Backlash i think

[Anthony1979]

Ive just done a full circle in the ra axis on my eq5 and theres a bit of play and a bit of tightness in certain areas.... I tried adjusting with the grub nut but when i take the slack out its more tight in places and when i tighten it a bit it becomes more loose in other areas anyone no why

[Anthony1979]

[Peter Drew]

It could be that the mechanism that holds the worm assembly in place is somehow moving.  When you adjust the worm mesh it could be pushing the worm holder back although the mesh will feel tighter.  When the wormwheel reaches its opposite looser position this will have been made looser.  The overall problem is eccentricity of the wormwheel.       🙂

[Anthony1979]

I dont understand sorry 

[Peter Drew]

23 minutes ago, Anthony1979 said:

I dont understand sorry 

Apologies, not easy to put into words.  I'm not familiar with the setup on the mount but usually the worm is in an adjustable bracket.  This allows the worm to be tightened in mesh with the wormwheel which you have done.  What I was trying to describe was that there was a possibility that the bracket wasn't firmly fixed after the adjustment and whilst you were turning it to check the backlash the bracket backed off thereby providing backlash again when the looser position is reached.  A spring loaded worm bracket would overcome this issue. I believe there is a mod available for this mount.    🙂

[Anthony1979]

It really frustrating because i cant get rid of it... All bolts are tightened after ive adusted the grub screw

[dodgerroger]

I recently stripped the dec axis on my HEQ5 as it had developed quite a lot of backlash. Bearings where replaced with quality items, cleaned and greased. It is much better but I was unable to fully remove the backlash entirely. I found it had a tight spot so I had to reach a compromise. It has the belt mod and guides very well but I am well under the recommended weight. It’s a mass produced item and I think it’s hit and miss on the quality of the machining. Get it the best you can a small amount of backlash is better than tight spots on axis 

[Anthony1979]

I will have another look when i take the motors off.... I dont really want to strip it down as im not that confident 

[Budgie1]

On the worm screw body there are 4 bolts and the grub screw. The adjustment is made using the grub screw and the bolts either side of it. The other two bolts secure the worm screw body to the mount.

When making adjustment, loosen the two bolts holding the body to the mount and then nip them up again. This is so the body can move as you adjust but is not loose.

Now slacken off the two bolts either side of the grub screw and check for play as you have in the video. Try to tighten the grub screw until the play has gone or is reduced. If it gets worse, loosen the grub screw and tighten the bolts either side of it a little, then try again.

The grub screw pushes the worm gear shaft into the main worm drive and two bolts push the worm screw body away from the mount body, so it's a case of altering the grub screw and the two bolts until you get to where there is the least play.

The bolts either side of the grub screw don't need to be tight, you may still have movement in them when the tension is set. 

Lastly, tighten the other two bolts for the worm screw body to hold it in place and check the play again. If there's a bit more play now, then giving the bolts on either side of the grub screw a slight tighten should take this out.

[dodgerroger]

3 hours ago, Anthony1979 said:

I will have another look when i take the motors off.... I dont really want to strip it down as im not that confident 

You don’t have to strip it down. My point is , even with new bearings and grease i couldn’t eliminate all the back lash. Don’t assume that you will be able to get it totally backlash free. A smooth rotation with slight backlash is better than it running with tight spots and binding 

[Anthony1979]

Thanks ive got the slack out but how tight is to tight..... I can rotate it all the way round and it feels smooth

[dodgerroger]

It’s got to be smooth if it’s tight it will feel rough, try it by hand and then use the hand controller to rotate. Listen for changes in motor pitch but if you turn it by hand with little resistance it should be good

[Anthony1979]

I can turn back hand smoothly and there no change in sound in the motors... Thanks

[dodgerroger]

Should be good for a field test now👍

[ollypenrice]

19 hours ago, dodgerroger said:

You don’t have to strip it down. My point is , even with new bearings and grease i couldn’t eliminate all the back lash. Don’t assume that you will be able to get it totally backlash free. A smooth rotation with slight backlash is better than it running with tight spots and binding 

Like you, I think this is normal. It arises from slight eccentricity and explains why some mounts use a spring mechanism to maintain constant pressure in the mesh. Is the backlash in the RA drive or the Dec? If it's RA just run the east side slightly heavy to keep the worm pushing against the wheel.

Olly

[Anthony1979]

3 hours ago, ollypenrice said:

Like you, I think this is normal. It arises from slight eccentricity and explains why some mounts use a spring mechanism to maintain constant pressure in the mesh. Is the backlash in the RA drive or the Dec? If it's RA just run the east side slightly heavy to keep the worm pushing against the wheel.

Olly

Ive got it going round smooth now... I loosened the two bolts behind the 3 on the front and then adjusted it then tighten the bolts back up... Seemed to have done the trick

[dodgerroger]

6 hours ago, ollypenrice said:

Like you, I think this is normal. It arises from slight eccentricity and explains why some mounts use a spring mechanism to maintain constant pressure in the mesh. Is the backlash in the RA drive or the Dec? If it's RA just run the east side slightly heavy to keep the worm pushing against the wheel.

Olly

The play is in the dec axis, I literally spent hours adjusting it until I got it the best I could. It guides very well so I’m not going to fiddle anymore. Part of the axis has no play and part has a just noticeable amount. I can live with it and can get reliable 5 minute subs from it. 

[ollypenrice]

2 hours ago, dodgerroger said:

The play is in the dec axis, I literally spent hours adjusting it until I got it the best I could. It guides very well so I’m not going to fiddle anymore. Part of the axis has no play and part has a just noticeable amount. I can live with it and can get reliable 5 minute subs from it. 

If it ain't broke...

Olly