11 replies to this topic

[big eye]

Can anyone tell me what the gears are made of in the lx90 gearbox I can see the large gears are made of a machined alloy as I have removed and cleaned them in the past there was red factory grease on the clutch face any way that's another story. It looked like the gearbox housing is plastic so I'm hoping that the gears are metal but I'm sure I will find out that they are plastic or maybe nylon. I don't want to open the gearbox but I'm hoping maybe someone has. Thanks for any info. Ian.

[OzAndrewJ]

Gday Ian

Its all plastic

Andrew Johansen Melbourne Australia

[big eye]

Gday Ian

Its all plastic

Andrew Johansen Melbourne Australia

LX90 Encoder.jpg

Thank you Andrew for the picture. now I know hope I never need to go in there maybe the plastic can handle the strain better than I give it credit. It's amazing how such a small thing can do such a big job.

[Piet Le Roux]

The gears are made of Delrin or Acetal : Delrin® acetal homopolymer (Polyoxymethylene POM) is the ideal material in parts designed to replace metal. It combines low-friction and high-wear resistance with the high strength and stiffness such applications require. It provides a wide operating temperature range (-40 °C to 120 °C).

[big eye]

The gears are made of Delrin or Acetal : Delrin® acetal homopolymer (Polyoxymethylene POM) is the ideal material in parts designed to replace metal. It combines low-friction and high-wear resistance with the high strength and stiffness such applications require. It provides a wide operating temperature range (-40 °C to 120 °C).

Thank you Piet for the information you have given me much more confidence.

[OzAndrewJ]

Gday Big Eye

It's amazing how such a small thing can do such a big job.

Not really.

You have a non reversible 154:1 reduction via the worm assy

so it doesnt really have much load on it to work.

 

Andrew Johansen Melbourne Australia

[carolinaskies]

Gday Big Eye

Not really.

You have a non reversible 154:1 reduction via the worm assy

so it doesnt really have much load on it to work.

 

Andrew Johansen Melbourne Australia

Between that and mostly low speed except during high speed slew they don't see alot of pressure.
The drawback is heat over time for Delrin in certain applications and avoiding jamming or chipping.  Not likely unless something else causes the jamming in the first place.  

[big eye]

Gday Big Eye

Not really.

You have a non reversible 154:1 reduction via the worm assy

so it doesnt really have much load on it to work.

 

Andrew Johansen Melbourne Australia

The electric motor must have a good amount of torque to operate at tracking speed. With that considerable ratio the motor has to be running very slow I wald say without the amp rating and the electronic control the motor could not maintain a perfect speed. Thanks Andrew for the specs on the gearbox.

[OzAndrewJ]

Gday Bigeye

 

Its actually a "relatively" toy motor.

The motor runs using 12V PWM so can get good torque at low speed

and the encoder feedback loop keeps it synchronised to sidereal.

The total gear reduction means any small woofs in the motors tracking dont show in the OTA.

ie the LX90 gearing is

 

Period    Fund
0559.5071     1x        WormWheel (154) teeth
0559.5071     1x        Worm + 48 tooth gear
0011.6564    48x           per tooth
0186.5024     3x        Compound 16/38 tooth gear
0004.9080   114x           per tooth
0078.5273     7.125x    Compound 16/38 tooth gear
0002.0665   270.75x        per tooth
0033.0641    16.92188x  Compound 16/38 tooth gear
0000.8701   643.03125x     per tooth
0010.4413    53.58594x  12 tooth gear on Motor
0000.0967  5787.28125x  Encoder Vanes  (108)

so about 10seconds per rev of the motor when tracking

 

Andrew Johansen Melbourne Australia

Edited by OzAndrewJ, 15 November 2020 - 08:17 PM.

[big eye]

Gday Bigeye

 

Its actually a "relatively" toy motor.

The motor runs using 12V PWM so can get good torque at low speed

and the encoder feedback loop keeps it synchronised to sidereal.

The total gear reduction means any small woofs in the motors tracking dont show in the OTA.

ie the LX90 gearing is

so about 10seconds per rev of the motor when tracking

 

Andrew Johansen Melbourne Australia

That's amazing I can see the motor in there and it is very small not much bigger than the motors in my HO trains I wish they could run that smooth and constant at low speed. Is the motor brush or brushless I'm guessing brush not much leverage in that small armature. Good specs on the ratios thanks.
 

[OzAndrewJ]

Gday Bigeye

The motor is a bog std DC motor. ( Its also used in the LX200 classics )

 

Its driven by PWM with encoder feedback, and whilst not perfectly smooth

its way more accurate than an open loop analogue drive.

 

Andrew Johansen Melbourne Australia

[big eye]

Gday Bigeye

The motor is a bog std DC motor. ( Its also used in the LX200 classics )

 

Its driven by PWM with encoder feedback, and whilst not perfectly smooth

its way more accurate than an open loop analogue drive.

 

Andrew Johansen Melbourne Australia

Thank Andrew I have more respect for what is going on in my lx90 now. You have satisfied my curiosity see if I can throw you a curveball later down the track.