Etching with Sodium Persulfate?

[rockgardenlove]

I've never used this before...only Ferric Chloride...so I've got some questions.


I'm ordering from Small Bear, so it's in powder form.  What's the etchant to water ratio you want to hit?  I'm guessing it's not too important, and that you can vary the strength of the solution without too many side effects?  Any info would be great.

Is it advisable to heat the etchant as it is with FeCl? 

How many PCB's should I be able to get done before the solution wears out?

Thanks very much!

[rockgardenlove]

Oh, and one more thing, how much should I expect to pay for a small but suitable drill press...any recommendations?

And how does a Unibit work without a drill press?  Well?

Thanks again.

[Meanderthal]

 Look up drill presses on ebay- they're cheaper than you might think. I just got one of the kind you attach a regular drill to... came with an ancient but functional drill, total cost about $18.00.

Unibits and varibits(I use a varibit now) work fine without a drill press, but, now that I know the difference it's the press from now on!

Can't help ya with the Sodium Persulfate though...

[Seljer]

yeah, heat the stuff up. I use a larger bucket filled with boiling water to keep up the temperature.

I got quite a lot of PCBs out of a small batch of the stuff (a couple of DL...no idea about how strong I diluted it, I used about 60g of the crystals), about 2 or 3 full PCB blanks worth (more than a dozen or so smaller effect PCBs) but the last etches go really slowly

[rockgardenlove]

Thanks guys.

I've forgotten...the holes for the stomp switches are 1/2", right?

Meaning the Unibit #1 should pull me through for most everything.

Thanks for the drillpress tip...there are lots of them, but they look rather cheap.  I mean, for those prices I'm kind of expecting a pile of crap.

Thanks!

[Meanderthal]

 Yeah, I was rather apprehensive about those mini-presses all the dropshippers sell... That's why I went for the use-a-regular-drill kind. Mine works great!

[rockgardenlove]

Alright, thanks again.
I can be safe in assuming that these are crap, eh?
http://cgi.ebay.com/28-size-3-pc-HSS-M2-Titanium-Unibit-Set-Step-Drill-Bit_W0QQitemZ120057021858QQihZ002QQcategoryZ50383QQrdZ1QQcmdZViewItem
8 bucks for 3 when Smallbear is charging 18 for one...hmmmm.

[$uperpuma]

Harbor Freight has one that is usually $40 on sale.  I've been using if for a few months, works great!

[Meanderthal]

 LOL! Those are exactly what I use! They should be called 'varibits' because they have 2 grooves, not one like unibit. They work great, even the one time I drilled through steel!
I have no idea how long they'll last in the long run, but you DO get 3...

[rockgardenlove]

Uh...what advantage do the Varibits have over the Unibits? 

I couldn't find one for 40 bucks at the Harbor Freight site...got a model name or anything?

Thanks!

[Meanderthal]

 It seems that the unibit (because of its one groove) gets hotter on one side than the other and can warp. The 2 grooves on a varibit even out the heat and also cut faster.
I'm serious- those elcheapos work just fine! I knew I was gambling when I bought em, but the gamble paid off!

[rockgardenlove]

Well, I'll give them a shot then.

If they die, I'll have quite the word with you over my lost 8 bucks.   

[Meanderthal]

 LOL! Even the pyramids will erode to dust someday... but I'm sure you'll be happy with the bits... I am!

[rockgardenlove]

Alright, ordered.  I had to pay 10 bucks shipping...kinda lame.  Hopefully I'll have good luck with then like you did.

Now I gotta get myself a laser printer. 

[Meanderthal]

 Ditto that(the laser printer), It'd be nice to work with a pcb for once.

[sfr]

Make sure you use some cutting oil with the drill bits if your going through metal, it will make the things last quite a while longer.

[rockgardenlove]

Thanks for the tip, would a hardware store have something like that?

[Paul Perry (Frostwave)]

yeah, any hardware will have some kind of cutting oil, either in spray can or a can. One brand I can't get out of my mind is Cool Tool - probably named by someone from EH