Other Silver soldering (brazing) drill extensions & deep hole drilling

[Mcgyver]

Janger asked for some pics of silver soldering drill extensions. I had a bunch to show, but didn't want to take the other thread so far OT

First example was making a new high precision spindle shaft for a mill - its close to a foot long. There is a way to drill long holes like this by first single point boring the hole say 1-2 the nominal diameter deep. The hole is then started perfectly. Now run a precision ground drill of the nominal size into the hole and cut just enough at the end to form a divot, that because its guided by the bore, will be perfectly concentric to the bore. then alternating between drill, reamer to nominal size, then use a nominal size drill to create a new starting centre at the end of the hole. Things stay true because over this short distance, the reamer is guided by the existing bore. Do this every 1/4" - 1/2 (depending on hole dia) or so and you can drill 20-30x the diameter and the hole comes out within a thou. As good as gun drilling with no special equipment. You need a precise grind on the drills, especially the nominal one used to keep establishing the starting diviot. I use a T&CG to sharpen them or use new high quality drills.

Note the wet rag as a heat sink when brazing the drill. SS is easy, clean, lots or flux and mostly try and get the heat there indirectly. I use air/propane most of the time (yes its more than hot enough) but on large pieces use the higher heat output of O/A - then you must definitely apply heat indirectly (propane air is easier and more forgiving). Not so much here because appearance didn't matter to me, but most of the time when SS'ing I use the technique Kozo Hiraoka covered so well in Live Steam so long ago. Clip little pieces of 1/16 dia SS, place them in the flux with tweezers and warm the two pieces up until it neatly wicks in. Neatest joints possible with no excessive SS blobs

then to the grinder

Second example is a 1/8 hole through 4" of cast iron - it ends up being the relief in the corner of a dovetail. Those drills/reamers were soldered with a butt joint and worked fine. In the first photo, the brass shim is there to keep the small diameter extension concentric with the reamer

30x the dia and its within 2 thou end to end

 

[PeterT]

I'm glad you kicked off this topic @Mcgyver Lots to learn & compare notes. I recently bought a some Harris Stay-Silv White flux & Harris Safety-Silv 56 silver braze wire to make up some components for my radial. Turns out I solved these particular issues by other means so have only been messing around with silver brazing, making small test samples. Its definitely a process I want to delve into further. I see so many model engineering assemblies that are bonded this way ranging from simple to complex. And special tooling like you showed.

This was my gear blank mockup. There was maybe only 0.001" diametric gap between the 2 components so that's how I made the tester. It appears I got penetration in the annular joint. All I have right now is propane/air torch. I snipped off little segments of SB wire like you described. After some heating, the flux went from frothing a bit to clear & then Zip, in flowed the solder. What surprised me was amount of heat required, the steel was a dull red color by the time flux was ready. I didn't have any issue removing the flux residue, came off easy by itself or hot water. But is took some Dremel work to de-blacken the non-flux blackened areas clean. I've bought some citric acid powder you mx with water but haven't had time to try that. I hear some people both prep & post-clean that way. Ant advice on that front appreciated.

 

[PeterT]

There seem to be a lot of different brands out there. I found some at jeweler supply places. Some branded, some house branded (ie. likely re-packaged). Very application specific. I found the Harris site to be good for understanding specs & applications. Not really an endorsement, just how I stumbled my way through. I ended up buying supplies online, the price was reasonable.

https://www.harrisproductsgroup.com/en/

 

[Mcgyver]

Just be careful with jewelry people....some use different nomenclature. If its clear from the package, no issues, but some of them call stuff silver solder that we'd call silver bearing solder - i.e. like 5% silver. When we refer to silver solder its material over 50% silver and is brazing, i.e. over 800F...silver bearing solder is not. SS has a tensile strength at or surpassing mild steels whereas soft solder is less than 1/10 of that. https://www.silfos.com/Lucas/Technical-Documents1/Easy-Flo45TDS.pdf

I think I'm using easy flo 45, in a 1/16" diameter wire (so I can clip pieces and place them on the joint Kozo style.) Silver brazing is probably a more accurate descriptor of the process, but I learned this stuff from some of the great British home shop and model enginering publications and am not changing my diction now to suit a bloody jeweller

There are two reasons (I can think of) to use SS - withstand high heat, and its high tensile strength. Where there is a large surface soft solder is often a good choice - i.e. its lower tensile strength is made up for by the surface. That might be an easier approach than SS for something like those gears...or loctite or an interference fit. Not saying you did so, but as a general statement it seems often people go to SS when soft solder might have been a better choice: less heat, not much of a heat affected zone, doesn't warp thin sheet and so on

 

[PeterT]

Totally agree, the (silver/braze/solder) words get thrown around rather loosely & as you say, varies again on the other side of the pond to make things even more confusing. I chose 'silver brazing' to hopefully make that distinction. I noticed the Harris website has changed since I last visited, but I downloaded a large-ish PDF guide a while back which has some nice tables listing all their brazing wires, fluxes, strengths, materials etc. I'll see if I can upload in the Resource section. Meanwhile here is Safety-Silv 45 spec sheet.

 

[Proxule]

slick work, thanks!

 

[Rauce]

I do a fair amount of silver brazing for bicycle frame work. I used Harris 45 and 56 with white flux at first. 45 for small fittings where you want a bit more of a fillet or a small gap needs to be filled and 56 for lugs and sleeves. 56 flows into tight spaces much better.

I bought some flux and wire from a supplier called cycledesign a while ago that I’m still using. They have a gray coloured flux called “stainless light” that I find works better than the Harris white flux. Stays active to a slightly higher temp and comes off very easily in warm water. They have a 48% silver wire that is supposed to flow just as well as 56 but costs a little less so I bought 5oz that I’m still working through.

 

[PeterT]

Maybe a good working definition for our discussion purposes

So what is the difference between brazing and soldering? The American Welding Society (AWS) defines brazing as a group of joining processes that produce coalescence of materials by heating them to the brazing temperature and by using a filler metal (solder) having a liquidus above 840°F (450°C) and below the solidus of the base metals. Soldering has the same AWS definition as brazing, except that the filler metal used has a liquidus below 840°F (450°C) and below the solidus of the base metals. Soldering can be considered the low-temperature cousin to brazing.

Metal Joining: Brazing vs Soldering

lucasmilhaupt.com

 

[PeterT]

I've heard people reference this line, but I found it a bit harder to source

SILVALOY 505

lucasmilhaupt.com

 

[Dabbler]

Really great descriptions of silver soldering!

 

[Ian Moss]

I didn't see any mention of black flux. I find it works well for me.

 

[Janger]

Janger asked for some pics of silver soldering drill extensions. I had a bunch to show, but didn't want to take the other thread so far OT

Second example is a 1/8 hole through 4" of cast iron - it ends up being the relief in the corner of a dovetail. Those drills/reamers were soldered with a butt joint and worked fine. In the first photo, the brass shim is there to keep the small diameter extension concentric with the reamer




View attachment 22696

I like this! I was wondering how to solve the alignment problem of the shaft and drill being of different diameters. Very clever!

 

[PeterT]

I didn't see any mention of black flux. I find it works well for me.

Coincidentally, I got an Amazon wire + black flux combo for a good deal, but haven't tried Black yet. I know Robin.R mentioned it when he was doing something cool, maybe brazing carbide or something. Some specs screen grabs.

 

[PeterT]

I do a fair amount of silver brazing for bicycle frame work.

Cool. Feel free to post some pictures & interested to what your torch setup is.

 

[RobinHood]

I use the black flux for all the silver brazing as well. Seems to work very well. As mentioned, Robin Renzetti uses it extensively and it was recommended as a companion to the 55% SS.

 

[Rauce]

Cool. Feel free to post some pictures & interested to what your torch setup is.

I went looking and couldn’t find that many photos… Here’s an early frame of mine from 6 years ago that is fully silver brazed with lugged joints. The lugs are cast steel and get cleaned out for a slip fit with abrasives prior to brazing. Tubing is 4130 cromoly with “butted” wall thickness profile, 0.7mm at the ends and 0.5mm in the center. This frame was about 1700gr complete before paint.

These days I generally tig weld the main joints and only braze cable stops and water bottle bosses.

I have a Victor 100FC medium duty torch with an elbow for interchangeable tips with tip sizes 1-4 for propane and a rosebud. I use a BBQ tank and a oxygen tank. In the past I used a medical oxygen concentrator but it’s a bit of a hassle to get going and light the torch compared to bottled O2.

 

[PeterT]

Is silver content brazing preferable over regular braze for lugged frames? I stumbled on Paul Brodie's channel a while back. Some of those joints look like fillets but I haven't watched them all yet. I had never heard of a 'fluxer' before (premixes into acetylene). He has a few brazing vids.

https://www.youtube.com/c/paulbrodie/search?query=brazing

 

[PeterT]

I went looking and couldn’t find that many photos… Here’s an early frame of mine from 6 years ago that is fully silver brazed with lugged joints. The lugs are cast steel and get cleaned out for a slip fit with abrasives prior to brazing. Tubing is 4130 cromoly with “butted” wall thickness profile, 0.7mm at the ends and 0.5mm in the center. This frame was about 1700gr complete before paint.

Nice. My buddy used to make his own roadie frames. I was amazed at how thin the tubing was & how nicely made the lugs were. He had a really neat, heavy duty jig so custom sizes & geometry layouts could be accommodated. I wish I had pics.

 

[Rauce]

Is silver content brazing preferable over regular braze for lugged frames? I stumbled on Paul Brodie's channel a while back. Some of those joints look like fillets but I haven't watched them all yet. I had never heard of a 'fluxer' before (premixes into acetylene). He has a few brazing vids.

https://www.youtube.com/c/paulbrodie/search?query=brazing

Silver and LFB (low-fuming bronze) can both be used for lugged and lugless (fillet brazed) construction. Silver generally lends itself better to lugs since it flows more easily and at lower temps. LFB builds up easier so its better for fillets, unless you have stainless in the mix. There's stuff called Nickel-Silver that I've never used which is like LFB but compatible with stainless, despite the name it is more like "nickel-bronze" in composition.

A big reason to use LFB as much as you can if you're doing higher volume production is cost, it's just so much cheaper. The flux is harder to clean off though.

I actually have an old fluxer but I've never used it, a friend gave it to me a few years ago. I'm passing it on to another framebuilder in a few days who will put it to use. It's a super simple device, it just uses gas pressure to bubble the fuel gas through flux that's been dissolved in acetone.