Bench screw swelling

[tablesawtom]

This is probably a question for  the finishing forum, but I bought a lake Erie bench screw and nut. Here in Iowa the humidity can get kind of high. I had my screw and nut at my shop, which has no heat or cooling, only a window fan if I open the window. The wood swelled up so that turning the screw got kind of hard. I took it home which is air conditioned and overnight it was fine. A couple of years ago it got so tight I couldn't turn it at all.

I have been thinking that maybe if I put an oil finish on it it might block the wood from taking on moisture. Has any one else had any experience with this and how did you fix it? I would like to use it on a Moravian bench I am building.  

Thanks,

Tom

[AHill]

I was going to suggest a penetrating oil like tung oil or BLO - but make sure you do that when it's low humidity. Otherwise, you're going to ensure it's always going to be tight. Make sure the finish completely cures before you use it - otherwise, it'll get gummy. Before I'd try oil, I'd try waxing the threads and see what that does. Some paste wax or beeswax could solve your problem without the fuss of the oil.

[cams2705]

I have the same bench screw from Lake Erie I used for my leg vice in my bench.  I also finished it with the same finish as my bench:

I dissolved paraffin wax (Gulf wax in the canning aisle) in turpentine.  I shaved a block of it into the turpentine (2/3 full) in a quart Ball jar and let it sit for a week and then strained it.  Then I filled the rest of the quart jar with BLO.  I applied 2 or three coats about a week apart.

I never had an issue and about twice a year i just take the block of wax and rub it on the threads of the screw and cycle it a few times.

[jteneyck]

No finish stops moisture, it only slows down how fast it penetrates to the underlying wood.  Shellac has the lowest transmission rate of most any finish, oil products being among the worst.  It's all in Hoadley's book and at the FPS website.  Whether or not any finish will solve your problem is going to depend upon how long the RH remains high in your area.  If it's elevated for weeks on end I think you will have a recurring problem.  The solution in that case would be to turn the threads deeper/smaller so that it works during the worst or nearly worst time of year.  

John

[iclark]

Count me among the paste wax believers. Just be sure to use the furniture version and not the floor version. OSHA required the manufacturers of paste wax for floors to add anti-slip stuff to the wax.

A good coat of wax on both the screw and the nut will help a lot. With use and over time, the screw and nut will wear in a bit so that the worst-case tight is not too bad but it doesn't get too sloppy when things are dry.

[tablesawtom]

I had the screw and nut at home for a couple of weeks to shrink it as much as possible. I took it back to the shop and applied BLO to both and man did I see a change. I could spin it a couple of turns before, but now It really spins. I brought it home last night to help control humidly. I have seen a couple of Moravian benches lately and I saw that the joints in the legs were pinned. The lower half of my bench is walnut so I ordered a couple of walnut dowels to pin it with, so I have time to let my screw dry as well as it is going to. 

I figure about 3 costs but I liked the first coat and  I will see about it after the second.

I have some actual bees wax so I think I will use it at the tail end of the build.

Tom

[Stwood_]

I've used mineral oil, blo, and beeswax. Beeswax worked the easiest.