Broaches

This topic has 12 replies, 6 voices, and was last updated 21 January 2017 at 15:42 by Mark C.

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1 March 2016 at 19:14 #18018
Maurice Cox 1
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@mauricecox1
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1 March 2016 at 19:14 #227803
Maurice Cox 1
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@mauricecox1
I am thinking of buying a 1/8" broach from RDG Tools. They list two; one with shim "A", and one with shim"B". What is the difference? I asked RDG but they were unable to be specific. They contacted the supplier on my behalf, and they just said they were for different size guides. But what size? Can anyone explain the differences please?

Maurice
1 March 2016 at 19:22 #227806
JasonB
Moderator
@jasonb
The A size fits bushes with a 1/8" slot which you will also be able to fit 1/16" and 3/32" broaches into.

The B size ones fit bushes with 3/16" slots so you will also be able to use 5/32" and 3/16" broaches in these

Basically its the width of the back of teh broach that determines if it is A, B or C and various numbers of shims are required for each combination of broach and bush

So the one you are looking at will cut 1/8" keyway, has a 3/16" (B) spine and requires a 1/8"B shim

I'll pop down to the workshop and take a photo in a while.

Edited By JasonB on 01/03/2016 19:24:06
1 March 2016 at 19:44 #227811
JasonB
Moderator
@jasonb
On the left is a B size broach and 5/8" dia bush, on the right are A size broaches and an A size 5/8" dia bush.

You also need shims for certain sizes as there is too much material to be removed in one pass of teh broach so you push the broach through without a shim first then add a shim behind the broach and push it through again to get to full depth. Some sizes may need a second shim.

If you are more likely to want 1/8" and below in future tyhen I would suggest the A size is better the will also work on smaller dia shafts
1 March 2016 at 20:18 #227818
Michael Gilligan
Participant
@michaelgilligan61133
Jason,

That's useful info. thanks

It looks like RGD needs to retain you as an Advisor.

MichaelG.
1 March 2016 at 22:51 #227846
D.A.Godley
Participant
@d-a-godley
I bought a broach from RDG last year , I also was ignorant so far as type's and shim's were concerned, but I spoke with Richard, either he or Christian are the guys to talk to when advice is needed , I received exactly what I needed.

But I must admit, Jason's advice does take some beating ! .
2 March 2016 at 17:00 #227974
Maurice Cox 1
Participant
@mauricecox1
Thanks for the information Jason. Very clear. I have one more question, about the guide. I wish to make my own, one for 1/2" and one for 5/8". How depp should the slot be please; for shim A ?

thanks Maurice
2 March 2016 at 20:32 #228010
JasonB
Moderator
@jasonb
For A series broaches
3 March 2016 at 19:54 #228132
Maurice Cox 1
Participant
@mauricecox1
Thanks very much Jason. Got everything that I need to procede now. Thanks again,

Maurice
21 January 2017 at 08:07 #279212
Brian H
Participant
@brianh50089
One more question about broaches, as I am thinking of buying a set of the small ones from RDG; What size of throat (if that's the right word) on a press is needed and are there any other special requirements for a suitable press, such as tool holding arrangements? RDG were unable to answer.

Brian
21 January 2017 at 15:03 #279300
JasonB
Moderator
@jasonb
The throat will really be determined by the size of the work you need to put into it before it hits the back of the throat. Throat is generally regarded as distance from the spindle or ram to the supporting column(s)

If you are thinking about height then the bigger the broach the longer they get plus you want to add a bit for the work and bush, if you look at page 136 of MSC's catalogue it gives lengths of broaches and that is fairly standard for all makes.

The small 1/16 – 1/8 ones can be pressed in on a drill press though the 1/8 is putting quite a bit of strain on the rack, I just put a stub end of bar in teh drill chuck and pull down the quill. On the larger one I borrow a friends hydralic press and just put the ram straight onto the top of the broach so nothing special needed.
21 January 2017 at 15:34 #279308
Brian H
Participant
@brianh50089
Thanks for that Jason, very useful.

Brian
21 January 2017 at 15:42 #279311
Mark C
Participant
@markc
Having broached quite a number of things with these I can reccomend getting the broach started and then checking it is square against the bush before keeping going. You might also find you need to "tilt" the whole lot very slightly to ensure the broach goes through square to the axis. I have a large (3 tonne I think – it's the biggest one I could easily buy for the job) which allows me a good "feel" for the broach starting to tip.

Mark
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