Hex Broach Options?
 

I've been looking at hex broaches recently from the major catalogues (Mcmaster, MSC, etc.), and the $130+ price tags are scaring me a little. Are there any tool suppliers that offer quality broaches at lower prices than these?

Re: Hex Broach Options?
 

Hex Broaches aren't cheap anyway you cut it!

Try Enco: http://www.use-enco.com/CGI/INPDFF?PMPAGE=84

They are about the least expensive I have found. If you find a less expensive source let us know. I'm sure there are lots of people around here that would like to know.

Re: Hex Broach Options?
 

I understand what a broach is used for but never actully cutting my own keyways could someone explain how one is used? Thank you very much

Re: Hex Broach Options?
 

a hex broach has a cylindrical end to it that is the same OD as the ID of the pilot hole in your part. This helps align it with the part. You then use a press to push it through the part. the broach gets progressively larger as you approach the top, until it reaches it's finished size.

With a standard keyway broach, you have a bushing that has the same OD as the ID of the hole you're broaching, with the profile of the key removed from the edge so that you can push the broach through with a press.

Re: Hex Broach Options?
 

You know, it's kind of ironic: Hex stock is relatively cheap, but the tool needed to use it is outrageous! You can buy an entire set of keyway broaches for the cost of one moderate sized hex broach.

Re: Hex Broach Options?
 

Do you have access to an EDM machine? That might also be an option.

Re: Hex Broach Options?
 

Thats a possibility I hadn't thought of. This is just for a potential prototype I'm thinking about, but I still haven't decided on spline shaft, which comes with bushings, or hex.

Re: Hex Broach Options?
 

they may be expensive, but they are more or less a one time cost especially if you design with the mindset that you only have one or maybe two broaches, which simplifies things. If there is another team in the area you could possibly borrow it, or share the cost (just agree on a size head of time).

Re: Hex Broach Options?
 

We made a hex broach this year our of a harden steel rod for our 2 speed gearboxes. We used a surface grinder to make the hex shape on the rod. I would 've taken a picture of it if we didn't loose it...LOL

Re: Hex Broach Options?
 

I've heard of using a sharpened Allen wrench, after hardening it. Unfortunately, I doubt it would perfom on a high carbon or stainless steel.

Re: Hex Broach Options?
 

Andrew;
here is an article supporting your idea.
It is from the Home Shop Machinist, 2002 Sept.-Oct. Issue page 36
titled:
"Make Your Own Socket Head Fasteners with the Brinkerhoff Rotary Broach".

It is an interesting approach and does use a hex key that is sharpened and hardened. Unfortunately the magazine does not provide online copies of the article. Enjoy Larry Upjohn.

Re: Hex Broach Options?
 

If this is for a school or robotics project, how about calling all of the shops within a 1hr drive and asking them to wire EDM or broach the parts for you? I bet you'd be able to find someone to do it for free within a weeks time of when you call. That is a conservative estimate, too.

Re: Hex Broach Options?
 

*cough* waterjet *cough*

If you can find a shop locally that has one that may be able to waterjet your parts for free, look into it. You might not always get the friendly shops, so another option would be www.dcwaterjet.com I believe you can have your gears dropshipped to them and they do the cutting.

Re: Hex Broach Options?
 

I don't think I'd waterjet something like that. I'd be worried about the draft.

Re: Hex Broach Options?
 

Here's one possible way:

"Make up a fixture to hold the [item] you want to broach the hole in. Ideally the end should be vertical but horizontal will do. Take a good quality allen key
and cut the short end off it. Drill a small hole about 4mm diameter through the
key about 1/2 inch from one end - you'll see why later. Then heat the other end to bright yellow and quench in boiling water to get a superhard tip. Grind the end to get sharp cutting edges.

Drill the hole in the piece to be broached at the size across the flats of the
allen key. Make it a bit deeper than you need so there is somewhere for the
swarf to go although if you want a bar magnet in there you'll have a smaller
deep hole anyway which will be fine.

Now you need a guide for the allen key to run in. Take a piece of steel about
3/4 inch thick and drill a hole through it just smaller than the size across
the corners (not the flats) of the allen key. Then tap the allen key through it
and you have just broached your first hole. Mount this piece of steel so the
hole in it is central to the part to be broached. You now have a guide which
will keep the allen key bang on centre all the time.

Now just tap the allen key into the workpiece a bit at a time and pull back to
blow out swarf. If the allen key sticks then use a small tommy bar in the hole
you drilled through one end of it. If you want the broached hole to be as dead
to size as possible then do this. Heat the workpiece in a flame to 200 degrees
C or so until you have broached to full depth. This will expand the workpiece
and the broached hole will be a tad undersize when cool. Then let it cool and
contract again and take a final cut in one hit to the full depth.

It's a lot of messing about to make one hole but you'll get it dead true and
dead to size if you do it this way.

Dave Baker at Puma Race Engines (London - England) - specialist flow
development and engine work. ."

Re: Hex Broach Options?
 

For that amount of work, I think I'd just buy a broach. And how do you grind the allen key without losing some dimension? Surely the end result would not be able to freely slide over a piece of hex stock like it would had it been done with a real broach.

Re: Hex Broach Options?
 

In this case, they were only grinding the end of the allen key. Think of it as a broach with one edge. Similar to a mortising chisel attachment for a drill press.

A clever machinist/toolmaker can do amazing things with rather simple machinery. In this case, the idea is to make a real broach. Even if you were to taper it and make several steps, it's really only the final step that makes much difference. Whether it will work or not depends on the precision of fit required.

Re: Hex Broach Options?
 

This year our team faced the same decision. Spend the money and get a hex broach or find a different way of locking it to the shaft. We decided to spring for the broach because in the long run we will most likely use it several times over the next several years. They are expensive but we feel we will get our money out of it. If you think you won't use it more than once or twice then I probably wouldn't buy it.

Re: Hex Broach Options?
 

And here is the OTHER answer...

EBAY!!

I just searched for broach hex on ebay, and found a few. Just need to get lucky - but they can be found for cheap.

Re: Hex Broach Options?
 

Go to a waterjet shop.
Ask them to demo their waterjet.
By cutting some 1/2" hexes in 1" steel.
And ask if you can keep it as a souvenier.
Proceed.

Re: 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.

Re: Hex Broach Options?
 

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.

Re: Hex Broach Options?
 

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?

Re: Hex Broach Options?
 

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.

Re: Hex Broach Options?
 

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

Re: Hex Broach Options?
 

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.

Re: Hex Broach Options?
 

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

Re: Hex Broach Options?
 

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!!

Re: Hex Broach Options?
 

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!

Re: Hex Broach Options?
 

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:

http://catalogs.shoplocal.com/jlindu...genum ber=418

(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?

Re: Hex Broach Options?
 

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.

Re: Hex Broach Options?
 

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.