Broaching question, key way size vs arbor press size

[WobblyHand]

Not that you need it but I think one one of the common ways to get a bit more capacity (height) out of an arbor press is to just suspend a small secondary table beneath the existing foot of the press. Kind of like a stirrup if you need to visualize something. The press itself isn’t modified, just the relative position of the support for the work.

-frank

Good idea. This would require some interesting design to pull off. Obviously need to additionally bolt the arbor table to the floor in the front to prevent lifting. Probably have to bolt the front of the press to the table as well. If I put some steel plate under the arbor press and used it as the anvil I'd get enough clearance. I'd need something like a piece of 9 x 18 x 3/4 plate if a single piece.

 

[francist]

Obviously need to additionally bolt the arbor table to the floor in the front to prevent lifting

Actually I don’t think so, the stirrup takes the load because it’s secured to the press. Imagine pulling your boot on to your foot while sitting in a chair. Kind of like this…

 

[Larry$]

I think you are in luck with the Arbor press, especially if you make the suggested under hung support. I use my 20 ton hydraulic press. Kind of a PIA because it is so slow. I've considered adding compressed air powered jack but another to a long list. Remember to release and restart the push to keep from bending the broach.

 

[WobblyHand]

Actually I don’t think so, the stirrup takes the load because it’s secured to the press. Imagine pulling your boot on to your foot while sitting in a chair. Kind of like this…

View attachment 417313

That would be for a long reach. I would have enough reach by the table surface. However, your diagram would allow a wider pulley to fit, since it isn't restricted by the pass through. Never having done anything like this, how does one size the bolts and how thick of a plate? 3/4 or 1" for the plate ok? 1/2" bolts ok, or do I need to go to 5/8 or 3/4?

 

[francist]

Not being an engineer and more of a “that looks about right” kind of guy I think I’d probably go for nothing less than 5/8” bolts and roughly the same for the plate. I suspect in reality that would be lots overkill but I’d rather be over than under. For a one-off modification (as opposed to selling add-on kits, for example) going to the next heavier size of hardware is often not a huge part of the cost and then I don’t have to sweat about the calculations.

If you want to chase the idea further here’s where I saw it done, DoubleBoost “Sunday Night Night Cap #293. Something tells me not to attach an actual link here but this is the video and it’s still up for viewing as of today anyway. There were two parts, this was from the second one.

 

[tq60]

Broach does not require too much power so most common arbor press should get it done.

Too short...creative cheating...

Make a"cheater bushing"

The standard bushing is designed to hold everything correct for correct depth.

You Canale another bushing to exact same dimension to practice your skills.

Then make the guide cut DEEPER.

This will allow the broach to be deeper into the work area before it actually cuts.

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