Adamo Posted March 26, 2015 Report Share Posted March 26, 2015 Hello My name is Adam i bought DDM60pro. I have a problem with the balance of newton 8". When OTA pointing south (in RA axis) the balance perfectly ! When OTA pointing west or east the balancing is lost!. Similarly in the axis DEC. if the telescope is horizontally the balance is perfectly ! In another position, it is only worse. Have any of you had this problem?How to solve it? how it is possible to keep balance in every position with Newton OTA? Best regards Adam Kisielewicz Link to comment Share on other sites More sharing options...
0 GeorgeCarey Posted September 16, 2015 Report Share Posted September 16, 2015 If you take a photograph of your system, from the front of the tube looking down towards the mirror, it might make it easier to describe what you need to do. Talk of axes, planes etc is confusing. Link to comment Share on other sites More sharing options...
0 RamaSpaceShip Posted September 16, 2015 Report Share Posted September 16, 2015 Hi Ian, Are you saying that as long as any radial imbalance in the OTA is symmetrical about the Dec axis plane that it does not matter and will have no negative effect on the mount operation????? I will try to be simple. You need to reason it terms of centre of gravity. The important thing here is that just the centre of gravity of the OTA matters. (This is static balancing, dynamic balancing is only needed when using high rotation speeds, and would be more complex). The goal of balancing the Dec axis is to put the centre of gravity of the whole OTA exactly on the RA axis. Nothing else is needed. To be able to reach that goal, you can, as a first step, put the centre of gravity of the OTA in the plane formed by the RA and Dec axes, so that sliding the OTA along its axis will allow to move its centre of gravity on the RA axis and thus realise the balancing. George's method replaces the RA axis by a thread for convenience, so that it becomes easy to show when the centre of gravity of the OTA is in the plane formed by the thread and the OTA axis. So yes, radial balance is sufficient. Hope you understand better. Bernard Link to comment Share on other sites More sharing options...
0 w0mbat Posted September 16, 2015 Report Share Posted September 16, 2015 Thanks so much to you all for your help. It seems to me that the source of my confusion is, as is often the case I find, terminology and what a word means to different people. There are an infinite number of radii in a circle so, to me, radial balance means balanced across all radial directions such that a round object could be placed in any position on a level surface and not roll. It seems clear to me now that this is not the meaning being used in most of these discussions. I think Mark has used the correct term to describe what it seems is necessary.......lateral balance. So after digesting all that has been written the understanding I have reached is as Mark says:- Hi Ian, If you align the corrector/camera assembly exactly co-axial with the counterweight bar (looking from the front), and you have 'perfect' longitudinal balance about the DEC axis, all you need to worry about is any lateral imbalance. The main contributors are the camera/filterwheel assembly, a finderscope if you have one, and the focuser motor on the OK3. If these off-centre weights cause any residual moment about the DEC axis, they must be balanced out. Thanks again to you all. I just wish ASA would get it's act together and publish manuals that properly explain important issues such as this to all it's customers. Regards Ian Link to comment Share on other sites More sharing options...
0 Waldemar Posted September 16, 2015 Report Share Posted September 16, 2015 For me the radial balancing using rolling on two up-side-down aluminum T profiles worked great. No more problems. The scope should not roll in any position. Simple and effective. Well anyway, just my 2cts Regards,Waldemar Link to comment Share on other sites More sharing options...
0 w0mbat Posted September 17, 2015 Report Share Posted September 17, 2015 Hi Waldemar, I agree that your solution is the ideal way to achieve "perfect" radial balance. However in the case of larger Newtonian apertures the weight necessary to achieve this becomes very large and therefore the moments of inertia may become a concern especially on a DDM60. As I have said I have already constructed and tested a counterweight system mounted on top of the tube rings. With this I can achieve radial balance in all OTA positions when rolling on level rails. However this adds around three kilograms spaced about 100mm above the top of the tube rings. This then will of course mean adding a similar weight to the counterweight bar. It was at this point I became concerned about the added inertia this involved and started asking questions in this thread. I could try this system back on the mount but my inexperience makes me nervous about this. I would appreciate any comments as to whether my concerns are justified. As you have seen other users say full radial balance is not necessary as long as the focuser is exactly aligned with the counterweight bar and then any lateral imbalance is corrected with small weights to make the focuser assembly weight symmetrical around the Dec axis plane. The steep learning curve continues! Regards and thanks Ian Link to comment Share on other sites More sharing options...
0 GeorgeCarey Posted September 17, 2015 Report Share Posted September 17, 2015 Full radial balance IS necessary, and can be achieved by a single weight, somewhere near the focuser/camera. This shows radial balance: 'Lateral' balance is illustrated looking sidelong at the telescope: The red circle shows a possible position for the counterweight. Link to comment Share on other sites More sharing options...
0 MarkS Posted September 17, 2015 Report Share Posted September 17, 2015 Hi all, I think we have had some definition problems on this thread. I would like to suggest three definitions related to DE balance for future use, as I'm sure balance issues will come up again: 1. Full radial balance means that the CG of the OTA/camera/finder etc lies on the OTA axis. 2. Lateral balance refers to the position of the CG of the OTA system relative to the DE axis when viewed from the front or back of the OTA. 3. Longitudinal balance refers to the position of the CG of the OTA system along the length of the OTA relative to the DE axis. Just a suggestion: it doesn't really matter what the definitions are as long as we are all using the same ones. Regards, Mark Link to comment Share on other sites More sharing options...
0 GeorgeCarey Posted September 18, 2015 Report Share Posted September 18, 2015 Good idea Mark. In that case, my posts have been based on the theory that lateral balance is needed, but full radial balance is not necessary. Obviously longitudinal balance is also required. Link to comment Share on other sites More sharing options...
0 w0mbat Posted September 18, 2015 Report Share Posted September 18, 2015 Thanks George and Mark. We now have a consistent basis from which to discuss this issue. Ian Link to comment Share on other sites More sharing options...
0 MikePaling Posted October 6, 2015 Report Share Posted October 6, 2015 Hi everybody ... I am new to this forum. After having a good look at the DDM60pro mount at the recent IAS show at Stoneleigh Park here in the UK I am seriously considering buying one .... this is the reason for me joining the forum. After reading this thread about balancing a scope on the mount I am becoming a little bit discouraged .... My question is .... whatever scope is fitted to the DDM60 ... is it absolutely vital that the scope is 100% balanced in every possible way before the mount will work as well as it should? Looking at what has been written in this thread it seems that all sorts of small counter weights are needed in all sorts of places ... and the sizes of these weight are only relatively small (often only a few grams) in comparison to the weights of various equipment added to the main scope. Also I have seen all sorts of jigs and contraptions being used to help fine tune the balancing of the scope with any additional equipment. Will the "direct drive system" used on the ASA mounts cope with set-ups which are even slightly out of balance ... compared to mounts that use more mechanical engagement using gears??? Just how critical is this "balancing problem" ??? I am worried :-( Mike Link to comment Share on other sites More sharing options...
0 GeorgeCarey Posted October 6, 2015 Report Share Posted October 6, 2015 Hi Mike, Did they have the mount running at the show? I went early on Friday and they were still setting it up. Do not be too discouraged about the balancing issue. I am the lunatic who used the 'hang it from a wire' technique, mostly because I can't resist tinkering with things beyond the point that normal people would have stopped. As far as I know, nobody else has gone to such lengths. Having said that, the DDM mounts are much fussier than the normal gears and worm type mount. As you will have seen at the show, the only thing that holds the scope in place and tracks the stars is a very strong magnetic field. If the scope is unbalanced then the currents rise and the software can get into a frazzle. I have had my mount for five years and balance has not been a major issue. I did have a few mechanical problems but ASA paid for the mount to be shipped back to Austria and repairs were not charged for. George Link to comment Share on other sites More sharing options...
0 robertp Posted October 6, 2015 Report Share Posted October 6, 2015 Hi Mike, even though the DDMs require more care in balancing the scope, from my experience there is no need to get it even close to perfect. I use the mount alot for solar imaging and I put whatever scope I use on the mount, balance it roughly just by moving the axis in both directions until they feel similar (I hardly ever use the balancing tool within autoslew). During my imaging sessions, I often take my doublestack filter off the scope, replace the eyepiece by a ccd and never bother to rebalance. In a permanent setup, trying to achieve a close to perfect balance is certainly worthwhile, especially when you completely rely on a bigger pointing file. When using MLPT, I guess that a slight off-balance does not matter. But like George, I sometimes feel a need to try to get something perfect. However, before you spend hours balancing your scope in a test rig, make sure that e.g. the saddle plate does not put your perfectly balanced scope off-center. Best regards, Robert Link to comment Share on other sites More sharing options...
0 MikePaling Posted October 7, 2015 Report Share Posted October 7, 2015 Hi George and Robert .... Many thanks for taking time to reply to my question .... I feel a lot happier now :-) I have been trolling through all other references to the "balancing problem" and can now see that it doesn't have to be 100% perfect although very desirable to get things as close as it can be. I didn't realise that there was a "Balance sensor" routine available in the software which sounds very useful indeed .... I hope that this is easy to use when I eventually get my DDM60! Regards Mike Link to comment Share on other sites More sharing options...
0 GeorgeCarey Posted October 7, 2015 Report Share Posted October 7, 2015 Where are you in the UK, Mike? I am happy to give advice when you get it. The learning curve can be a bit steep. Link to comment Share on other sites More sharing options...
0 GeorgeCarey Posted October 7, 2015 Report Share Posted October 7, 2015 This shows the balance tool in operation. The idea is to get the two red bars to hit the same spot. https://www.youtube.com/watch?v=SlVCVl9lCPk Link to comment Share on other sites More sharing options...
0 MikePaling Posted October 7, 2015 Report Share Posted October 7, 2015 Hi George ... I live about 15 miles north of Nottingham. The sky conditions up here are not brilliant most of the time ... but I have to live with it! You have just posted a link to the "balance tool" in operation .... is this something that is done within the AutoSlew software? Thus far I haven't found any reference to this bit. Regards Mike Link to comment Share on other sites More sharing options...
0 GeorgeCarey Posted October 7, 2015 Report Share Posted October 7, 2015 Yes, it is part of Autoslew. I had a look for the user manual but ASA appear to have a new website layout and I could not locate the English version. Link to comment Share on other sites More sharing options...
0 Waldemar Posted October 7, 2015 Report Share Posted October 7, 2015 Within AutoSlew on the top bar go to 'drive' then 'servo-settings' then 'balance'. Choose DE subsequently RA. With the + and - button you can change the Amp. scale for fine balancing. Move weights (or scope) untill the red bars are lined up. Regards, Waldemar Link to comment Share on other sites More sharing options...
0 MikePaling Posted October 7, 2015 Report Share Posted October 7, 2015 Hi Waldemar ... Thanks for this information. As yet I have not placed my order for the DDM60 .... apparently the details about the balance tool is on the latest version of AutoSlew but the only manual available on the ASA web site is an earlier version so there is no mention of it:-((( Regards Mike Link to comment Share on other sites More sharing options...
0 Waldemar Posted October 7, 2015 Report Share Posted October 7, 2015 Yes Mike, ASA is not very open handed with information and manuals. Should be no reason to not buy this incredible piece of technique, but it is a hassle sometimes, to say the least. A lot of knowledgeable people on this forum, though. That helps. The word is out that in early 2016 a new DDM60 maybe launched, more expensive no doubt, but probably worth waiting for... Waldemar Link to comment Share on other sites More sharing options...
Question
Adamo
Hello
My name is Adam i bought DDM60pro.
I have a problem with the balance of newton 8".
When OTA pointing south (in RA axis) the balance perfectly !
When OTA pointing west or east the balancing is lost!.
Similarly in the axis DEC.
if the telescope is horizontally the balance is perfectly !
In another position, it is only worse.
Have any of you had this problem?
How to solve it?
how it is possible to keep balance in every position with Newton OTA?
Best regards Adam Kisielewicz
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