First time trying to cut thread....couldn't even get change gears on

[Garyg]

Thought I would try to cut a 5/8 18tpi. Its a craftex cx706 8x20. This is the chart I used.


Chart


The chart shows H 70 for the first, 50-60 for second and 75 h for the third. The problem is the 75 H which is the "L" on the chart. It won't fit on the shaft. I assumed the "H" is the spacer. It is like the shaft is too short.




This the "L" gear that attaches to the lead screw. There is the "H" spaced behind it. Which is not wide enough. The gear would have to go out another .250 to be parallel. They are not too quick to change either.

Below is how it looked from the factory before I started.



Its almost like the "L" gear doesn't move but then how do I get it to mesh with the outer Z4 gear.
I spent 3 hours on this and gave up. I thought I was somewhat mechanically inclined.

 

[ddickey]

Those middle and top gears move on a slot do they not?

 

[intjonmiller]

My reaction as well. That arm should rotate and the two gears not directly attached to the leadscrew should move in their slots. Is that not happening or have we misunderstood the problem?

I assume you have the manual, which is where you got that chart? http://busybeetools.com/content/product_manuals/CX706.pdf Change gear operation is on page 23. Assuming you still need help please use the part letters from Figure 23 and the step numbers as outlined to explain the problem again so we're all on the same page, figuratively and literally, so we can better assist you.

It may even be worth recording a quick video with your phone or digital camera, then posting it here.

(Edited to fix a silly autocorrect in the URL.)

 

[Garyg]

I do have the manual. I had to take the gears off . They move up and down in the slot so you can adjust the backlash. That's no problem with the the Z1 to Z4 gears. Its the last one "L". The way it comes from the factory the "L" gear is mating with the inner gear. that is the bottom photo, You can't actually see the inner gear its mating with. To do a 18 tpi the chart shows the bottom gear "L"mating with the outer gear Z4. that's the first photo. I can't get the bottom gear to mount this way.
The bottom photo shows the bottom "L" on a angle as its just resting on the shaft. The shaft is too short to attach it and have it mesh properly . The spacer behind the gear is not wide enough either.

 

[Ulma Doctor]

i think you may need to remove the double gear and invert the gear so that the smaller gear is towards the headstock.
the bottom gear will ride in its normal position without need for a spacer.
the gears can then be adjusted to approximately .001" backlash at that point

 

[Randall Marx]

I think I see a space between your banjo and the hub that it should rest against. When you rotated the banjo into position, it may have slid to the left as viewed in the most recent photo. That might make the difference in shaft length and may help with the alignment problem. If the spacer is still to thin, you might substitute a small gear that will not mesh with anything to act as a spacer that is exactly the same thickness as your other gears. I'm not certain, but hope these suggestions might at least trigger a helpful thought for you.
Good luck.

 

[Tozguy]

Gary, hang in there. The change gears on my CT043N can be a bit stubborn too. I always have to use a puller on one of the gears.
It is normal that a gear does not slide all the way onto the shaft so that the screw and washer on the end can press the gear all the way home.
Gear alignment was a bit lacking even when properly installed. I had to add/replace spacers to get full width contact.

Not to slight the help you are getting here but being in Ottawa, maybe if you swing by the BB store someone can show you how it works if they have a CX706 on the floor. I have always appreciated the help from the guys at the Ottawa store.

 

[Tozguy]

Also, Craftex manuals can be a bit 'brief'. Other suppliers of basically the same lathe (ex. Grizzly) often provide better manuals.
Here is an example: http://littlemachineshop.com/instructions/ThreadingSC4.pdf

 

[prasad]

You may want to download manual for Grizzly G0768 from their web site. It explains the gear arrangement clearly.

 

[NortonDommi]

Here's a tip for setting backlash, also your gears should be a slide fit so a bit of fettling may be in order. Sometimes the banjo needs a rework as well to get full range of movement.