Measuring Drill Press Feed Handle for Knobs

Perhaps going to a GOOD hardware store and picking up a few different nuts in that size range for test fitting would be helpful here.

Or, you could turn them down to fit knobs you already have.
 
The measurements with a digital (Mitutoyo) caliper I got is:

.4345 for the unthreaded portion of the lever (rod)
.4860 for the top of the threaded portion
.4360 for the indentations in the threads

I used the #472 Starrett thread gauge that I have as per Tony's post, and 11-1/2 was the best fit for the threads on the threaded portion of the lever.

Correct me if I'm mistaken but I don't think it's 7/16-20 or 7/16 at all (he stated that's the unthreaded portion). From what I make out of Nelson's measurements .4860 is the major dia of the threads & .4360 is the minor (as good as his calipers can get into the root of the thread.

.4860 is just over 12mm so it can't be M12. Nelson said he seems to have measured 11-1/2 TPI. 1/2-13 is a common thread size & very common for knobs, 7/16-20 not so much. 13 TPI is a lot closer to 11-1/2 than 20 TPI. .4860 is on the small side for a 1/2-13 thread but that is still within a Class 1A thread (just barely).

Nelson, I think 1/2-13 should be you next try, as mentioned, grab a nut from the hardware store. If you still can't figure it out you could always go with one of these "universal" knobs. You just thread them on & don't need to worry about thread pitch. I've used them in some cases & never had a problem with them. They don't come in Phenolic though.

http://www.use-enco.com/CGI/INSRIT?PARTPG=INLMKD&PMPXNO=25223060&PMAKA=328-2365

If you check out the catalog page there's a few different ones like tapered instead of ball & red.
 
What do I need to measure the thread accurately?
I know that this is a late post for something you have already solved, but I took the following approach: Just measure the minimum diameter of the screw with a vernier caliper. Go to an art supply store and acquire wooden balls of a diameter that pleases you. Drill a hole into each one to match the previously measured diameter. A slightly bigger hole will insure that the ball won't split. Now just screw the wooden balls onto the threads of the levers. They thread on nicely and stay put. Mark
 
As it turned out, the only knobs I could get that sorta fit were 1/2"-13 at Reid Supply. They don't go all the way in (they need to be deeper, but they don't carry that).
Cost me $100 worth of the wrong sizes to learn this. Measuring wasn't that helpful, although by caliper it measured .48. Thread measured 11 on the thread guage.

Always get the ones that have a metal insert. If you force the plastic threaded ones even the slightest bit, they crack. They will crack from ordinary use when you pull them down.
Get phenolic with brass threaded inserts.

They don't make 1/2"-11 or a deeper one, so this is the best I can do.

Thanks fellas.
 
Do the rods unscrew? Two options if they do - take one to the hardware store to fit a nut or turn down and thread to fit what you already bought.
 
Always get the ones that have a metal insert. If you force the plastic threaded ones even the slightest bit, they crack. They will crack from ordinary use when you pull them down.
Get phenolic with brass threaded inserts.

One of the reasons why I suggested the universal ones. They won't crack like the prethreaded ones you mentioned. The universal ones are not hard like phenolic & the thread forms when screwed on. Thread pitch does not matter, only the diameter range. Perfect for cases like yours.
 
What worked for me I purchased a RF30 mill/drill that didn't have any handles price for 3 handles and 3 knobs was kinda high. I went to local hardware store bought 3 long bolts they were metric and I can't remember the size. Stopped by the local driving and asked if they had a few scarred up balls I could buy, they handed me a bag full a couple of dozen or so for nothing. They said they have some means of checking the balance as they use them and these were off. Balls were in great shape.
Now when I was a kid I took apart a couple they were full of little rubber bands and a ball in the center with liquid but I figured I'd try them clamped the ball with a wooden carpenter clamp with the ball centered in the through hole of my drill press counter bored and drilled through with spade bits. No liquid, no rubber bands just a couple of colors of some sort of rubber material. Drove the bolts through and they work great and a lovely zombie yellow green color.
I don't know if standard balls are made this way but I sure found a source of file and other thingy handles. Can't claim to be an original thougt as I saw somewhere about using them for file handles but was real concerned about spurting goo.
Anyway it works and was cheap.
 
Anyone else looking for knobs?
Junkyard garden tractor shifting knobs.
If they don't fit just heat the shaft and push them on.
 
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