Can we discuss broaching machines.

Miguels244 · Jan 25, 2018

Broaching machines.

So it occurred to me I'd like to broach some mid sized parts.
Rifle actions and equivalent sized objects.

I know nothing about broaching machines and tooling them
Hydraulic?
Horizontal?
Vertical?
New used?

Milland · Jan 25, 2018

Quantity of parts to make? Budget? Own use, or parts for sale? All will be revealed with a little more info...

Miguels244 · Jan 25, 2018

Milland said:
Quantity? Budget? Own use, or parts for sale? All will be revealed with a little more info...

Budget is the question...
Parts for sale and job shop.
Not production, I'm an automation designer, I can build that machine.
I'm a budding garage guy...and want to be able to do something most people can't.

Milland · Jan 25, 2018

Well, let's get into materials you want to cut, the "aggressiveness" of the profiles (how far from a simple round hole), whether you want to one-shot or are willing to using multiple broaches to get the final profile. Are you designing and making or farming out the broaches, or using commercially available cutters?

Miguels244 · Jan 25, 2018

Milland said:
Well, let's get into materials you want to cut, the "aggressiveness" of the profiles (how far from a simple round hole), whether you want to one-shot or are willing to using multiple broaches to get the final profile. Are you designing and making or farming out the broaches, or using commercially available cutters?

I'd have the broaches made.
Something like a rifle action.
Not a huge cut.
https://d2t1xqejof9utc.cloudfront.net/screenshots/pics/42897bd0e99e88fc4e74c5df08e85cd1/large.jpg

brian.pallas · Jan 25, 2018

You say broach, I think keyway, but I don't think that is what you are wanting to do? Do you have any kind of drawing or a hand sketch of what you are wanting to do?

Miguels244 · Jan 25, 2018

brian.pallas said:
You say broach, I think keyway, but I don't think that is what you are wanting to do? Do you have any kind of drawing or a hand sketch of what you are wanting to do?

See above.

reedeprintice · Jan 25, 2018

I have 2 broaches , if you want to talk shop call me 530-877-2875 Jess

72bwhite · Jan 25, 2018

It's basically 2 slots about .450 wide .140 deep with a .496 radius.

think a modified double d style broach there would be about a .700 dia threw hole.
the kicker is it need to be about 9 inches long.

reedeprintice · Jan 25, 2018

Looking at your picture there my newer surface broach may be a good pick , it happens to be for sale.

Mud · Jan 25, 2018

I've been pull broaching holes in proprietary parts in my shop for 20+ years. I rebuilt my machine from a minibroach straddle broaching machine, and my broaches are all custom built to our specs.

I'm pretty sure you won't be able to do what you want. Because I've looked at quite a few machines over the years and talked to lots of shops that do similar work and have never seen a broach machine built with metric fasteners, or a with metric pull head,. :crazy:

Johnny SolidWorks · Jan 25, 2018

Miguels244 said:
Budget is the question...
Parts for sale and job shop.
Not production, I'm an automation designer, I can build that machine.
I'm a budding garage guy...and want to be able to do something most people can't.

The problem with machinists is they always just want to make every little thing themselves.

The problem with automation designers who are also machinists is they always want to design, make, assemble, and run production on every little thing themselves

I'd look at using what you have, and broaching on your mill or lathe (assuming you have them, or plan to) before I'd go for a dedicated broaching machine.

Then again, I have a couple of tools I make that require a broached hole for a 1/2 or 3/4 ratchet, and doing them or getting them done is a real pain in the balls. Now you've got me thinking about designing and building my own....

Lanso · Jan 25, 2018

I’ve had 2 broaching machines over the years, both hydraulic Pioneer machines because they are local for me, always gave me good service. One was used and worked just as good as the new one, very simple machines.
Vertical will be a shorter stroke than horizontal

Milland · Jan 25, 2018

My first guess would be to draw (with tolerances) the geometry you want to cut, then get quotes from a couple of broach manufacturers. I would think that a one-shot pull broach would work for you, so a horizontal machine. You need a guide of some form to ensure the broach can't rotate away from the right clocking for your part, and a robust method for holding the action is needed.

The broach maker should be able to recommend cut per tooth, profile change, etc. From there you'll have length, and so minimum pull distance. Then you can balance the cost for your setup (broach, fixturing, machine) against getting the parts wire EDM'd or other methods appropriate for low volume and make your choice. One other possibility is just having a short push broach for the final ~.005" cleanup after rough EDM as a way of simplifying the broach and machine (just an arbor press), and removing any heat affected material left over from the EDM work.

Miguels244 · Jan 25, 2018

The machines seem simple enough.
I was mostly looking for general information.

Milland · Jan 25, 2018

I had a re-think on it being a single-pull, I reminded myself of a pull-broach I'd bought that made internal splines. It was roughly 50" OAL, with perhaps 44" of cut areas, and a depth of ~.060". You might need two pulls, or a longer cutter to keep load per tooth reasonable. But the broach vendor is the best one to make that judgement.

Ziggy2 · Jan 25, 2018

Miguels244 said:
The machines seem simple enough.
I was mostly looking for general information.

They appear simple because you do not know what you don't know.

You are incorrectly looking at this from a machine design viewpoint. The problem is that the broach tool is what will drive the machine design. This includes total stroke length, hydraulic force needed, tool speed, part fixturing, etc.

A single part machine is rather simple but the design changes dramatically as soon as you design it for production. It is one thing to pull the tool through the part and make your profile. It is a completely different critter to have the part drop out, the broach return to home, uncouple from the pull cylinder, have the part go into fixture, have the tool get pushed into the part, pulling ram than couples to the broach tool and pulls through.

The controls are a piece of cake, the project is in the very small mechanical details that aren't readily apparent until you have actually operated a broach.

Miguels244 · Jan 26, 2018

Ziggy2 said:
They appear simple because you do not know what you don't know.

You are incorrectly looking at this from a machine design viewpoint. The problem is that the broach tool is what will drive the machine design. This includes total stroke length, hydraulic force needed, tool speed, part fixturing, etc.

A single part machine is rather simple but the design changes dramatically as soon as you design it for production. It is one thing to pull the tool through the part and make your profile. It is a completely different critter to have the part drop out, the broach return to home, uncouple from the pull cylinder, have the part go into fixture, have the tool get pushed into the part, pulling ram than couples to the broach tool and pulls through.

The controls are a piece of cake, the project is in the very small mechanical details that aren't readily apparent until you have actually operated a broach.

Of course a continuous production machine is a different animal.
That's not what I want.
What I want is a machine I can use to broach the modified double d one at a time in a single operation.

What I am asking about is the machine and gothcas.
Why horizontal vs vertical.
Power requirements.
Brands.
Are used machines worth it?
Approximately tonnage.

Lanso · Jan 26, 2018

The horizontal vs vertical is an easy one to answer, as I said in my previous post: the horizontal can have a much longer stroke.

Lanso · Jan 26, 2018

Also, I would definitely buy used even if you had to rebuild it.
Your broaches will probably be custom made and not inexpensive.

Can we discuss broaching machines.

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