• We want to encourage those of you who ENJOY our site and find it USEFUL to DONATE and UPGRADE your membership from active member to donating or premium membership. If you want to know the differences in membership benefits, please visit THIS PAGE:

    https://www.hobby-machinist.com/premium/

    Donating memberships start at just $10 per year. These memberships are in fact donations that help pay our costs, and keep our site running!
    Thank you for your donation, God Bless You

  • As some of you know, I have wanted to stop managing H-M for some time. It's a tremendous strain on my personal life. I want to set up my own shop. In September, September 15, to be exact, it will be 8 years that Hobby-Machinist has been in existence.

    I have been training VTCNC to run things here. Dabbler is going to learn too. I feel that they are ready to start taking over the operation. I will be here to help in case they need, but I don't think they will. Tony Wells is and will be here also to consult with. I will be doing backups, upgrades, and installing addons. Other than that, I will not be around. I am leaving this place in good operating condition, and financial condition.
    --Nelson
[4]
[3]
[10] Like what you see?
Click here to donate to this forum and upgrade your account!

Ulma Doctor

Infinitely Curious
H-M Supporter - Gold Member ($25)
Joined
Feb 2, 2013
Messages
0
Likes
0
#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
2016-07-14.jpg
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
 
Last edited:

hvontres

Active User
H-M Supporter - Gold Member ($25)
Joined
Dec 29, 2013
Messages
315
Likes
71
#2
Hmm, that hand looks kinda familiar....:)
 

jpfabricator

Active User
H-M Supporter - Gold Member ($25)
Joined
Sep 19, 2012
Messages
3,060
Likes
757
#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
H-M Supporter - Gold Member ($25)
Joined
Feb 2, 2013
Messages
0
Likes
0
#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
2016-07-14.jpg
2016-07-14.jpg
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!
 
Last edited:

chips&more

Active User
Registered
Joined
Mar 19, 2014
Messages
2,426
Likes
1,741
#8
UD that’s excellent! There’s no stoppin yah now! You can make anything!
 

Ulma Doctor

Infinitely Curious
H-M Supporter - Gold Member ($25)
Joined
Feb 2, 2013
Messages
0
Likes
0
#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

Active User
H-M Supporter - Gold Member ($25)
Joined
Jan 23, 2012
Messages
1,216
Likes
154
#10
nice job. another thing on my bucket list. . . . running low on saturdays. . . . dang, i best hurry up.
 

Tony Pisano

Registered
Registered
Joined
Nov 2, 2017
Messages
48
Likes
51
#11
We used to do that in a lathe by offsetting the tailstock. I always thought that it was fascinating that it worked. I watched the video but cringed seeing the guy wearing gloves while running the machines. That was always a no no as far as safety goes in the shop I worked in. A spinning drill bit or cutter can grab a glove just as it will a shirt sleeve and you'll be wrapped up in a split second. We could wear gloves when handling sheet metal or cleaning out chips in the bed of a lathe that wasn't running, but never while operating a lathe, drill press, or milling machine.
Otherwise, I enjoyed the video.
 
Last edited:

mikey

Active User
H-M Supporter - Gold Member ($25)
Joined
Dec 20, 2012
Messages
4,009
Likes
4,318
#12
The broach is cool but I really enjoyed your commentary! This was the most fun machining video I've seen in a long time - thanks, Doc!
 

Ulma Doctor

Infinitely Curious
H-M Supporter - Gold Member ($25)
Joined
Feb 2, 2013
Messages
0
Likes
0
#13
Thank you very much mikey, i really appreciate your kind words.
i'm glad you enjoyed the post
 

Suzuki4evr

Registered
Registered
Joined
Sep 29, 2017
Messages
333
Likes
361
#14
I
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


View attachment 186864
View attachment 186865
View attachment 186866
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.
View attachment 186867
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
I saw that youtube video as well and am planning to make one myself. Magnet is a nice idea.
 

stioc

Registered
Registered
Joined
Feb 22, 2017
Messages
172
Likes
356
#15
Nice video, I didn't know you were AvE! lol
But...does the HSS cutting broach has to be about as big as the hole? Meaning if I want to make a 2" hole a square I'm SOL?
 

Ulma Doctor

Infinitely Curious
H-M Supporter - Gold Member ($25)
Joined
Feb 2, 2013
Messages
0
Likes
0
#16
I
I saw that youtube video as well and am planning to make one myself. Magnet is a nice idea.
thanks for looking, i hope you have fun making your rotary broach!

Nice video, I didn't know you were AvE! lol
But...does the HSS cutting broach has to be about as big as the hole? Meaning if I want to make a 2" hole a square I'm SOL?
yes sir, you'll need a piece of tool steel large enough for the hole -
but it can be any tool steel that can be made harder than the stuff you intend to broach.
i can envision a turned and then hand ground tool that has a 3/4" to 1-1/2" shank and a 2" square on the other end
you'll give some side relief. 3 to 5° should be sufficient and you'll hollow out the end of the tool to create the cutting edge
 
Last edited:
[6]
[5] [7]
Top