Thread: Bottle stoppers

Dallas, are you "strengthening" the threads with thin CA after cutting?

What TPI is the 1/4", 20 or 24 or 28. Coarser threads work better in timber.

What pilot hole size are you using? In wood generally, you have to use a smaller hole than in metal, 1/4" normally you would use a 5mm drill bit, I would go to a 5.5mm bit and chamfer the top of the hole.

I use 3/8 nub bottle stoppers and have the Ruth Niles mandrel etc.

I got them before postage became ridiculous.

Yes Pat, I try adding CA after the thread is cut and sometimes there is enough thread left that they will hold and other times not.
The 1/4" threads are 20 TPI and I have tried the recommended drill size of 5.1mm and also the next size down of 3/16" with the same results. I have been filling the stripped thread holes with epoxy and redrilling and tapping but I'm sure not everyone has to go to that trouble.

In my experience ( I have made hundreds ) it depends largely on the timber being used, dense timber threads with better results as said above you need a much smaller drill than for steel, take it slow, once made I always put Epoxy on the thread when assembling.

I agree with the comments, timber species, hole dimensions etc are very important, my preference is always hardwood and generally the hardest I have. The only other idea I can think of is if the timber you prefer isnt ideal for the thread cutting. Then try adding CA to the hole you intend to tap before tapping,ie coat the walls and give it what ever time it needs to completely dry. Also take it easy with tapping slow and easy is the way, I would avoid end grain unless its hard wood. Good luck.

Thanks all, there are a few ideas in there that I can pursue that are slightly different to what I have been doing.

I used to have the same problem but eliminated it by using a 5.5 mm drill bit for the pilot hole. Previously I was using 5mm.

I use a dab of mineral oil on the tap, I use the tap in cordless drill and pre drill about twice the depth needed.
Previously I wasn't drilling deep enough and would strip the the thread I was cutting.