How would you make this

[Speedy Builder5Participant @speedybuilder5]

How would you make one of these. The original is some sort of cast?? aluminium alloy and is part of a winding mechanism for winding back a swimming pool cover. A 'friend' arrived with the complete mechanism. Spare parts are not available as the rest of the mechanism is a right angled gear box – also made of Al Alloy, which was assembled and then swaged together. To get to the broken bit, I have had to machine away part of the swaged bit to release the components and thought of a way to get it all back together again.
To give you an idea of size, its length is about 50mm, and the boss diameter about 18mm with a 9mm hole running through it. The maximum outer diameter is 34mm and the angular groove between the 18mm boss and the "finger" is 4mm x 18mm deep.

I proposed to make the replacement from a bit of bronze. I have at my disposal a lathe and manual vertical mill and rotary table.

Question – How best to make it ?
BobH

[Speedy Builder5Participant @speedybuilder5]

Swimming pool cover winder component

[JasonBModerator @jasonb]

From Bronze would allow you to silver solder on the tab in which case it is mostly a straight forward turning job, turn the outer face of the tab after soldering.

 

If you want to do it from solid then it's a trepanning job followed by milling away to leave the tab

Edited By JasonB on 12/06/2018 16:21:35

[Speedy Builder5Participant @speedybuilder5]

I thought about that, but didn't have confidence that the silver solder joint would be strong enough – the size of the joint pad would be about 3mm x 10mm.

[Jeff DaymanParticipant @jeffdayman43397]

For two piece construction in bronze you might try making the tab as a cup shape in the lathe, open end out, then milling away the cup to leave a tab and a ring with a centre hole. The centre hole of the ring could be passed over a turned bronze core and then silver soldered. The ring and tab part would be strong as possible because they would be made from one piece, and the silver solder joint being a ring all around the centre core would also be strong.

Good luck.

[VicParticipant @vic]

Notwithstanding that this part may have been abused, its looks to be cast from a material that perhaps wasn’t up to the job. Given that you’re likely making it from something tougher the replacement part may not need to look exactly like the original provided it performs the same function. I’ve found this in the past with parts I’ve made. They ended up looking somewhat different because of the (different) process used to make it. This is a judgment only you can make but bear it in mind before slavishly copying what’s in front of you, it could save you some time and effort.

[Speedy Builder5Participant @speedybuilder5]

Vic, you are spot on the money, I couldn't work out why it was so complicated. It was designed to have "slack" in the movement to help engage a square peg drive into the end of the roller of the pool cover. But the "Customer" is a slave to detail !!
Jeff's idea is a good one – in fact the one I went for in the end (after snapping my finest 3mm wide boring tool – Grr)

[VicParticipant @vic]

Nice job!

[Howard LewisParticipant @howardlewis46836]

He'll be back soon with the next weak link in the mechanism; "Can you just? Shouldn't take you long"

Howard

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