Topics

Worm gear adjustment EQ3-2

julianporter5@...
 

In another thread there seemed to be a common problem with the worm gear being a bad fit. Mine is so bad that the belt slips as the gear doesnt rotate around a fixed axis. If I use the adjusters on the worm gear to remove the slack, the worm gear  becomes so stiff that the Nema 17 motors can’t turn it smoothly and again the belt slips. Does the EQ5 have this problem? Has anyone looked at re-engineering the worm gear on the EQ3-2 to overcome this problem? 

Prasad
 

This is a common problem with any worm gear reduction system. If the meshing between the worm and gear is tight you will achieve very little backlash but you will also run into plenty of friction making it hard to rotate. If meshing is loose then easy to run but with more backlash. The trick is to adjust the meshing where you get decent level of (slight or very little) friction with livable level of backlash. If you get too much of backlash then it is of poor quality. Manufacturing quality of gears makes a huge difference. AGMA (American Gear Manufacturers Association) has standards for quality - AGMA-Q15 being the toughest. Q-10 is the minimum. Lower the number poorer the quality or, in other words, more problems in making it work. 

If it becomes too tight then please loosen it slightly, a small bit at a time, until it just begins to run without difficulty.  Every drive can have this problem depending on the worm+gear combination. Since most of us are working on previously owned drives we can not say if the unit was handled badly like may have been dropped or worm shaft suffered damage or got bent, etc. 

I have worked on Vixen GP and Vixen produced great products. My OnStep-GP is absolutely on top in performance. I have also seen a Explore Scientific EXOS-2 drive where the quality is rather poor but livable if well adjusted. Currently working on a Vixen SP mount that has been dropped and has a broken casting. 

Prasad



On Saturday, November 30, 2019, 10:09:58 AM EST, <julianporter5@...> wrote:


In another thread there seemed to be a common problem with the worm gear being a bad fit. Mine is so bad that the belt slips as the gear doesnt rotate around a fixed axis. If I use the adjusters on the worm gear to remove the slack, the worm gear  becomes so stiff that the Nema 17 motors can’t turn it smoothly and again the belt slips. Does the EQ5 have this problem? Has anyone looked at re-engineering the worm gear on the EQ3-2 to overcome this problem? 

julianporter5@...
 
Edited

This is the loose end of the worm gear.
Is there even a proper bearing or just a hole in the metal?
All other bearings in this mount are metal to metal. Not a ball bearing in sight.



The other end is held OK



The only adjustment is this set screw. The 4 bolts hold the bottom section in place.



When I tighten the set screw to release the gear and allow it to turn there is a lot of play in the loose end of the worm gear. 
Am I missing something to do with the adjustment procedure?

tnut55
 

I dont know how you set it up on this mount but on my exos1 which is similat, the end you say is ok comes loose allowing the worm to slide in the housing.  Then backlash goes through the roof.  Pull in and out on the lose end.  If it dludes, you need to adjust the other end.


On Sat, Nov 30, 2019 at 11:07 AM, julianporter5@...
<julianporter5@...> wrote:
This is the loose end of the worm gear



The other end is held OK



The only adjustment is this set screw. The 4 bolts hold the bottom section in place.



When I tighten the set screw to release the gear there is a lot of play in the loose end of the worm gear. 
Am I missing something to do with the adjustment procedure?

tnut55
 

I did not notice that.  I wouldn't expect a bearing but rather at least a bronze bushing.  Are there internal threads in that hole around the loose shaft?


On Sat, Nov 30, 2019 at 11:22 AM, tnut55 via Groups.Io
<tnut55@...> wrote:
I dont know how you set it up on this mount but on my exos1 which is similat, the end you say is ok comes loose allowing the worm to slide in the housing.  Then backlash goes through the roof.  Pull in and out on the lose end.  If it dludes, you need to adjust the other end.


On Sat, Nov 30, 2019 at 11:07 AM, julianporter5@...
<julianporter5@...> wrote:
This is the loose end of the worm gear



The other end is held OK



The only adjustment is this set screw. The 4 bolts hold the bottom section in place.



When I tighten the set screw to release the gear there is a lot of play in the loose end of the worm gear. 
Am I missing something to do with the adjustment procedure?

tnut55
 

Also, the other axis should be the same way if it has the same setup.  Maybe compare the two to see what may be missing if anything.


On Sat, Nov 30, 2019 at 11:27 AM, tnut55 via Groups.Io
<tnut55@...> wrote:
I did not notice that.  I wouldn't expect a bearing but rather at least a bronze bushing.  Are there internal threads in that hole around the loose shaft?


On Sat, Nov 30, 2019 at 11:22 AM, tnut55 via Groups.Io
<tnut55@...> wrote:
I dont know how you set it up on this mount but on my exos1 which is similat, the end you say is ok comes loose allowing the worm to slide in the housing.  Then backlash goes through the roof.  Pull in and out on the lose end.  If it dludes, you need to adjust the other end.


On Sat, Nov 30, 2019 at 11:07 AM, julianporter5@...
<julianporter5@...> wrote:
This is the loose end of the worm gear



The other end is held OK



The only adjustment is this set screw. The 4 bolts hold the bottom section in place.



When I tighten the set screw to release the gear there is a lot of play in the loose end of the worm gear. 
Am I missing something to do with the adjustment procedure?

Prasad
 

I would suggest that you unscrew the set screws all the way and remove the worm assembly to inspect the spots where the set screws made contact. If the screws had been "over-tightened" (previously) you are likely to see some damage (dings or depressions) at the points where they made contact. These dings would prevent you from adjusting them further because the screws will try to settle back into these ding spots.

It is hard to predict but this is one of my past experiences. I used a tip of a 6" flat file as a scraper tool to level the ding. Luckily the ding was easy to remove. YMMV

Prasad



On Saturday, November 30, 2019, 12:21:31 PM EST, <julianporter5@...> wrote:


[Edited Message Follows]

This is the loose end of the worm gear.
Is there even a proper bearing or just a hole in the metal?
All other bearings in this mount are metal to metal. Not a ball bearing in sight.



The other end is held OK



The only adjustment is this set screw. The 4 bolts hold the bottom section in place.



When I tighten the set screw to release the gear and allow it to turn there is a lot of play in the loose end of the worm gear. 
Am I missing something to do with the adjustment procedure?

julianporter5@...
 

Yes there is a bush.

I totally stripped the mount down after I bought it following these instructions. 

I will have to take the worm gear apart again and check all the bits are present and not worn 

https://stargazerslounge.com/topic/137084-eq3-2-strip-down/