MetalworkingFun Forum

I can vouch for a guy in central MA (actually there are a couple I could vouch for) but he isn't a pompous arse as Ken describes him.

Without an optical comparator, you could cut the screw in half lengthways and measure quite easily with a compass

(02-15-2015, 08:37 PM)EdK Wrote: [ -> ]

(02-15-2015, 08:17 PM)f350ca Wrote: [ -> ]Same as Willie ran into, my compound I had to fix was metric dial with English tpi to get the dials right. Might want to have a close look at it, it could well be a metric thread form cut at 30 deg as mine was.

How would you measure the angle of the thread?  

Ed

I had a 29 deg cutter already ground from another job, it didn't fit, so I dug and found out about the metric flavour. Ground one at 30 degree and presto we have a match. I also have a set of Starret rules that have 60 and 30 degree angles ground on the ends, they fit my protractor, could poke the tapered end of the rule into the tread and check the angle on the protractor.
Are both ends of the nut worn or just the end that flexes to remove the backlash?

(02-15-2015, 11:11 PM)f350ca Wrote: [ -> ]...
Are both ends of the nut worn or just the end that flexes to remove the backlash?

The whole nut is worn. I'm about to take the saddle off and inspect the Y nut. I'm guessing it'll be in just as bad shape.

Ed

The 'Y' nut actually looks good. It looks like a normal acme or trapezoid thread should and with very little wear detectable. The problem is that the thread OD in the nut is too big so no matter how much I try adjusting the backlash screw it's doesn't help get rid of any of the slop. So I have a few options to consider.

1. See if Enco has replacement parts available or can get them.
   
2. Impose on Ken, again, to have him make me some new nuts.
   
3. Try making the nuts myself.
   
4. Purchase some 1" x 10TPI acme rod and nuts to match and make new lead screws.
   
5. A combination of 3 & 4.
   

Number 1 is a no-go per Enco.
Number 2 I know is doable but would rather not impose on Ken. He has his hands full with snow storm after snow storm.
Number 3 is intriguing but I'm not sure if I'm up to the task.
Number 4 see number 3.
Number 5 I would purchase some 1" x 10TPI acme rod and a nut to match and make a new 'X' lead screw. I would use the exiting 'Y' lead screw and make a better fitting nut for it.

First I need to determine if the thread is acme or trapezoidal. Then I can go from there
Might be time for me to learn a new skill.  

Ed

If you have a 10 TPI Acme threading tool you can stick that in the threads to see the fit.  If not, they're not hard to grind.  I even did one when I had to make a new compound screw for my Logan (twas my first try at grinding an acme cutting tool and cutting an acme thread).

Edit: I know, pix or it didn't happen..

I don't think I can grind accurately enough to distinguish between a 14.5 degree angle and a 15 degree angle. I already know it's 10TPI, I just don't know the angle.

Ed

Ed, does your X lead screw have any thrust collars on it?   

That was another issue when I was making my tail stock lead screw. The minor diameter of the acme screw thread was smaller than the diameter my thrust collar needed to be, so I had to add some diameter.  Just something to watch out for.

   

(02-16-2015, 05:42 PM)Highpower Wrote: [ -> ]Ed, does your X lead screw have any thrust collars on it?   

That was another issue when I was making my tail stock lead screw. The minor diameter of the acme screw thread was smaller than the diameter my thrust collar needed to be, so I had to add some diameter.  Just something to watch out for.

Yup, it has thrust bearings and they're a nice sliding fit to the lead screw.

Ed

If you are going to make the parts Ed, there's one word of caution I have for you to save a big "Aw crap" moment: Be sure if you are making the left hand or right hand version of the thread! Don't ask me how I know that your best efforts can all go pear-shaped if that's overlooked.

yep been there and done that.