Thread: Looking for a 0.444" diam ball bearing

0.444" is 11.28mm.

Nev

Originally Posted by SurfinNev

0.444" is 11.28mm.

Nev

Whoops - I had 6.62 mm (even got that wrong ) on the brain because the ball bearing has to be pushed into the wood precisely half way.
Thanks

From here Metallic Balls - Small Parts And Bearings Categories it looks like 11.112 or 11.5 are the standard sizes.

Originally Posted by petersemple

From here Metallic Balls - Small Parts And Bearings Categories it looks like 11.112 or 11.5 are the standard sizes.

Thanks for the link Peter.
Unfortunately the 11.112 mm size has a minimum order of 50 at $400+ and the 11.5 mm size are no longer produced.

If you can't find anything that suits you closer, then let me know. The showroom is only just down the road from where I live, and I have bought individual 1/4" ones from them before in person. I can probably pick you up a few and post them off if needed.

Originally Posted by petersemple

If you can't find anything that suits you closer, then let me know. The showroom is only just down the road from where I live, and I have bought individual 1/4" ones from them before in person. I can probably pick you up a few and post them off if needed.

That's a very kind offer - I'll keep that in mind.
Thanks again.

Hi Bob,

Building a Janka Hardness tester that would be a great project... I have a couple of ideas,

Firstly the 0.444" ball size might be used in a standard bearing of some kind. I have no idea how you would find the right bearing.. sifting through bearing catalogues perhaps.

Second idea, see if you can find a manufacturer of Janka hardness testers and buy the ball as a spare part.

Regards
Ray

Originally Posted by RayG

Hi Bob,

Building a Janka Hardness tester that would be a great project... I have a couple of ideas,

Firstly the 0.444" ball size might be used in a standard bearing of some kind. I have no idea how you would find the right bearing.. sifting through bearing catalogues perhaps.

Second idea, see if you can find a manufacturer of Janka hardness testers and buy the ball as a spare part.

Regards
Ray

Hi Ray,

It would indeed be a great project and that was what I had in mind - until I walked past our materials testing labs at work and saw we had a brand new fully computerised Lloyds 50 kN materials testing unit. This thing does compressive and tension testing up to 50 kN so all I need is a 0.444" ball and I am in business. The process is pretty straight forward and involves measuring Force versus depth of penetration of a 0.444" ball up to it's radial penetration depth. The computerised bit will be very useful because it can automatically do the stats on batches of measurements etc.

What I would like to do is measure the hardness of some unique WA timbers for which there is limited or no data.
A full testing regime is pretty long winded since, as you can imagine, it involves a lot more than a spot test on one sample of wood.

As timber hardness varies between trees of the same species and even within the same tree (i.e. with depth into and along the trunk) by as much as +/- 20% a complete test requires many hundreds of measurements. Now I'm not planning to go to all this trouble, but seeing as mill and season my own timber I am in a useful position to extract the samples do this both for green and dry timber.

Bob

I like Ray's idea of looking for a spare part.

I did a bit for fossicking around on the web and now realise I don't even need a ball - I could use a hemisphere turned up on the end of a mild steel rod.
That would make it even easier to hold on the anvils of the material testing device.
Could be a good use for my mini rotary table?

Ball bearing material would be much harder than mild steel.

If you still want some, the best place to try is a company that reconditions electric motors.

They throw away truckloads of ball bearing races in sizes from tiny to enormous (they always replace the armature races).

Ask nicely and they will probably help you out - gratis.

My Bro in law got several large metal ammo cases full of old sealed ball races that way a few years back. Most were still 100% OK and we use em on all the equipment.

Rob

Originally Posted by nearnexus

Ball bearing material would be much harder than mild steel.

Sure, but all I and doing is indenting wood. T'would be nicer to have a harder material if possible.

How about buying a 12mm shoulder bolt,cut off the head and then shape it to a dome?
If you know someone with a T&C grinder you may be able to set it up on that to take the diameter down to 0.444 and then radius the end. While a smooth radius is ideal hardness measuring either involves indenting with a set load and measuring the indent or indenting to a set distance and then measuring the load to do that. Either way for a comparative measure a slight loss of geometric form should not be a deal breaker. I would think it more important that it was smooth so the material did not drag.

Michael

Originally Posted by Michael G

How about buying a 12mm shoulder bolt,cut off the head and then shape it to a dome?
If you know someone with a T&C grinder you may be able to set it up on that to take the diameter down to 0.444 and then radius the end. While a smooth radius is ideal hardness measuring either involves indenting with a set load and measuring the indent or indenting to a set distance and then measuring the load to do that. Either way for a comparative measure a slight loss of geometric form should not be a deal breaker. I would think it more important that it was smooth so the material did not drag.

using a bolt is a good idea.
I just got myself a set of adjustable reamers - I figure I drill a 7/16 (0.4375") hole in some 1/4" steel plate and ream the hole out to 0.444" in diam and use that as a template to match against the turned down bolt?
Then polish it off as needed?

BTW The testing device automatically ramps up and measures load as function of distance and puts out a graph/table for every compression increment (as small as 0.3 microns!)
All I then need to do is read off the load at contact (ie first non-zero reading) and then at 0.222" later.