This project will have its knockers

[Ham]

I have a fancy to make a door knocker out of a statue of Ganesha I found in an antique place in India (no idea how much of an antique it is - cost me less than a tenner)



The height is just about right - 14cm, the weight? oh, a mere 800 gm (nearly 2lbs in old money)

The challenge is to contrive a knocking mechanism hinge, with the following key features:

1 - No chance of it falling off. In my mind that will be achieved by a U shaped bracket to bear the hinge pin brazed to the Lotus flower? pointy disc, anyway at the back but screwed and threaded through to the main body (which is a single brass casting) for security, it is unclear to me exactly how secure that disc is.  I would need to consider that drilling and bolting might actually make that connection LESS secure. See detail of head and rear photo.

2 - Able to hinge about the vertical CoG. It will be attached to a single bolt through the door, so liable to turn if that isn't achieved. In my mind, the "U" arms are wide apart, allowing horizontal movement and enabling shims to be dropped on the axle once CoG has been found

3 - Able to have it's lifting angle restricted - really I don't want anyone lifting it past 45% to knock. Again, I thing these shims have multi use.

Any practical thoughts or suggestions? If anyone has the necessary tools and fancies, I would be happy to commission. I am after all going to have to go and find someone to do the work.

Even if you don't have any practical suggestions, feel free to chip in with any social advice or opinion. I discussed the concept with quite a few people in India, and nobody thought it disrespectful. However I'm not overly certain I want to identify my house as apparently Hindu to the outside view, when it isn't.


Detail of head



Rear photo


Side view

[David Martin]

Drill and tap two bolt holes through the lotus flower. Bolt an apropriate bracket on and epoxy the bolts in place. The bracket should be U shaped  (a bit of square channel should do) in elevation and you can offset the hinge as appropriate. Trim the bracket to get the desired maximum angle.

Create an anvil somehow - maybe a large flat bolt suitably coloured - that will sit at the correct distance out from the door.

[tiermat]

There is plenty of katerial, there, to drill and tap one bolt through the flower and in to the head.

I would then make a frame, U shaped side on and inverted T shaped when view from the front.  The cross bar of the T making the pad, the hinge being on the end of the leg of the T.  I would go with 2 bolts through the door as 1 probably won't be strong enough to support 2lb of brass.

Where's loadsabikes when you need him?

[Ham]

The anvil is the easy bit - use the current door knocker's one.

The connection between the disc and the head is probably a spigot out from the disc, probably 6mm or less. You can see it is not the same casting, therefore to rely on it to support the weight long term would be hopeful. Equally if you drill through the contact point, you will weaken that attachment (if it doesn't come free). And of course a mount on the contact point is away from the vertical CoG.

[Wobbly John]

What does the existing anvil look like, and how thick is it?

If I was to do it, I'd start with some 10 or 12mm square brass rod. Drill through for the pivot 5 or 6mm from the end and radius the end about the hole. Cut off 11 or 13mm from the rounded over end. Make two more of these (but possibly not drilled all the way through). File a flat area on the back of the sunflower and silver solder (if you try to braze, you'll probably melt the brass casting) one block on - a steel rod through the pivot hole will help you keep it in the right place and level.

I'd cut a backplate - either a rectangle or a circle from 2-3mm brass plate, drill 5mm holes in this and the backs of the two other blocks. Then these two blocks can be assembled with a steel (stainless?) pivot pin through the knocker and silver soldered to the base plate.

All that is left to be done is to tap the holes in the backplate to take a couple of M6 bolts to go through the door  - or you could tap them before soldering and fix bits of threaded rod in the back and use dome nuts on the inside.

It's something that it would be possible for me to do...



...but I ain't offering. 

[Ham]

Here's the existing



I figger the anvil will do the job

and the rear fixing (2 domed nuts)