Broaching

[clevinski]

Thanks all for the info and clips, as it sure helps to "see" the process in action (all I found during my search was large high speed machines). Didnt realize that the broaching could be done at a very show speed (like the hand arbour) but seeing it done on that and a hydraulic press (something I want to build) sure makes it clearer. OK, dont laugh now, but before today and reading these posts I wondered how I would secure the work ..... yea, feel stupid, but 10 seconds of video clip and my brain went AH-HA

I couldn't visualize it AT ALL until I saw it done in one of these videos, and then I had the same "DUH!" moment that you did. After I saw it once, it was, "Why didn't I realize that before???".

 

[kevin]

If this is something you don't do often, or if you typically need only one a few sizes. consider making your own boraches:

https://sites.google.com/site/lagadoacademy/useful-links#misctools

P.S.

I once made a square broach for punching sqaure holes in 1/8" thick aluminum - I just used square steel stock, heat treated to harden, and punched it through with a hammer. This was a pretty simple application, and aluminum is so soft its hard to go wrong, but this convinced me that making your own broaches is not all that difficult. Of course, this gets into the old "Do I make a tool or buy a tool?" debate; I think the answer is something each person has to decide for his/her self, based on personal circumstances.

 

[stern]

Well, not sure if or when I will get a broaching set, but knowing I can "do it" on a press does make me happy. Have looked at presses before but never bothered as I couldn't think of a use for it, until now. Seems aside from "pressing stuff", I can broach stuff, I can punch stuff, and why not bend and shear stuff ?

Been debating using my disassembled HF 3 in 1 bender.sheer/roller as scrap steel or deciding if I want to make a "better one" out of the bits. After all my "broach digging" I have decided to go ahead and make a hydraulic press (will make it heavey enough to do 50+ tons) and make some tweeks to allow me to add a bending jig and sheer to it, so I can use it for a crap load of things. Also will probabaly make a steel punch attachment for it. Since getting a hydraulic pump is expensive (about $300 +) I will bite the bullet, get a half decent pump and a BIG ram. While its a bit costly, sure cheaper than buying a 50 ton one (I can use I beam for the framing), and the more things I can set it up to do, the more "cost effective" it will be.

 

[docn8as]

several "poor boy " alternatives from over 70 yrs of working w/ tools ...

i have broached square holes in mild steel using squared off lathe bits w/ no relief /clearance...hole is drillled a tad larger , maybe 1/32 o/size , depending , & chamfered lightly to start the bit ...which is bashed thru w/ a 3# hammer ...eye portection w/ hard steel on hard steel & straight on hitting ( prevent chip )....straight thru w/ out removing ...you cannot be timid...if you are , back it out ,clear & go again .....largest i have done this way is .455 ( ground a 1/2 in bit on surface grinder ) for a knuckle buster chuck wrench ( external square head adjuster screws ).........it has been called "bash broaching " by IIRC rick sparber

gears & pulleys on old tyme farm equipment were round key pinned ....shaft inserted & a hole drilled at the junction of shaft & gear/pulley ..a pin , usually a 16 penny or 20 penny jail was driven in & ground off ...drilled hole will want to run off a ta d in the softer metal so it shud be started a little 'off"...this is also useful when you have drive fitted a bushing to make sure it doesent spin , if you think the fit was a tad light ..like in fitting a bushing to a face /back plate to cut s new thread....


multiple hack saw blades , the inner ones thinned if necessary for size can cut an internal key way ..finish w/ file been there....

cape chisel & file been there

if you have a broach & no press , a lead hammer will drive th e broach ...it is h-- on the hammer , but so far have not chipped /broken a broach ,,,,again we are still talking mild steel

for larger square holes , a shaper works great ....make a boring bar to replace the tool post ..bolt it to the clapper & cut UP w/ clapper locked ...( slack is taken out )...this is straight thru & does not have the cantlever of a tool holder hung down from the tool post ..."ride' the ram & put on 2-3 thou each time it retracts ...using doc's leonardo tool holder , in shaper board tool holder sketches allows near double th e width & d.o. cut ...

if you have a mill ......center punch & scribe a circle the diameter of the square needed......drill out the corners w/ a small drill3/32 , 1/16 whatever needed ........NOW drill out the large center hole ..now use the smallest end mill diameter to square out the hole .( CAREFULLY >LITE CUTS )...i
.made handles for 7 in van norman vise & 6 in palmgren milling vise last winter w/ this methood ...thanks to an atlas crftsmn board poster

FWIW ...a 3 T greenard arbor press was not enuf to broach a keyway in a 2 in long flat belt pulley for an antique shaper ...IIRC ,,it was a 3/32 ..

these are my experiences ,,,when they are what i have only read or heard , i so state

best wishes
docn8as

 

[benmychree]

What you are talking about is not broaching, but punching; a punch with no die to back it up. My last choice would be a hydraulic press, as there is no "feedback", that is there is no sense of the force being applied to the broach. With a arbor press, you can feel the force being applied to the tool; if the feel tells you that something is the matter, you can deal with it; with hydraulics there is no feedback, the broach breaks, and it costs you. The guy who talks about easing up on the arbor press ram occasionally knows what he is talking about; sometimes the broach is not in good alignment, and is subject to lateral movement which may cause binding, or breakage. Another thing to watch out for is trying to broach keyways longer than the broach guide or "plug". This is not recommended, and can cause breakage. Hammering on a broach is just plain stupidity; you paid a premium for the tool, the hammer is gross abuse of the tool, and should NEVER be done.

 

[oldgoaly]

I like this hydraulic arbor press, I've used a manual one hard on bad shoulders, a regular hydraulic press doesn't give you much feedback on how much pressure is being applied, you could break something if you are not careful. I traded for this, had it rebuilt by "HiBall" and it is awesome!!!!

 

[Privateer]

Another question regarding broaching. As this thread was aptly titled, I figured it'd be better suited to add to it. This question pertains to the sizing of the broaches and collars. I've seen sets labeled #00 or #18, etc.. and broaches with an A, B or C next to them, even though they indicate the same size. e.g. 1/8" A, or 1/8" B. I get they're different in some fashion, however I've yet to find a definitive resource that adequately explains it. If someone could either explain or provide a resource, it would be very helpful. Thank you in advance.

Terry

 

[Maxx]

Another question regarding broaching. As this thread was aptly titled, I figured it'd be better suited to add to it. This question pertains to the sizing of the broaches and collars. I've seen sets labeled #00 or #18, etc.. and broaches with an A, B or C next to them, even though they indicate the same size. e.g. 1/8" A, or 1/8" B. I get they're different in some fashion, however I've yet to find a definitive resource that adequately explains it. If someone could either explain or provide a resource, it would be very helpful. Thank you in advance.

Terry

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

It has to do with the size of the bushing.

 

[benmychree]

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

It has to do with the size of the bushing.

It has more to do with the body size of the broach; as noted some broaches may cut the same size keyway in two different body sizes, the reason being that smaller broaches are limited in the length of key that they will cut; an A size will not cut a key as long as a B size, and so on, due to the smaller broaches being shorter than the larger ones. Cutting keys in holes any much longer than the broach plug is looking for breakage, especially in the harder metals. In my shop, I had a Mitts & Merrill keyseater; with it I could cut keys from about 1/16" to 1 1/4" wide and 12" through; not a home shop tool.

 

[Privateer]

So as an example an A 1/16" has a 4" stroke, vs a B 1/16" with a 6" stroke? I realize 1/16" may not extend to both A and B, I was just using an arbitrary size.

Terry

Or by length, do you mean the depth at which the broach will cut the keyway? In the above example, a 1/16" wide keyway, cut to a depth of X" for A and Y" for B?