Watch Parts Pen

[jimmyz]

I am trying to make a watch parts pen for my son-in-law. Although I am using lots of gears, the face is actually an ink jet printout of a face he likes (I know that might be considered cheating!). All the metal parts are glued on with the smallest amount of ,medium CA that I can use to hold the part in place. The face is glued to a thin piece of cardboard to give it more body and then glued with Modge Podge to the tube. The problem I have had three times now is with the material used to make the background for the tube peeling off the tube during casting.

I have used black nail polish, black powder coating, and black spray paint from the auto parts store. I normally wait a day before doing anything with the tube after coating the tube. In each case, after casting and hardening, the black coating on the tube is coming off in various locations (probably more near the ends). Needless to say, this has been extremely frustrating, given the amount of time it takes to get the blank to this point.

I am using Silmar 41 with 5 drops of catalyst per ounce. It's polyester resin, so no pressure pot. The casting sits in my basement workshop at normal temperature to cure. I have been placing the cup of PR in a bowl of warm water during mixing to reduce bubbles.

I don't want to use carbon fiber sleeves for the background.

Any recommendations for changes to permit a successful result would be greatly appreciated!

 

[jttheclockman]

First of all I have a hard time believing that any of the materials especially powdercoating has failed. Have used that stuff many times and it is hard as a rock. The tube needs to be cleaned with acetone and I like to sand it some to give the material a little tooth. Even sanding with the grain of the tube will allow this and not cause swirl marks. If using spray paint I like to use the high heat stuff (used on barbecues)

Using Silmar without a pressure pot is asking for trouble especially doing those watch parts because all the air pockets created with those gears. and you add the modpodge to the list. Wow. Anyway if you are warming the resin make sure you warm just the resin and not with the catalyst in it. You will kick it off too fast. My recommendation for resin is one of the epoxy resins. I like to use Liquid Diamonds.

Back to your tube, you need to clean it well and not touch with finger tips after especially when adding parts to it. Your oils will cause failures. Wear latex gloves if you have too. Make sure the paint is cured and not just dry. I like to place in sun or in a toaster oven on low heat. Before you go to cast you need to also make sure that CA has off gased to prevent bubbles. Good luck. Post photo when done. One other thing the method you use to hold the tube still while applying the parts should be some way as to not scrape the paint as you turn it and also do not put pressure on the ends as to push on the paint as it can cause small hairline cracks on the end that are unseen. I like to use a dowel close to the size of the inside dimension and use double sided tape (small piece on each end) and built a cradle so the dowel sits in it as I spin it.
I have also had good results using self adhesive backed vinyls such as used in the auto industry. Then you do not have to worry about finger prints.

 

[leehljp]

Are you using any kind of "release" agents on the casting moulds? What cleaning agents are you using on the tubes? Are you laying or standing the tubes on a table that has been cleaned or sprayed with any of these: WD-40, oil based, silicone based or wax cleaning agents such as furniture wax? These things migrate/transfer onto tubes, blanks and wood. John mentioned fingers, those too transfer oil too.

 

[EBorraga]

Depending on the paint used, you may need to spray a coat of clear over it with PR. I Paint everyone of my tubes. Clear will keep it from reacting

 

[jttheclockman]

Depending on the paint used, you may need to spray a coat of clear over it with PR. I Paint everyone of my tubes. Clear will keep it from reacting

Can you please tell him what clear to use?? Or give him an example of paints and clear used.

 

[EBorraga]

Can you please tell him what clear to use?? Or give him an example of paints and clear used.

Trial and error, but any clear on the shelf with paint will work. I use an air brush. But I use automotive 2 stage paint and clear. I mix it all by hand. House of Kolor is what i use, but it aint cheap