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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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Dennis

Reply to
DT
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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.

Reply to
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!!

Gunner

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

Reply to
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.

Bob

Reply to
Bob Engelhardt

Nice.

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................

Dan

Reply to
dcaster

awesome project.

i
Reply to
Ignoramus7096

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!

Wes

Reply to
Wes

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.
Reply to
DT

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