PDA

View Full Version : Hidden (flush) bronze nut?



Garret
03-20-2010, 01:14 PM
Hi -

OK - there's gotta be something like this out there - but in quite a bit of searching, I haven't found it.

Application: rudder straps: bronze strap 1/4" thick, 2" of rudder, another strap. I can put flathead bolts through from one side - but I don't want nuts on the other side (probably silly, I know). Need 3/8 or 5/16 diameter.

I've seen insert nuts like these:
http://img.alibaba.com/photo/11080876/Insert_Nut.jpg

but I'm hoping to find ones that are a) bronze & b) flathead - with a taper like that of a flathead bolt - so they end up flush to the strap.

Anyone know of such a thing? Yeah, I could make 'em, but.....

Thanks!

rbgarr
03-20-2010, 01:36 PM
If the bolt is bronze, peen it maybe.

Garret
03-20-2010, 03:15 PM
If the bolt is bronze, peen it maybe.

Hi Dave -

Yup - could do that. But then I might as well just rivet it. The idea is that I'd like 'em removable - that way I can remove the rudder shaft w/out lifting the boat about 12 feet.....

Thanks

Soundman67
03-20-2010, 03:27 PM
bronze machines pretty easily. can you buy good bronze from your local metal supplier or recycler and drill tap the right piece to insert into your wood?
you may be able to find a local machine shop that could do it relatively cheap too.
how big do they need to be for your application?

Doug

Tom Robb
03-20-2010, 03:34 PM
Use a regular hex nut and inlet it into the rudder.
Or try McMaster/Carr?
Flat box knock down furniture uses stuff like your picture. It wouldn't likely last long on a boat.

paladin
03-20-2010, 03:44 PM
Garrett, those are PEM fasteners...research Pennengineering on google.

donald branscom
03-20-2010, 04:59 PM
Garrett, those are PEM fasteners...research Pennengineering on google.

PEMor PEM NUT= Pressure engineered machining
Made to be inserted into a metal plate with hydraulic press.

One of the fasteners shown is a spoke nipple.
The first one shown is simular to a PEM nut.
http://i43.tinypic.com/vsdie1.jpg
This is a PEM nut.

donald branscom
03-20-2010, 05:05 PM
PEM nut installed into metal plate.
http://i41.tinypic.com/2h69e2t.jpg

Canoeyawl
03-20-2010, 05:09 PM
What you are looking for are called "sex bolts"
(use the quotes!)
here's (http://www.fastenal.com/web/products/detail.ex?sku=0123347) a start, you may not find them in bronze, but they can be made without much trouble, or,
Can you tap the rudder strap?

donald branscom
03-20-2010, 05:10 PM
This is what you want, you may find it in stainless steel.
It is called a "blind" nut for wood working.
http://i40.tinypic.com/2ignoud.jpg

Peter Malcolm Jardine
03-20-2010, 05:21 PM
There is also what is known as a barrel nut...or binding post, or another name is sex bolts. They are available from these guys, this is their PDF catalogue, and if you scroll down a bit, you will see a lot of different kinds. They seem to make stainless, copper and brass, (steel) but not bronze.

http://accuratemfg.com/CATALOGS/Architect%20Catalog%20Web%20Current.pdf

rbgarr
03-20-2010, 05:43 PM
Hi Dave -

Yup - could do that. But then I might as well just rivet it. The idea is that I'd like 'em removable - that way I can remove the rudder shaft w/out lifting the boat about 12 feet.....

Thanks

Ah, I see.

Paul Girouard
03-20-2010, 05:47 PM
Hi Dave -

Yup - could do that. But then I might as well just rivet it. The idea is that I'd like 'em removable - that way I can remove the rudder shaft w/out lifting the boat about 12 feet.....

Thanks


I remember Jim Ledger writting about why rivets are the way to go , a loose nut and the rudder falling off , IIRC , where good reasons to rivet this connection.

I could be wrong , on who wrote it , but IIRC it was Jim on one of his rebuild treads on the boat he has in the water , not the new build thread.

Made sense to rivet it.

Peter Malcolm Jardine
03-20-2010, 06:06 PM
The sentiment expressed about making one is bang on as well. I could make one quite easily on a metal lathe.... bronze rod, first drilled then tapped to the appropriate thread size, then turned down to fashion a head on one end. Start out with rod that is about twice the size needed, then the head will be formed and still leave enough thickness around the tapped center....

However, on a little more investigation, it would seem that either National bolt and nut, or Fastbolt make sex bolts in silicon bronze.... give them a call and I think you will get some results.

SMARTINSEN
03-20-2010, 07:25 PM
What Donald shows are called "T" nuts

Vinny&Shawn
03-20-2010, 07:35 PM
Another method used often is to let in a piece of 1/4" bronze plate with tapped holes to receive the bolt or machine screw. You can use any thickness plate that suits the application.

Garret
03-20-2010, 07:45 PM
Thank you all for responding! I love this forum. 20 years ago, I could ask 3 or 4 people. Now I can ask hundreds from all over the world. Al Gore sure did great when he invented the internet :D

Seems that when I dig, what I want isn't available in bronze.

So - time to fire up the lathe. I figured it only made sense to see if they were available before I spent the time to make my own (not that my time is worth a whole lot ;-). I'm planning on probably 5/16 bolts - so the "nut" side could be from 5/8 rod.

Makes me wonder if I'm just strange (please don't answer that) or if there might be a place for such a thing. While bronze might not have a lot of popularity, I'd think that a true flathead "nut" that matched the appearance of a flathead bolt on the other side might be marketable.

As far as nut & bolt vs. rivets goes for safety, I'm pretty comfortable with a nut & bolt in this situation - especially since there will be at least 6 if not 8-10 of 'em. I just don't see the vibration necessary to loosen up a properly torqued nut happening - and the major problem with nuts loosening is improper torque.

Cheers -

Garret

Todd D
03-20-2010, 08:04 PM
Why not just tap the plate for the appropriate size threads. I would go with NF for a 1/4" plate. If It was my boat I would drill a counter sink into the outside of the far side and then peen the bronze rod to fill the counter sink. You can always drill the peened end of the rod to remove it.

Garret
03-20-2010, 08:31 PM
Why not just tap the plate for the appropriate size threads. I would go with NF for a 1/4" plate. If It was my boat I would drill a counter sink into the outside of the far side and then peen the bronze rod to fill the counter sink. You can always drill the peened end of the rod to remove it.

That's a thought - but I wasn't 100% comfortable with 1/4" of threads. If it were 3/8 plate - no problem - but that's thicker than I need for the straps themselves.

htom
03-20-2010, 10:19 PM
You could use flathead bolts from both sides, into a bronze coupler embedded in the rudder (or a pair of bronze heli-coils, embedded in epoxy in the rudder.

S B
03-20-2010, 11:13 PM
Have you considered putting a threaded sleeve in the wood and a flush nut either side?

waynec
03-20-2010, 11:50 PM
Application:

rudder straps: bronze strap 1/4" thick, 2" of rudder, another strap.
Criteria:

I can put flathead bolts through from one side
I don't want nuts on the other side
Need 3/8 or 5/16 diameter.
bronze
flathead

- with a taper like that of a flathead bolt
- so they end up flush to the strap.


Might try McMaster-Carr http://www.mcmaster.com (http://www.mcmaster.com)

. . . a long way around would be to use Thomas Register http://www.thomasnet.com (http://www.thomasnet.com) to seek out fastener manufacturers who make bronze fittings, then narrow it from there.

Garret
03-21-2010, 07:44 AM
Have you considered putting a threaded sleeve in the wood and a flush nut either side?


Hmmmm.... Or - turn that idea around - internally threaded rod through the rudder & a flathead bolt from either side. No - I hadn't though of that. Bronze rod is easy to find, all I'd have to do is cut off, drill & tap. Easy!

Nice idea - thanks!

Garret
03-21-2010, 07:48 AM
Might try McMaster-Carr http://www.mcmaster.com (http://www.mcmaster.com)

. . . a long way around would be to use Thomas Register http://www.thomasnet.com (http://www.thomasnet.com) to seek out fastener manufacturers who make bronze fittings, then narrow it from there.

I'd checked McM-C. The problem there (as with others) is finding bronze. I'd also checked ThomasNet.com (remember when it was about 20 paper volumes that were out of date as soon as they were printed?) - but only found mfr's who would maybe do a custom job - 5,000 pieces or the like.

Thanks though.

Garret
03-21-2010, 07:51 AM
You could use flathead bolts from both sides, into a bronze coupler embedded in the rudder (or a pair of bronze heli-coils, embedded in epoxy in the rudder.

Wow - I missed this post. My apologies - as I think you came up with the winning idea. I like the idea of a metal connection between the sides - so will probably go with the coupler.

Sometimes the "go to first unread post" function here in the forum skips some.

Vinny&Shawn
03-21-2010, 07:53 AM
I/4" inch plate tapped will work well and won't come loose if let into the wood and torqued up properly.
If you prick punch the end of the bolt where it sits flush with the plate, just enough to hold it from working,it can be backed out with no damage to threads and used again.

Garret
03-21-2010, 09:10 AM
I/4" inch plate tapped will work well and won't come loose if let into the wood and torqued up properly.
If you prick punch the end of the bolt where it sits flush with the plate, just enough to hold it from working,it can be backed out with no damage to threads and used again.

Hi -

I could do that, but don't completely trust only 1/4" of threads. If it were 3/8 plate - fine - but it ain't. I was taught that depth of thread should at least equal the diameter of the bolt. Yes - if I use 5/16 bolts it'd only be 1/16 less, but, after chamfering the hole, it could end up less than 1/4".

If I use the coupler in the center idea I can get 1/2" or more of thread & that makes me feel better. I know, I probably worry too much. Worrying about an external nut (or 8) on a rudder is probably silly anyway!

Thanks though -