Re: Reducing DEC Backlash with Titan 50
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Thanks Michael, but its not clear how this works on both sides of the meridian. I am also operating remotely so everything has to work without dragging, snags etc. ? Aubrey ? Sent from for Windows 10 ?
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From: Michael HermanSent: Saturday, May 8, 2021 10:14 PM To: [email protected]Subject: Re: [Losmandy_users_io] Reducing DEC Backlash with Titan 50 ? Aubrey, To maintain a constant torque on the RA axis, which is what you are seeking, you need to use a weighted cord wrapped around the RA axis.? Using an unbalanced counterweight rod the torque will vary as the RA axis rotates.?? You put that hanging weight on after your counterweights are balanced.? I am using 1 pound weight....I had tried 7 pounds earlier.? I'm not sure what is an optional weight to use.? My scope is a C14EdgeHD.? ? Here is a way I implemented on my Titan RA.? I hope the photos are clear enough.? The weight hangs to the East and always provides an Eastward torque.?? ? ? Thanks Michael for the comments. Fortunately at this time I only have one issue. That is when I am starting out in the lower east imaging, I have nice round stars with 10 min subs. But as the Counter weight Shaft and weights begin to pass the 45 degree angle, I begin to have more flattened stars. As it gets closer to the Meriden I get round stars again. I think I might have too much east bias on the weights. I am getting about 1+/- Arcseconds PEC when guiding. But I have to use the onboard PEC function. I have noticed that if you want good results with the G2 PEC you pretty much have to run it on each target as you begin each DSO. If you do it that way it will work on both sides of the Meriden. I use Maxim DL 6. for guiding and an SX Superstar. My Telescope is the AT 10¡± RC with CF Arms and shroud and 60 mm guide scope so I am caring about 50 LBS load with my heavy camera. ? Aubrey ? ? Sent from for Windows 10 ? ? Aubrey, It's the RA that this matters most on a Titan RA drive.? Variable friction causes the drive speed to slow then speed up...it's either periodic or non periodic error.? Either way you want it to be near zero friction.? That's what the bearings are for.? But the worm has the ring gear and no bearings at that interface...just friction.? So that needs the best lube and that's the question.?? You also want near zero backlash else you get autoguiding time lags and hysteresis that PHD2 does not like.? So that's the other end of the coin....no friction but no autoguiding!?? Between those two extremes is the optimization point.? Springs can help if they keep the surfaces in contact but not too tightly.? Lubes are essential to minimize friction. Aligning bearings to keep balls from pinching (the Titan has these bearings in a massive cylindrical sleeve...they can't go off axis...the OVision worm did this for the G11 and they used a Belleville R4 spring washer for the end bearing). Have fun,...get some nice images! ? Thank you. I have always just tightened my endcap down and did not notice it. I will check it out when it gets it¡¯s annual oil change. ? Thanks ? Aubrey ? Sent from for Windows 10 ? ? it¡¯s a spring washer rather than a spring, and is housed inside the worm block assembly.
Regards,
? -Paul
On Sat, May 8, 2021 at 12:47 PM, Aubrey Brickhouse wrote:
Can I ask a question on this subject. I have a fairly new Titan and I have never seen a spring in the assembly. I have relubed it several times but have never taken out the worm and so I can not say if mine has one or not. ? Thanks ? Aubrey Brickhouse ? Sent from for Windows 10 ? ? Dan, yes, indeed. I have a Titan50 and a G11 :)
The spring loaded adjustment I'm talking about is not for the whole worm block -- it's at the end of the worm block, on the opposite side of the gearbox. It pushes a spring-loaded bearing into the worm block, preventing it from moving horizontally, side-to-side. It may look like this, below, or have a single slot that you can use a screw-driver or a quarter to turn. If it's not pushed in far enough, the worm will float left to right:
Regards,
? ?-Paul
On Sat, May 8, 2021 at 10:27 AM, <dkfcpalfd@...> wrote: Paul:
Thanks for responding.? Do you have a Titan?? Losmandy has been telling me that they came out with spring-loaded worms for the G11, but not the Titan.? When I first heard about the spring-loaded worms for the G11, I initially was told that feature was in development for the Titan.? Then, several months later, that went away, and I have been hearing from them that spring-loaded worms may never happen for Titan.
Right now, I'm going to try adjusting up the TVC on the HC.... the Gemini-2 website says that is a built-in DEC backlash compensation adjustment that is available.
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