Hex Broach Options?

buy a 3/8" hex and go!

$130 is not all that expensive if you consider all of your options. if you buy the right size, a size that will fit all your applications then that one broach will probably last you your entire life.

as long as you use the broach correctly and feed it plenty of high quality lube then you’ll be fine.

we do a lot of broaching in our lathe. put the material in the chuck and the broach in the tailstock…lock, crank, broach. very simple.

no more keys, no more trantorqu…just cheap hexagon stock.

our 3/8" hex broach is going strong after hundreds of broachings.

We use 3/8" (used in kit transmission, too), 1/2", and 3/4" (used in kit transmission, too). We added the 1/2" to our arsenal this year to drive the shooter wheels.

The 3/4" was expensive (like $400), but the 1/2" and 3/8" are less than one night at the Omni. These broaches will last you a very long time. We do not use keys anymore, just hex broaches and very cheap hex stock.

This solution is a very reliable and maintenance friendly design.

Pardon my ignorance, but for those teams that use hex shaft, what’s the standard practice for when it comes to putting bearings on a hex shaft?

For us, the beauty of using the metric system (whenever possible) is that 10mm bearings work great with 3/8" hex (look at kit tranny hex shafts). 1/2" work great with 12mm or 14mm bearings. 3/4" work with 20mm bearings. I can show you pictures and cross sections when I get more time.

I solved this problem once by buying these and welding them to some sprockets. It worked very well. They are available from Small Parts .

Paul is more brave than I…

we use double bushings!

to pass a 3/8" hex through a bearing we buy a bronze bushing from mcmaster at 3/8" ID, 1/2" OD for about $0.12.

we broach it…

then stick the bushing and the shaft into a standard .5" ID bearing. voila! one hex stuck through a round hole…everything is true and round.

putting the hex through a bearing is a fine solution, but for high load application i prefer to have the double bushing to help spread the forces around.

We turn down the ends of the shaft to fit it through a smaller bearing than the hex.

Call up a nearby shop that has broaching capabilities and ask if they can help you out. Bake them some cookies along with a video of some competition footage. In five years of asking local machinists for help I’ve only been turned away once. They are very often happy to help - just be respectful and courteous and explain what your using them for.

Last year I called up a distributor and ask about getting a 1/2" hex broach for a reduced cost. Next thing you know they sent us one for free!!

Use your power of communication and salesmanship, you’ll be surprised!!

Doug, you said it! I’ve not asked a lot, but I did get a shaft and some sprockets machined down for no charge. I think there are certain trades like machining and welding that, if you appreciate their art, will go way out of their way to help you. They guy who turned down out driveshafts one year proceeded to give me a 1/2 hour shop tour and offered to let us feed off their scrap metal pile as well. It never hurts to ask…politely!

I’ve been searching around some more for less expensive hex broaches and so far the least expensive I have found are the “Value” hex broaches at J&L:


(see bottom of the page)

Has anyone used these? They are significantly less expensive than Dumont anywhere but I am wondering about the quality. I am no stranger to cheap import tools and believe they have there place but I am wondering if these are just a waste of money or a good deal. I haven’t had good luck with cheap import taps and dies but have found some of the import drill bits, end mills and collets to be of decent quality for my needs. Does anyone have any guidance on “value” broaches?

While I haven’t bought import broaches, I’d be a bit leary. It really comes down to how much you plan on using it. If you had a specific piece you’d like to broach and you don’t think you’d ever use it again, perhaps saving the money and purchasing an import broach is good. But if you know your team may use it each year - buy a Dumont and you’ll know it’ll get the job done when you need it too. I’d hate to imagine having to broach a part 2 days before ship and have it fail (imports will simply break). Don’t put your team in that position. If you do go with an import, make sure to use lots of cutting fluid and stick to broaching only Aluminum and Mild Steel components not stainless (which some stock gears come in). Hope this helps provide some insight.

Thanks for the good advice. I was thinking about the same thing but wondered if anyone would reply with a “Yeah, they work fine and are justs as good as Dumont”. I kind of doubt I will hear that though. Like you said, I suspect they would do fine for aluminum and mild steel but anything harder would wear them out quickly.