Search found 439 matches

by macfrank
Sat Mar 27, 2010 9:35 pm
Forum: Lighting & Electronics
Topic: Door opener
Replies: 17
Views: 17233

Most RC motors use PWM (pulse width modulation) so a simple switch will not work. You would need a circuit to generate the correct pulses to open and close. If you don't want to build a PWM circuit, another option is to use a DC motor with a reduction gearhead. Something like this or even better thi...
by macfrank
Tue Mar 23, 2010 8:52 am
Forum: Scratchbuilding
Topic: Cheap Styrene
Replies: 65
Views: 101900

Haven't been to Red Star in Culver City in a few years and since they aren't on the web don't even know if they are still open. Red Star closed about 6 years ago; the owner was tired of retail and decided not to sell the store to Michael, who wanted to keep it open. All the other stores on the West...
by macfrank
Wed Mar 17, 2010 10:57 pm
Forum: Construction
Topic: Anyone use Easy Cast Clear Casting Opoxy?
Replies: 10
Views: 11389

Alumilite also sells a clear resin that I've heard works very well but I've never used it myself. The Alumilite clear resin produces non-sticky, water clear parts, but it has two serious issues: 1 - it sets in about a minute, so you have to degas & pour it in that time. 2 - You need to heat the...
by macfrank
Tue Mar 16, 2010 8:59 am
Forum: Finishing
Topic: Which is better for small seams, mR surfacer 500 or 1000 ?
Replies: 4
Views: 7081

Kylwell wrote:500. Dab it on, let it dry, sand smooth. Repeat as needed.
And no need to sand - Use a microbrush or q-tip soaked in denatured alcohol or nail polish remover to remove the excess. That way detail around the seam isn't sanded off.
by macfrank
Mon Mar 15, 2010 9:09 am
Forum: Scratchbuilding
Topic: Very good, free 3D modeler software
Replies: 42
Views: 194473

I'm interested in making an attempt in prototyping a model in a CAD program and then have it sent out to a company to produce a master either by 3D printing or rapid prototyping. I was wondering what program I should get? Any good advice? I read that some people use Blender 3D with some CAD tool ad...
by macfrank
Sun Mar 07, 2010 6:07 pm
Forum: Lighting & Electronics
Topic: Noticed an odd effect w/4060 - can someone explain?
Replies: 9
Views: 7783

In my actual builds I usually break off the unused leads and then use epoxy to insulate the exposed metal and stick the chip in place. If you're using a real CMOS device, (40xxc series or even 74Cxxx series) you really do have to connect unused inputs to V+ or ground - tearing the pin off isn't the...
by macfrank
Sun Mar 07, 2010 5:09 pm
Forum: Lighting & Electronics
Topic: Noticed an odd effect w/4060 - can someone explain?
Replies: 9
Views: 7783

CMOS devices are both static sensitive and have high impedance inputs, so unused inputs have to be tied to ground or a voltage. The 4060 only has one potentially unused input - reset - so if you left it floating, it may have been resetting on its own. CMOS devices can sometimes seem to work even tho...
by macfrank
Sun Mar 07, 2010 4:58 pm
Forum: Lighting & Electronics
Topic: Question about led's
Replies: 27
Views: 16577

The LED series/parallel array wizard is probably one of the easiest ways to calculate the resistors and current required to drive an array, with any source voltage.
by macfrank
Fri Feb 26, 2010 6:46 pm
Forum: Lighting & Electronics
Topic: Trying to plan out electrical choices for future projects
Replies: 7
Views: 5996

I think lower voltages are usually better. Why not run a low voltage power bus (3.3V or 5V, GND) using either a heavier gauge bare wire (adequate for the current rating) or copper tape, the have the LEDs source or sink off the bus? I/O for the LEDs is cheap. You can always coat the bare wires/tape u...
by macfrank
Mon Feb 22, 2010 4:27 pm
Forum: Finishing
Topic: Dried Up Model Masters paint
Replies: 6
Views: 5686

The only problem I can think of with turning the bottles upside down is when you go to use the paint again you may have a problem getting the lid to open and for that just soak the jar upside down in some rubbing alchohol for a few hours. Or acetone for a few minutes (a few drops under the rim whil...
by macfrank
Tue Feb 09, 2010 6:05 pm
Forum: Finishing
Topic: whats the fastest way to remove brushed on acrylic
Replies: 19
Views: 24872

It IS dried :? I have some windshield washer fluid that says protects to minus 20 degrees, it says de icer on it, anything in that washer fluid that could harm anything ? the ingredients are, water, & methyl alchohol. OR would windex be better ? how long does a soak in this stuff take usually ?...
by macfrank
Tue Feb 09, 2010 3:20 pm
Forum: Finishing
Topic: whats the fastest way to remove brushed on acrylic
Replies: 19
Views: 24872

Another vote for denatured alcohol - especially if it's dried Model Master Acryl.

Windex works OK on simpler acrylics like Tamiya or Gunze Sangyo, but works very slowly on dried and cured Acryl.
by macfrank
Mon Jan 25, 2010 1:53 pm
Forum: Scratchbuilding
Topic: DIY photo etch?
Replies: 11
Views: 17008

Sorry, hope I didn't step on anyone's toes. I should have thought about how old some of my research on DIY etching is. Of course the technologies should have improved since then. Not a problem. The toner transfer method works best when you can control the temperature and pressure. That's why you ne...
by macfrank
Fri Jan 22, 2010 6:19 pm
Forum: Scratchbuilding
Topic: DIY photo etch?
Replies: 11
Views: 17008

The slightly better motorized laminator is better. But for sub 1mm resolution with consistent results, you need one of those expensive professional laminators, or switch over to a professional photo-resist set ups. This circuit board was made with the laminator in my article and a Press N' Peel ton...
by macfrank
Fri Jan 22, 2010 12:16 pm
Forum: Scratchbuilding
Topic: DIY photo etch?
Replies: 11
Views: 17008

I have an article here at SSM on making PE. The chemicals are cheap, but corrosive and for best results, you still need a laminator. I haven't done much with the galvanic methods, but it is an interesting way to etch. The main drawback there is that for best results you need a good regulated, curren...
by macfrank
Thu Jan 14, 2010 9:57 am
Forum: Lighting & Electronics
Topic: LFSR-based "random" circuits
Replies: 8
Views: 9994

Not sure if this is a good idea but to create more 'randomness', one could interface any EPROM (especially from old machines) and read from it. The data that comes out, is quite random methinks. But that would repeat the pattern every few K bytes (depending on the size of the EPROM) which may be pe...
by macfrank
Thu Jan 14, 2010 9:54 am
Forum: Finishing
Topic: Is there a faster way to smooth and polish a canopy?
Replies: 25
Views: 20347

I bought some flex pad sanders from Micromark, and they're great for removing small scratches and polishing plastic. The 150, 280 and 320 grit remove material quickly and the 600 and the 2400/4000/12000 grit pads are fantastic at fine scratch removal and polishing. You can quickly bring clear plasti...
by macfrank
Tue Jan 12, 2010 7:15 pm
Forum: Lighting & Electronics
Topic: Power supply and LED voltage
Replies: 9
Views: 8869

That helps, but heat will be a problem. If I use a different voltage wallwart and rearange the led's in series can I lower the heat output by using less resistors? With 4 white LEDs at 3.3V and 20ma each, your absolute minimum is going to be slightly higher than 1/4 watt (264mW) - either driving al...
by macfrank
Tue Jan 12, 2010 4:54 pm
Forum: Lighting & Electronics
Topic: Power supply and LED voltage
Replies: 9
Views: 8869

The LED series/parallel array wizard should give you the resistors and wiring diagram that you need. It looks like you'll need two 270 ohm resistors for the four LEDs... but you're dissipating 480mW -almost half a watt of heat.
by macfrank
Sun Jan 10, 2010 1:17 pm
Forum: Finishing
Topic: Interplanetary UFO finishing and decaling
Replies: 12
Views: 16452

tonyG2 wrote: ie

Engine interior and I think I'll scrounge some clear plastic to insert as blanks and tint red for the engine glow effect.
Wow, other than the fins those bear only a faint resemblance to the LE kit engines.
by macfrank
Thu Jan 07, 2010 4:46 pm
Forum: Construction
Topic: Shapeways now offers rapid prototyping in full color
Replies: 1
Views: 3744

But (there's always a but) the resolution is very limited and there are size and geometry restrictions that go far beyond Shapeways already excessively restrictive printing limits.

If you want something big, lumpy, grainy and without too many surface details and in color, yeah, it's great.
by macfrank
Thu Dec 24, 2009 3:52 pm
Forum: Finishing
Topic: Flex pad sanders
Replies: 1
Views: 3137

Flex pad sanders

I recently got some Flex pad sanders and they're excellent. The 150, 280 and 320 grit sand away material quickly, but the really useful ones are the 600 and the 2400/4000/12000 grit pads. I was able to sand off all molded on panel lines from a clear canopy, then quickly bring the plastic back to alm...
by macfrank
Wed Dec 09, 2009 4:40 pm
Forum: Lighting & Electronics
Topic: LFSR-based "random" circuits
Replies: 8
Views: 9994

From my perspective, most of the applications where I'd be using random-something would be microcontroller-based. So for what I'm doing it's usually better to solve problems with more code rather than more circuitry. Still, I have given some thought to adding another source of randomness - maybe lo...
by macfrank
Wed Dec 09, 2009 2:51 pm
Forum: Lighting & Electronics
Topic: LFSR-based "random" circuits
Replies: 8
Views: 9994

I think the main issue with the LFSR is that the 555 is producing a regular clock signal. National Semiconductor used to make a handy audio frequency noise generator IC that was easy to work with; they're next to impossible to find now. You could amplify the popcorn noise in some diodes, or thermal ...
by macfrank
Tue Dec 08, 2009 5:52 pm
Forum: Scratchbuilding
Topic: LOOKING 4 1/35 DML #3311 VeitNam Helicopter crew
Replies: 2
Views: 5834

Re: LOOKING 4 1/35 DML #3311 VeitNam Helicopter crew

Guys needing some pilots for my big aliens dropship project! If any one has any leads on Veitnam style 1/35 helicopter figures please shoot me a email! Thanks Steve IIRC, DML/Dragon sold their Loach crew separately years ago. About the nearest thing now is the Trumpeter US Army CH-47A Crew which co...
by macfrank
Mon Dec 07, 2009 6:51 pm
Forum: Lighting & Electronics
Topic: Soldering directly to batteries
Replies: 7
Views: 8250

I would use large-diameter heat shrink tubing to hold the two cells and the wires together, then I'd 'lock them in' with epoxy putty. I've done it, and it works well. (just a dab of epoxy in the heat shrink "pucker" where the wires come out and another dab on the other end - I had both wi...
by macfrank
Mon Nov 23, 2009 1:33 pm
Forum: Lighting & Electronics
Topic: "Raven" Microcontroller host board design: ver. 2
Replies: 4
Views: 4771

Re: "Raven" PIC host board project continues...

Constantly redesigning the same thing does get tiresome. :) I suppose it really would help if I were using design software that provided autorouting, too... The free version of EagleCAD has a pretty good autorouter. The only limitation of the free version are: * The usable board area is limited to ...
by macfrank
Thu Nov 19, 2009 9:54 am
Forum: Lighting & Electronics
Topic: Heat Shrink Question
Replies: 20
Views: 21165

I don't know if that will do the trick for heat shrink, though. Don't know what it would do to heat shrink, but an errant reflection will cause permanent eye damage - minor stuff like blindness. Leave the stupid stuff to the stupid people; they do it better. If the soldering iron method isn't worki...
by macfrank
Thu Nov 19, 2009 12:52 am
Forum: Lighting & Electronics
Topic: Heat Shrink Question
Replies: 20
Views: 21165

Add another vote for the soldering iron at temp method. It doesn't even have to touch the heat shrink.
by macfrank
Tue Nov 17, 2009 1:45 pm
Forum: Lighting & Electronics
Topic: How do coin cell battery holders work?
Replies: 2
Views: 4955

I've seen two types - one has surface mount pads on the sides/underside and the other has pins.

Here's an example with pins...

and with tabs

There's also a type that looks just like the pin version, but with contact tabs.