HEX broach too big for our manual press

[Craig Roys]

We had the same problem when we started using hex. We use one of these for broaching and just about any other press needs...not too big, but plenty of force. There is a floor version as well.

Dake 10 ton press.

[Michael Corsetto]

Like Anthony said, we have used lathes and mill knees in the past to hex broach. Neither are recommended.

We've spent the last few years scouring Craigslist and found a 5 ton/8 ton compound arbor press similar to this: http://www.machine-recycling.com/Sep...bor-press.php6

The travel is plenty and the press is very rigid/square. As a bonus, I'm pretty sure the tool will outlive any of us on the team

If you spend long enough looking, you can find a good deal on one. We got ours for $550.

-Mike

[techhelpbb]

Either bolt the press to a steel frame suitable to support the pressure and put blocks under the work piece when you run out of travel or:

I bought this recently and it works fine for the AndyMark (Dumont) broach:
http://www.ebay.com/itm/261742003018

Mine is currently in my garage on a custom cart made of 2x4 and 3/4 plywood with locking casters. It was lifted with a car engine hoist. Shipping from Ohio took 1.2 days to NJ. The ram has a 1/2" hole in the end and there is a metric set bolt which doubles as a stop when the ram is lifted. Put a longer metric bolt in there and you are all set to broach. Mine has a casting void at the bottom which makes no difference to operation.

Also consider this (see Craig Roys post above):
http://www.ebay.com/itm/261956665389

The advantage of the Dake press is the pressure gauge.
You can use a short ram hydrualic piston from Harbor Freight filled with glycerin as a pressure gauge plate on the previously listed ratcheting arbor press.

[sanddrag]

Ours fits just barely on our Grizzly arbor press. They don't sell the exact model we have anymore but judging by the ones they do have, it's probably a 5-ton. 2-ton is pretty small for broaching 1/2" hex. I'm a big guy, and we've broached certain things 1/2" hex (steel) to where I had a 4 foot pipe over the handle and was just about hanging off of that to get it to go. On a two ton press, you'll struggle with anything more than 6061 aluminum, about 1/2" length through bore.

If you do want to keep your press and use it with longer broaches and things, there's two things you can do. You can chuck up the arbor in a 4-jaw chuck on a lathe and drill a hole into it, or you can build a custom table for your press, that has a sturdy place for you to set the part below the press.

[Hikel team 319]

this is the setup that 319 uses as Ty was explaining it earlier in this thread

[Jared]

Don't broach using a lathe or mill - the thrust bearings aren't designed to be loaded while they aren't spinning and aren't usually cheap and easy to replace. Also, you'll likely end up moving the head on your mill, and you'll need to tram the head before you use it as a mill again.

[FrankJ]

Originally Posted by Hikel team 319

this is the setup that 319 uses as Ty was explaining it earlier in this thread

My that is a awfully big C-clamp you have there.

[RoboChair]

Originally Posted by Tottanka

So, we just received the HEX broach from andymark, and it doesn't fit into our manual 2 ton press.
The Broach is too long, and therefore we cant really use it.

Are there any solutions anyone has for this kind of a problem?
Will cutting the Broach somewhere in the middle, and therefore doing 2 presses every time we make a part work?

thanks!

Remove the arbor of your arbor press. Drill a hole into it with a lathe or some fancy jig so the hole is straight(does not need to be centered). Operate your broach as a 2 step process, start with it in the hole, push it the rest of the way through with the flat to the side of your hole.

Even if it doesn't fully fix it, it still increases the "Effective Travel"

[RoboChair]

Originally Posted by Jared

Don't broach using a lathe or mill - the thrust bearings aren't designed to be loaded while they aren't spinning and aren't usually cheap and easy to replace. Also, you'll likely end up moving the head on your mill, and you'll need to tram the head before you use it as a mill again.

I've broached with the knee of our bridgeport mill against the turret arm. It works and it sucks, and it isn't detrimental to the machine if done right.

[Chak]

Originally Posted by RoboChair

I've broached with the knee of our bridgeport mill against the turret arm. It works and it sucks, and it isn't detrimental to the machine if done right.

Can you explain how to do it right?

[4911 BR]

Originally Posted by RoboChair

I've broached with the knee of our bridgeport mill against the turret arm. It works and it sucks, and it isn't detrimental to the machine if done right.

I've done this using the knee. It is a two person job. One to hold a support tube, the part, and the broach. And one person to operate the knee.

[RoboChair]

Originally Posted by Chak

Can you explain how to do it right?

So, you will need a few things.

A knee mill
A hex broach(or other broach)
The part you want a fancy hole in
Some piece of metal with square ends(like really square, you have a knee mill there is no excuse) and a hole through the middle

Your support piece needs to be at least as long as the broach or have several progressively longer pieces if you find the total travel to be in issue. Don't use multiple pieces to support this set up, it's a good way to break your $200 broach that you are trying to use cheaply. Take your sweet time.

Place your first or only support block(tube) on the back of the knee ways and make sure it is stable. Place your work on top of the support so that it lines up with the hole. Line your broach up with the whole set up doing as best as you can to have everything perfectly straight, take your time please. When you are sure you are good to go begin cranking the knee of your mill up slowly until it makes contact with some part of the turret(the part that nobody EVER moves back and forth on a mill but you could if you wanted) slides on a flat part only. Ours has a dovetail slide and we used the further down bottom flange of the dovetail. If you plan to do this often, just set up the turret so it is set up perfectly over the Y-axis knee ways.

This next part is really important.

When you are sure it's settled and ready to broach, crank the knee up a full turn and back it off to let the broach recenter itself. Keep doing this full turn back off step until you run out of travel, repeat until done. The backing off step may not be 100% needed, but it will prevent the chance of many unwanted things happening to your set up.


EDIT: Done carefully, it can be managed with one person, but 2 makes it far easier and you can take turns cranking.

[Andy Baker]

Another thought:

While all of this advice is well and good, here is a simple solution. Consider making the size of your starting hole larger. If you start with a bigger starting hole, then the broach will fit down into the hole further and you may not need to buy a new arbor press or create a new setup suggested by the brilliant people in this thread.

For instance, if you are creating a 1/2" Hex hole, start out with a 0.520" hole instead of a 0.500" hole. For most applications, I contend that you don't need the middle of the hex flat to transmit the torque, only the outer 1/3 of the hex flat. (If you want to test this, put a hex wrench on a piece of aluminum hex stock. Hold the stock in a vice and torque the wrench until the aluminum is stripped. You will see that the middle of the hex flat is unused. This is actually the same thing I did when designing the churro many years back.)

Here is a pic to show what I mean:



Hope this helps!

Andy B.

[Cory]

My only concern with this would be that it might be harder to keep the broach aligned with the bore since you no longer are relying on the fit between the .500 dia shank on the broach and the hole in the part to ensure initial alignment.

Otherwise this is a perfectly good way to broach something. You'll see that any parts that have been rotary broached will end up with a rounded center and only have flats on the corners, like Andy drew above, since the broach requires some additional clearance over nominal.

At some point the best solution is just to drop $500 on a new arbor press that is actually large enough so that you can do this easily and more repeatably, if you're going to be broaching a lot of parts.

[Dpaulson]

I have been doing shafts and broaching a long time. We always start the hex broach in the lathe with the piece in the chuck and a center in the tail stock.As we get 3 or 4 inches in we move to the arbor press but I find no problem doing the process in the lathe. Drill a big hole a lot more force then the broach. Yes arbor press is fine for broaching a keyway but that hex broach has to be straight Most of this work is in alumimun
Dave Paulson
15 years mentoring
Team 599