Made a special press for broaching

As part of a custom machine I have been fabricating (later) I needed to broach 1/4" keyways in 1 1/8" holes in two steel flywheels and two collars. I figured no problem, just call up a buddy where I used to work and see if they can press them in the shop. To my surprise they no longer have an arbor press with a high enough throat to press the 12" long broach. Several friends have home hydraulic presses, but they have short strokes and you need to do a lot of resetting to get a broach through, at least two presses and maybe three for each pass of the broach, two passes per hole. That's a lot of fussing around. Hmm.

So, I sez, let's build a press just for broaching. I have two possible hydraulic sources. The first is one of those cheap, 4 ton manual Porta-Power sets. But they are very high pressure (10,000 psi) and use small diameter cylinders. I didn't think I could find a sub 1" cylinder with a 12" stroke. Even then it would be a lot of pumping.

My other source is an old 12 volt hydraulic system that operated a Corvair convertable top. I built it into a tire bead breaking machine about 35 years ago and it works fine for that, but I no longer use it. I put a gauge on it and it just hit 300 psi as it stalled out.

A quick email to DuMont and they said I needed 700 pounds of force for a

1/4" broach in 5/8" mild steel. A 2" piston would give me around 950 pounds.

I looked on the HGR Surplus web site and they have lots of pistons. I drove over and immediately found a 2" diameter, 12" stroke cylinder, brand new for $19.99. Cylinders are real cheap at HGR, most are $10 or $20.

Since I already had a C frame for the tire machine, I just cut it down to the correct height and bored a few holes and mounted the cylinder on top. The hydraulic pump mounts on the upright and the existing steel braided lines were just right. I'm good to go, only a few hours of work.

I cycled her back and forth for a while to bleed the air then give it a shot. It does flex too much, I'll have to add a strongback to the 4" channel frame. And I actually had to start the car I had it hooked to, the extra couple of volts gave me just enough to push through, but it is at the absolute limit with a 1/4" broach. Every keyway broached perfectly, and those shaft collars were tough steel.

Here is a photo:

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'Nice piece of work, Dennis. This is a little late to comment about it, but if you're going to use a multi-tooth broach in an open hole, a pull broach might be a lot easier for home construction. The hole provides the only guidance you need.

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Ed Huntress

Very nicely done! Either add another lenght of challen at 90' to the back of the press..or simply add a pair of 3/16' x 1' bars down each side of the press. This will prevent bending of both the back and the top and bottom of the press. The secret would be installing them at a distance you can get other work pieces into the press without the bars interfering..such as a large gear. Personally..I think Id make a totally new assembly using a better configuration, but..shrug.

Very well done Sir!!


One could not be a successful Leftwinger without realizing that, in contrast to the popular conception supported by newspapers and mothers of Leftwingers, a goodly number of Leftwingers are not only narrow-minded and dull, but also just stupid. Gunner Asch

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Gunner Asch

Nice. I love doin' stuff like that. Very satisfying.

I went to HGR Surplus:

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acres_ of surplus stuff!! Jeez, I could spend a week there.


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Bob Engelhardt


I want to get a couple of hydraulic cylinders so went to the HGR website. Lots of cylinders, but most are one of a kind and have no specs listed. So that was disappointing. Oh well................


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awesome project.

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When you pushed the broach though, did you let up once or twice to allow the broach to recenter itself? Reason I asked is I used a hydraulic press once and tried to just take one long stroke. There was angular misalignment and the broach snapped.

Nice solution to your problem at hand!


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I'm back, I was gone for a day. I did press it in stages to allow everything to self center. Especially when you are broaching a thin part (mine was 5/8") there is opportunity for the broach to tilt as only one or two teeth are contacting at once.

This was a quicky solution and it worked, but it needs upgrading. I will add a

3" channel strongback at 90 degrees to the existing upright, that should stiffen the press quite a bit. The way it was, every time a tooth cleared the bottom of the workpiece, the flexing allowed the broach to jump ahead until the next tooth engaged.
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