Silver Solder

I use superglue to hold the metal block. The purpose of the block is to prevent you from compressing the gap when you are turning between centers. The metal block does all the work, the superglue is to make sure the block doesn't fall out. I have made two cranks this way and it works well.

It is also possible to make a crank out of two pieces of drill rod and two flat plates. Many people have good luck with this. One guy told me he made a dozen cranks and they all held up well. I had one made and it failed quickly becuase the silver solder did not flow very well. After my failure I leave a couple tips from the successful guys. First is that you need about 2 thou clearance for the silver solder to flow. Second is to cut some tiny grooves in the plates with a small triangle file to ensure the silver solder flows into the joint well.

chuck

I went into a jewelry, hobby, shop and bought a 2" (3" ?} ssquare, 1/32" thick piece. Cut it with a tin snips and it is just the right size for braze my bandsaw blades.

Paul in AJ AZ

turning out the connecting rod journal first, then

I'd suggest soft soldering that "brace" and using "Tinners fluid" (acid flux) to make the solder wet the steel. There's a branded acid flux ("Duntons") which is often available in small bottles in hardware stores. That way you won't risk raising the temperature of the workpiece enough to start affecting its hardness. If you insist on silver soldering it you're probably going to have to use your O/A torch, a piece that large is too big a load for the usual Bernz-O-Matic size propane/air torch.

Jeff

Thanks, Chuck. Good tips... and since they come from successful "crank turners" they are evidently valid. I never thought about CA glue - I guess it would work as you mentioned - compression strength rather than tension. Good idea. (I still want to learn silver soldering(brazing) just because it's something I haven't done - and I'm just *that way*. Thanks again. Ken.

Jeff, I was planning on using the OA torch anyway... mainly because I'm pretty good with it and familiar with the heat/areas affected by it. I will check out the flux at the hardware store as you mentioned, (Dunton's). I've never heard of it, but I would imagine it's similar to the acid flux found in plumbers acid core 60/40 solder. I'm looking forward to learning/doing a little silver soldering (brazing) as I understand it's considerably stronger than regular ol' solder, and the strength can be an issue in certain situations. Besides the fact that it's just a good thing to learn new stuff. Thanks for the post. Ken.

Thanks for the warning, Jerry... Along with being unfamiliar with silver soldering (brazing) - I'm also unfamiliar with 4140.. Lots of new stuff going on in my life Ken.

What are you using for the flux, Paul. I understand the jewelry solder is called "hard", but I don't know if it uses a different flux than the others.... I'm still just getting a few minutes here and there to read the web links on this "talent", so bear with me. Thanks. Ken.

I'm not near my shop but the flux is a white paste and I have to mix it with some water (I use it so seldom..). I think it is labeled as a brazing flux.

Paul in AJ AZ

Or maybe make a split bushing similar to the rod end to fill the gap?

michael

I have made two cranks from 4140 bar strock. They take me about 30 hrs to machine from solid stock. Personally I would not use silver solder for this job because of the risk of warping the crank from the heat when you remove the block. Super glue works very well for this job and breaks loose at 300 degrees vs 1000 degrees. chuck

On Wed, 09 Jun 2004 02:29:18 GMT, snipped-for-privacy@netzero.net (Ken Sterling) vaguely proposed a theory ......and in reply I say!: remove ns from my header address to reply via email

I just wish that a guy with a name like Sterling would stop asking about experimental-type engines.... .

Sometimes in a workplace you find snot on the wall of the toilet cubicles. You feel "What sort of twisted child would do this?"....the internet seems full of them. It's very sad

I'm not even sure about what I *need* to do this

The way I learned it back in Dad's jewelry manufacturing plant, "easy", "medium" and "hard" referred to the melting temperature of the solder, "easy" being the lowest.

When making a piece of jewelry in a multi-step process, by soldering the main pieces together first, and then adding other bits to the assembly, we used the "hard" solder first, and the "easy" last. That way, with carefull heating, we could get the "easy" solder to flow without melting the earlier "hard" soldering.

'Course we had to have a whole bunch of differently alloyed solders to properly color match yellow and white golds, pink gold, and silver.

Making platinum jewelry was left to the senior jewelers. That stuff was welded, and it took a "white heat" to do that, while wearing "welding glasses".

Jeff

Good point - ever had a block break loose on ya while machining? I kinda like the idea of not having to heat it up too much to remove the block (of course you could probably just tap it and knock it out of there also as it's not set into any kind of a recess or anything). Ken.

Chuckle.... ain't ya glad my name ain't Maytag? Ken.

This is kinda what I've been led to believe by putting together the info I've been reading, etc.

I can see how this would be beneficial as you would destroy all your previous work if all the solder melted at the same temp. I understand also that the "hard" solder also provides more strength in the joint, even tho it takes more heat to make the joint, and I think the hard solder has a higher silver content (percentage wise) if I'm correct.

You must have had some good opportunities for "real time" learning since you were exposed to this trade. Had to be interesting. Thanks for the post. Ken.

On Fri, 11 Jun 2004 02:40:02 GMT, snipped-for-privacy@netzero.net (Ken Sterling) vaguely proposed a theory ......and in reply I say!: remove ns from my header address to reply via email

Fascinating! Mid-mounted engine!

And only about $150K in today's money!

Sometimes in a workplace you find snot on the wall of the toilet cubicles. You feel "What sort of twisted child would do this?"....the internet seems full of them. It's very sad

I have done it twice without any problems. The hard work is done before you install the block. The hard work is completely finishing the rod bearing. After the rod bearing is done, band saw off the excess stock leaving the main section square. I like to square the main up in the mill so I can get it square enough to hold in a 4 jaw.

Make a block that fits the rod web gap and super glue in place.

Holding one main in the 4 jaw and the other end with a live center turn the other main round and leave it oversize. Don't take too heavy of a cut because all the torque is going through the rod. Flip the crank and turn the other side round but oversized.

Now that the main is round you so can use a steady rest. Set the crank up between centers. I use a steady rest next to the rod. The configuration is like this. headstock ->left main (steady rest) |rod| right main

Chuck, A question in inbedded in the following.....

The plans I have indicate to turn between centers, rather than using the 4-jaw and tailstock. Maybe between centers would be easier? And another question below...

Why flip the crank? Couldn't you turn both ends of the main shaft while in one mounting?

I do have a steadyrest, but the crank is only about 8-1/2" long overall and it would probably just be in the way. I think I also have a follower rest - but it may get in the way of the throw of the connecting rod journal. Thanks. Ken.

Initially I put one square end in the chuck and support the outside with a center because the effect length is 1/2 this way. You could turn the whole crank between centers but it long and skinny and you cannot take very heavy cuts. It painfully slow to reduce the square crank to round turning the whole crank between centers but of course it can be done. My

I use the steady rest for two reasons. One is that it is tough to turn a 10 inch long shaft (1/2 inch diameter) without taper. The steady rest running next to the rod bearing effectly cuts the lenght in half. The second reason is that you need to face the outside parts of the web and the steady rest adds a lot of rigidity for this operation.

I made both of my cranks on an atlas 12x36 lathe which is not too rigid. Simpler techniques might be available on better machines.

chuck