Broaching

This topic has 12 replies, 7 voices, and was last updated 8 December 2019 at 11:31 by Pete Rimmer.

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7 December 2019 at 14:06 #440650
Dell
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@dell
Hi all
Is there anyone on this forum that could cut a 11mm hexagonal hole in a piece of mild steel rod either by broaching or other method ?
The rod is small enough to post approximately 6” and anyone willing and able to do it if they could PM me.
Bellow a picture of what is to fit in it ,although the hole needs to be approximately 3” deep the hex only needs to be 1/2 to 5/8” deep.
Thanks in advance Dell

update I have a 11mm rotary broach with a 16mm shank but the holder is to expensive for just one job.

Edited By Derek Allum on 07/12/2019 14:08:32
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7 December 2019 at 14:06 #27000
Dell
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@dell
7 December 2019 at 14:15 #440652
Pete Rimmer
Participant
@peterimmer30576
Do you have a pillar drill or milling machine Derek? You can make a basic broach driver using some scrap stock and a ball bearing. Simply drill an off-set counterbore in the stock and load it in your drill/mill then make a similar one for the broach but with the hole central, and put the ball bearing between them with some grease for lube. I've broached a couple of things like this.

wobble broach

Edited By Pete Rimmer on 07/12/2019 14:15:36
7 December 2019 at 14:38 #440654
Jeff Dayman
Participant
@jeffdayman43397
Just thinking outside the box a bit – if a rough and ready tool would do for this job rather than a beautifully finished custom broached job, here's an alternate idea. Buy a cheap deep hex socket from a hardware store or auto supply. Turn and bore a shank of mild steel, or find a piece of pipe the right ID and OD. Cut the square drive section of the socket off with a cutoff wheel in an angle grinder or Dremel type tool. Weld or silver solder remaining hex portion of socket to shank / pipe. Tool made.
7 December 2019 at 15:46 #440661
not done it yet
Participant
@notdoneityet
I recently enquired about wobble broaches in this thread. Might help a bit.

**LINK**
7 December 2019 at 18:20 #440675
Dell
Participant
@dell
Thanks for the replies

the tool I want to make is a clock mainspring winder to get the mainspring out of the clock barrel for servicing and or replacing so I will be using it quite a lot .

although I will be using the tool I made regularly I hopefully won’t be using the broach more than once that is why the tool company said I should get the 16mm shank broach and it SHOULD be strong enough to press in , but I would prefer to do it or have it done with rotary. Broaching as I understand it would do a better job job.

Dell
7 December 2019 at 18:34 #440678
JasonB
Moderator
@jasonb
Another option is to just mill half a hex into a semi circle of steel which is quite easy to do and solder or even loctite two of them into a hollowed cylinder.
7 December 2019 at 19:29 #440690
Dell
Participant
@dell
That would be an option JasonB if I had a mill.
7 December 2019 at 20:51 #440701
not done it yet
Participant
@notdoneityet
Any particular reason it has to be a hexagon? As above, there are hexagon socket sets out there, if a square hole is out of the question. I used to have a socket set with a hexagon driver, even – probably 1/2” across the flats, though.
8 December 2019 at 07:42 #440718
John Haine
Participant
@johnhaine32865
Wobble broach
8 December 2019 at 08:58 #440722
Dell
Participant
@dell
Posted by not done it yet on 07/12/2019 20:51:49:

Any particular reason it has to be a hexagon? As above, there are hexagon socket sets out there, if a square hole is out of the question. I used to have a socket set with a hexagon driver, even – probably 1/2” across the flats, though.

The reason it has to be hex is that the spring let down arbor is hexagon and I need to be able to change to the arbor that fits the square of whatever mainspring barrel I am removing the spring from, the picture in first post is only one of six and each end of each one has a square hole to fit different clock barrel arbors.

Dell
8 December 2019 at 11:24 #440739
Tim Stevens
Participant
@timstevens64731
It would help if we could see what the 'Let down arbour' actually looks like. There are often alternative ways to solve problems which only come to light when the whole system is clear. For instance, why does the 'arbour' need a hexagon spindle? Could an alternative work just as well (eg square)? And is the 11mm dimension critical, or might 7/16" do just as well? (7/16" = 11.11mm)?

Cheers, Tim

Edited By Tim Stevens on 08/12/2019 11:24:56
8 December 2019 at 11:31 #440741
Pete Rimmer
Participant
@peterimmer30576
EDITED:

If you made a cap for the non-cutting end of the broach with a small bearing in it. Put the part in the lathe chuck then dialled in some off-set on the tailstock you could probably push it through using an old dead centre in the tailstock.

Edited By Pete Rimmer on 08/12/2019 11:35:40
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