Gallery, Projects and General > How do I??

Can't find a 3/4-16 female adapter.

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jcs0001:
Richard:

It's easy for me to an "armchair machinist" but here are a couple of ideas :wave:

One option would be to form a delrin nut/collar over the existing threads, use the motor itself and files or cutters to turn the outside of the delrin nut cylindrical (in place) to the size needed for the inside diameter of your pulley.  Leave one end solid.
You will need a drill press or drill and hand tools for this.

A problem may be the heat and the nearby bearings of your motor - not sure if you could shield these.   More info on using delrin/acetal to form nuts on existing male threads:

http://bbs.homeshopmachinist.net/threads/43645-Making-Acetal-leadscrew-nuts-the-easy-way

Also I suspect your lathe has the ability to do left hand threads - most of the mini lathes do.  If enough of the parts are intact, you can turn the spindle by hand (make a "jury rigged" handle for the outside end) to form threads on the inside of the pulley or on one end of a sleeve.

John.

sparky961:

--- Quote from: RichardDepetris on November 20, 2016, 03:03:33 PM ---I plan to mount the motor externally by attaching a pulley to the rear end of the spindle.  The problem is that it is 3/4"-16 left male threaded.

--- End quote ---

Now, I don't have a mini lathe so I can't say for sure, but I wonder exactly what we're trying to rig up here.  I'm picturing that there's a threaded part of the spindle (or one of the gears/pulleys in the drivetrain) that the OP wants to make a threaded adapter for.  This adapter would take a pulley that would then be driven by the treadmill motor.

So.... what happens when you reverse the motor direction?  I see no mention of pins, grub screws, or keys here.  Also, correct me if I'm wrong here but I doubt that threads are intended to take loads in this manner.

I'm very suspicious that the OP is trying to take what they think is the "easy" way, but perhaps isn't actually the easiest or the best way to do it.  It could even be rather unsafe, dare I say it.  However, until I see some pictures it's really just speculation.

RichardDepetris:
Thank you guys for all the help.  Coincidentally, I already purchased the cap nut that Baron suggested before I posted.  It is a workable solution, but less than ideal. I put the question out there to see if there was a better option.

After your replies, I decided to stop the self-obstruction and just do it. I have a few bad habits I need to break. First, I tend to look for an ideal solution and dismiss ones that would suffice. Second, I fear failure and frustration to the point of complete paralysis.  Finally, this fear prevents me from working with the tools and materials I have until I get better stuff.

I am in the process of putting together a build writeup for this lathe project.  I will have lots of photos and detail as much as I can. I will post them in the appropriate forum when I'm done and will alert you when it's up. 

Again, thanks.

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