Chassis fixing problem...a little help requested

[berryr99]

Good morning all,

I am progressing reasonably well with the Chris Ward locos.

However I have hit a problem.

I want to attach the chassis by a 12 BA nut and bolt. I have drilled the hole, positioned the nut and superglued it into position on the loco. However, every time I tighten up the bolt the nut becomes unglued.

The question is - am I right to use superglue or is there another glue that people have found to be more secure ?

I was thinking about using Milliput as a last resort around the nut

I think I could at a pinch use an 8 BA nut but this would mean chopping the chassis about a bit more and still might have the problem of the nut becoming unglued

Currently the chassis is holding with the just the screws in, they protrude a couple of mm above the loco floor where the nuts go on but I don't think they will hold long term. Another option might be to make a small plasticard plate for the top of the bolt to screw into, fix it onto the floor of the loco and that might hold it.

I would welcome any thoughts/views on the way forwards.

Thanks

Bob

[Graeme Dunbar]

My understanding is that cyanoacrylate glue has a low shear strength and this combined with the small surface area will be troublesome. The small size may be an issue with any glue so increasing the effective surface area may be the only solution. Araldite may be a bit stronger.

Can you glue a couple of rectangles of brass or plasticard across opposite flats on the nut or file a hexagonal (or even just square) hole in a small rectangle of material?

Alternatively, how about soldering the nut to a small rectangle of brass and gluing that?

[Hugh Norwood]

I have just drilled the hole in the body 0.5mm smaller than the clearance diameter and found that by slowly screwing in the bolt, it cuts its own thread into the plastic - not nut is required..

[rod335]

This is maybe a more elaborate method but for some years now I have not trusted nuts to hold loco bodies on. They seem to have an annoying habit of coming loose inside bodies where you can't get at them to refix them. I now therefore use a piece of 1.5mm brass tapped for the mounting screw, usually 10BA, sweated to the upper face of the footplate. owever, for a printed body, the same basic principle should be able to apply, a tapped piece of brass of sufficient thickness can be glued to the underside of the body, it would be no thicker than the nut, but the increased area would provide a larger gluing surface. Tapping holes is not difficult and taps are easily obtainable from Expo, Eileens etc. The piece of metal used does not have to be elaborately or even neatly shaped, and the bigger the better.

Rod

[Isle of Stoner]

The Chris Ward locos I've built, 2 Fairlies and a side tank, I've superglued the chassis in with just a small blob at each end. I needed to remove one of the Fairlie chassis and it just popped out with a small amount of leverage. I'm a simple soul but it worked for me.

John W

[berryr99]

Many thanks for the advice received, I find this forum really helpful.

Specifically:

Hugh - I know I should have done it this way but I forgot to re-read your advice on the posting about the Chris Ward loco !

Rod - My skill level is about zero at this stage and I was worried about tapping metal: I will learn it one day !

Graeme - Was concerned about soldering brass, I know I shouldn't be but I refer to the above comment about skills !

Taking all suggestions into account I have found a way forward that I think will work (bench tested it and seems OK)

I have drilled a piece of plasticard with a hole just slightly narrower than the nut. Then using a pair of pliers I have force-fitted the nut into the hole and then sealed it in with superglue. Then I will trim the plasticard down and fit it to the footplate to give the additional adhesive surface needed, I might Araldite it down. I will probably conceal the fitting with a crewman.

Thanks again for the very helpful suggestions

Regards

Bob

[berryr99]

John,

Thanks for that - I have just posted on this and I decided to ignore the system warning that another post on the subject had been made !

Hmmm.... One of things I am trying to do is increase my skill level (because its nearly zero right now !) and whilst I respect the suggestion you made in the Chris Ward posting I didn't feel it would actually let me do that.

It does seem an effective was of solving the problem though.

Regards

Bob

[Hugh Norwood]

I have drilled a piece of plasticard with a hole just slightly narrower than the nut. Then using a pair of pliers I have force-fitted the nut into the hole and then sealed it in with superglue. Then I will trim the plasticard down and fit it to the footplate to give the additional adhesive surface needed, I might Araldite it down. I will probably conceal the fitting with a crewman.

That reminds me of a way I used to make a "keeper" for nuts.
In a thick piece of plasticard, I drilled a hole slightly smaller than the nut. Then I put the plasticard flat on a piece of wood with the nut resting on the hole. I then presed down with a hot soldering iron. The nut melts its way into the plasticard making a very tight fit. If you use just the end of the iron, there's no problem with actually soldering the nut (or mucking up the iron tip).

Take awya the heat and with a bit of trimming you have the perfect holder for the nut. You fix this to the chassis (or whatever) then glue on top of it a further piece of plasticard with a clearance hole in it. This stops the nut popping out.

[berryr99]

Thanks Hugh.

This falls into the category of "I wish I had thought of that"

Your way would place less stress on the nut and this would obviously better.

I will make a second keeper plate as you suggest as this will finally and firmly secure the fitting.

Regards

Bob

[engerth399]

Hi,
I find a 2 part epoxy resin an effective way to hold a nut in a non-metal body.  Care will be needed to keep the threads clean and I always run a tap through it after the glue has set to clean out the threads.

Peter

[berryr99]

Thanks for all comments - I finally secured the chassis with the "pressure fit nut to plasticard, super glue in and then superglue the plasticard to the cab floor" method.

I found a tool in my computer repair kit that was very helpful for handling small nuts and bolts.

Its a wire claw that is tensioned by a push button on the body of the tool, bit like a biro.  I think they would be available via Maplins.

It is excellent when trying to get small screws in - my fingers are like bananas !

Bob