Ulma Doctor

Infinitely Curious
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Feb 2, 2013
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Shop Made Rotary Broach
i have a job that requires a square hole to be pierced through a piece of machined steel. the material is too thin to be push broached for fear of fracture.
i don't have pull broaches or the puller for that matter, so i'm doing the next easiest method i have seen.
i copied the design from a fellow youtuber, the credit is all his, i just copied the idea.
here is a link to his video


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one improvement i made was that i added a relief for a small ,but powerful, rare earth magnet to retain the ball in the upper half, after dropping the ball a couple times.
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mine is not as nice as the video's producer.

here is a video of my rotary broach in action!

thanks forwatching and reading!
#rotarybroach
 
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Ulma, nice job! I subscribed, now let's see some more videos LOL.

Sent from somwhere in east Texas by Jake!
 
here is the job the broach was made for:
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the upper drive hub (below ,top) looked exactly like the other one before the project started.
i just didn't think to write the job up before i started working.
Hobart Corporation no longer supports this grinder drive hub and offers no other parts to replace this assembly.
planned obsolescence at it's ugliest.
there are hundreds of these grinders still in operation , all have this Achelle's Heel that will render them useless,
UNLESS OUT OF THE BOX THINKING IS USED!!!
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I bored the hub to .995" id to accept a square broached slug 1.00" OD x .850" long

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here is the retrofitted part, below left
the new part, below right, is a factory part for the current production grinders, the two assemblies are not compatible and not interchangeable.
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Here is my answer to planned obsolescence,
NOT ON MY WATCH!
 
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Thank's guys for looking and for your very kind words!
the rotary broach really wasn't hard to make, the other work was a little more time consuming but, sure was fun!:grin:
 
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