What Are You Building Today

[dsavitsk]

I don't know what you mean by ink, but I'd tend to do this sort of thing on a laser over a CNC. https://www.ponoko.com/

also, probably vellum, not velum

[luvdunhill]

Cool! Thanks! I don’t see any animal membranes, but it will have to do. 

[Emooze]

I would agree that laser is the way to go with cutting paper. Marking, just thinking out loud here, you would need pretty fine control over the laser power level to ensure you didn't also burn through the paper. You could also probably rig up a fine pen to do the lines too.

I think a hobby-grade machine could achieve the precision you need. Below is my experiments with a diamond drag bit on brass and that emblem is less than 1.5" tall. There's definitely some artifacts from inaccurate steps but this is straight out of the box, no tuning.

[ironbut]

Love the tongue (very R.Crumb)!

 

Not sure how you'd feel about buying something pre-made but you might contact Hoyt and see if you can get just the the dial face or even something custom?

https://www.hoytmeter.com/analog-panel-meters.html

[n_maher]

1 hour ago, luvdunhill said:

Question for those with CNC thingys:

i have a project where I would like to create a translucent dial. Something like rigid paper or plastic with a velum look. I need to put some markings on it, a scale from 0 to 100mA. 
 

How would you approach this? It would be less than a few inches in diameter and a kidney shape. So, I would need a method that could also cut out a complex shape. I also wasn’t sure how well CNC could ink? If not ink, a very thin line could work, perhaps not even all the way through the material - like an etching.

Of course I just need like two, so that’s a factor as well.

I'm pretty sure that I could do this for you on the Dremel Digilab that I have access to.  Give me a dimensioned drawing of what you want and I might have some scrap plexy that we could try out first before.  I should warn you, it might take me a while to get to it. I'm like Mikhail-levels of slow these days in getting projects. done. 

Speaking of project, COVID speaker project #2 is nearly complete. 

[luvdunhill]

I really suck at drawing. Is there a good open-source program that will produce a drawing you can use @n_maher? It’s something I need to just find time to learn.

Timeline isn’t an issue. I still am waiting on Japan to start shipping to the US via EMS.

[n_maher]

@luvdunhill - I think there are certain autodesk products that you can get an education (free) license for that would be useful for you.  I'm spoiled and have access thru work so it's never really been a thing that I paid a whole lot of attention to. That said, I got your sketch and if time permits I'll try to turn it into a dxf tomorrow at work and see how the laser reacts to it. The challenge (for me) will be figuring out how to program the combined cutting/etching operations into a single program so that it does it all at once and there's no (or at least less) chance that centers get misaligned.

[Kerry]

I use Fusion 360 from Autodesk. There are free versions. It takes a little time to master the program, but once you do it’s quick and powerful. 

[spritzer]

Seconded

[RudeWolf]

Thirdereded.

It's free and you can access your stuff from everywhere. And it's not AutoCAD which is purpose made to suck.

[G600]

This one might give you guys a good laugh.

I don't own a heat gun, so poor man's way...

That being said, it gives a warm and smokey sound 

[Fitz]

15 minutes ago, G600 said:

I don't own a heat gun, so poor man's way...

I just used my lighter before I had a heatgun (or it wasn't somewhere nearby).

[swt61]

When I lived in South Texas, I'd just set it outside for a minute.

[swt61]

Wrong thread.

Edited September 7, 2020 by swt61

[luvdunhill]

In other related news... look what showed up from Japan:

Its friends are still stranded in Japan, waiting on EMS service to resume...

 

 

 

[JoaMat]

Draft of BIAS 580V regulator. Works in LTspice. After the voltage doubler is a Maida regulator. Q1 is a to247 mosfet, C1-3 are 27.5 mm film caps and rest of parts are surface mounted.

 

For Maida regulator see:
https://www.ti.com/lit/an/snoa648/snoa648.pdf?ts=1600430373786&ref_url=https%3A%2F%2Fwww.google.com%2F
https://www.diyaudio.com/forums/vendor-s-bazaar/209067-21st-century-maida-regulator.html
https://neurochrome.com/collections/power-supplies/products/21st-century-maida-http://www.pmillett.com/HV_reg.html

Edited September 18, 2020 by JoaMat

[Kerry]

Nice!  Great idea.  I expect your kitchen table to be occupied and results forthcoming  

[dingding123]

I think some of the resistors are spec'ed at 2W as per the 21st Century Maida design. Would it be ok if you replace them with SMD parts?

[JoaMat]

Yes, you are correct. In the 21st Century Maida design R3 and R9 are power resistors.

When used for “BIAS 580V” the need for current is about 1 mA, mostly for the voltage divider R5/R9. Highest heat dissipation would be R9, 0.6 W and I’m thinking of two 0.1% thin film resistors here.

As for capacitors the C5 (220nF/630V) also needs to be a through hole.

Edited September 19, 2020 by JoaMat

[JoaMat]

Tested the 21st Century Maida Regulator as a Bias 580V regulator.

Got 558 V with the components I had at hand. It takes about 15 seconds to reach desired voltage.

To be continued (maybe). 
 

[JoaMat]

Here is my T2 power supply, now with Pro Bias Maida regulator style.

The small board with three blue filter capacitors is the 21st Century Maida Regulator by Tom Christiansen producing 580 volts after change of resistor. The Maida regulator replaces the 10m90s current source with Zener string and filters. I feed the regulator with unregulated 660 VDC. Only 5.1M resistor on psu board is used. Works great.

 P.S. still need some wire clean up…  will probably never happen

Edited September 21, 2020 by JoaMat

[Fitz]

Decided to finally see if I can fix up my HP 3582a spectrum analyzer that's been out of commission for a while since a water leak in the basement soaked the back panel. It would let out an impressive amount of magic smoke when plugged in. Fortunately, seems the water only really got into the IEC inlet and destroyed the EMI filter, as I haven't been able to see any signs of damage anywhere else (and it wasn't powered on when this happened).

Lots of melted plastic and even a hole straight inside the filter:

Corcom still make the same right-angle inlet/filter to fit the narrow space in the back of the chassis, so fingers crossed that once I install a replacement, it'll power back up like normal.

[swt61]

You have made so many awesome things, for me and in general. I can't imagine you talents not being used, so hu-rah!

Also, wouldn't it be easier to install the replacement without your fingers crossed?

Of course I fully admit to zero knowledge in this field.

[Fitz]

35 minutes ago, swt61 said:

Also, wouldn't it be easier to install the replacement without your fingers crossed?

Nah, it's an old repair tech trick. Helps quite a lot actually if you have the proper technique. 🤪

[swt61]

I missed you Fitz! This place is definitely better with you in it!