How do I calculate the voltage needed to plate with zinc?

[adamthomas]

Originally Posted by seanc

You can't go wrong with a quality unit like the Lambda (or HP, or many of the other brands that seller had). That was going to be my recommendation, not the other "PEPE" unit.

Yeah, I decided not to go the route of the P.E.P.E unit just because it looks kind of cheesy. I'm sure some nice stuff comes out of Taiwan and China but probably not at the lower end like the unti I referenced.

Originally Posted by seanc

The only other thing I would have looked for is a switchable meter, so you could read low current more accurately. But as long as you're using 1 amp or more, the Lambda meter will be fine.

The dual stage metering is the reason I was initially leaning towards the 5A HP 6281A unit. It allows you to switch between .9volt/.6amp and 9volt/6amp metering, but in the end, there was only a marginal price difference between this unit and the 10amp Lambda so I went for the Lambda. It looks like the ammeter actually has gradations at every 1/5th of an amp so this should suit me fine.

Now all I have to do is master my amperage caclulations for odd shaped parts......should be fun. If you have any shortcuts for calculating the actual surface area or nuts, bolts and odd shaped parts, I'd love to hear them. I would imagine that the increased surface area of a threaded item adds to the complexity to a small degree. Is this additional area significant enough to consider in my calculations or is there a general fudge factor I can use to cover the difference?

Thanks again for all your help.

[adamthomas]

Originally Posted by superglide56

Adam, I have the identical Lambda model. No complaints from me.

Thanks superglide56, that's good to know. Nothing like first hand experience. I llok forward to getting this unit into my hands for some testing. Now all I need to do is locate or make some good quality leads for it.

[seanc]

Adam:

It looks like the ammeter actually has gradations at every 1/5th of an amp so this should suit me fine.

You're all set then! Good deal.

I would imagine that the increased surface area of a threaded item adds to the complexity to a small degree.

A threaded rod has double the surface area of a non-threaded rod of the same diameter! Do take the threaded portion into account.

In practice, since the electrical force field doesn't penetrate fully into the thread grooves, I cut it back by @ 20%. Has worked well for me so far.

Caswell has 2 surface area calculation pages for download. They are a good start:

Surface area calculator

Calculating Area For Electroplating

I've analyized the spreadsheet, and found some of the calculations to be in error, by as much as 15%. While that might not be enough to prevent decent plating, I've come up with my own spreadsheet formulas for bolt, nuts & washers.

Sean

[adamthomas]

Thanks for the pointer to the spreadsheet. I looked it over and found it to be fairly inaccurate as well. Plus it does not include anything for metric fasteners which is primarily what I am dealing with since I'm in the process of doing a resto/mod on a 1973 240Z.

Question for you on the spreadsheet. When it refers to the "HEX DISTANCE ACROSS FLATS", is this referring to the diameter across the top of the bolt head, or the width of one of the outer flats(wrench surface). If it's the diameter across the top, is this based on the (inradius x 2=distance between to opposing flats) or the (circumradius x 2=distance between two opposing points)?

It's also odd that it does not include an automated caclulation for the head surface area but rather look for you to calculate this and input it manually. Should be easy enough to add a field for the width of one of the faces and work it into the formulas. I plan on doing this when I re-work the spreadsheet for metric fasteners.

[MrPontiac]

seanc, my new rectifier allows me to adjust voltage and currant flow, it has a reostat for both, only thing i don,t understand with both positive and neg terminals removed my voltage shows 12 volts minute i hook it up to my 1/2 pipe even tuned up all the way it only shows 1.2 volts im confused? Now i can control amps from 0 to 20 amps with not trouble simply by holding a button in to a desired amount then releasing it.

[seanc]

Adam:

Thanks for the pointer to the spreadsheet.

Don't know the answers re: the spreadsheets, as I don't use them. As soon as I realized there were errors, I created my own spreadsheets using accurate formulas.

Was too busy over the holiday, but I'll gather my stuff together & send to you. Send me your email address by PM.

Sean

[seanc]

Originally Posted by MrPontiac

my new rectifier allows me to adjust voltage and currant flow, it has a reostat for both, only thing i don,t understand with both positive and neg terminals removed my voltage shows 12 volts minute i hook it up to my 1/2 pipe even tuned up all the way it only shows 1.2 volts im confused?

That's exactly how a power supply behaves. The voltage self-adjusts for the load resistance & current.

Now i can control amps from 0 to 20 amps with not trouble simply by holding a button in to a desired amount then releasing it.

And that's the way you want to do it. Zinc plating is current dependent, not voltage.

Turn your voltage control up past the point that's needed, then adjust the current control for the current you want. The voltage will auto-adjust downwards.

Sean