# Flexible dial indicator holder.



## kd0afk (Dec 11, 2013)

This will be my next build. I can't afford $200 for the real thing but I can afford to make a few. I got the balls on the mail the other day and today I'm having a cookout/metal softening session.



I'll be posting photos and videos on YouTube to document the build.


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## kquiggle (Dec 11, 2013)

I look forward to seeing your progress on this. For what it's worth, I tried "softening" some ball bearings by heating them to red heat with a MAPP gas torch, and just letting them air cool. This worked pretty well, but it did leave them with a coating of black scale (although the scale was fairly easy to polish off with some abrasive cloth). I don't know if some kind of anti-scaling treatment would help or not, but it might be worth looking into.

I have read reports that some people have used borax powder for this (preheat the metal to about 600 deg. F and dip in powder to coat). There are also commercial anti-scale powder available.

Just some thoughts - good luck in your cookout!


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## kd0afk (Dec 11, 2013)

The plan is to cook the food and then heat the bearings in a can filled with sand in the coals and bury the whole thing with new coals and let the whole thing burn itself out. I'll be poking the coals to make sure they are well buried in the ash as it starts to die so that they will cool as slowly as possible.


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## purpleknif (Dec 11, 2013)

Seen similar ones for about $45 w/indicator.


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## velocette (Dec 11, 2013)

Hi 
it is possible to drill holes through ball bearings with a concrete drill bit slow!!! speed lots of pressure and lots of coolant-lubricant.
The annealing process will help to make it a bit easier keep in mind that cans are soft soldered an will melt it out before the can reaches bright red.
Be aware that some sands will leave glazed coating on very hot steel.
 keep us posted on this project please

Eric


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## kd0afk (Dec 11, 2013)

purpleknif said:


> Seen similar ones for about $45 w/indicator.


All the materials have cost me $30 and I can make three of them


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## kd0afk (Dec 11, 2013)

Here's how I did the fire. It took a whole bag of charcoal. I filled the can with red hot coals stoked them well and put the can in red got coals and stoked them for about and hour. Also used wood in the fire. The can reached a dull red just above the coal line. Even if the can desoldered it wasn't disturbed so the bearings should stay in one place. I also had a bucket of ashes that I piled on top to further insulate them so they'll cool slower. 
We'll see how they are in the morning.


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## kd0afk (Dec 11, 2013)

Sorry, here's the photo of the fire.


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## kd0afk (Dec 12, 2013)

Success!!!
I pulled the balls out of the ashes and a file cut em like cold rolled. 
Next step: drilling


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## kd0afk (Dec 12, 2013)

How can I reharden them? Red hot and cool in air? The data sheet I read says 1204 c as the quenching temp. 
Would I also need to temper the balls or can I just harden them?


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## kquiggle (Dec 13, 2013)

Do you even need to re-harden them? Given how you are planning to use them, it doesn't seem like they are going to be exposed to much force or friction. If you don't buy that, you could just case harden them with something like Cherry Red.


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## kd0afk (Dec 13, 2013)

I probably don't need to reharden them. I was just wanting to cover my bases.


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## tornitore45 (Dec 13, 2013)

Hard surfaces are harder to grip, if the balls need to have a friction grip they bare better off soft.  For the same reason drill bit shank are left soft.

Annealing call for very slow cooling to relive stress but if all is needed is to soften to a machinable level, simply heating to cherry red and avoid quenching is sufficient.  I just pull the part slowly out of the torch flame and always been able to drill afterward.

I paid money for the Brownell anti-scaling powder and is nothing but borace, probably mixed with charcoal to reduce decarburization.


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## Jyman (Dec 13, 2013)

One of the best and cheapest ways to avoid scaling, is to use a heavy liquid hand soap. Just cover everything you want protected. Guys in the metal fab shops around me use the soap method


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## chucketn (Dec 13, 2013)

tornitore45 said:


> I paid money for the Brownell anti-scaling powder and is nothing but borace, probably mixed with charcoal to reduce decarburization.


 
What is borace? 

Chuck


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## Swifty (Dec 13, 2013)

chucketn said:


> What is borace?
> 
> Chuck



It's just borax.

Paul


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## Cogsy (Dec 13, 2013)

It's likely that the balls were originally only case hardened. A lot of bearings are, which is why they don't last long after you start hearing them make noise, they wear through the hard case into the soft material underneath and fail. If they're through hardened they cannot be made as hard as case hardened or they become too brittle. Less hard = less life so many manufacturers opt for case hardening.


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## kd0afk (Dec 14, 2013)

I took the video down and I probably won't be filming any more till I get a proper camera and mount.


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## kquiggle (Dec 14, 2013)

Nice video - appreciate the effort you are making to document this.

I wonder if you needed to heat the steel balls that long. In my quick and dirty test (with much smaller steel balls), I just heated them red hot and then let them cool, and they drilled OK. If, as was suggested, they are only case hardened then likely this would work even for larger sizes. I wonder if they could even just be "spot softened" - just heat spots on opposite sides of the ball to allow drilling.

I've got some old bearings around somewhere - maybe I'll make a few tests . . .


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## kd0afk (Dec 14, 2013)

I think I read a thread somewhere that they used a dull drill bit to friction heat a spot so they could drill. You just maked me member it.


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## Omnimill (Dec 15, 2013)

Standard Bearings are made from chrome steel* and are, according to "how it's made" hardened after rough shaping. They are then ground to size and then lapped. I doubt case hardening would be deep enough for this.

* used bearing races in the larger sizes are a handy raw material for all sorts of tools if you have a forge. Some folks make knives and woodworking tools from them as they can take a keen edge once re-hardened.

http://www.mountainhollow.net/graphics/belt-wharny.jpg

Chrome steel is certainly not a "soft material"!


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## kd0afk (Dec 15, 2013)

Omnimill said:


> Standard Bearings are made from chrome steel* and are, according to "how it's made" hardened after rough shaping. They are then ground to size and then lapped. I doubt case hardening would be deep enough for this.
> 
> * used bearing races in the larger sizes are a handy raw material for all sorts of tools if you have a forge. Some folks make knives and woodworking tools from them as they can take a keen edge once re-hardened.
> 
> ...



Is the knife forged from the races and balls, like Damascus? I like it.


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## Omnimill (Dec 15, 2013)

To be honest, I can't remember how they make them but lots of folks do because they look so neat, don't they! I suspect the bearing is wrapped in stainless foil and heated before placing in a press to consolidate the race and balls but I'm only guessing here.


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## kd0afk (Dec 19, 2013)

I'm playing around with the wire rope ends and I need to know how much to compress them for a good swage.
The terminator is aluminum with a 1/16" hole and an outside diameter of .245"  I saw a sheet on copper ones that gave a diameter of .203". Will this be sufficient for aluminum?
Also I have aluminum, can I make these little cable ends or is it a special type of aluminum?


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## kquiggle (Dec 19, 2013)

Just happened to run across this video which may be of interest here - drilling into a ball bearing using a solid carbide bit. Of course, ther may be reasons other than drilling for why you might want to "soften" a ball bearing (for example, drilling followed by tapping), but still interesting:

https://www.youtube.com/watch?v=-XA0BywJdR4


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## kd0afk (Dec 19, 2013)

kquiggle said:


> Just happened to run across this video which may be of interest here - drilling into a ball bearing using a solid carbide bit. Of course, ther may be reasons other than drilling for why you might want to "soften" a ball bearing (for example, drilling followed by tapping), but still interesting:
> 
> https://www.youtube.com/watch?v=-XA0BywJdR4


Already softened and drilled them. They came out perfect.


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## kd0afk (Dec 19, 2013)

I finished the base except for the stud on the bottom. I believe the noga magnetic bases except an 8mm x1.25 thread but I'll have to confirm that. Or I might make it fit a Starrett mag base. I think that's a 1/4"x20 but again I will find out for sure.
I also still have to make the cable and the top section. So plenty more work ahead.


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## kd0afk (Dec 21, 2013)

All the parts are made and it works ok. I need to work on the balls and  spacers. I also need to find someone who can crimp stainless steel ends on to my cable. Aluminum just didn't have the holding power. When I tightened the cable up it gave way. 
Anyway, if someone wants to do a good deed and you have a way to swage stainless steel, please let me know. Until then, I'm dead in the water.


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## kd0afk (Dec 21, 2013)

It's all but finished.


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## kd0afk (Dec 22, 2013)

I'm going to redo the cable ends to something stronger. Tom Lipton over there at Ox Tools gave me a hot tip on solder swaging. 
I'm also having trouble with the fit of the balls and spacers so I'm going to try and lap the spacers and see if that helps.  Once this thing is fine tuned and completed it should be plenty strong.


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## kd0afk (Dec 22, 2013)

Here's the latest photo. I'll post again when it's on a magnetic base and holding an indicator.


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## kd0afk (Dec 22, 2013)

Funny thing, it wants to be curved. If it's locked when it's straight, if you bend it it loosens up. If it is curved when locked, it doesn't want to straighten out. I think it's because the circumference of a circle is longer than the circumference of a polygon with the same diameter point to point. 
Does anyone know if this problem is solvable?


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## kquiggle (Dec 22, 2013)

It's looking pretty good. A question: On the straight segments, how did you turn the inner "chamfer" - is it a straight cut, or is it curved to match the radius of the ball?

About your locking problem - seems you need some way to keep tension on the cable - some sort of very strong spring attachment maybe? Alternatively, is it possible to use some sort of cable which has a bit of stretch or elasticity?


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## kd0afk (Dec 22, 2013)

I ground a cutter with the same radius as the balls and used that to cut the inner chamfer.  There really is no room for a spring. I think the problem is in the geometry of the thing. The flats that make up a polygonal shape are shorter than the circumference of a circumscribed circle of that polygon. I.e. if you wrap a string around a piece of 1" hex bar, it will be shorter than the circumference of a piece of 1" round bar. When the holder is coiled and locked the cable conforms to a polygonal shape. When it is straightened out the cable still wants to maintain that same length but when straightened out it wants to be the circumference of a circle but it can't. Conversely, when it's straight and then locked and then bent it loosens. 
If this is the problem, what would be the solution and springs won't cut it.
Maybe making the hole through the spacers smaller and instead of a through hole in the balls, make the hole hourglass shaped so that the cable. Is bent into a curve instead of around sharp corners?


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## tornitore45 (Dec 22, 2013)

> What is borace?



Borace is Borax when the Italian part of my brain overpowers the English.


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## kd0afk (Dec 22, 2013)

tornitore45 said:


> Borace is Borax when the Italian part of my brain overpowers the English.


Not helpful.


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## Omnimill (Dec 23, 2013)

kd0afk said:


> Does anyone know if this problem is solvable?



It may be due in part to the size of the holes in the bearings, the bigger the holes the worse the effect. Try again, this time with much smaller holes?


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## kd0afk (Dec 23, 2013)

I'm going to order more balls and instead of boring the holes to allow the cable ends through I'll countersink the holes so that the holes have an hourglass shape with a small diameter of 1/8". That should help.


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## Omnimill (Dec 23, 2013)

Perhaps you could try sleeving the existing ones to prove the idea?


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## kd0afk (Dec 23, 2013)

Omnimill said:


> Perhaps you could try sleeving the existing ones to prove the idea?


That's a very good idea


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## Jyman (Dec 26, 2013)

I think the reason why it sits the same way as the cable is because the cable hasn't been heat treated to release the tension in the cable. 

My thoughts would be to try heating the cable to get it to relax


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## kd0afk (Jan 7, 2014)

I got a few of the new balls machined with the countersunk holes. I strung them up on the cable and theres no change in the cable length. I'll know better when I get the last couple parts made and can assemble the thing.


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