Fixing a disk to a shaft with set screws (disk is too large for them), or?

zondar

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Hi,

I've acquired a 3" diameter disk of brass, and I'm considering how to attach it to a 1/4" shaft such that it can be repositioned by sliding it on the shaft (oriented radially, similar to how a hand-wheel is mounted).

Driving set screws through the whole radius (i.e., ~1.375" to the shaft) seems way too much, and I don't have an extra-long tap anyway. Angling them through a shorter distance - in from the side of the disk - might be possible, but it seems difficult to accomplish (I'm quite new to machining) and probably would not hold well.

I actually have two disks, one 3" by 1/2" thick, and one 3" by 1" thick. The larger one is too heavy for the 1/4" shaft (it will flex too much), so I've settled on the 1/2" one. I could machine off a half-inch from the 1" disk, leaving a smaller shoulder, say 1" in diameter, that could easily be drilled and tapped through the 0.375" depths, but it seems like a crime to cut away that much of the ridiculously-expensive brass. Also, that shoulder would be a quite undesirable addition in terms of how the device is supposed to work.

Ultimately, I could press or shrink-fit it, etc. (as discussed in a previous thread), instead of having it movable, but as this is all experimental I may discover that I need to change things later.

I've been finding that there are always smarter ideas out there. What other ideas and options might there be?

Thank you.
 
You don't need to thread thru the entire disk . Just drill the hole for minor diameter of the tap you plan on using , then open up the hole to tap clearance diameter leaving 1/2" or so for tapping . No special tools needed .
 
Yes, I see, thank you. But I don't think I can do that with sufficient accuracy or safety.

I only have a tiny lathe (Sherline), and it's not reasonable to attempt to hold (with only 2 jaws of a 4 jaw chuck) and spin a >1 pound 3" diameter disk sticking out for its whole diameter. :-/
 
You could file (or cut) a tapered keyway and make a corresponding tapered key from brass. Essentially securing the disc to the rod with a wedge. That would be repositionable without impacting mass properties.
 
You could file (or cut) a tapered keyway and make a corresponding tapered key from brass. Essentially securing the disc to the rod with a wedge. That would be repositionable without impacting mass properties.

That's an interesting option! I'd probably consider it a semi-permanent method, but that's OK in this case. I do have some jeweler's files, too. Thank you.

As I'm thinking about "semi-permanent" options, I could use CA glue and (hopefully) remove it with heat if necessary. That would likely be easier.
 
Yes, I see, thank you. But I don't think I can do that with sufficient accuracy or safety.

I only have a tiny lathe (Sherline), and it's not reasonable to attempt to hold (with only 2 jaws of a 4 jaw chuck) and spin a >1 pound 3" diameter disk sticking out for its whole diameter. :-/
No mill ? I would post a pic of what you're trying to accomplish on here . There are plenty of members on here from Cali that could help out . It's really a 5 minute job only . :dunno:
 
Plus, you could drill and tap an angled hole for a set screw. Also you could make a small collar, say 3/8" wide and drill it for a set screw. Then attach the collar to the face of the brass with small screws. I would use 3 myself. That would make the hub.
 
No mill ? I would post a pic of what you're trying to accomplish on here . There are plenty of members on here from Cali that could help out . It's really a 5 minute job only . :dunno:

Haha, someone from Cali could do the whole project in an hour or two, and better than I could, too. But this is my windmill to tilt at! :)
 
Use the Sherline as a horizontal drill press: drill bit held in the chuck and disc mounted on the carriage in a horizontal position
You follow? You would need to be creative in mounting the disc- spacers, bolts or clamps, etc.
Then drill and tap as outlined in post 2
-M
Chewy's idea is good also, to make and attach a collar which is what I would do
 
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