position it first, then squeeze it in the vice .This tape also works where you can't use a regular magnetic chuck like they have on surface grinders.
