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About this blog

I'm going to have a go at a DIY stepper focuser for my dob and will post progress here

Entries in this blog

 

It’s alive 2!

Finally bit the bullet and knuckled down to wiring the handpiece- really made a rod for my own back though with the very tight space for the wires...it’s going to be really tricky getting the other half of the housing on there without squashing wires 🤦‍♂️ But it works-almost perfectly-almost that is except the pwm on the LED isn’t pwming 🤔 I swapped from a nano to the new Arduino nano every and I’m guessing the code isn’t totally compatible... 0E01F364-3061-4211-904D-1334A76EFE8A.MOV

markse68

markse68

 

Magnetic coupling

Initially I planned to make the focus motor quick release and the magnetic coupling made some sense but I ended up going for a simple screw mounted motor so it makes less sense now 🤔 But it’s done now and it works really well- better than I’d expected. It allows for lateral misalignment yet is a nice stiff rotational coupling for the sort of torque required to turn the moonlite knob. A ptfe pad keeps the magnets slightly separated so the two plates can move a little easier against each other. Th

markse68

markse68

 

3D printed housings arrived

I had to wait an unbearably long time but the 3D printed housings arrived this week and they look great 👍 Surprisingly everything fits- a bit snug but it fits! I’d hoped to get the handset all soldered up today but wasted too much tome shopping so I’ve just been staring at it- psyching myself up to it and trying to plan the best way to wire it- it’s a tight fit and I don’t want to screw it up. The little round pcb is a reverse polarity protection pcb I built for something else that also used li-

markse68

markse68

 

The motor mount

Working on the motor mount this evening- needs a bit more work but the general idea's there. I'm going to use a magnetic coupling and am thinking to make it quick release so I can take it off if I don't want to use it.

markse68

markse68

 

Slight improvement

24C2AE88-8FBD-47E7-BD34-716FB9018988.MOV Managed to square up the waveform for the step at the expense of halving it’s max frequency🤦‍♂️ But I’ve changed the driver board for the version that actually has half step input so my new max speed is about 3sec/rev which looks ok I think. It’s slmost working how I want it but I need to figure out how to shape the response as it’s too long in the very slow movement then suddenly shoots off into high speed- not sure why as the step times should be lin

markse68

markse68

 

It’s alive!

It’s very rewarding to see the motor moving 😊 Few issues though- it’s not a very linear response at all. I have a feeling that I need to make the step pulse train symmetrical high/low and just vary the frequency. The Trinamic driver I’m using has this feature called microplier where it interpolates input steps to output 256 micro steps for each input step (or 2 as that’s minimum input resolution I can chose without using serial interface) Nice feature as it makes the motor really smooth but it r

markse68

markse68

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