Boring bar sizing

I'm wondering if there would be enough material in the design to allow drilling the hole greater than the finished depth so as to facilitate use of a reamer, but then insert a short plug in the hole to keep the ball from being pressed in too deeply. I believe we're talking about making a spinning top, yes? There should be ample material to support an over-depth hole.

-frank
 
I guess I don't know much about reamers. I've never seen or heard of a flat-bottomed reamer. I was under the impression that all reamers required a chamfer to enter a hole that is smaller than the reamer so grinding it off might be interesting.
 
francist said:
I'm wondering if there would be enough material in the design to allow drilling the hole greater than the finished depth so as to facilitate use of a reamer, but then insert a short plug in the hole to keep the ball from being pressed in too deeply. I believe we're talking about making a spinning top, yes? There should be ample material to support an over-depth hole.

-frank
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Yes, we're talking about top making. Sure, anything is possible, and with enough skill that would certainly be an option. However, to get those insanely long spin times (+15 mins or so) you have to have the utmost in balance. To me the idea of a plug like that sounds a lot like an operation that could introduce some balance issues. I'd prefer to just get good enough at boring to be able to do it as a bore.

I will note, however, that one could drill a hole deeper than needed, ream it to size, press the ball to the bottom, and then turn off the extra material exposing the bearing. I found this video last night that did just that.


That top spins for around 8-10 mins, as seen here:
 
wildo said:
I will note, however, that one could drill a hole deeper than needed, ream it to size, press the ball to the bottom, and then turn off the extra material exposing the bearing. I found this video last night that did just that.
Click to expand...

There's an idea, and not a bore gauge in sight, too.
 
cmantunes said:
They aren't the most common thing in the world but they are out there. For example: http://bondeproducts.com/index_files/FBRHLSET.htm
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Hmm, this is interesting. A reamer is guided into and down a hole by the chamfer on the front edge; otherwise, it will tend to drift and cut oversize. These reamers lack that chamfer and looks like they would cut on contact. It would be interesting to see how accurate a hole they cut and if they would produce an interference fit as required here, assuming you could special order one to the right specs.

I've reamed hundreds of holes over the years and have never seen a reamer like this, cmantunes. I will admit that they exist; I just don't see the logic.
 
I wonder about drilling deep enough to use a reamer, then ream to the right depth. The step in the hole would stop the bearing from getting pressed too deep. I don't know and have not tried it, but it might be a workable idea.
 
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