# Broaching Tool



## darkzero (Feb 17, 2010)

How do you use a broaching tool, like for cutting keyways? Are they really effective?

Is it as "simple" as it seems, just pushing down on the part & it just cuts with the down ward force as you advance the work piece in small increments? What about for harder metals like steel, seems like deflection of the tool would be an issue causing alignment issues while cutting or even a taper?

Could they be used in a drill press assuming a vise with a cross slide is used or is a mill absolutely necessary?


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## GMLRS (Feb 17, 2010)

I would use a press without much play in it. Use oil!, Ive only done it twice,make sure all the broachs cutting surfaces are sharp and undamaged.

Since its only an 1/8th of an inch, you could possibly make a tool like a "old Shaper machine" would use.

Broaching Video
http://www.youtube.com/watch?v=3qLjuZKBHXQ


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## Atlascycle (Feb 17, 2010)

Will,
typically a keyway broach is used in a press, it requires a bushing for the hole to guide the broach as it is pushed through the bore to cut the keyway.
Broaching a keyway on youtube. 

Jason


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## gadget_lover (Feb 17, 2010)

To use a broach...

The tool comes with a collar and shims. The collar has a slot in it to accept the broach. The broach is small at one end, bigger at the the other with lots of steps. Each step is a cutting tooth. The difference between big and small end is fairly minor.

You generally cut the keyway is several passes. After the first pass, you place a shim behind the broach so that it is pushed away from the center. This makes the next pass cut deeper. If you need even deeper, you add a second shim and do it again.

A manual press is often recommended so that you can tell if it is binding.

Daniel


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## KC2IXE (Feb 17, 2010)

some bigger broaches are designed to be PULLED through the hole, less likly to break the broach


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## precisionworks (Feb 17, 2010)

A good explanation here: http://www.dumont.com/procedur.html

Both broaches & arbor presses are pricey ... my two DuMont sets cost $500 on eBay (over $1500 new) and an arbor press will run from $1000-$2500.


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## 65535 (Feb 17, 2010)

They are definitely not a worthwhile investment unless you need to cut key ways regularly. They cut really smoothly in aluminum brass and mild steel parts as well as other similar materials.

Usually unless you are fabricating your own drive train parts you won't need a set. 

They do wear out and they are expensive.


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## precisionworks (Feb 18, 2010)

> not a worthwhile investment unless you need to cut key ways regularly


+1

My sets have paid for themselves many times over ... but the are used on a regular basis. Most smaller shops can't offer this service, especially when a custom bushing needs to be machined in order to broach a part - which I often do 

With a magnetic sine vise & surface grinder, broaches are easily resharpened. DuMont broaches are good for many resharpenings before replacement is needed.


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## 65535 (Feb 18, 2010)

precisionworks said:


> +1
> With a magnetic sine vise & surface grinder, broaches are easily resharpened. DuMont broaches are good for many resharpenings before replacement is needed.



And that only double the cost of the set if you have to buy those things to sharpen them. :nana:


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## darkzero (Feb 18, 2010)

Thanks fellas.


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## precisionworks (Feb 18, 2010)

> double the cost of the set if you have to buy those things to sharpen them




In fact, more than double ... my compound magnetic sine vise cost more than the surface grinder:


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## 65535 (Feb 19, 2010)

Oh wow I completely missed that you said magnetic sine vice, and you actually have a compound magnetic sine vice, sheesh, you must be made of money.  Or at least you used to be made of money.


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## precisionworks (Feb 19, 2010)

> you must be made of money.


Only in my dreams 

There are three reasons that I have enough tooling to get through most jobs - eBay, auctions, and Ted the Tool Man. My work schedule doesn't allow attending many auctions as they are mostly held during the week. EBay has been a good source for high dollar tooling at fire sale prices, if there's enough time to find the right tool. Ted has supplied lots of tooling (like the compound sine vise). New ones run around $2500 from a top maker like Suburban Tool, but mine was nearly new (although probably 40 years old) and cost about 15% of new price. Sine vises lead a gentle life, usually kept in the toolroom & never seeing service on the factory floor.

Here's a nice looking one for a decent price, and the shipping is cheap for a 60# item: http://cgi.ebay.com/4-1-2-x-7-COMPO...QQptZBI_Tool_Work_Holding?hash=item3351b9030b


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## chew socks (Feb 19, 2010)

Could someone please measure the thickness of a shim for a broaching kit? I lost the one we had for our FIRST team. I ground a new one but i had to estimate the demensions.

Thanks,
Kirk


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## gadget_lover (Feb 19, 2010)

I'm pretty sure that it would be different for each broach manufacturer.

Logoc says.... The shim is to move the broach out enough that the cutting edges (teeth?) will engage for the second pass That means the shim should be the same thickness as the broach at it's thickest point. Or maybe just a tooth or two thiner. If it's too thin, then some of the teeth will not engage.

But logic does not always apply. 

Daniel


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## precisionworks (Feb 19, 2010)

> please measure the thickness of a shim for a broaching kit?


Daniel is correct ... the shim thickness varies with the broach.


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## Atlascycle (Feb 20, 2010)

To Figure out the thickness of the shim you can first run the broach through and then measure the depth of the key way and see how much deeper that it needs to be cut.

Jason


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## 65535 (Feb 20, 2010)

Measure the height of the final tooth on the broach in reference to the spine. Measure the depth of the keyway in the plug and figure out what shim you need for the depth you want the keyway cut.

Contacting the manufacture is a great way too.


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## liveforphysics (Feb 20, 2010)

Broaching doesn't need to cost more than $40 to get setup.

I needed to broach some custom splines on the inside of a piece of stainless on a run of precision parts. 40 parts, each with 9 splines needed. 

I ordered the broach from china-tool place online. 

Made an indexable clocking broach guide. 

Welded together a custom broach guide setup, and mounted it onto my old log-splitter. 

We've only done 25 of the 40 parts now (waiting for demand to build back up), which is 225 slots broached on the same cheapo China broach. High sulfur cutting fluid is critical here with the stainless IMO.


Here is a quick video I took of the broaching process done on a log-splitter.
$40 in parts total, plus some scrap and junk laying around and I can do the 9 spline patter on the ID of the parts. The custom broach place wanted over $2,000 to make me a custom broach to do what I was able to put together for $40.

http://www.youtube.com/watch?v=RI8Abe0GFxM

Enjoy.


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## precisionworks (Feb 21, 2010)

> Broaching doesn't need to cost more than $40 to get setup.


Agreed, as long as the power source (log splitter or hydraulic press) is free of charge ... if there's another free one laying around, please ship it to me 

Broaches can be pushed with any device that will force the tool through the material. I've seen it done with a hydraulic press and with a 10# sledge hammer, and both produced acceptable results until the broach snapped & became a projectile. Only an arbor press allows the operator to feel the progress of the broach as it cuts.


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## StrikerDown (Feb 22, 2010)

precisionworks said:


> Only an arbor press allows the operator to feel the progress of the broach as it cuts.



A log splitter might let you feel the broach also! but it would be more painful!  :devil:


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## chew socks (Feb 22, 2010)

precisionworks said:


> Daniel is correct ... the shim thickness varies with the broach.



Hmm i supose that makes sense, as do these numbers. I had originally ground it down to .05 and it was still too big. But its a 1/8 broach so by the chart that would be a .031 broach instead.


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## precisionworks (Feb 22, 2010)

The DuMont sets come with a number of steel shims ... which promptly get lost in the swarf & sucked up in the ShopVac 

I've made a number of shims from brass sheet stock, available from Brownells & other suppliers. Thickness should be close to the recommended number, but is not too critical unless it's way too thick.


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## chew socks (Feb 22, 2010)

precisionworks said:


> The DuMont sets come with a number of steel shims ... which promptly get lost in the swarf & sucked up in the ShopVac
> 
> I've made a number of shims from brass sheet stock, available from Brownells & other suppliers. Thickness should be close to the recommended number, but is not too critical unless it's way too thick.




Haha yea thas probably where ours is too. unfortunatly our kit only came with one. But now that i know i can go regrind it right, cause i was told they were coming out too big right now.


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## lightmyway (Mar 23, 2010)

http://homepage3.nifty.com/amigos/slotter/slotting_tool-e.htm 
This may be of interest.


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## 65535 (Mar 23, 2010)

That's pretty cool, might even work for making blind keyways that don't go all the way through, very cool.


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