taking one frame at a time since 1999

'soft' steel balls... good idea? + silver solder question

Hello everyone,

Just a quick question about ball bearings... I came across these ball bearings which say they are 'machinable' and low carbon...

I was wondering if it would be a good idea to buy those or not... I have so far used stainless steel 302 steel balls, as I found recommended here mostly as well, but still had to anneal them to make it possible to drill through them... This means they're softened anyway of course, but I don't know how comparable that would be the ones offered here... It says they're 'soft polish AISI 1018 Carbon Steel'. Say, I'm using ordinary mild steel for the joint plates, would these softer steel balls still be hard enough to work well as a bearing?

I noticed with other steel balls I used which were annealed by someone else, that they may have gone too soft, as of some even the surface seemed to be affected and showing some irregularities... The ones that I tried annealing myself were still quite hard but possible to drill through with some patience...

I'm very new to ball and socket armature making and have just been diving into it since the last couple of months. I might open another thread for more of what I'm working on, but here's a link to a little test of what I've achieved so far:

* edit: just adding a question about silver solder... Which so far I've been buying at a store at my university (I need to check the exact brand/name of the stuff sold there again), but it seems it is turning out pretty expensive (14p per cm) (I'm going through it quickly sometimes, due to learning and needing practice, making mistakes, etc.). I found some online suppliers where it seems a lot cheaper, but I don't know what to consider exactly for good quality. I know it has to be high silver content, so about 55%? I read about a brand name in another topic, but it seems to me that it is a US brand as I couldn't find it easily to buy from UK suppliers (I'm in the UK). Is there anyone out there with good advice on UK suppliers for silver solder? I found something 55% called 'Fontargen A 313', about 20 pounds for 5 meters... does this say anything to anyone here?

Thanks for the time reading this as always, appreciating any help. :)


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Just don't "ram" the drill (or center drill) into whatever you are drilling.That's a sure way to break drill bits,center drills or drill cock-eyed/crooked holes. With twist drills drill/peck until you get a good start into the work,but you drill,back it up,drill,back the drill out again(clear chips) continue and proceed to depth.With center drills... a smooth,continious pressure (feel the centerdrill as you plunge it into the work).Peck drilling does not work(or is necessary) when center drilling.If there is squeeling,chatter,dark blue/purple chips(slow down),you might also want to look at the working tip/cutting surfaces of your tool.Always a good idea to use cutting oil when drilling,reaming or taping if using HSS or Cobolt tooling.

I'm like 2 years late on this post  I've been unintentionally 'on leave' away from 302 stainless balls, one should not need to anneal balls to drill it. Annealing process can be tricky. I've done annealing & hardening on regular steel stock, but stainless steel I'm not familiar about annealing or if it can be done or if it's difficult. Cobalt drill bits is the way to go for drill 302 SS and just lasts longer for general metal drilling than HSS drills ....

316 balls not recommended. Even cobalt drills has difficult time. 302 is just the right  hardness where it can still be drilled and the ball hard enough so it will not wear against the plates. One always wants the balls slightly harder than the plates.

Also especially doing any metal cutting, machining, tapping, use a good lubricant fluid ... this is my fav ... can be used on all metals ...

@Roos Mattaar .... I am impressed ... cool  bird armature being more complex than usual humanoid armature. My beginning armatures many, many years ago back in the 20th century  were not anywhere as involved as this! You got some skills there!

Haha, thanks for the 2 year late reply. ;) I did find out in the end that I could easily (well, taking my time, drilling slow speed, getting quite bored at the pillar drill ;) ) drill through the ss302 balls. For some reason when I first tried I couldn't and I was biased thinking to have read that it wasn't possible. Trying to anneal the balls hadn't been a great move, as I found later it had damaged the smoothness of the surface. :S I remember it was difficult to find clear information of the exact temperatures and speed of heating and cooling down and with the staff in the fabrication centre we just guessed on the information we had using the ovens they had for ceramics and which could be programmed to heat up to a certain temperature within a certain time, etc.

Anyway. so ss302 with good drill bits seems to work out fine indeed. :) Yep I have some cutting fluid. The link you posted doesn't seem to work, but I can copy the name and look it up. I used what they had in the metal centre when I worked on my bird, now I have some of my own, tectane CO507 or so, anyway, it works. ;)

Thank you! Yep I did choose a rather complex project to start with, haha! It was a great journey with lots of mistakes and a great learning curve. :) And looking forward to do more armature making, now in my own workshop. :)

For the vast audience, this is working link ... called Tap Magic. they have various lubricants but this is the original formula I like that works for all metals ....

One can purchase elsewhere. Just posting  Amazon because they seem to have monopoly as 'One World' supplier to the masses survival needs  ... but I digress! 

This is good timing! I've just bought my first ball&socket armature, an Armacreatures professional. Looks good but at $250 AUS I won't be buying many more.So I've been looking for information and sources of materials to make my own over the last couple of days. This link was very helpful:

A little more research told me that 302 stainless steel cannot be hardened anyway and is supposed to be a compromise between hardness and machinability.

I'm considering using brass for the plates and connecting bars as I can get suitable sizes on-line at sensible cost here in the outer wilds of Australia. Does anyone have experience of brazing brass to stainless steel?


Edit: OK I've answered my own question with a quick look on YouTube. Should have done that first! Silver solder it has to be. Expensive stuff, but we should only need a pin-head sized piece per joint. Plenty of heat and the right flux being the key to a good joint with minimal wastage of the solder.

Brass will braze to steel just fine. I use low carbon steel or 302 rod for connecting rods. You actually never want to use hardenable steel or you will wind up having the ball snap off the rod at the braze point. Using brass for the transition base for the clamps is fine (and much nicer to machine) but for the bearing plates will not work well. Brass is too soft a material and will "gall" (not move smoothly). A low rent fix is to "tin" the bearing point on the plate with pure tin or other soft solder (tin is best); use low temp solder flux for this. Flow the solder on to the plate bearing point and flick/shake the excess off leaving a uniform film. If it's still a touch rough you can whip up a cheap lube of graphite mixed into Vaseline; works great. The ideal way to go is using 510 phosphor bronze for the clamps/bearing plates. This is the good stuff. Trick is it comes in sheets so you have to cut or shear it into strips; not fun. Not cheap either. Still, if it looks like life won't be right without making a lot of armatures, invest in slicing up a few square feet of the stuff; you won't regret it.

How does 510 phosphor bronze compare with O1 steel?  I switched to O1 from 1018 for stiffness, which has been helpful with the teeny joints people ask for these days.

Can't say; haven't done a comparison. but I've made teeny joints with 510 p bronze, and it works fine; the alloy is specifically designed to be a bearing surface, and it is very strong. If I needed an even stronger joint, I could use steel with 510 thin washers let in as the bearing surface. The same approach allows for smooth moving aluminum joints as well (I like the lighter weight for flying rigs). I don't think steel on steel, even when you select complimentary grades of hard and soft alloys, are as silky smooth as 510.

I've used washers in hinge joints and really like the result.  And no, I've never had steel on steel be as silky smooth.  Guess I'll have to get some 510 and try a few joints.

You won't be disappointed. The only hurdle is prepping the sheets (if you're going with solid plates); 510 is tough stuff, steel-like in its machinability and cutting it into nice strips is not a fun activity. Once you have it in proper widths though, it's pretty smooth sailing.

And in a few minutes reading the rest of us gain the equivalent of years of experience and become instant experts. Thanks for sharing this invaluable information.

I have a pile of assorted Aluminium stock, so Phosphor Bronze washers in Aluminium joints is where I'm going to start my experiments in building lighter weight armatures as soon as I get some of the items nearer the top of my ToDo list out of the way. One of the first priorities is making an effective support rig for the seemingly heavy (this is the first armature I have actually held in my hands so who am I to judge?) Armacreatures armature I have just bought.


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