wormix

18 hours ago, mikeDnight said:

My AZ5  (little squealer), as when i got it from RVO it sqealed like a stuck pig. RVO couldnt have cared less, so I dismantled it to find there was no grease on any of the parts that needed it. After greasing the necessary parts the mount worked fine. Not as good as an AZ4 by a long way!

That’s interesting - I’m considering an AZ4 / 5 as a quick setup mount for my ETX125 and just assumed the AZ5 would be superior. 
 

30 minutes ago, Danjc said:

Brings back memories the ETX90 great little scope. 
I wonder if mike weasners mighty ETX site is still going ? 

It’s not updated anymore, but it’s still there to browse through if needed. 
 

Hopefully won’t need any of the info on there for a while, as this version seems to be in excellent condition - barely used.  

Just arrived - I have absolutely no need whatsoever for a 90mm Mak but I have a real thing for the ETX range and this will go nicely alongside my 125 OTA.  May just use it as a display piece - a poor mans Questar perhaps  

Next up - ETX80.......

maybe.....

Great job! - Can I ask where you source your timber from?

M42 needs to be on your list - easy to find and will keep you going all night long

Good evening everyone

A few months ago I purchased a HEQ5 / Orion 10” combo, primarily for the mount that I wanted for my 150PDS.  I found the 250mm OTA far too large to use on an EQ Mount and so I set it aside to play with at a later date. 
 

I decided that I would build a Dob base (copying the original design) for it as that should be more user friendly than the EQ Mount. I have never used a Dob, and the largest aperture I have used previously was a 200mm OOUK

I finally finished my mount today and unbelievably the sky has cleared as well. I’m very impressed at how easy the Dob is to use, and this sitting and observing thing will be hard to move away from. 
 

The first object I navigated to was Andromeda, and the massive increase in aperture was clearly apparent with it being very clear and obvious. I then moved on to the great Orion Nebula - my first visit this season and was totally blown away. The view in my ETX125 has always been nice but in my 250mm it is utterly unbelievable. All the features are so clear, with the nebulosity displaying almost like a photo!  I was considering not keeping this scope as it is very large, but the first 2 views I’ve had, coupled with ease of use and comfort mean itsstaying. 

If you’ve never used a 250mm Newt before I strongly recommend giving it a whirl!  

All done - needs a bit of tweaking but seems to work well. 
 

There is a bit of stiction that I will need to work through. May try the Vinyl Record idea to reduce it a touch. 
 

Next up is working on the horrendous Focuser. 

A bit more done on this project over the past couple of days - some 20mm nylon spacers arrived so I could create the bearing blocks and I’ve now done a test for to check I got my measurements right. 

The scope moves nicely in Alt with the aid of some tension in the hand screws tightening the scope up to some Teflon pads.

Next up is a slap of paint before final assembly.  

Vacuum Coatings seem to be very well priced and a quick forum search suggests they do good work;

http://www.scientificmirrors.co.uk

Thought I would share the base I have been working on. I recently picked up a HEQ5 Mount which came with an Orion XT10 OTA.  I felt that a 250mm scope was way too large for an EQ Mount so I decided to build a dobsonian base for it. 

To make life simple I have essentially copied the design of current Synta bases and have asked for some advice and dimensions on here and as usual people have been really helpful - so thank you to you.

Currently I have the timber cut and assembled, all fit on a single sheet of ply - I’m mulling over cutting out some panels in the side to reduce weight but probably won’t as I’m lazy!

The tube mounts will run on nylon bearings much like the original design, with hand screws running in brass bushes through the side panels to maintain tension.  The Azimuth axis will run on Teflon furniture gliders for now - was a toss up between lazy susan and teflon.

Just waiting on the brass bushes and nylon spacers before doing a test assembly - fingers crossed it all works.  Then a slap of paint and I should be ready to experience the joys of late aperture!  

Overall happy with the results so far - only issue my bad maths meant the circular panels were cut slightly too small.  

Here we go again - acclimate early, looks like early part of the evening will be ok  

5 hours ago, PeterW said:

FLOs ClearOutside app gives an indication of whether it’s likely to be dewy. Still, cool, humid nights are the worst. Long extension tubes, dew bands, warmth, dew zapper/hairdryer...  sometimes there’s not much you can do. I had a very clear session once, only problem was it was very windy... only thing we could do was to use binoculars in the lee of a building.

peter

Thanks Peter, completely forgot about the dew point bit of clearoutside. 

I think it was just one of those nights, plus I am surrounded by water and after a reasonably “warm” day that couldn’t help. I won’t overly panic and go buy a load of heaters just yet!

cheers

You are a star, thank you

I believe these bearings are all the same size, so any model should do. 

Im specifically looking at the 250p

ta

Evening all,

Could somebody owning the above scope please tell me the rough dimensions of the little nylon blocks the tube mounts rest on?

cheers

As somebody else has mentioned, I used to use Skee Tex whilst fishing and found them excellent. Have a really thick sole which really helps cutting heat loss through the base of the foot. They do a field boot version that looks good. 

I have never had it as bad as last night, so assume it was just one of those nights. 

There is water everywhere this morning like it’s been raining 

will explore a few shield. Any advice on fogged you EPs and finderscope?

cheers

Evening all,

Got prepared for an imaging session early today - all set up and ready to go, but have really struggled with dew on every surface. 

Was almost impossible to find my target due to moisture on finderscope and eyepiece, and when finally lined up realised the primary and secondary on my 150PDS where also frosted so I’ve had to call it a night without achieving anything. 

Is it the case that sometimes there is just too much moisture in the air and there is nothing you can do?  Not sure a dew band would have helped either tonight?

cheers

Good evening all,

I have an Orion IntelliScope 250 OTA that I need to build a mount for. To start with I was just going to copy an existing mount and to ensure I’m in the right ballpark would anyone be able to tell me what height off the base the Alt pivot is?

As it’s a synta tube it should be the same on a skyliner 

cheers

On 09/11/2019 at 17:03, Alan64 said:

The gaps when test-fitting the focusser onto the optical-tube...

How would you go about rectifying that?  Where there's a will, there's a way.

Is it my imagination or is the tube slightly angular right under the focuser?

Squeezing that back will close up those gaps some?

6 hours ago, Alan64 said:

The procedure works particularly well with metal focussers...

...but that is a rack-and-pinion, and as the plastic unit that I'm working on currently.  The adjustable bearing, there at the top within the image at far left, allowed for precise centring, with a tolerance of +/- 0.5mm all round.

However, I believe that your focusser is a Crayford-type, and has set-screws to adjust its alignment.  Although, there just might be a way to improve it nonetheless via this method.

This is a distributor of PTFE sheet there in the UK...  https://www.directplastics.co.uk/ptfe-sheet

The 0.25mm, the thinnest they carry, is nigh the equivalent of a sheet of .010" that I have, and at 0.00985".  I've used that  slightly thicker within these projects; 0.015" and 0.020".

These are the materials I use when working with the PTFE...

The roll of clear tape is double-sided.  The aluminum-foil tape is that used for HVAC systems, air-conditioning and heating.  You may not need the aluminum however.  It is only to build up the substrate of the focusser's housing.  It all depends upon the spacing round the drawtube when inserted.  The aluminum tape does allow for fine adjustments, as it's even thinner than my thinnest sheet of PTFE(0.005"), and at 0.0035" to 0.004".  If the spacing is rather tight, then all you'd need is a single layer of double-sided clear-tape applied to the housing's surface, and then the appropriate thickness of PTFE.  In addition, all bare surfaces to be joined must be wiped down with either 91% rubbing-alcohol or !00% acetone, and for proper adhesion.  If you apply a second layer of aluminum on top of the first, then the first will need to be wiped, and so and so on; also, the surface of the PTFE before pressing it onto the double-sided tape.

The PTFE will lift straight up from the double-sided tape easily enough, perpendicularly, but when pulling the PTFE parallel to the tape, it will not budge in the slightest; good thing that the drawtube slides in and out, bearing against and parallel to the PTFE.

Great summary - thanks Alan I will give it a try. 

Alas my Focuser is a rack and pinion type not a super advanced Crayford 

cheers

10 hours ago, Alan64 said:

This is one of the worst plastic focussers, and with which I've ever had to tussle...

 

Hours I spent today, installing the drawtube's bearing materials, ripping them out, then re-installing them.  I had to use several layers of aluminum-foil tape, to build up the substrate.  However, I had to step the layers, a partial length here and a full-length there...

...trial-and-error, over and over.  Now, the drawtube racks in and out along its entire, albeit short, length straight and true, smooth as butter, and with no slop or binding whatsoever.  I had almost given up hope, but now, I don't how to act.

Now to re-blacken the interior of the drawtube, and satin-blacken that part of the drawtube which descends into the light-path.

I have a horrendous focuser on an Orion XT10 that flaps about all over the place  so need to give this a try.

Is it just a case of lining the draw tube with aluminium tape and overlaying that with Teflon?

Evening all,

Just wondering if anyone has successfully AstroEQ’d a non goto HEQ5? And if so, how well does it work and how simple was the process?

Cheers

Evening all,

Does anyone know the size of the small countersunk screws used to fix the motor cover on a HEQ5?

cheers

I have the 8” version of this scope and whilst the views are ok there are a couple issues that David picked up above. 

Firstly,  I have mine on an EQ5 with aluminium tripod and it is a bit bouncy especially in stronger winds - I think the 8” is pushing it for this mount so 10” would be a challenge.  I think a dobsonian basenis more suited from here on up  

The Primary cell is quite frankly awful - all the adjustment is exposed which in one hand makes it a doddle to collimate, unfortunately you will get a lot of experience as those same exposed screws means it loses collimation all of the time. 

The positive is they are generally cheap so a good intro into the larger scopes. 

Cheers