T-nut pulling out

[Steve Aiken]

Well, it's not exactly a t-nut. It is part of a cradle pivot hinge that installs in the bed of the cradle and the pivot bolt screws into the 'nut'. You can see it here http://www.woodworkersworkshop.com/s...w/29_CHNG.html. The problem I have is that after a few days, the 'nut has pulled out of the cradle by about 1/8 inch.

I did not use epoxy. Would you recommend removing the 'nut' and reinstalling it with epoxy? Any tips?

Thanks,
Steve

[pat warner]

Looks like you have to drill through and put the T of the T-nut on the other side of your stick.

[Joe Kieve]

No need to use epoxy if you do as Pat said, put the nut on the other side.

[Greg R Bradley]

If you have installed it so that it is possible to pull out then it has to be installed backwards.

Those are called Propeller Nuts and are a variety of Tee-Nut. The MUST be installed so that the screw pulls it tighter into the wood. The screw head and the flange of the Propeller Nut are at the extreme opposite ends of the assembled part.

[Steve Aiken]

cradle_hinge_instruction.png




Thanks for the replies. It is not feasible to drill out and put the nut on the other side. I have installed it per the instructions.

[pat warner]

Don't want to risk a baby on the deck. Change hardware for offspring's protection.

[Lee Schierer]

cradle_hinge_instruction.png
Thanks for the replies. It is not feasible to drill out and put the nut on the other side. I have installed it per the instructions.

It appears that you may have allowed too much space between the rocking part of the cradle and the stationary part. Those nuts were designed to support a vertical load, not a load that would tend to pull them out. You might be able to replace them with a threaded insert depending on what size thread the bolt has. Knife_1.jpg

[Andy Giddings]

Seems a strange way to design a hinge of that type. Unless the cradle uprights that hold the hinge are very strong and do not flex (which I find hard to believe as it looks like 3/4 thick but a narrow depth), the t nut will always be prone to coming out unless its epoxied in as suggested by Steve. If the t nut was on the opposite side of the upright it would be a lot safer - but obviously less attractive

[william watts]

It may be that there is to much play between the cradle supports and the swing part, allowing the cradle to shift from side to side. That would pull the T nut loose. You could install a washer between the T nut and the nylon T bushing as a spacer to eliminate any play, maybe one on each side. T nuts are usually installed so the bolt threads in from the side opposite the head. That's an unusual application for a TV nut. The diagram sure helps.

[Greg R Bradley]

cradle_hinge_instruction.png

Thanks for the replies. It is not feasible to drill out and put the nut on the other side. I have installed it per the instructions.

Wow, that is amazing. The designer basically violated the instructions of the hardware designer. I buy Propeller Nuts from several different suppliers and they are all very clear on intended purpose.

If you install it that way then you are completely relying on the glue, which would normally not be used in the assembly at all.

The only place I've ever seen hardware threaded in from that side is where you add a Tee-Nut to a leg for an adjustable foot. This only works because you have constant weight holding it together. Even then, it is prone to failure.

A possible work-around is these, basically designed for the above purpose with additional holding power: http://www.rockler.com/screw-on-tee-...se-size-thread

Designed to have screws hold them in.

[Steve Aiken]

Thanks again for the replies.

I measured the cradle bed length and compared it to the length between the pivot points on the leg assembly. The bed is, in fact, 5/16" short - better than 5/16" too long, I guess. I will look to find a couple of washers to give me an extra 1/8 inch on either side and I'll glue these to the Propell nut flange.

I sent enquiries to the Canadian distributor and the American supplier and received similar replies. The recommendation was to gently back the nut out by turning clockwise, apply a small amount of epoxy on the barrel and retighten the nut. I'm expecting that with the epoxy and a couple of spacer washers, that it shouldn't loosen again.

I'll post project photos shortly.

Steve