cubepro iOptron SmartStar CubePro AZ Mount

[Geoff Lister]

I bought this mount, from FLO, at the beginning of January 2020.  https://www.firstlightoptics.com/ioptron-mounts/ioptron-smartstar-cubepro-az-mount.html These comments are after a month's occasional use.

I already have a selection of Celestron & Skywatcher (Synta) GoTo mounts, but I wanted something smaller for a grab-and-go with quick setup. Overall I am very pleased with my choice.

The GPS locks in a few tens of seconds, and the mount emits a short "beep" to indicate the lock (the top-right corner of the display also changes from "ON" to "OK"). Provided that the mount is pointing towards its designated starting Az & Alt positions, (see below), the automated slew to the selected target is accurate and, after final centring, tracking is excellent. It is very quick and easy for solar white-light observing when there is a gap in the clouds. The single object alignment (2 and 3 object alignment is also available) is ideal for daytime, when only the Sun is visible.

The mount incorporates a holder for 8-off 1.5V AA cells, and there is a socket for a 12V,  2.1mm ID/5.5mm OD power jack. I have measured the current consumption. Initially (no tracking) it is between 75 & 90mA; whilst tracking, between 90 and 130mA; 2-axis slewing at maximum rate, up to 470mA; and 2-axis slewing at 128x standard rate is about 155mA (about 10mA less if only 1 axis). Generally, the standard zinc/manganese dioxide "alkaline" cells have a capacity between 1700 and 2850mAh. The manual indicates a supply range of 10V to 14V and >1.5A (the supplied PSU is rated at 1.5A - so, in theory, out of spec!).

The mount has a 3/8" - 16 UNC internal thread (heavy duty tripod), and is coupled to the top of the tripod by a long, captive, bolt. The tripod's legs are locked in position by rotating a plastic tray (with holes for 3 off 1.25" eyepieces) similar to the Synta ones.

There are a few areas with significant differences to my other Celestron and Skywatcher mounts, and other "features" of note:-

(1) The Cube's dovetail clamp is on the right, whereas on the Synta mounts it is on the left. Thus any Synta OTA is going to be upside down on the cube. This is not a problem with most focusers, but the finder is now bottom right, and A RACI with eyepiece facing downwards, is unusable. The OTA from my Heritage 130p has the helical focuser pointing directly downwards (I believe it is possible to remove and reverse the truss tubes, but then that would make the OTA incompatible with my other mounts). The 127mm Mak from my Skymax system is right at the top end of the mount's OTA-weight range, and I have glued a second finder shoe at 180 degrees to the original, so I can use my 6x30 RACI finder. I have a Celestron C90 Mak. spotting scope, designed to go on a tripod, and this works fine with the cube - the finder moving from top left to top right.

(2) The supplied system includes a 12V 1.5A mains PSU. This supply is a small block with a permanently-attached mains input lead. This lead has a "European" small, round-pin, (incompatible with standard UK socket) mains plug. It has similar spacing to the plugs supplied with UK shavers and electric toothbrush re-chargers, but, the pins on the supply are of a smaller diameter. I tried the plug in two plug-in shaver adapters; there was no problem with electrical contact, but it was far too easy to dislodge the plug with a small movement of the lead; easy to disconnect in the dark (leads and supply are black). I cut off the plug and fitted a UK BS1363 square-pin plug.

(3) With my Synta AZ/Alt systems, the default starting position is with the OTA pointing North and the OTA level or pointing to the NCP (Virtuoso Dob. mount). With the Cube The default starting position is with the mount facing South, and the OTA/dovetail clamp, vertical. This makes it far more difficult to attach the OTA. With a horizontal dovetail clamp, the clamp supports most of the weight of the OTA, and just requires a gentle push to adjust the OTA's dovetail plate position in the clamp. With a vertical clamp, you have to support the full weight of the OTA + any clamp-to-plate friction. I have found a solution that seems to work for me. Unlike the Synta system, the Cube remembers the mount's position at power-down. So, at the end of a session, I slew the mount to AZ 180 degrees, Alt to 0 degrees, and then power down. The mount seems to accept this as a starting point for the next session. (I have yet to try the Az at zero [= North] end/restart setting).

(4) The initial "South" starting point is more difficult than North, (no Polaris equivalent) and the mount has a strong stray magnetic field, so you cannot use a magnetic compass near it. I have found the best method is to use a compass to identify an object (roof/tree/pole) roughly due South, point the OTA's finder at the object, tighten the tripod's mounting bolt, swing the OTA vertical (spirit level across objective end shroud/ dew shield), and tighten the Alt knob/balance weight shaft. Remove spirit level - its a long way down to a concrete paving slab when the mount slews!
(5) The Cube mount relies on a level tripod for its initial accuracy. However, the little bubble level incorporated in my mount was not well aligned. With a leveled tripod, using a "good" builder's spirit level, the mount's bubble was off-centre, with one edge of the bubble touching the black line. I got round this by putting a Tipp-ex white blob on the level's glass, positioned to just cover a properly-leveled bubble, and leveling is now just a game of "Hide the bubble".

(6) Some of the advertising photos show the handset as though it is attached to one leg of the tripod. There is no way of doing this with the supplied kit. The handset has a little lanyard, and there is a small raised "button" on the North face of the Cube. The lanyard slips easily over the button, and is a reliable "dock" for the handset. However, both the lanyard and the button are black, so in the dark, it is difficult to find the button, and ensure that the lanyard's loop is open and correctly positioned. I made a tripod-leg docking clamp, similar to the ones supplied with the Synta tripods. I find the lanyard is best for daytime solar, and the (home made) docking clamp for night use.

(7) The Alt axis drive is from a sleeve on the main Alt shaft. The coupling is performed either by the locking knob, or by the end of the balance weight shaft. In both cases, the drive is through metal-to-metal friction with the end of the drive sleeve. There is no compliance in this coupling, so a minor release movement completely unlocks the drive. I have added a thin fibre washer (of a type often used in plumbing joints) to absorb any minor changes due to temperature or a nudge on the OTA. It's still not the same as an adjustable clutch, but it seems to stop inadvertent release (and associated loss of alignment).

When I have a few suitable photos, I will add these as an edit. Photos now added.

90mm Mak from Virtuoso system and Ioptron-supplied 1.4kg counterweight. Note "glow-in-the-dark" tape added on mount's lanyard attachment button, handset, eyepiece tray and tripod legs. DIY docking clamp for handset - in dark, easier to use than lanyard.

Skymax 127mm Mak and 3.5kg counterweight from SkyTee mount. Note, extra finder shoe (the black one) on OTA, so RACI finder works.

 

127mm Mak in "zero" position. Note that you are fighting gravity when sliding the OTA into the dovetail clamp.

 

Cosmos 90mm refractor and 1.4kg counterweight. Note upside-down position of RDF and focus adjustment shaft.

 

Heritage 130P OTA showing focus tube facing downwards.

Geoff

Edited February 18, 2020 by Geoff Lister
Photos added

[Geoff Lister]

Modifications for dual OTAs.

For lighter OTAs, the mount uses the locking knob in place of the counter-weight shaft. With the heavier OTAs, the balance is achieved with the counter-weight shaft, and a counter-weight roughly equal to the weight of the OTA. By adding a dovetail clamp to the locking knob, I can now mount 2 equivalent OTAs with the same overall weight as 1 OTA + 1 C-W.

I drilled and tapped the locking knob, giving it a 1/4" - 20 UNC (standard tripod) internal thread. My dovetail clamp has a similar thread, but I wanted a clearance hole, so drilled this out to 6.5mm. A suitable slotted, cheese-head, machine screw + star washer, sits in the clamp's well and attaches the clamp to the knob. Alignment of the 2 clamps is done with a "pound shop" spirit level.

This shows the altitude drive interface and the modifications.

The bronze sleeve is just a very thick washer, with a metal-to-metal coupling on its inside face, so I am experimenting with replacing it with a couple of thick fibre washers to give a variable altitude clutch action.

 

Heritage 130P OTA (now correct way up) and 127mm Mak. OTA (with RACI finder in alternative position) in balance on a piece of 2cm x 2cm wooden "rod".

Geoff

[jefrs]

Typing correction fluid (white paint in a pen) or Sharpie Silver make good night-visible marks for alignment and switches etc against dark/black surfaces.  Both can be cleaned off if desired.

[W0nderste]

@Geoff Lister

Hi Geoff,

thanks for the all the info in this thread.  I am looking for a compact Goto mount as a 'grab and go' unit and there is very little info out there.  How are you getting on with the ioptron now?

I have Celestron Omni 127mm STC which is 3kg so should be ok on this.

just trying to decide between this, the skywatcher GTi and the Skywatcher star discovery mount

[Geoff Lister]

8 hours ago, W0nderste said:

How are you getting on with the ioptron now?

Still very pleased with it.

It has a definite advantage over my Skywatcher mounts, in that I can enter a comet's orbital parameters and do a Goto. With the Skywatcher Synscan system, I have to find the RA & Dec of the comet, for the time/date I want to observe, and then enter them in the handset.

8 hours ago, W0nderste said:

just trying to decide between this, the skywatcher GTi and the Skywatcher star discovery mount

As I understand it, equipment availability in the UK is very limited due to Covid/Brexit delivery through the ports, combined with a higher demand during the lockdowns.

Geoff

[W0nderste]

10 hours ago, Geoff Lister said:

Still very pleased with it.

It has a definite advantage over my Skywatcher mounts, in that I can enter a comet's orbital parameters and do a Goto. With the Skywatcher Synscan system, I have to find the RA & Dec of the comet, for the time/date I want to observe, and then enter them in the handset.

As I understand it, equipment availability in the UK is very limited due to Covid/Brexit delivery through the ports, combined with a higher demand during the lockdowns.

Geoff

Thanks Geoff, glad you're still happy with it.  Do you use the Mak127 on it much?

I'm not so worried about stock, this will not be my main scope.  I'd rather pick the right option

[Geoff Lister]

On 17/12/2020 at 18:38, W0nderste said:

Do you use the Mak127 on it much

Yes, both for night-time and solar (with solar film cap).

[Geoff Lister]

UPDATE:-

I wanted to check on the gearbox lubrication, so unscrewed the covers.

The altitude final drive pinion uses the altitude shaft as its bearing, and the clamping knob links the two to provide adjustment and drive. More detail of the worm drive:-

Connector side of the main PCB (note RA/DEC, although mount is Az/Alt):-

32-bit ARM micro-controller (top left), quad op-amp, probably for encoder interface [designers seem to like 1 Megohm resistors] (top right), and dual motor driver for brushed DC motors (bottom right).

Power input side. The 16V electrolytic is probably the limiting component for maximum input voltage.

[Geoff Lister]

And now for the 8408 handset

As I had my screwdriver handy, I thought I would have a look inside the handset. The manual refers to replacement of a 3V lithium button cell, size CR1220, for RTC operation, and it was clear that the system was not retaining, and incrementing time, when the mount was switched off. The nominal capacity of a CR1220 is 36mAh at 100uA. The data sheet for the microcontroller shows a dormant current consumption of 1.4uA at +25degC,  with a Vbatt of +3.3v; equating to a useful life of about 3 years. If the cell is discharged, the mount powers up with default time/date and Az/Alt at the zero position of 180 deg. and 90 deg. respectively; with a good cell, the RTC runs, giving reasonable time at restart, and the Az/Alt angles are those displayed at power-down.

Handset main board:-

Top section with STM32F103 Microcontroller (middle), Winbond serial Flash memory (top) and xtals 32.768kHz (RTC) & 8Mhz (CPU clock)

Middle of board with 3V cell and MAX3232 RS232 transceiver. Given the obvious board space available, it's a shame that they could not have fitted a holder for a CR2025 cell, with a capacity of 163mAh.

Bottom of board with MC34063 switching regulator and the RJ8 (RS232) & RJ12 (HBX) connectors.

The underside of the board forms the keyboard contacts with individual button LEDs, a buzzer (with protective cover still left covering the hole), and the two connectors. I have added some strips of glow-in-the-dark yellow/green strips, to make the handset easier to find in the dark (all the LEDs turn off after a short period of inactivity).

Geoff

Edited March 18, 2021 by Geoff Lister
Extra battery info added.

[Geoff Lister]

Counterweight Shaft

The mount is supplied with a 150mm long by 19mm diameter counterweight shaft, and a 1.4kg counterweight. These feature in some of my earlier photos, and, as also mentioned above, the shaft works fine with the (20mm internal diameter) counterweights from my Skywatcher SkyTee 2. Different OTAs require different counterweight combinations at different distances along the shaft. To avoid having to balance the mount after each change of OTA, particularly for the larger ones, I used my modeler's mini-drill, with a cutting disk, and marked the shaft at (roughly) 1cm intervals along its length, starting at 4cm. I checked balance for my regular OTA's, noting weight used, and particular mark adjacent to the inner face of the weight. I now have a small table of OTAs, with weight(s) and distance(s) for each.

Geoff