Designing the Motor Mount

This has been the single hardest design problem so far.  The stepper motor to drive the spur gear that turns the 60 tooth worm gear needs to be perpendicular to the polar axis.  It also needs to be attached in some way to the polar housing so that it can move as the polar axis adjusts latitude.   Also, getting a good fit of spur to worm gear may require some fine adjustment of position.  This somewhat approximates the relationship of the parts.

I will mount the stepper motor to the overall assembly with this mounting bracket.

The mounting bracket uses slots on the bottom, so sliding the bracket relative to the worm gear gives me motion in that direction.  

That flat section where the motor sits at the far end will have an upright in which I will bore a hole to locate the end of the spur gear.

I will cut a 1.065" slot in a piece of acetal that will slide onto the underside of the polar axis housing.   It will be held in place by two 6-32 screws in slots on the acetal allowing adjustment up and down for precise engagement that direction of spur to worm gear.  The last direction has no obvious way to adjust,  so I need to do that pretty accurately. 

There is no way to put threaded inserts into the polar axis housing walls; they are to thin.   Two possible approaches. 

1. Epoxy 6-32 nuts inside the housing where the screws will go.  To do this usefully I will apply epoxy first then turn the screws (with release agent in the threads), then bake to cure the epoxy.  Remove screws. 

2. Put the screws pointing out from the inside of the housing epoxied in place.  Because I need a slot in the acetal for adjustment,  even a little slop in positioning will not be a problem. 

The downside of acetal making fine bearings is that it is devilishly hard to clamp down in the mill vise.  If the sides are not pretty parallel,  as is usually the case with anything cut on a table or cutoff saw, you will not get a terribly flat edge for clamping  

I am being a bit more precise on this because for the reasons listed above,  at least some of this does need to be pretty precise.  I am squaring pieces using a fly cutter which is both precise and makes a nice finish as well.

European Cell Service

I am going to Europe later this month.   I have a Galaxy A14 cellphone.  I believe you can buy a SIM that let's you have service while there.  Have any of you done this?

Spectacular State of the Union Speech

Trump is a very good public speaker.  Aside from that Democrat who I did not recognize who was escorted out of the chamber by the Sergeant-At-Arms, Democrats basically sat on their hands even in spots where basic human respect might cause you to applaud.  (My wife looked at this and said this is so junior high.)

His emphasis that tariffs will be reciprocal after April 2 is important.   Free trade is good.  If nations want to give advantage to their industries and thus workers in those industries at the expense of theie consumers of those goods, I can see an argument for it.  Reciprocal tariffs allow this to continue.  It also encourages foreign investment here to produce goods in America. 

I do believe that making us as self-reliant as possible on strategic materials and manufacturing is important.   The collapse of 1177 BC was partly a consequence of the Eastern Mediterranean civilizations being reliant on each other.  When climate change started causing disruptions, they could not handle it. 

Trump read from a letter from Zelenskyy seeking a U.S.-led peace process to end the war.  He also encouraged the Greenlanders on their pursuit of self-determination and reminding them they are welcome in the USA.

Zelenskyy Got His Nose Thwacked Properly

He wants to kiss and make up.

Trump can be mean but he makes things happen.  It may be an ugly peace but even an ugly peace is better than continuing war.

As Much As Trump's "Throw in a hand grenade and see what happens" Approach Unnerves Me...

 3/4/25 CNN:

A plan for Gaza formulated by Egypt would exclude Hamas from governance of the enclave once the war ends, a draft of the plan obtained by CNN shows.

The plan is being discussed by Arab leaders meeting in Cairo in an emergency summit on Tuesday, with Egypt’s president proposing a Palestinian committee to temporarily govern Gaza – taking over from Hamas and eventually handing power to the Palestinian Authority (PA).

“With the help of its Palestinian brothers, Egypt has worked to create a Palestinian administrative committee of independent professionals and technocrats, who will be tasked with governing Gaza with the expertise of its members,” President Abdel Fattah al-Sisi said at the summit.

The committee will be responsible for overseeing the relief process and governing the strip’s issues for a “temporary period” in preparation for the return of the PA to Gaza, Sisi said.

The plan will be presented to US President Donald Trump in the coming weeks, Jordanian official sources told CNN earlier.

Egypt is proposing the formation of an independent, technocratic Palestinian committee to rule Gaza for an interim 6-month period “under the umbrella of” the West Bank-based Palestinian Authority (PA), whose members would have no affiliations to Palestinian factions, the document said....

The postwar plan, the document said, requires arrangements for transitional governance “in a way that preserves the two-state solution” to the Israeli-Palestinian conflict and “prevents the outbreak of new conflicts.”

Speaking at the summit in Cairo, Egypt’s president said he has faith that Trump is capable of adopting “serious and effective” solutions to the war in Gaza.

“The time has come to adopt a serious and effective political pathway that leads to a fair and lasting solution for the Palestinian cause, in accordance to the resolutions of international legitimacy,” Sisi said. “I have faith that President Trump is capable of doing this.”

 

Murray-Gellman Amnesia Effect

 I am sure you are aware of this.  If you have any first-hand or expert knowledge of an event or fact, if you see it covered in the news, it is almost always wrong, sometimes grievously so.  But even though you know the journalist got this wrong, you are generally prepared to trust them on subjects about which you know nothing.

I just had that event.  There was news coverage a few years ago about how fluoridation lowers IQ. 8/23/24 NPR:  "A newly released report from the National Institutes of Health says fluoride in drinking water at twice the recommended limit is associated with lower IQ in children."  

1/6/25 New York Times:

Study Links High Fluoride Exposure to Lower I.Q. in Children

The results of a new federal analysis were drawn from studies conducted in other countries, where drinking water contains more fluoride than in the United States.

If you do not get past the first few clickbait lines, you will miss that these studies involved much higher fluoride levels than are used in U.S. drinking water, in places like Iran, India, and China, where water is sometimes naturally very high in fluoride.  This study from JAMA Pediatrics is a meta-analysis of existing work.  Read the data and you will see that this is a problem only at pretty high levels:

In 31 studies reporting fluoride measured in drinking water, a dose-response association was found between exposed and reference groups (SMD, -0.15; 95% CI, -0.20 to -0.11; P < .001), and associations remained inverse when exposed groups were restricted to less than 4 mg/L and less than 2 mg/L; however, the association was null at less than 1.5 mg/L. 

Did Trump Appoint an Antivaxxer to Run HHS?

3/2/25 Fox News article by RFK, Jr. Saying go get MMR.