Titanium and Steel

[chunkolini]

I have just received a fascinating request. I get offered all the weird jobs.
A customer has asked me to make a sculpture featuring his Mum's replacement hip and knee joints.
He acquired them post cremation.
As far as I know they are probably titanium.
I dont imagine as dissimilar metals they could be mig welded together. How about brazing? unlikely I imagine.
Drilling and bolting? how hard is titanium to drill and perhaps tap?
What is interesting we both had the same idea; use the hip joint as the stamen in an orchid.
Anybody got any thoughts on joining the two materials.
Thanks

 

[eSCHEn]

I can see the stamen idea very clearly, funny how you both came up with it.

Is TIG an option? I'm no expert but I think it'll do Ti but gas is expensive? SWK will be along I'm sure.

Each petal with thread on end, hip joint drilled and tapped (if possible) then screw petals in. Thread lock to hold in best position?

Looking forwards to seeing this one, very interesting project!

 

[roofman]

bizare but a great idea too..."watch list" on this one

 

[MattH]

You can drill Titanium but it work hardens really easily so you got to be spot on with the speeds and pressure and make sure your bits are very sharp.

Tapping is a Bas###d. What I do is tap a couple of threads with a taper tap and then clean out with a bottom tap then go back to the taper and go a bit deeper. If you don't and try to go full depth with the taper it just grabs and jambs. Using the bottom tap every couple of threads give the taper clearance.

 

[eSCHEn]

Okay I am spending my lunch break looking up hip replacement materials now

"Most prosthetic parts are produced using high-density polythene for the socket, titanium alloys for the shaft and sometimes a separate ball made of an alloy of cobalt, chromium and molybdenum." SOURCE

Sounds like it might be a bit of a bugger to work with.

 

[chunkolini]

Useful information already.
For the stamen another idea I had was to weld up a cage in stainless, put the hip into it and crimp it closed.
I am sure it all doable.
Lets hope he wants to go ahead with it.
I should hear more in a few days from him.
I love weird stuff like this.
My Mum had her knee done a few days back, she yelped out loud when I mentioned this.

 

[eSCHEn]

Cage idea sounds good. It could form part of the design quite naturally such as a gazinia's centre. It would look lovely in stainless as you could alter the polish level to contrast against the hip's natural shine and texture.

Have you seen the pieces yet chunkolini? I'm curious as to what they look like after the intense heat...

Fantastic project if it comes about and you're just the chap for it

 

[arthur]

Eeww, each to his own lol

 

[cumbriasteve]

So the lady got and now you have been asked to up the bit that's left, are you sure he was not when he came up with the idea

 

[eSCHEn]

So the lady got and now you have been asked to up the bit that's left, are you sure he was not when he came up with the idea

Best emoticon usage ever.

 

[lundtang]

You can't braze titanium. what you can do is make fully colours with electrolysis. Titanium can be tig welded but I don't know with dissimilar metals.

 

[Maker]

Can you take a picture of the joint? I've got the ball from one but I can't picture the other parts.

 

[Parm]

I have just received a fascinating request. I get offered all the weird jobs.
A customer has asked me to make a sculpture featuring his Mum's replacement hip and knee joints.
He acquired them post cremation.
As far as I know they are probably titanium.
I dont imagine as dissimilar metals they could be mig welded together. How about brazing? unlikely I imagine.
Drilling and bolting? how hard is titanium to drill and perhaps tap?
What is interesting we both had the same idea; use the hip joint as the stamen in an orchid.
Anybody got any thoughts on joining the two materials.
Thanks

Just a bit of Usfull (useless) information, I've seen these being made in Sheffield recently, it's hot forged titanium of the highest quality. Forged parts machined and then hand polished. I've even got a few reject hip joint knocking about in the workshop that were salvaged fom the waste bin

 

[oddbob]

It'd be cool if you could utilise the joint(s) ...a poseable orchid? Much more faff, but could be interesting.

 

[Kent]

weird dood that customer Its worth a fair bit as scrap and there are safety precautions you need to consider in the welding and working of titanium, I will leave that to someone with more current experience to explain its been a while and things have likely moved on in the last two decades

 

[Gareth J]

replacement joints have a pointy bit on them that are rammed up a bit of bone to hold them in place.... don't they?

poke that bit into some molten lead and let it set? or even ram it into an appropriately sized steel hole. They're one offs so I'd be concerned about messing up the finish by doing anything very hot on them.

 

[chunkolini]

We are just at the talking stage, my instinct is to avoid heating or modifying them and work a way of caging them to the structure.

 

[PTvor]

There's lots of information out there on joining titanium,

http://www.totalmateria.com/Article136.htm

It can be soldered but it's a total mission. If you wanted to make a business of soldering titanium for jewellery or repairing spectacle frames, you could do it. As a one-off where you can't wreck the materials you've been presented with, forget it.

It can be tigged, but I gather that's a specialised thing with everything done to avoid contamination. You could farm the welding out, but I'm not sure it can be welded to anything else. You are only looking for an ornamental weld though.

It could be joined mechanically, say by tapping and putting in a stud.

I'd guess that caging the bits and maybe adding a discrete touch of glue to stop them rattling might be the easiest.

 

[rosinante]

Chunko,
How about just drilling say 3-4 mm then use brass rod as "dowels" and epoxy in, could be very discreet and pretty strong, certainly enough for a sculpture, possibily even the end of the stalk could be filed/forged to be a tight taper fit in a suitable hole again with epoxy or even just a push fit so it could be removed for polishing?
Chris

 

[brewdexta]

Here's my hip joint, I use it to grind up garlic and other stuff in the kitchen. I got it from a friend who was a theatre nurse, its done a few miles I believe They use to swap the ball and leave the joint in some cases, and if you hadn't kicked the bucket by the time the socket was worn out they had to whip the old one out and replace the ball and socket. Remote control for size comparison, the welding mug is in the dish washer.