Ίσως αν η πλοιοψηφία ή έστω όσοι προβάλονται από τα ΜΜΕ ήταν σαν τον Βασίλειο Θερμό, ίσως να το είχα σκεφτεί δύο και τρεις φορές πριν γυρίσω την πλάτη μου στην εκκλησία.

Impeller design

I got my hands on a new pair of impellers for a pump that had the old ones replaced. A couple of things got my attention in terms of impeller design.
The pump is a two stage pump which means it has 2 impellers to move the water in and out of the pump.
These two impellers have different sizes but have essentially the same design.

The first thing that got my attention was the dimples on the back side of the impeller. Wondering why those might have been there, the golf ball came to mind and how the dimples on the golf ball help it achieve less drag when flying through the air and reach further distances. It seems that the designer of this particular impeller used dimples to reduce drag while the impeller is spinning.

The second characteristic that caught my attention where the symmetrical lines on both the faces of the impeller. Closer inspection revealed that the impeller is actually made of 3 parts. The top one that resembles a funnel, the middle section that includes the channels that guide the water in and out of the impeller and the back side with the dimples.
These 3 parts are welded together. The welds are not continuous where the 3 parts touch but intermittent. Each series of welds cross almost perpendicularly the channels of the middle section. The welds could have been from a laser welding machine.

Closer inspection through the inlet of the impeller bellow shows how the middle section touches but is not welded at those points. The funnel section seems to have been made in a press as the circle around the funnel and the inside elongated markings show.

A photo of the radial view of the impeller shows how the welds touch the middle  section.

The impeller is manufactured by stainless steel 316, while it bears the marks of the manufacturer.

Also the sides of the circumference show that a cutting tool was used to define the impellers diameter. There was also some metal residue that I removed at the edge of the impeller. Quite interestingly the inside of the flat plane of the impeller also has dimples. This could be either for drag reduction as mentioned or for avoiding placing the sheet metal in the wrong side up by the workers.

The axle of the impeller seems to have been welded in place.

Πως τα ΜΜΕ διαστερυλώνουν την πραγματικότητα

Το μάρκετινγκ http://www.iefimerida.gr/: 

Η πραγματικότητα:

Για το ALFA Nero Μπορεί, που είναι το εικονιζόμενο σκάφος στο φόντο του Καμένου, κανείς να διαβάσει εδώ.

Από ότι βλέπω την αλλάξαν την εικόνα...LOL

Toughbook CF H1: How to access the bios without a keyboard

I recently got a used Toughbook CF H1 Field unit for play and job purposes.

It did not came with a cradle and I had thought it would be a pain to get into the BIOS and change anything if needed.
However when I gave it to my toddler to play with it, as it was turning on she pressed "KEY" button and entered the BIOS! :0
In there the A1, A2 buttons where working as left-right and the camera-RFID buttons as up-down.
The barcode button was the enter!

So there  you have it in case you where wondering like me.
How I have to open the thing up remove the WWAN module and add a USB port that I have seen floating cheaply on ebay.

update 22/6/15:
the WWANto USB card exchange didnt worked as planned. The internal USB port worked, but failed to recognise any USB storage that I plugged in. It did however recognise and was able to use, a wireless keyboard that I used with my android dongle. Perhaps it was just a (bad) cable issue but didn't test it further.