Question about keyway broach nomenclature

opscimc · Oct 11, 2012

If you go to the, say, MSC web site and search for "keyway broach," you will find sets come in "Style A, B, C, D and E." However, no description is given for what these "styles" are, nor can I find anything about them in Machinery's Handbook. Other catalogs refer to A, B, C, etc. being different "Types." The MSC site gives the min. and max. widths of the cutters and bushings in a given set that includes a few different "styles," but that doesn't provide a clue as to what "style" or "type" means.

Companies that manufacture broaches (e.g. DuMont) assume buyers already know what A, B, C, etc. mean, so they don't bother giving a description. DuMont shows a picture of 6 different broach "shapes," but sell sets running from A-E, so I can't even assume A corresponds to the first shape in the picture, etc. Can anyone point me to a reference that gives a precise description? Thanks in advance.

magneticanomaly · Oct 11, 2012

I believe the letter "styles" refer to the width of the spine of the broach and therefore the width of the guide slot in the guide plug or bushing, and also to the height of the broach from the smooth back to the top of teeth,which affects the depth of guide slot and thickness of shims needed. Each letter covers a range of standard keyway sizes.

I can't give yo uany numbers,but I am pretty sure a phone call to Dumont would.

opscimc · Oct 11, 2012

magneticanomaly said:
I can't give yo uany numbers,but I am pretty sure a phone call to Dumont would.

I sent them an email some time ago without getting a response, but just now sent them another via their web site. Since they may not respond to that one either, I'm still hoping someone can point me to the information I'm looking for.

Ray Behner · Oct 11, 2012

A series: 1/16 - 1/8
B series: 3/32 - 3/16
C series: 3/16 - 3/8
D series: 5/16 - 1/2
E series: 5/8 - 3/4
F series: 7/8 - 1

opscimc · Oct 11, 2012

Ray Behner said:
A series: 1/16 - 1/8 ...

So, if I understand correctly, they might have used a better word than "style" to denote a range of broach widths cut using a particular bushing, since "style" implies the different broaches could be rectangular, hexagonal, round, etc. as shown in the photo on the main DuMont page?

opscimc · Oct 11, 2012

opscimc said:
I sent them an email some time ago without getting a response, ...

I got a full response from DuMont, so cancel my question.

In case anyone comes across this thread later when searching the archives, the answer is that "Style" is a somewhat misleading term for describing the broaches. Style B doesn't give you an art deco (or hexagonal) broach, but rather gives you a broach that cuts keyways of width somewhere in the range 3/32" - 3/16" wide (specified by you), whose teeth are on a frame whose width fits into the slot of a "Style B" bushing. If you want a keyway a little wider than 3/16" you step up to Style C, whose frames (and slots in the corresponding bushings) are wider than those of Style B.

"Keyway broach" always refers to broaches that cut rectangular keyways in one side of the OD of a hole. Depending on the shims used, that rectangle could have the same depth as width, i.e. it could be square, but it still wouldn't be called a "square broach." A square broach is one that removes material from the entire hole, turning a round hole into a square one.

Sorry if this material is too elementary for people who already know this, but it took me some time to be 100% sure of it so I thought it would be useful to at least a few people.

hardtail69 · Jan 28, 2016

opscimc said:
I got a full response from DuMont, so cancel my question.

In case anyone comes across this thread later when searching the archives, the answer is that "Style" is a somewhat misleading term for describing the broaches. Style B doesn't give you an art deco (or hexagonal) broach, but rather gives you a broach that cuts keyways of width somewhere in the range 3/32" - 3/16" wide (specified by you), whose teeth are on a frame whose width fits into the slot of a "Style B" bushing. If you want a keyway a little wider than 3/16" you step up to Style C, whose frames (and slots in the corresponding bushings) are wider than those of Style B.

"Keyway broach" always refers to broaches that cut rectangular keyways in one side of the OD of a hole. Depending on the shims used, that rectangle could have the same depth as width, i.e. it could be square, but it still wouldn't be called a "square broach." A square broach is one that removes material from the entire hole, turning a round hole into a square one.

Sorry if this material is too elementary for people who already know this, but it took me some time to be 100% sure of it so I thought it would be useful to at least a few people.

i am also a newbie and i needed this same information so thank you very much indeed. Why manufacturers can be so myopic as to needed information is beyond reasoning. perhaps they figure we will obtain the information by osmosis? it is like the insert tooling guys never telling you the size of the damn screw that holds the insert in... they are not all standard,nor are they readily available at the hardware store. They are in fact very specialized, so please tell us what the designation of the screw is when you sell us the tool. cause the screw is probably the first thing you lose in the swarf lol.

L Vanice · Jan 28, 2016

hardtail69 said:
i am also a newbie and i needed this same information so thank you very much indeed. Why manufacturers can be so myopic as to needed information is beyond reasoning. perhaps they figure we will obtain the information by osmosis? it is like the insert tooling guys never telling you the size of the damn screw that holds the insert in... they are not all standard,nor are they readily available at the hardware store. They are in fact very specialized, so please tell us what the designation of the screw is when you sell us the tool. cause the screw is probably the first thing you lose in the swarf lol.

DuMont is not the only maker of broaches. I will not take the time to look up the exact details, but other makers use Roman numerals I, II, III or 0,1 and 2 for their keyway broaches that actually fit the DuMont bushings of the corresponding letter sizes and vice versa. As I recall, A is 0 or I, B is 1 or II, etc.

Larry

triumph406 · Jan 28, 2016

hardtail69 said:
Why manufacturers can be so myopic as to needed information is beyond reasoning. perhaps they figure we will obtain the information by osmosis?

If you for instance ordered broaches from the Mcmaster catalog, it would have been obviuos what style A,B etc meant. At least it was to me.

mixdenny · Jan 28, 2016

This is the beauty of a named standard. You put a USB plug in a USB port. You install a D-2 chuck on a D-2 spindle. I've broached lots of keyways and don't know exactly what A, B etc, mean, other than the obvious that each one is progressively larger. You don't need to know. Just use an A broach in an A bushing with A shims. They are all marked.

Dennis

James H Clark · Jan 28, 2016

hardtail69 said:
i am also a newbie and i needed this same information so thank you very much indeed. Why manufacturers can be so myopic as to needed information is beyond reasoning. perhaps they figure we will obtain the information by osmosis? it is like the insert tooling guys never telling you the size of the damn screw that holds the insert in... they are not all standard,nor are they readily available at the hardware store. They are in fact very specialized, so please tell us what the designation of the screw is when you sell us the tool. cause the screw is probably the first thing you lose in the swarf lol.

hardtail69: A word to the wise, when you purchase insert tooling, take the time to also

order extra screws and anvils and chip breakers. then you will have the parts when needed

and also the correct part numbers to re-order. This was a lesson hard learned for me. You

will find that most of this stuff can only be found with the original makers.

JH

Twistit · Sep 18, 2020

Owner/Operator

L Vanice said:
DuMont is not the only maker of broaches. I will not take the time to look up the exact details, but other makers use Roman numerals I, II, III or 0,1 and 2 for their keyway broaches that actually fit the DuMont bushings of the corresponding letter sizes and vice versa. As I recall, A is 0 or I, B is 1 or II, etc.

Larry

I too am looking for this information and have now spent hours going over websites. I now Know that ABCD refer to the base dimensions of the broach not the cut dimension. Whoopie. What's the dimension of A,B,C and D. I need to make custom bushings for select hole sizes. The broaches are on order and they are A,B and C sizes. Id like to make the bushing before they get here but what width/depth do I make them is the question of the day. If some one knows please post or email me at [email protected]. Thanks, RonW

Twistit · Sep 18, 2020

Owner/Operator

triumph406 said:
If you for instance ordered broaches from the Mcmaster catalog, it would have been obviuos what style A,B etc meant. At least it was to me.

Well I just looked at McM/C and they don't tell me what size A,B,C and D are in regard to their bushings. Just that an A broach must be used with an A bushing. Does anyone know how wide an A broach "butt" is or a B or a C. If so where do you find it?
RonW

L Vanice · Sep 18, 2020

Twistit said:
Well I just looked at McM/C and they don't tell me what size A,B,C and D are in regard to their bushings. Just that an A broach must be used with an A bushing. Does anyone know how wide an A broach "butt" is or a B or a C. If so where do you find it?
RonW

I could just measure my broaches.

In the absence of broaches on hand, you could look at broach catalogs. The key information will be the maximum cutter width for each group of broaches. The max cutter will be about the same as the slot in the bushings. If you look at page 8 of the DuMont catalog, you will see that I am correct and that they even specify the body width of their broaches. And page 9 even shows the corelation between the letter and Roman numeral size groups.

Pilot-Precision-Products 8 Pilot Precision Products

Larry

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