Knurling shafts and bushings for a tighter fit

kinsler33

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Aug 17, 2014
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I think someone mentioned recently that you can knurl the outside of a loose press-in bushing by rolling on a file, and while that works well, I've discovered that my coarse diamond files do a better job of this than a steel file.

In the pictures I've put a piece of discarded pendulum rod, fairly hard steel on this one, between my two coarsest diamond files (https://timesavers.com/i-9605367-6-piece-diamond-file-set.html) and pressed down fairly hard on the top file while rolling (not scraping) the poor little steel rod between them.

The resulting knurl is quite uneven and looks just like the diamonds on the surface of the coarse file (enlarge the last picture if it'll enlarge.) But the diamonds dig deep and displace a lot of metal, and when you try pressing, say, an arbor thus knurled into a wheel you'll get a thoroughly businesslike fit that shouldn't ever come loose. Much nicer than Loctite: faster and more secure.

Mark Kinsler

knurling1of3.jpg knurling2of3.jpg knurling3of3.jpg
 

David S

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Nice going Mark. While I have used the narrow width of a steel file before I haven't tried with a diamond one.

David
 

shutterbug

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Interesting idea. I'll have to keep that in mind for my next loose bushing.
 

bangster

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Mark, I'd like to add this to the Useful Hints & Tricks open thread. OK?
 

Uhralt

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I found that the escape wheel/verge combinations from Timesavers are not a perfect fit as sold. In most cases the verge needs to be adjusted. I stopped to buy them and rather fix the existing escape wheel and verge, if possible.
EDIT: I guess this comment would fit better to your other post regarding the 50 teeth EW Seth Thomas.....
Uhralt
 

kinsler33

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I found that the escape wheel/verge combinations from Timesavers are not a perfect fit as sold. In most cases the verge needs to be adjusted. I stopped to buy them and rather fix the existing escape wheel and verge, if possible.
EDIT: I guess this comment would fit better to your other post regarding the 50 teeth EW Seth Thomas.....
Uhralt
Thank you, in any case. I'll be posting a video (I hope) of the escapement while it's running, and perhaps someone can tell me where I've messed up.

Mark Kinsler
 

Harry Hopkins

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I would just like to add that a nice sharp small round file used just as Mark describes works very well when trying to improve the grip of an arbor for a small hub. Same principal but can use less pressure and knurl a smaller area. I have done similar but just rolled the arbor with the round file while arbor was on scrap piece of aluminum.
 

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