Part Sourcing Assistance/Advice Thread

[nopants]

http://www.diyaudio.com/forums/showthread.php?p=4338609

since there seems to be some talk about jfets afoot

[Zashoomin]

Just curious - has anyone been brave enough to try the new, V2.0 Khozmo attenuators?  I say that PE is now stocking them (in some values) and that more are available direct from Khozmo.  At ~$400 for a quad w/ upgraded resistors it would appear to be a pretty good value as long as it's not as fragile as the earlier ones.

 

http://khozmo.com/products_dale_shunt.html

I bought one a about a month ago and got a V2.  The build quality on it is fantastic and is pretty solid imo.  Paint on the outside is a bit prone to scratching and fingerprints if you care about that kind of thing.   Otherwise very satisfied.  

[eggil]

The only one I purchased from them about 2 yrs ago does duty as a door stopper since it never worked. Very pretty though.

[nopants]

Speaking of useless hardware, has anyone looked into anodized/colored screws? My Megatron is so black I have to spend a few seconds looking around for screws, figured it might be a (not so) cheap cosmetic upgrade, plus it'll make me feel less blind.

 

found some vendors:

http://www.probolt-usa.com/aluminium/aluminium-bolts-socket-cap.html

http://www.fastener-express.com/metric-aluminum-socket-head-cap-screws.aspx

 

prices are insane, not all that surprised anymore. Anyone found anything else?

[chiguy]

I buy black oxide screws from McMaster.

[gepardcv]

Ditto, but McMaster doesn't have all sizes and types of screws available in black. I planned to look into sending plain steel screws sent out to get powdercoated as a custom job, but never got around to it.

[chiguy]

Looking back through my email, I've also ordered from Bolt Depot https://www.boltdepot.com/Default.aspx

[Craig Sawyers]

In the UK I use these guys to buy black high tensile metric screws.  http://www.modelfixings.co.uk/ht_metric_countersunks.htmand http://www.modelfixings.co.uk/high_tensile_steel_caps.htm

 

In general it seems that high tensile screws are black.  Or black enough.

 

Powder coating has the problem with paint build up - so you can't get a socket or driver in the slot anymore.  Or if you do, it damages the powder coat and the bare metal shows thought.  Got the badge on that one.

[bhjazz]

Does anyone know where to find the M8x0.75 nut for an Alps Blue Velvet?  I'm working on a project for a friend and that is one piece that has escaped the parts box.  Sure, the local hardware store has some similar items, but they're just the standard thickness.  Meh.  Thanks!

[n_maher]

I'm sure you can find them (google tells me so) but the issue is going to be how to find one of them and not 100 or 1000 of them.  Honestly, your quickest and cheapest solution may just be to buy another pot and save the nutless one for a project when you can have a front panel made with a threaded mount to overcome the missing part.  No, I'm not kidding.

[UFN]

save the nutless one

 

 

//UFN

[nopants]

you could probably also thread it yourself if you buy one of those combo bits

[bhjazz]

So $16 for a new pot or $16 for 250 nuts?  Hmm.  I suppose I could buy EVEN MORE nuts and be the sole seller of RK27 nuts on the west coast.  

"Do one job, and do it well."

 

After even more googling (you know how this goes) I found them here.

 

Edit: In the future, I found searching for "panel nut" was the most successful.

Edited June 1, 2015 by bhjazz

[Mister X]

http://www.parts-express.com/nut-washer-for-potentiometers-m8-diameter-shaft-10-pcs--023-674

[bhjazz]

Nice.  I actually have my eye on a power supply at Parts Express as well.

[gepardcv]

A lot of power inlets (like the Schaffner FN1394-10-05-11 or FN284-10-06 or FN9290-10-06) hold two fuses, one on the hot side and one on the neutral side. This seems strange to me: if the fuse on the neutral side blows, the circuit will fail live. On the other hand, if the amp is plugged into a reverse-wired outlet (pretty likely IMO, I don't trust any house wiring to have been done correctly), then both sides are fused just in case. Thoughts on the tradeoff?

[cetoole]

I probably have a spare nut. I can check tonight.

[kevin gilmore]

the reason why those power outlets are done that way is for europe and 220-240v

where both lines may be hot WRT ground.

[Helium]

I'm after some help with my latest chassis design.

It's an off board KGSSHV, in which Camexpert will be fabing all the panels and drilling the heatsinks.

Which leaves me to create all the brackets, I've bought 16mm equal angle x 3mm x 1 metre lengths.

Cutting is a no brainier, I've bought a little metal mitre box for this.

It's the accurately positioning of the drill holes is where I may struggle, with my limited knowledge and tools, this is my plan...

I have 100% accurate paper print outs of the drawings, which I'll use spray adhesive to stick on the brackets, the quick test I did last week proved to be a good technique for accurate hole location.

I plan use a Stanley knife to cut a cross for the centre of the holes in the aluminum.

Then using a automatic centre punch as starting point in the middle of the cut cross, which I'm hoping to find the exact centre by feel.

This is where I start to get nervous, I bought several #2 centre drill bits to make a pilot hole using a drill press.

From what I've read and watched, it's best not to clamp down the aluminum, instead it's best to let it float on the drill press and let the centre drill bit grab the metal and find the punch hole. Bearing in mind the spinning bit would be very close to punch proximity to enable this, doing an alignment beforehand.

Then finally a pass through with the final drill bit size, an M3 or M4, again with the piece of aluminum floating on the drill press.

That's the plan, sorry it's so long winded, am I on the right path?

I've experimented a lot on drilling precisely located holes. This is a technique I've developed for myself and it's working for me. Drilled >20 cases already.

1. First make drawing in FPE software to the size of your panel/case. In the drawing use as narrow lines as possible for increased accuracy.

2. Print it with scale set to 100% (A4, A3, A2 or whatever your panel size is). This is very important to ensure that printer/plotter prints precise size according to drawing. Sometimes the printer outcome is different by fraction of mm/inch to what you expect. It will ruin accuracy. Measure the paper drawing with ruler ot caliper. If not perfect, either calibrate the printer or search for another one. It may take time to find a printer/plotter which prints precisely. Also, make sure you use the following settings as on screnshot attached (this is all about FPE software, other software setting may be different). Print in B/W mode, not color so that only one printer cartridge will be engaged for maximum accuracy).

3. Cut the outer shape (=panel shape) of the drawing with Xacto knife guided by metal ruler.

4. Stick it precisely to the panel by using glue (you will remove it later with solvent). Don't apply too thick layer of glue. As thin as possible. Wait for the glue to harden.

5. Now you proceed to drilling itself. Slightly punch reference points to be drilled on paper with carbide scriber. The scriber must protrude the pater and reach the metal to leave mark on it. This is very important to put the scriber exactly in the center of reference point (funny enough, it's harder than you can imagine). That's why I recommend to apply thin layer of glue and use thin paper for printing. Use good lighting and magnifying glass if necessary.

I use this carbide scriber:

http://www.amazon.com/gp/product/B00004T7S1?psc=1&redirect=true&ref_=od_aui_detailpages00

6. Punch paper (and panel underneath it) with automatic center punch. After you mark the center of the hole with carbide scriber (step #5), it's easy to punch it with center punch, it doesn't wander. I use this center punch:

http://www.amazon.com/gp/product/B000HTAH70?psc=1&redirect=true&ref_=oh_aui_detailpage_o02_s00

Try to punch once only. Only if you see that it is offset, make second ot third strike to remedy.

7. Take good screw-driver drill, preferably cordless. Chuck must be good (tricky to find drill with chuck that doesn't stagger on the shaft).

8. Make starting cavity with drill bit for ceramic tile. It has totally different shape from usual drill, but it doesn't wander. I use this one:

http://my-shop.ru/shop/products/1885540.html?partner=6414&gclid=CjwKEAjwkcWrBRDg5u6SuPS11C0SJAChLLAHXLrav1hkXKRHwcnHVHuU2tZX_i9WsiFiGHJPUOUJKxoCu9zw_wcB

Mine has 4 cutting blades. 2 cutting blades (more common) will do the trick as well, I guess.

Just make small cavity with it. Don't try to drill through, of course. Always apply oil at drilling. I use WD40.

The cavity made by ceramic drill bit will ensure that the final drill bit will not wander.

As you can notice, the whole process is about minimizing wandering of the bit.

8. Now you are prepared to drill the final hole. Don't try to use generic drill bit. Instead, use spotting drill. I use this one made by Europa Tool (if talking about 3mm hole, there are different sizes):

http://www.ebay.co.uk/itm/3mm-HSS-Co8-90-DEGREE-NC-SPOTTING-SPOT-DRILL-EUROPA-OSBORN-8214020300-D25-/271833566150?pt=LH_DefaultDomain_3&hash=item3f4a8b0bc6

What's so special about spotting drill? First, it has very short fluted part. It means that it's sturdy and doesn't bend when you press the drill against the material. Believe me, drill bits under size of 5mm with large fluted part do bend when you press it down.

Then, it has no side cutters. It means that it cuts material only with its tip. Side cutters tend to bite the material which make the bit wander sideways.

Use oil at drilling and VERY low RPM (~1 revolution per second). For that screw-driver drill must be used, not usual drill. Screw-driver drill will maintain torque at low RPM.

Spotting drill is not designed to drill trough thick material, but it's good enough to drill through 3-4mm.

And yes, when drill panel up to 1.5mm thick, don't use drill bench. Better by hand (just control it that you hold the drill vertically).

9. You are done. Remove the paper and clean the panel. Deburring may be needed (I use Noga tools).

 

This method is about drilling small holes (e.g. for screws, standoffs etc). For large holes (e.g. for Neutrik connectors), knock-out punch must be used (that is another story, and there are also some trick to share).

[lkong]

I'd like to see how you deal with D-style holes.

My step bits solution always lead me to filing and ditching.

[nopants]

speaking of holes I'm really tempted to buy a square hole punch, a hole saw produces good results but it's really time consuming... especially when you want to use inlets with built-in switches

[Helium]

speaking of holes I'm really tempted to buy a square hole punch, a hole saw produces good results but it's really time consuming... especially when you want to use inlets with built-in switches

IMO square hole punch is useless for me. I've got one, 1inch x 1inch, and never used it. Not to mention they are very expensive.

However, round hole punches are used very frequently. I've got the whole set from 10 to 31mm to fit all Neutrik connectors, pots etc.

Avoid D-holes and square holes as much as possible. Round holes are much easier to cut. And more accurate.

I even chose to install separate Neutrik powercon+switch+fuse holder combo instead of single AC inlet module. Just for the fact that the latter requires square hole.

[nopants]

feel free to sell it my way

 

if I wasn't intent on getting rid of stuff I build I wouldn't have a problem using my own standard for power connection

 

switching gears, has anyone heard of situbes.com? A little gimmicky but some stuff seems useful, like the delay circuit and OLED meter

[chiguy]

Hole punches for me have deformed the metal around the hole.  What do you do to get around that?

[nopants]

yeah that's one disadvantage of hole punches but usually it hasn't been enough of an issue after I deburr the hole. They're still good enough to install neutrik connectors behind the faceplate.

 

I guess I've also only made holes in aluminum so there's that. Last resort is to use rings for cosmetic effect, which is what I ended up doing for the Megatron