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Parts arrived! Time to build


Kevin Whitcomb
 

Everything I ordered has come in (I think, I need to double check)! I need some other parts which are available locally and I can start the build. The plan for the electronics is to put them in the right fork (plan A) or in the main electronics bay on the rover cart. My thought is to put it in the fork arm so that if in the future the telescope is taken off the cart and put on a pier but it would be easier to put it in the electronics bay on the cart just because it was always the plan to do that and 12/24V power will be run there.

I have some questions before I get started though and one of them is heat dissipation. The heat syncs that came with the stepper motor drivers don't appear to actually make contact with the chip and I was wondering what you guys thought would be a best-practice for fixing that? I could mill down a channel approx 1mm (or less to make good contact or is a layer of thermal epoxy better?

    


Khalid Baheyeldin
 

On Mon, Nov 16, 2020 at 04:10 PM, Kevin Whitcomb wrote:
I have some questions before I get started though and one of them is heat dissipation. The heat syncs that came with the stepper motor drivers don't appear to actually make contact with the chip and I was wondering what you guys thought would be a best-practice for fixing that?
Depends on what model of drivers you got.

If they are TMC5160, they don't heat up, so don't worry too much about them.
Put the heat sinks on the MOSFETs next to it, and that should do it.

If they are TMC2130, they do heat up a lot, and need heat sinks, or perhaps
a fan as well.

Or is it another model still?


Kevin Whitcomb
 

It's the TMC5160 

 


Khalid Baheyeldin
 

These don't heat up noticeable.
I ran them without heat sinks, and they barely were ~ 42C or so.

So don't bother machining anything for thermal control.
At least until you test things out.

See this thread.


Dave Schwartz
 

With stepper drivers its the MOSFETs that do the current switching and thus are the components to heat up. Before the 5160, all the drivers had the MOSFETs integrated on the controller chip and thus the whole chip heated up and the heatsink needed to be in contact with the chip (or the copper area the chips was in contact with if the chip was on the bottom). But with the 5160 they are discrete external parts so the 5160 chip itself doesn't heat up appreciably and the heatsink only needs to be in contact with the MOSFETs (and if the electrical design is conservative, or you're using them well below their limit, they won't heat up much anyway).

The 3M double-sided sticky tape works fine to both hold the heatsink on and conduct heat... that's what its made for.

On 2020-11-16 4:38 p.m., Khalid Baheyeldin wrote:
These don't heat up noticeable.
I ran them without heat sinks, and they barely were ~ 42C or so.

So don't bother machining anything for thermal control.
At least until you test things out.

See this thread <https://onstep.groups.io/g/main/topic/77997821#27160>;.


George Cushing
 

Your workstation is far too organized!
Cave.jpg


Drew 🔭📷🚴‍♂️
 

As George pointed out, you will need to reorganize your workstation to OnSteper's high standards.