Low-profile saw arbor — a use for a rotary broach!

[woodchucker]

why put an integral screw in the cap. Just put a socket head cap in a counterbore. The low profile then does not have to rotate to lock down, it becomes a cap/washer.. With an integral cap/screw you now need to fight friction of the saw to tighten and loosen. Just the screw in a counterbore makes it much easer to tighten and loosen. And you get a proper screw.

 

[mcdanlj]

Well, I already explained why I did it. But you don't have to like it...

 

[woodchucker]

Well, I already explained why I did it. But you don't have to like it...

not that I didn't like it, didn't read that. still can't find it.

 

[mcdanlj]

Because rotary broaching is fun magic!

 

[Parlo]

I never understand why the nut either has a male thread or a countersunk clearance hole. I make mine with a blind female thread in the nut and tighten down from the top with a cap head screw. The bonus is a high tensile thread and a larger allen key socket compared to the same thread countersunk screw. Also a nice flat finish on the nut face. Using the sizes on the drawing an M16 could easily be used where a 14mm A/F allen key could really tighten the slitting saw, no more slipping.

 

[mcdanlj]

@Parlo I may not completely understand your design. Do you just use a really long cap-head screw?

@mksj's design uses a counterbore for a cap head screw in the cap, not a countersunk screw, so it's still a flat presentation on the arbor cap.

When I made my first version, I copied the junk arbor I had bought in using a countersunk screw, not yet understanding the limitations of countersunk screws.

I have a design and all the bearings and stock to make a larger rotary broach holder to take ½" stock, so I could make a version of this design that takes a 10mm or ⅜" hex wrench instead of 6mm (the maximum metric size broach I can make from 8mm stock). But I didn't think it was necessary. And the larger the broach, the higher the force required.

 

[Parlo]

Not very long, the 1" locating portion of the nut can be reduced to 20mm dia after a 10mm long register almost to the top for more rigidity. I use a 25mm R8 sidelock to hold the body.

 

[Parlo]

@Parlo I may not completely understand your design. Do you just use a really long cap-head screw?

Here are a few images to help explain the principle.

 

[woodchucker]

Here are a few images to help explain the principle.

Really nicely done Parlo.

Mine are much simpler.. For different size saws, both slitting and slotting.

 

[Parlo]

Mine are much simpler.. For different size saws, both slitting and slotting.

My plan was to eliminate the small ring on the cap that supports the flange. The ring is the locating diameter less the counterbore diameter. The solution was to leave it solid and have a much larger thread on the other end.