Category Archives: Uncategorized

Monport Laser 80mm Rotary Table

Monport Laser 80mm Rotary Table

Monport Laser

Rotary Table

We typically think of a rotary device being used to laser engrave round items.  But did you know that you can set your rotary up on a horizontal plane to engrave multiple flat items?  In this example I’ll use my Monport laser, 30 watt fiber with the 80mm rotary chuck to engrave 6 business cards at once.

While this is actually really easy I haven’t found a definitive place that covers all the basics of setup for this operation.  And that’s what I try to do here at John’s Tech Blog.  Make it simple and include important steps that just aren’t clearly documented elsewhere.
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New HTTPS Site Certificate

I thought I had upgraded my SSL certificate on John’s Tech Blog but it expired on Jun 30th.  I was able to install the new certificate on the morning of 1 July.

Don’t be alarmed if you have to accept a new certificate when visiting the site.  Nothing fishy going on.  Just me installing the new certificate incorrectly before the other one expired.


USB Data Blocker

USB Data Blocker

Road Warrior Pro Tip

How many of you will charge your phone in any provided USB jack?  In the airport?  Rental cars? In a hotel or coffee shop?  Plugging your phone, that has your personal data in it, into unknown sources is a security risk.  You NEED a USB Data Blocker.

Let’s use your car as an example.  Your car has a USB port more than likely.  If you plug into it the stereo head unit in it KNOWS you plugged it in and will proudly display the song you are playing or will offer to sync with your phone.  You know, for your convenience .  If it is your own car that is fine.  If it is a rental car, that’s not so fine.

Here is how it works.  The charging cable you stuck in your laptop bag or purse has 4 wires inside of it.

  • Vcc Power
  • Data +
  • Data –
  • Ground

Those two data wires will move your data whether you like it or not if the device on the other end asks for it.  Enter the USB Data Blocker.
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HDHomeRun Issues on Roku

HDHomeRun Issues

I have an HDHomeRun HDHR5-4US which i reviewed, and I generally love it.  However, about a year ago I moved to a “new” house and the previous owner left all the TV’s that were wall mounted.  All were fairly old TV’s and none of them smart.  I hooked Roku’s to all of them.

That is when the trouble began.   I installed an attic antenna and got good signal strength, and symbol quality on the channels that were important to me.  I could watch those channels WITH NO ISSUES on my phone or on my laptop.  The old Roku connected TV’s were another issue altogether.   The channels would pixelate horribly and the stream would fail frequently.  I have super fast internet and the TV’s are all close to the wifi router as well with great signal.

I really believe it is a transcoding issue with Roku.  Or rather the fact that Roku does not transcode.   Again, it works on my computer, phone, and Firestick devices work fine.


So, to mitigate the problem I bought a new TV for the Bedroom.  An LG 43UQ7590PUB from BestBuy.  Before I bought it I confirmed the LG WebOS had an HDHomeRun app.  However, when I got home there was no app in the LG store. Previous WebOS versions had it available.  I contacted LG Support and they told me to hook up a Roku!


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xTool Infrared Laser Focus

xTool Infrared Laser Focusing

xTool Infrared Laser Module

xTool IR Module

I purchased one of the xTool Infrared Laser modules and while it is super cool there does seem to be some internet chatter that the manual focusing mechanism is not 100% accurate.

There is a flip down bar that positions the laser 20mm from the work surface however the optimum focal range is 1mm or less.  That means even a tiny positioning error can greatly reduce the effectiveness of the engraving operation.

There are a few strategies for manual focusing the module however the best of the bunch in my opinion is to use a USB microscope to visually dial the beam down to the finest possible size.

I purchased a USB microscope from Amazon a long time ago for my first laser I owned and had to knock the dust off of it.  Set up is easy however software doesn’t really exist but the microscope works fine on a Mac with QuickTime Player.   It used to work with Photo Booth but doesn’t really seem to anymore.  It takes one still shot and then disconnects on my M1 Macs.

Aim and Observe

I wish I could give some kind of detailed, highly technical steps but the reality is that you just aim it at the laser dot, hit fire, and move the xTool Infrared Laser Module until the beam is the smallest you can get it.  You have now achieved optimum focus.   Here is a video for clarity.

Th, Th, The…..That’s All Folks!

1,000,000 Hits

Looks like either today or tomorrow John’s Tech blog will flip the counter over past 1,000,000 hits.

I started this web site to document my projects.  In the computing world and especially the Linux world people who have years of experience often forget they are trying to communicate to newbies sometimes.

My approach was just to simplify things and to document the process FOR MYSELF so I could redo it in 6 months or a year later when it broke.


And here I am almost a million hits later.


It’s That Time Of Year Again – Egg Printing

This is just a cut and paste from my old blog which I hope to make go poof one of these days.  Just moving the content here for posterity.  The content might need to be refreshed a bit but, you know, I’m a busy guy.


Printing on Eggs and Shit.

So I’ve got a couple 3D printers and a vinyl sign machine and I’m always looking at related forums and reading the industry magazines. One day on I stumble across the Sphere-O-Bot which shows a 3D printed frame with a couple of NEMA 17 motors and an arduino. And I think “I have to make that”. Forget that I have absolutely no reason to print on eggs or ping-pong balls but just as a man climbs Everest because it is there so it is with me.

There is a kit from a place called J-Robots or you can source the parts yourself. The software is open source. The thing is that an Arduino Leanardo, a Brainboard, and two stepper motors and drivers will set you back over $60 maybe more with shipping. Then you need the hardware and the other related stuff. Might as well get the kit.

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Using 2 Smart Lights in a 3 way switch configuration

We all know what 3 way switches are even if we don’t know what they are called.  It is a light that has 2 switches, like at the top and bottom of the stairs.  What I did here was to wire up two smart switches that are not 3 way switches in a 3 way configuration.



If you have any interest in Home Automation be sure and check out the YouTube Channel of Digiblur and his Discord chat room.  Great resource.   Let’s get to the switches!

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Repair, Not Replace

I’m a big proponent of fixing stuff rather than replacing it.  The “new” home I moved to has a built in audio system in a lot of rooms and on the front and back porches and even a speaker way out in the woods on a deck.

The speakers on the back porch are all fouled up and only produce sound from the tweeter.  The outdoor speakers are all Polk Audio Atrium55’s which are discontinued.

Polk Audio Atrium 55

So, as luck would have it, so are the replacement speakers ( Part Number RD0756-1).  Can’t find them anywhere.

The successor to these speakers seems to be the Atrium 5’s which cost $250 at Amazon, Best Buy, eBay……….everywhere.

So let’s see how I deal with this………

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