# Taper attachment fine adjustment



## ErichKeane (May 4, 2021)

SO I was on craigslist or something the other day, and found a lathe that is just like mine! I looked at the pictures and I saw this:




That is a picture of the taper attachment, which I have.  HOWEVER, the knob assembly on the left is something I'd never seen before!  I ran out to my lathe to take a look, and saw this:



You'll see that I have the hole in the top-part, and a bolt in the bottom part (right side).  I unscrewed the bolt just to find out that the threads were made out of muck!  Turns out I have the holes, and someone lost the fine-adjust assembly before I bought it.

Next step, was to sketch my plan with important measurements.  I found that the holes were .750 each, and there was a 1" elevation difference.  I chose 5/8-11 for the thread, since it is the largest tap I have.  I considered a thread that divided better, but based on how rarely I use this taper attachment, and how it tends to be 'measure off an existing thing', I didn't think I would ever use the thread to measure anything so much as just turn slowly.  I figure I can up-size to a 3/4-20 or something later if I find it necessary.



I started with the smaller part.  I had a scrap of 1" 12L14 that worked perfect for this one.  I turned it down to a touch less than 1", and made a just-less-than-1" stub on the end.



I put it in my mill to cross-drill and tap.  The tapping was a giant pain, and the threads-out-the-side of the arc were awful, so I also ran a mill across both sides.  I don't know if I capture it, but it DID manage to slip in my 5c collet at one point so one side is a little mangled, but not enough to change function.  Plus, its on the back of the lathe 





Back in the lathe, I turned off the extra material and rounded over the end.




Starting on the next part, I had a 1.5" 12L14 that I had to turn a bunch off of and do the same lathe work as above, just a little longer.  The top is an inch taller, the bottom is closer to 1.5", since I have that much room (and more!).







A quick trip to the bandsaw saves me removal later:



I cross-drilled clearance for 5/8" here.  I ended up having to use my boring head, since I had no matching drill bit.  However, in retrospect, there is no reason this side needs to be 5/8".  I have the threaded rod designed with a shoulder on one side, and the knob holding it in place on the other, so in retrospect I could have made this something that would have let me use a washer + all-thread.  Oh well, looks like I have to single point (I need the practice for the dividing head anyway!).





I milled flats on both sides to deal with the shoulders later.  I finally got to use my planer gauge!




And the two parts finished and in place!  Just the threaded rod (I ordered some 12L14 for it) plus the knob left.  I have a little more engineering on how to attach the knob correctly.  I've considered threading the back attachment for it then loctiting the knob in place, or a taper pin, or just a set-screw.  I guess I'll have to think about it!


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## brino (May 4, 2021)

Great photos and write up, thanks for sharing this.

I've never seen that adjustment either......

-brino


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## ErichKeane (May 4, 2021)

brino said:


> Great photos and write up, thanks for sharing this.
> 
> I've never seen that adjustment either......
> 
> -brino


Ya, me neither!  I never even guessed what the two holes were for!  It is a fairly unique lathe, so I'm not surprised about it existing, but surprised that I've never seen ANY taper attachment with something like this.


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## hman (May 4, 2021)

They ALL oughta come that way.  Trying to fine-adjust something with a slot and a hold-down bolt is all too frequently an exercise in fluster-ation!


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## ErichKeane (May 4, 2021)

hman said:


> They ALL oughta come that way.  Trying to fine-adjust something with a slot and a hold-down bolt is all too frequently an exercise in fluster-ation!


I agree completely! The one time I used this, I spent about 45 mins dialing it in. This one has 3 bolts to tighten that made it time consuming.  I'm hoping this will make the next taper I cut easier to dial in!


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## Weldingrod1 (May 4, 2021)

I built that into my taper attachment, based on the Hardinge parts and Ken's casting kit.

Sent from my SM-G892A using Tapatalk


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