I’m playing with my taps and threading holes, I’m making cam locks out of maple like these
View Image I’m making the handles out of maple and the rotating pin out of birch dowel. However my 1/4″-20 bolt (metal) is loose in the thred. This is a low force application (not like trying to hold a router up) so I’m not worried about the strength of the thread or maple handles, I’d just like to get the thread a little bit snugger. Anyone have experience with this – what’s the best wood (assuming harder vs softer is better), what’s the best size for the pilot hole for a 1/4″-20 thread? (I chose this thread because it’s pretty coarse.) My taps are the cheap chinese kind – probably fine for wood and lousy for metal Thanks, Mark
Measure it with a micrometer, mark it with chalk, cut it with an ax.
Replies
A couple of ideas: You can use a threaded insert. The 1/4-20 is very common, should be easy to find in a local store or for sure by mail order. If you wish to keep the "wood" technology, you can strengthen the internal threads by using either epoxy or super glue (my choice). After doing an initial tap, coat the threads with the glue of choice (experiment here to see which one you like best) then re-tap. The wood fibers will now be reinforced with glue and should hold significantly better although not as well as the threaded insert.
I have always used a slightly smaller drill size for wood than I use for metal. Again, experiment, tap a hole put in a bolt and try to pull it out.
By the way, you really ought to buy a quality 1/4-20 tap. Use it only for wood to keep it as sharp as possible.
Jeff
Thanks, I considered the threadded inserts. I have some smaller ones in the shop but I didn't want to go out.Yes I know I need good taps and dies. Just didn't want to spend the money - maybe this project will push me over the edge... Since I purchased the cheapies (as an experiement they were $15 for a full set on ebay) I've actually used them quite a bit - knowing that I'll use them means I can justify spending more and I'll always have the cheapies "just in case" (or to give to my kids)Any recomendations for a good set of taps and dies? And how do you sharpen a tap?Thanks,
Mark
Measure it with a micrometer, mark it with chalk, cut it with an ax.
>> And how do you sharpen a tap?By grinding the rake face of the flutes, with a slip stone, die grinder, Dremel tool, etc. Here's a manufacturer's web page with info on rake angles.http://www.precisiontwistdrill.com/techhelp/help_pages/rake_angles.asp
Check out Lee Valley. I was looking in there last night and saw what looks like a sweet set. CAD$
http://www.leevalley.com/wood/page.aspx?c=2&p=41791&cat=1,43000
M<ark,
My copy of ICS mechanic's handbook suggests drill #7 as size for 1/4"x20tpi. Decimal equiv. .2010
Regards,
Ray
Did a quick experiment (on my "lunch" break - I work at home when I'm not traveling).203125 (13/64") made the threads too lose
.1875 (3/16") worked great in red oakMark
Measure it with a micrometer, mark it with chalk, cut it with an ax.
Mark,
Experience is a great teacher!
Cheers,
Ray
See FWW Sept/97 or Warner's magazine, (the later not a freebie).
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