Maximum width front jaw for Yost 9" front vise (used as tail vise)

[Bobby Newsom]

Vise is 9" wide, benchtop (and endcap/rear jaw) are 21.5" wide. My question(s):

1) Is this 9" vise able to accommodate a full-width (21.5") front jaw, centered at the halfway point (as shown in pics below)? Dog hole(s) (3/4") will be drilled in top of front jaw. Haven't decided how far from front of table the first row of dog holes will be. My main concern will be excessive racking, especially if using dog hole(s) that are closer to the edge of the bench.

2) If answer to #1 is NO, then what is the maximum width front jaw that would be appropriate for this size vise?


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[Bill Dufour]

As the jaw gets wider it has to be made thicker so it does not bend under load like a caul for clamping. At some point the extra thickness required is more then the vice travel. If it was 50 feet wide it would need to be 12 inches thick or more so it could grab squarely at one end at a time. In that example the vice needs 24" of jaw opening. just to accommodate the extended jaws.
look at a flatbed trailer or bridge decks. They are arched so they get flat under load.
Bill D.

[Steve Eure]

I have that same vise, and yes it will rake. I have about 18" long jaws on it. I made a "equalizer" out of a stack of large craft sticks, (large popsicle), that I use when I need an extra hand. Just set them on top of the vise, and flip down ever how many you need and your good to go. It is a pain though.

[Bobby Newsom]

Good info. Is there a formula or ratio to determine the proper jaw thickness given a certain width?


As the jaw gets wider it has to be made thicker so it does not bend under load like a caul for clamping. At some point the extra thickness required is more then the vice travel. If it was 50 feet wide it would need to be 12 inches thick or more so it could grab squarely at one end at a time. In that example the vice needs 24" of jaw opening. just to accommodate the extended jaws.
look at a flatbed trailer or bridge decks. They are arched so they get flat under load.
Bill D.

[Bobby Newsom]

I have a piece of 4/4 hard maple that is plenty long to double up and glue to the walnut front jaw. So it would be: walnut endcap/rear jaw - maple/maple/walnut front jaw. I checked the thickness of this setup, and it would only leave me about 4.4" of travel on my vise screw. So more frequent dog holes would be necessary.

Thoughts on this setup?

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