Here's another subject I know has come up in the past,or at least I know that "silver brazing" is no stranger to subject matter.This is one skill I have yet to really master. I find myself needing to braze very small ball bearings to very small diameter rods.As small as .0625 to .125 with rod ends ranging from .03125/.040 to .0625 and the metric equivalents.Pretty much anything larger than .125 is a "normal" ball joint in my mind. I find it somewhat intimidating,not just because I have never silver brazed anything before,but because the bearings and rod ends are so very,very small.Maybe it doesn't matter if it is a .0625 bearing or a .250 bearing being soldered to a rod end? I've read in the past that Laika used micro/mini torches to solder .0625 bearings so not to fry them bearing beyond recognition and others have said you don't really "need" that. This is something i have to get comfortable doing and get used to doing "very well",otherwise I'm not going to be much use when it comes to fabricating armatures.
I have been making ball joints for character I am currently working on, and I also have been using ss balls as small as 1/8'' (I work better with fractions). I go about it the same way as I go about using 1/4'' ss balls, using a propane torch and assorted pliers and tweezers to hold on to the things. The only real difference I can see is that since everything is smaller, things tend to be harder to handle and heat up much faster. To minimize everything flying away, I will heat the ss ball down and the rod up so the ball rests on an aluminum plate on a tile floor. This way if I lose the ss ball, it doesn't disappear in carpet (not to mention less of a fire risk). It does take practice. I still will have to try more than once to get a solid joint from time to time.
I know Micro Mark has some decent tools for handling "miniature" parts such as bearings and screws,nuts and bolts, as well as "miniature torches". Those might be helpful?I'm just concerned that I'm going to waste allot of bearings(like dozens) trying to heat them up properly for brazing.Just wondering if I should (just for the small parts) use a smaller,miniature torch for it?I mean...would it make heating up the bearing and rod easier and less troublesome?I'm also hoping that Abbott Ball can drill the small bearings.It would alleviate allot of trouble and time if it doesn't raise the cost too high?
I use stay brite solder for the 1/8 ball joints as the melting point is low
I hold the 1/16 rod in a vise and put the ball on top with the flux and solder in the hole then I put some metal stock on the ball and heat it up with a propane torch and when it melt the solder you can see the ball slide onto the rod and then I take the heat away.
Well,part of this is stemming from something I'm working on(been working on) for a long time and I'm just trying to get it off the ground(so to speak).While the scale I'm working in I think would be considered "larger" than average,the parts and assemblies are still pretty small.The ball sockets need to be small in order to be contained within,so I have sort of painted myself into a corner (so to speak) with needing to use such tiny joints.One of the parts is going to have a "square" end,so I'm wondering if that may present any major issues when brazing it into a very small 3/32 (.09375) bearing?I may need to touch it a tad with a file to make it fit into the hole,but I'm wondering if I should do anything else to assure it is in "solid"?Also,for these really tiny joints,I'm wondering if I might get away with "epoxying" them into place because the joints are so small,I'm not sure they will be under the same strain as other joints in the armature?Any thoughts?
I would say no to epoxy but I am sure others have tried it and I worked but I would not trust it if it had to twist.
Well,"no twisting" that I can think of.I'm actually working on designing "small" jointed hands which is proving to be quite troublesome.The two ball joints will both be 3/32.One at the wrist and the other at the base of the thumb.Even at 1/4 scale the hands are quite small.I'm running into design issues with joints and proximity to joints.Namely the two ball socket joints I am employing in this design.The joints will be snugged only as much as they need to be,so they won't be *cranked* on like typical armature joints,the hands won't be "loose",but due to the size of some of the screws,I don't think I can snug them down hard.Some of the screws will be 000-120 in size and I'm going to try to use 00-90 and 0-80 if and when I can.The base of the hand is what is giving me the most trouble.I spent all weekend just drawing/drafting the same part(s) over and over again(I was making myself a little crazy).What I had originally in mind just wasn't working on paper.I re-designed the base of the hands(top and bottom) into one large plate,but the corner of the hands have this small 3/32 ball socket at the base of the thumb and then another at the wrist.All the fingers are to be hinge style joints holding all the assemblies together,again mainly with the super tiny 000-120 screws up to 00-90 and 0-80.Many of the parts are very small, .075x.125(varying in size/dimension),others are .100 x .125(again varying in dimension),but I'm working with .040 s.s plate(probably 302 or 303 stainless).If I can get this to work,I'm going to have the parts photo-etched reducing the machining and machine set up time.I'll only have to make one fixture to do one of two things;hold the parts in place, mill a seat for bearings to ride in,drill and tap parts.The remainder is all clean-up and finessing,but things should fit together like Legos.So,I'm not sure if I should consider "epoxy".I'd rather silver braze it.I need to learn how anyway.
I have been thinking for a 3/32 ball joint the rod can be soldered to the side of the ball instead of drilling a hole in the ball. Got pictures of what your trying to do?
Yeah,I have a very "crude" and simple" sketch.All the stuff I drew up over the weekend is in the recycle bin.If you wanted to braze to the ball,wouldn't you just need to orient the ball(after you braze it in with a rod) to make it "on its side?".Maybe I'm not understanding what you are doing?Anyway,here are my very simple sketches.A friend of mine will be drawing the finished prints up in AutoCAD for me.After the P.E company has a look over to see if there are any problems,I'll find out how much this may cost.Thing is,I have 3-4 other 1/4 scale hands differing slightly in size,so if this one works I am pretty sure I can use the same "model" for the rest of the hands,I'll just be using some different screws maybe? I should be able to get quite a few pairs out of one 24" sheet.
just an idea I had about small ball sizes was to solder to the side of the ball but it would limit twisting action
Well,one could(if they have the tools) either mill or grind a slot on the surface of the bearing for the rod to sit,set it in with at least "one" screw to hold in place then silver braze it.Basically filling in the slot with silver solder and burying the rod in solder.Then clean it up with a file,maybe polish it?