One step back, one step forward.

[catsittingstill]

Lowes did indeed have brass # 8 wood screws.

I went to put them in the first thing this morning, and the very first one broke off halfway in.

To put this in context, I drove more than fifty of this exact same type of screw, into ash gunwales, when I made Patience.  The first eight of them I had to back out again because I couldn't for the life of me get them to go all the way in (it turned out my combination bit didn't drill out the unthreaded part of the shaft deeply enough.)  Some of them, the threads were like ruffles when I got them out--the strain had been so great the brass threads partially melted. 

Not.  One.  Of.  Them.  Broke.

So I know what I'm doing with brass wood screws.  Okay?

Not only did this POS cheap screw break, it broke deeply enough inside the wood that I couldn't get any kind of grip on it with my Leatherman.

I took the thwart to the hardware store, where I should have gone in the first place, and looked up my friend Steve there, who removed the broken screw for me, at the cost of drilling it out with a bigger drill bit, enlarging the hole.  He also advised me to 1) drill out the deep part of the hole with a bit 1/64th inch larger than that part of the combination bit when working with hardwoods 2) use soap, not wax, on the threads of the screw and 3) drive a steel wood screw of the same size into the hole first (which I would have done if I'd had one.)  He also said that all brass woodscrews were cheap Chinese crud now, so they aren't as sturdy as the ones I had when I worked on Patience.

I bought 8 of the hardware store's brass wood screws anyway, went to Lowes and returned their cheap POS screws (which I characterized politely as a "quality control problem"--and which had actually cost *more* than the hardware store screws (grrr.)) and came home, the entire morning gone.

After lunch I put in seven wood screws.  None of them broke.  I unclamped everything, took thwarts-plus-knees out, sanded knees, put 6 mil plastic between thwarts and knees (so as not to epoxy them together accidentally) and put all seven screws back in, filled up the enlarged hole with dookie schmutz, smeared dookie schmutz on the knees and clamped thwarts-plus-knees back into the boat.  Tomorrow the knees should be a permanent part of the boat, and tomorrow evening the dookie schmutz should be hard enough for me to re-drill the 8th hole.

I'm giving serious thought to putting up some bronze wood screws for this application.  Steve is checking whether he can order them for me.  Bronze should be tougher than brass.

Tomorrow I have to work at the clinic, and I have Folksingers Anonymous in the afternoon and a guest coming in the evening.  Hopefully I can squeeze in a little boat work--if I paint the gunwales with epoxy *before* OVFF they can get half their curing time while I'm gone and can't work anyway.

Comments

[judifilksign.livejournal.com]

Wow. Epoxy cures really slowly if it will only be half-cured while you're gone.

I'm looking forward to seeing you! (Dances a little.)

[catsittingstill.livejournal.com]

Epoxy cures at a rate that depends both on the type of hardener and on the temperature. They make different hardeners for different applications (if you're putting fiberglass on a boat you generally want a formulation that cures slowly so you have plenty of time to get the fiberglass evenly wetted and smoothed down and all the bubbles out--if you're using it to repair camping equipment you generally want one that cures quickly so you can use the item in an hour or two.)

The formulation I'm using cures to be "tack free" (meaning not sticky) in about six hours at eighty degrees. At that point it is solid but still "green" meaning some of the chemical bonds are still forming. As it continues to cure it gets harder and stiffer, more resistant to cutting and sanding. Until it is fully cured (about seven to fourteen times the length of time it takes to cure "tack free") any varnish brushed over the surface won't dry properly.

So the epoxy will be not-sticky in eight to twelve hours (given that the temp is now more like seventy degrees) and probably fully cured in a week. I can work with the parts, sand, drill, whatever, after they've cured overnight (well, a little longer for sanding, or the dust balls up and sticks to stuff) but to varnish it needs a week.

[boywizard.livejournal.com]

I'm not going to say 'I told you so', since I have been there. I've never twisted off a stainless steel screw. Silicon bronze is a good choice, though. It's WAY stronger than brass, nearly as good as stainless in my experience. Costs about twice as much as stainless, but may be worth it in small quantities. Definitely prettier than the steel, unless you like the silvery look. Soap is a good lubricant, but not superior to beeswax, IMO. More readily available, though.

[catsittingstill.livejournal.com]

Yeah the major issue is the need to order a week ahead of time. :-7 Stainless is available in the hardware store, it turns out.

What I *could* do is use stainless, order the bronze, and remove the stainless and drive the bronze in when they come.

Hmm.

The bronze are about 35 cents a screw or 25$ for a box of 100 which is about what brass costs anyway. Though the shipping is going to drive that up.

Re the wax/soap issue--I had originally figured wax; soap tends to attract water and wax tends to repel it and I don't want water creeping into my woodwork and rotting out the screw holes. But Steve tells me the friction of driving a screw tends to melt the wax and then the wood tends to absorb it, which both reduces the lubricating effect and can even locally swell the wood, making the screw hole tighter and the friction thus *greater*. Soap on the other hand doesn't tend to melt at these temperatures, according to Steve, and is thus a better choice for this application.

Probably I'd have to do some sort of Consumer Reports type study and drive a hundred screws into ash with wax and a hundred with soap, to sort it out and I don't feel up to that :-)

[boywizard.livejournal.com]

I have serious doubts about wax being significantly absorbed into the wood, or about the wood swelling due to any such absorption - especially with hardwoods such as ash. But, I've never performed your suggested 100-screw comparison test. I don't like the idea of soap, which I also think is hygroscopic. For preventing water absorption in screwholes, provided that I don't plan to remove the screws, I dip the screw in epoxy before driving it. This is not an option for your removable thwarts, though. (Actually, the screws can be removed if necessary by the application of heat, but one doesn't want to do it on a regular basis.) Using stainless until you can get the bronze sounds like a good compromise solution.

[catsittingstill.livejournal.com]

Your doubts about wax absorption are reasonable enough. I will probably go back to wax presently when I am less gun-shy and 2) have some beeswax again (I had five ounces and it *all* got used up for the wax tablets project.) The stuff isn't cheap, but it's not like I need a lot of it for this application.

[boywizard.livejournal.com]

As we are going to both be at OVFF, would you like to have some beeswax? I have what is for me probably a lifetime supply (10-12 pounds) and I would be happy to bring a half-pound or so for you. It didn't cost me anything, so I have no qualms in giving it away. It can be my contribution to your project. I won't have any internet access after about 5:00 on Friday, so I will have to look extra hard for you. Remember, I'm Santa Claus, and my real-world name is Wes Metz. I assume your icon is actually a picture of you.

[catsittingstill.livejournal.com]

I will be at OVFF and I would be most grateful for some beeswax!

My icon is a picture of me and I'm slightly over six feet tall. I won't say you can't miss me but it takes some doing.

If I have time I will try to bring some pictures of Constance. If you have time, I would love to see pictures of your boats, but if it would be a lot of trouble I can of course wait for you to put them on your website.

[catsittingstill.livejournal.com]

I should warn you that I love cons but I have the attention span of a kitten on crystal meth when I'm at one. I am looking forward to meeting you but I can't guarantee that I won't get drawn away in the middle. I hope it won't happen, but if it does, please ascribe it to my warped brain chemistry and not to any ill intent on my part.

[boywizard.livejournal.com]

Of course - I understand completely, and I will try not to monopolize your time; I will enjoy meeting you, though.

[catsittingstill.livejournal.com]

I am looking forward to meeting you too :-)