Speed / Captive Nut Backing Fiberglass?

[Capitain Mike]

Originally Posted by SabreKai

If I'm reading this correctly, you can only get at the holes from one side. So see about getting some blind nuts, which are cylindrical tubes, threaded on the inside with a flange on one end, which has some teeth in it. Usually they go into an enlarged hole from the back and when you put the bolt in from the other side, and tighten it, the teeth bite into the material and hold the nut in place. A bit of epoxy helps hold it there.

However you can put them in from the same side as the bolt if you drill a slightly smaller hole, epoxy them and tap them into the hole. Only problem is that they may get drawn out if you apply too much force to the bolts. Better to fit them in from behind.

Here's what they look like

Google Image Result for http://www.bandbhobbies.com/shop/images/prod_gpmq3327.jpg


Sabre

I have seen something similar but don't know where I will post it if I can find it. The base is flat and round without teeth there are perforations through the base, to enable it to be bonded to something else. A setscrew (threaded all the way) is attached at right angles to the base plate so that the threaded part can go through a hole and a nut attached.

[motion30]

If it were me I would try and get a backing plate underneath Perhaps an aluminum plate drilled and threaded 3/8'' will do it

[Capitain Mike]

Originally Posted by motion30

If it were me I would try and get a backing plate underneath Perhaps an aluminum plate drilled and threaded 3/8'' will do it

3/8 what? the aluminium will not like the stainless steel (corrosion)

Article: Bimetallic (galvanic) corrosion risks from contact with galvanised steel or aluminium

[Blue Stocking]

Why not make that slide-on clip doodad with st.steel flat stock.

[motion30]

Originally Posted by Capitain Mike

3/8 what? the aluminium will not like the stainless steel (corrosion)

Article: Bimetallic (galvanic) corrosion risks from contact with galvanised steel or aluminium

Really ? you dont know how to use ss bolts in aluminium? Ill bet you on your boat there is ss bolts or screws into aluminum

[Capitain Mike]

Originally Posted by motion30

Really ? you dont know how to use ss bolts in aluminium? Ill bet you on your boat there is ss bolts or screws into aluminum

I do but does he?

[motion30]

Originally Posted by Capitain Mike

I do but does he?

I am sorry you could be correct. I guess I expected that he would

[44'cruisingcat]

Stainless T-nuts?

[aboutgone]

here is what your looking for....... McMaster-Carr for .125 panel...1/4 20 bolt.............Ed

[batkins61]

Originally Posted by Blue Stocking

Why not make that slide-on clip doodad with st.steel flat stock.

I don't think I could fab a piece that would be thin enough to fit between the two overlapping fiberglass parts, bend it tightly enough and round enough to provide enough spring to be a "clip", etc.

The one-size-up screws I got are actually holding for now, so this project is dropped much lower in the stack. I don't expect them to last, however. The top of the pedestal has a grab rail which gets constant use, so eventually those screws will stress the fiberglass enough to loosen.

So far, I think the knurled rivet nut provides the best solution. With a bit of epoxy behind the crimp, it will be about as permanent as I will need. Several places (Grainger, McMaster-Carr) provide kits that include a number of nuts of various sizes, an installation tool, and a case. Once the need becomes great enough I'll probably get one of those. I'm sure I'll find uses for them elsewhere as well. Btw, they come in steel and aluminum, and in a limited fashion, in stainless steel as well.

Thanks all! Great discussion!