Helpful hints, handy tricks and useful trivia

[ShiFu]

Record your discoveries here.
If you stumbled across something useful from someone else please give credit to them.

Silicone Baking Sheet
I'll start it off by saying member Edwin Croissant posted a picture of his soldering area which included a big silicone baking sheet. It is perfect for keeping small parts from moving around while soldering and it protects the work bench from burns.

[Eucyblues]

Melamine 'Magic Eraser' pad

Credit also to Edwin C for being inquisitive enough to try the Melamine 'Magic Eraser' pad on his soldering station - This stuff used to be quite expensive when it first came out (like a lot of things) but it's now cheap (eBay etc).

So just cut a pad to replace your damp foam pad and away you go - works dry - doesn't burn (surface shrinks slightly at the tip contact point ) - nice and clean - great stuff EC!!

 

[Eucyblues]

DIY Liquid Polystyrene AND Tough Waterproof Labels

When i was a teenager (about half a century ago), an old(ish) guy I knew used to make wooden jewellery - pendants etc and he showed me how he made his DIY coating.  I've seen it since mentioned in hobby forums but it's worth re-telling here for it's a useful thing to know

It's based on expanded polystyrene and (either) thinners, acetone, or MEK.  I use GP thinners because I have it and it contains acetone and ketones.

Add a small (maybe 50mls) to a CLEAN GLASS jar - break up your poly into small bits and drop them in the jar - it'll dissolve almost immediately.  Keep adding poly until you get to the desired thickness (about nail polish consistency or a bit runnier).  You'll be swoggled at how much foam it chews up. 

You now have liquid polystyrene - It'll dry to a clear semi-gloss tough flexible coating which can be further polished with fine paste if needed.  It can be used on almost anything (except styrene type plastics obviously).  It's cheap and can be made in small quantities as needed.   

It can also be used in place of commercial styrene glue.  Joints made with this stuff are every bit as strong as those using poly cement.

Now to the particular use I put it to today:

I'm in the throes of finishing the boxing of the DC Valve Controller (I really do find boxing a chore  ) .  It has 5 mom push buttons on the front and i was initially going to use the standard plastic knobs, but they were a bit klunky and the thickness of the box prevented them clicking properly so I thought I'd try a printed fascia like you see on washing machines and other commercial goods. 

I looked for printable white film but it was in short supply, expensive and long delivery - so scrap that.

I drew up a few layouts using OpenOffice Draw (not a bad little program - has vector capabilities), and printed them out both on an inkjet and a colour laser. 

Very, very basic artwork - looks better in real life than in the photo - I'm sure it can be improved (a lot) but it'll do the job.

I opted for the inkjet and after testing the process on thick paper, I finally used glossy photo paper.

I made up a batch of liquid-poly and gave the artwork 2 coats on the front (didn't affect the printing) (soft brush - don't make the LP toooo thick) - try to do a sort of flood coat quickly - because it's VERY fast drying - don't overwork it - you can do both coats within about 5 minutes - use a floodlight or similar to speed up drying in cold weather.

Turn the paper over and give about 4 coats on the back - I also put extra dobs where the button shafts were going to press.

Let dry thoroughly - cut out, smooth the cut edges, and using your finger or small brush, dip into the jar and carefully run around the edges to seal them.

You now have a VERY TOUGH waterproof label - this stuff is mega strong

I ground down the button shafts so they just protruded a tad from the front face of the box, made sure they were smooth and put a tiny piece of masking tape over the end of each just for a tick of extra padding (EDIT-looking at the photo of the drilling and buttons again - it was all a lot neater at the beginning but the plastic buttons were problematical and i hacked a bit, then I ground down the shafts etc so it looks a bit nastier than is should.).

Now, since the label is coated with LP, you can very readily stick it to the box by brushing some more LP on the back (I did it around the edges only) - It'll activate both the back of the label and the surface of the box.  I put some masking tape registration strips on the box first to accurately locate the label - then held the edges down with more tape until set - (Mine has slight bumps at the buttons - if you have flat label it'll stick without taping)

I took the tape off too early and the top edge popped because of the button bulge - had to fix it and if got just a tad messed - but clickety-click it works a treat !!

PS - the buttons are:
Top Left - Step Open (1 degree per step)
Top Right - Step Close (ditto)
Centre - Initialise
Bottom Left - Fully Open
Bottom Right - Fully Close 

PPS - If you want a lighter duty result with no brushing - you can spray the artwork with Incralac or equal - (used for coating brass) - it's a lacquer finish which is also compatible with the LP       

[Eucyblues]

DIY Thermowell

Because of the motorised ball valve project, I need 15mm copper fittings to at least one of the deph cooling connection so I decided to make a thermotee from a 15mm threaded brass tee and cap - I want this one to suit the 4mm dia cheapy thermistor type sensor which you buy with the LCD displays,

I first filled the inside of the cap with solder flush with the end of the cap ) you can slightly overfill and form a meniscus - it'll shrink on cooling.

Then to extend the depth of the well, I carefully inserted a short length of 3/8" copper gas pipe using needle nosed pliers (happened to have the 3/8" - EDIT you could use 12mm if necessary(Nope-12mm would be too big-3/8" is a good size)) - MAKE SURE IT"S CENTERED AND VERTICAL.

Insert the pipe slowly and the molten solder will only slightly bulge in the cap and won't overflow.  It will enter the inserted pipe but won't fill it.

Let the mass cool down so the main solder is solid, then apply a gas torch only to the small pipe extension - heat to soldering temperature and carefully fill the the central pipe.

Before cleaning up you'll end up with the result shown in the first 2 photos.

When cool, clean it up as needed, flip the unit over and center drill for the sensor making sure you are really in the centre and also make sure you leave the hole blind.

You can use silver or leaded solder - I tried both and both work fine.  As it's cooling water either going to waste or in a recirc system, and the surface contact area is tiny, I can't really see the need for silver solder, but if you're concerned about downstream effects then by all means use silver solder throughout.

EDIT: If you want a longer/deeper well with a smaller tube for a boiler sensor then pre-drill the cap for a push fit of your tube - fit the tube, fill the cap with solder to the extent necessary to fix the tube in place

Now you have a threaded cap with a through tube - to blind the tube, brush with or dip the end of the tube into solder flux, use a gas burner to make a small puddle of solder on a sheet of cement board and dip the tube into the puddle - the solder will be drawn into the tube - let it cool and dress it down - job done
   

[law-of-ohms]

Awesome, thanks guys. You've all god me thinking of things to post.

[Eucyblues]

Ground Plane Tip

If you're messing with prototype boards and want to create a ground plane or other shielding, try getting some self adhesive copper foil from eBay or similar - (used for guitar pickups)

It's tough enough and solders easily so just cut a piece to size, stick it down, solder a tag wire to earth and you're done -

It can be cut with a scalpel so fancy shapes can be managed if you have a steady hand