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Ulma Doctor

Infinitely Curious
Active Member
Joined
Feb 2, 2013
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3,483
#1
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


2016-07-14.jpg
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2016-07-14.jpg
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.
2016-07-14.jpg
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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jpfabricator

Active User
H-M Supporter-Premium Member
Joined
Sep 19, 2012
Messages
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697
#3
Ulma, nice job! I subscribed, now let's see some more videos LOL.

Sent from somwhere in east Texas by Jake!
 

Ulma Doctor

Infinitely Curious
Active Member
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#5
here is the job the broach was made for:
2016-07-14.jpg

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!!!
sri9UlDwfon_KoV1xpLctR7Ou1YTTiklO7cn2Iei0-GJkkQLpeChC7R6I9n48fFXleza7_UPSA=w333-h572-no.jpg
I bored the hub to .995" id to accept a square broached slug 1.00" OD x .850" long

WDclbPB9IhyDKgYWB1xvd9aUOFoSZD9VBTm35wNhYsNSY6meztApZANWrqiOVZiFOd98SOtONw=w567-h594-no.jpg
2016-07-14.jpg
2016-07-14.jpg 2016-07-14.jpg
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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.
2016-07-14.jpg
Here is my answer to planned obsolescence,
NOT ON MY WATCH!
 
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Ulma Doctor

Infinitely Curious
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#9
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:
 
Last edited:

davidh

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Jan 23, 2012
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#10
nice job. another thing on my bucket list. . . . running low on saturdays. . . . dang, i best hurry up.
 
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