Back to basics - barebones altaz mount

[Wavytone]

The ultimate in simplicity:

http://www.herculesoptica.com/4.html

Nice to see some innovation from someone with a CNC machine.
Now if only they'd made a provision for encoders...

It's sold through AliExpress.

[Ukastronomer]

Ill tell you why I would not want one

The belts will slip, at some stage
They will need replacing lets hope they are available
Over complicated to me

I prefer BASIC altaz

https://www.widescreen-centre.co.uk/sky-watcher-skytee-2-alt-azimuth-mount.html

[Ukastronomer]

Encoders

Then it would not be simplicity

BASED in China

Guangzhou Head Office

Guangzhou number with the Software Technology Co., Ltd.
Address: Guangzhou Wuyang Siyou a Tai Hang Road No. 18 Building, Room 1308
Zip Code: 510600
Tel: (020) 87396965
Fax: (020) 87396481

But it looks nice, won't take my Triplet though

[bojan]

Very nice design :thumbsup: Low cost, but not "cheap"

Re belts slipping, no way.. and they last ages in application like this, being not loaded (of course, balance is essential here but the applies to worm gear).

[Ukastronomer]

I don't know what you mean not loaded any pulley system is loaded, place a scope on the mount driven by turning the knob and you are moving a load via a belt that has to be kept tension-ed ?

[bojan]

By not loaded I really meant not overloaded...
Of course the belts need to be under certain tension, but for this application ~1N is more than enough.
And the ones pictured can be loaded with more than 100N I am sure
The load imposed by moving the telescope (provided it is balanced) with reasonable acceleration should not be higher than 0.1Nm, so this translates to ~10N.

According to SPD-SI technical data (http://www.sdp-si.com/PDFS/Technical-Section-Timing.pdf, page T62) 5mm wide GT3 belt can be loaded with 11Nm..

BTW, idea is not new.. see here one example:
http://siderealtechnology.com/16InchNightSky/16InchScope.html
Or here: http://www.dfmengineering.com/news_telescope_gearing.html

And, my DIY Dob has friction transmission (and no slippage!).. well, not the same thing but still illustrates the issue.

[billdan]

They have some interesting gear on the Hercules website.
How about Four 80mm APO scopes for LRGB imaging (filters included with the price, cameras not included).

[Ukastronomer]

:thumbsup::thumbsup:

[bojan]

Forgot to mention - exactly the same principle (timing belt on friction wheel) I used ~13 yo for motorized focuser (I still use it for visual), see attachment.
Tension is controlled by means of excentric drum (motor is inside it).

[skysurfer]

Nice mount.
Tilt it to your latitude and you have an equatorial mount.

[Wavytone]

but no counterweight. Has to be level.

[Ukastronomer]

yes but that has teeth the other is a plain surface

Still leaves one shiny surface

[bojan]

If you look at the photo carefully, you will see the flat groove on the focus knob (so belt can't fall off) - because I wanted to be able to use it manually by lowering tension (and friction)... Teeth are on the small pinion.

I belive they were driven by the same idea when designing the mount we are disscussing.
The only problem I see with that mount is relatively low transmission rate, so the positioning will be quite cuarse.
But probabbly OK for shorter FL and lower magnifications....

[Wavytone]

Well, it arrived... interesting. A a visual travel scope this would very easily take a 100mm refractor and certainly a step up from what i had before. It would also take my MN56 mak newtonian well enough, though that will need a decent tripod.

Each axis has a roller thrust race, approx 90mm diameter. Massive overkill, mechanically. The central stud also has a thrust race and a hefty knob to tighten the pressure, resulting in modest drag (friction). Probably feasible to add encoders with some custom parts, if you wanted to.

The belt drive is effective. No noticeable backlash. The pinion has a flat and a setscrew to lock it on the shaft with the knob; it would be rather easy to undo this and make a DIY shaft driven by a small motor (if you wanted to motorise).

It requires 8mm bolts to attach the dovetail base (trip to Bunnings) and there is a 10mm threaded hole for a counterweight bar, so I'm off to find one that fits (mine is 12mm).

Central hole in the base appears to be ¼" x 20, though there are 2 x 8mm holes at 35mm apart and 2 x 8mm at 70mm apart, if you want to bolt it onto a substantial baseplate of some sort.

Only downside is that the edges of the roller thrust races are a little exposed and dust will get in. A felt ring would fix that and keep the dust out (simple DIY job).

[FlashDrive]

Photos please Nick ....I take it you bought one ....!!
I know there are ' web ' photos ....but would like to see yours all setup with a Scope .

[Stonius]

So...happiness? I'm curious as to what else you have to add to get it working. How do you attach it to the scope? How do you attach it to a tripod? Given goto mounts are available for $600, I wonder if it's a real alternative, or more of a novelty?

Best

Markus

[Wavytone]

Markus,

OK Depending on how you source these it may not be cheaper than just buying a complete rig, but if you have some of the bits it will make a nice mount. You need to add...

1. Tripod - I have one, good enough.
2. A dovetail base - I have one, eg https://www.aliexpress.com/item/Dovetail-Base-S7947-Vixen-Clamps-with-2-Brass-screws/32829615013.html?spm=2114.search020 4.3.15.5f2325f5exUoJf&ws_ab_test=searchweb0_0,searchweb20 1602_10_10065_10068_10130_10547_319 _317_10548_10696_453_10084_454_1008 3_10618_10307_537_536_10131_10132_1 0902_10133_10059_10884_10887_321_32 2_10103,searchweb201603_51,ppcSwitc h_0&algo_expid=eb3c0c9b-e4ad-4242-8359-2d91ab8d1c5d-2&algo_pvid=eb3c0c9b-e4ad-4242-8359-2d91ab8d1c5d

3. 2 x M8 cap screws to bolt above onto the head.
4. Counterweight bar and counterweight. The bar must have a 3/8" thread to fit, and the weight needed is 1-2kg.

Alternatively a trip to a machine shop to have the hole drilled and threaded for M12 - which I may have to do - as I have a spare bar (and weight) with M12 thread. I've already contacted Hercules and suggested they make the hole M10 or M12 n future to match the commercially available bars.

BTW the belt drives give a reduction of 8:1.

[Wilso]

Hi Nick,

Nice light weight travel mount you've picked up there!
Would it need the counterweight? or would just a sturdy tripod surfice as with a dm4.
Looks like it would be buttery smooth though.

Photos :shrug:

[Wavytone]

You could indeed use it without a counterweight provided its bolted onto something solid !
Yes it is smooth. The central knobs allow a variable loading to be applied so its adjustable from very free to having useful drag.

[Stonius]

Is the mount interface the dovetail? or is that for the scope? I only know Film TV tripods that use a bowl system. I'm not sure what a standalone astro tripod uses for interfacing to the head.

[Wavytone]

The base is flat. Central hole 3/8" 16tpi, plus two holes M8 either side, 35mm apart, and another pair of holes M8 70mm apart.

It fits fine on my ancient SLIK Master tripod with a 3/8" screw.

Pretty sure it would bolt onto this tripod
https://www.bintel.com.au/product/skywatcher-star-adventurer-tripod/?v=6cc98ba2045f&gclid=EAIaIQobChMIk_7d8YqG4QIViY2PC h38kQS_EAQYASABEgLOcfD_BwE

[Sunfish]

I suppose the dovetail bolts to the mount with the 8mm bolts just like the giro2
Thanks for that link . I might just get two .

I could add a drive to my giro 2 deluxe with two scopes or maybe Argo encoders and get a similar result. But a fair bit more weight.

A lot of old school one-off alt az here but without the nice looking Chinese cnc aluminium look. Love that anodised finish.

http://www.tech2000astronomy.com/giro_G3_mounts/

[ariefm71]

What do you think is the realistic capacity of the mount, Nick? I'm interested to pair it with a 7" Mewlon. I know the webpage says 20kg but I think it's too optimistic

[Wavytone]

It would take it but the focal length is too long for a mount that doesn’t track - it will be a PITA.

[ariefm71]

Yeah. I saw folks with an 8 or even 10” Mewlon on T-Rex or DM6. Is it possible to replace the two big knobs with slo-mo extension cables?

[Wavytone]

Maybe you could do that ... but on a T-Rex they’re driving a worm. On the the belt drive reduction is 8:1 which is coarse for a long FL.

[Wavytone]

Finally assembled ready to go...

[Stonius]

Looks great! Let us know how she goes! :-)