300p flextube mount play

[mindburner]

I'm not sure if this is a problem or normal on the 300p dobsonian. But there seems to be a bit of play in the up/dpwn axis. Also the stepper motor encoder sometimes, but not always moves when the tube is moved up and down by hand. I would have thought this should not have moved and only moved when the hand controller was used. The scope also bounches back slightly as can be seen at the end of the video.

Here is a small video showing the 'problem' any help or advice appreciated. Sorry about the quality/orientation, but it's better at full screen.

[Space Cowboy]

Have you tried tightening the tension nut?

[mindburner]

hi

just been reading DrRobin's posts re the tension nut on the clutch. To be honest I was a little afraid to mess with it, incase it became worse. Classic case of adjusting something not related maybe and making the issue worse.

[Space Cowboy]

If when you manually move the scope up or down do the gears engage i.e does it make a whirring sound? If not then its too slack. With my scope after a while the tension slackens and I need to tighten the nut maybe half a turn.

[mindburner]

hi yes but only after the scope hasmoved a bit

there is a bit of play, maybe 5 mm or more. I will check the tension

[brantuk]

You can move the tube with the motors engaged and it will still track - that's a feature (quite a nice one too) and it remembers where it is wether moved manually or with the arrows.

On mine there's a bit of backlash in both axes and there are specific alignment instructions to reduce this either side of the meridian, during setup. I also found the goto upgrade helped a bit because there's backlash settings you can fine tune.

Unfortunately there's a little play in my motors though that cant be adjusted without replacing the motors. But it's enough to get in the right area with a low power ep and then adjust. Also the PAE helps

[mindburner]

I must say I have not tried the backlash compensation yet. Thats a very good point as I also have the GOTO handset now. Do the settings stay after the handset is switched off?

My main concern was the fact the the encoder wheel moved a bit but not continuously (it stopped and started) when the scope was raised/lowered by hand. I would have though it should have moved in sync with the scope or not at all and only when the handset was used.

You can move the tube with the motors engaged and it will still track - that's a feature (quite a nice one too) and it remembers where it is wether moved manually or with the arrows.

On mine there's a bit of backlash in both axes and there are specific alignment instructions to reduce this either side of the meridian, during setup. I also found the goto upgrade helped a bit because there's backlash settings you can fine tune.

Unfortunately there's a little play in my motors though that cant be adjusted without replacing the motors. But it's enough to get in the right area with a low power ep and then adjust. Also the PAE helps

[brantuk]

Been a long time since I had the dob out cos I've had two new scopes since last winter - but from what I remember the lat/long and TZ are retained but I allways have to set the correct time.

My encoder wheels have never "stop/started" - they've allways moved continuously by hand or by the handset. So I'm not sure if you may have a problem there?

[mindburner]

Been a long time since I had the dob out cos I've had two new scopes since last winter - but from what I remember the lat/long and TZ are retained but I allways have to set the correct time.

My encoder wheels have never "stop/started" - they've allways moved continuously by hand or by the handset. So I'm not sure if you may have a problem there?

thats great brantk. I will experiment with the tension nuts and backlash. The encoder wheel is eratic. Here's another (badly shot) video of the wheel moving. The encoder turns if the tube is move up and down quickly but not all the time if tube is moved more gently.