Threading dial gear

[Buzzer John]

A while ago I posted about my CW mortar project and mentioned that it was on hold for a while because of other projects. One of those projects is a threading dial for my Star lathe. While threading the breach plug for the mortar I had to keep the half nuts closed all the time so as to not lose the thread. This meant a lot of hand cranking. A thread dial would have been a really big help. I had made one for my W C Young lathe that I used for the internal thread and it was a big help. So, the first step in making the device required a mating gear to be made. The lead screw is a 9 thread. Somewhat unusual but it works. That said, I wanted a 36 tooth gear with an acme profile. I had hoped to make it from aluminum, but didn't have any on hand of the needed diameter. I did have a bunch of old wire sizing dies that looked like about the right diameter. I took a stab at grinding a fly cutter to the approx profile of the thread and used a spin index blocked up to get near the matching slant on the teeth and started cutting. I'm quite satisfied with the result. The pictures are not as clear as I would like, but I can't figure out how to get this camera to take good close ups. It' a Cannon Power Shot 550. Any suggestions would be appreciated. I still have to make the mount for the device. I will post pics as I progress. John

 

[8ntsane]

Hey John

Looks like your gear turned out pretty nice. Thanks for sharing that.

 

[Buzzer John]

Re: Threading dial gear updated

I finished the thread dial assembly today and it works just fine. It isn't very pretty, but I'm happy with it. John

 

[Old Iron]

Looks great to me and as long as you like it, It has to be just right.

Paul

 

[GK1918]

Looks good Buzz Ill also bet due to the width you must have a keyed lead screw? I lucked out on my
big lathe its a twin screw so I made my gear from a simple brass washer and an exaust valve for the
dial. Sure makes life easier with a dial and cross slide stop. I never was in favor of reversing causing
more ware on half nuts. May sound dumb but I cleaned the lead screw and put black ink then pressed
white paper for an imprint then rolled the washer on the ink paper then with air whizzer ground out
the teeth. Its been there atleast 5yrs still works perfect. I will also add some people have asked about
twin screws which is the feed screw used with half nut has no keyway the other shaft does, witch in my
words mean, whenever you see a twin lead screw machine, that means it can feed and cross feed at
the same time used for tapers kind of set and forget. High teck for 98yrs old sam

 

[Buzzer John]

Sam, please excuse my ignorance, but what is a keyed lead screw? I am strictly self taught at this home shop machining and therefore did not have a very knowledgeable teacher. I like the way you made that gear. It is pretty neat. John

 

[Hawkeye]

John,

The old Southbends and my Hercus have a slot milled the length of the leadscrew. Inside the apron on the carriage, the rotation of the screw can be used by the half-nuts for threading. For powered operation of the carriage or the crossfeed, the motion is taken off by a worm gear with a key running in the slot.

 

[ScrapMetal]

Here's a decent pic of what Hawkeye is talking about with the leadscrew only it's on my SB.



See the slot running down the center of the leadscrew? That's it.

-Ron

 

[GK1918]

Buzzer John

See Rons SB photo, ok I meant- picture- that lead screw with no slot and another shaft above that one
with no threads only the keyway. SO-machines like this, you can get away with a simple tooth washer.
Machines like Rons (with that slotted) needs a fater gear like yours to jump said slot. Now on my SB 9A
I got an Ebay $10 Atlas dial these guys say they are the same they are not but will work, you get a click
when it jumps the key cause the gear isnt fat enough.
Anyone know why its only the SB 9 the dials are gold all around $100 A dial within reason listed already
has fifty bids. Heavy 10s 16s etc. go for 25-30 bucks?? May as well get a new one from Jeff Beck $100

Sam I do better with a camara

 

[Buzzer John]

Thanks to all for the explanation of the lead screw types. My Star lathe does have that slot in it, and it is indeed used for both power feed and threading. My bigger lathe, the WC Young, has two screws and no slots. I never noticed the difference until the question was asked. When I made the threading dial for the big lathe I did use a much thinner blank. I see now I lucked out when I couldn't find any of that material when I made the Star dial. For a long time I did not feel a need for the dial, since I always threaded by hand cranking the lathe. However, when I was working on the breach plug for the mortar, it became obvious that a dial would be a big help. I used the dial on the big lathe while threading the tube, and this reinforced the notion of it being a big help. Now what would be a really big step up would be to come up with some way to rig a quick change gear box to the lathes. I have seen one article where someone actually made one for his lathe, but that is a bit beyond me. Changing the gears is not so much the problem as is the greasy mess. It takes longer to clean up than to change. I am used to having my hands dirty while working, but greasy is not good for good griping. I keep toying with the idea of getting a newer lathe, but haven't been able to talk myself into it. I really like the Star and have a sentimental attachment to it. It was my Grandfathers and while it is worn I still can get it to do most of what I need. Again, thanks for all the information. John