Q:What if Mojo doesn't make a can big enough for you?

[marku52]

A: put it in the washer, and then put it in the Anti-Dryer, and hope that it Anti-Shrinks.

Well, no. That doesn't work very well. I have to give multi-props to Jonson, who inspired me to attempt this, and to David Schwab, who ran into me over at TalkBass, and encouraged me to share this.

Long story short: I am making replicants of an old Gibson bass pickup, and needed cans. No one makes them in this size, but I remembered seeing some pictures from the "Rowe pickup" thread where Jonson had actually *made* pickup cans. WowZa. I contacted Jonson, who very nicely gave me some excellent advice, and based on this, I went ahead. I bought Nickel Silver sheet from McMurray metals, in TX. and since I have a small mill and press, tried to make a press tool to make my cans.

I wrecked a lot of Nickel Silver. But after messing with entry radii, male-female clearances, and changing material thicknesses, I am making "acceptable" cans. They have wrinkling at the bottom. Once in a while I tear a corner off one in the press. But they mostly work, and look pretty good. The unprofessional looking area does tend to be buried in the guitar. And if I had to buy tooling, I never would have bothered, not knowing whether I would ever be paid back for my investment.

So here are some pix of the tool and the process.

[WolfeMacleod]

Markus, I'm really, really impressed!
(and depressed, sinc eI don't have the tools to do this kinda work myself..lol)

[Joe Gwinn]

One way to reduce wrinkling is a clamp plate that forces the nickel silver sheet to pull out from between clamp and female die while the male die is forming the can.

[marku52]

You know that is a lot of the advice that I got, and maybe with real tooling it would work. With my setup, and a cover plate, it just increased the press force a LOT, I started tearing the corners off stuff, and the wrinkles, to my GREAT ANNOYANCE, weren't really any better.

Advice from the Web:
Wrinkling can be caused by:
Too little clearance between male and female
Too much clearance between male and female

which just tells me that there is a real art to designing these tools....

there are some great deep drawing videos on you tube

YouTube - ‪Metal Stamping : Williamsburg Metal Stamping: Deep Drawn Aluminum Can‬‏

[copperheadroads]

That looks great Markus
I have recently bought some Nickel Silver sheets for making baseplates & when I find time gonna buy or build a press
I'm not happy with the how my baseplate edge turns up ,Its too rounded ,I'm looking for a sharper 90 degree angle
I'm really impressed with your covers

[belwar]

Wow this a really great thread. You've inspired me to try this! Would you be willing to write about your clearance and radii ammounts?

Also what type of steel did you use for the tooling? Just standard 1018?

You could probably also improve the wrinkling by use a set of presses.. so that you bend it in stages

[DoctorX]

By any chance, did you grease up the blank before clamping it and drawing it into shape?

[big_teee]

By any chance, did you grease up the blank before clamping it and drawing it into shape?

I would think you would want a lite coat of lube on everything!
T

[marku52]

Wow this a really great thread. You've inspired me to try this! Would you be willing to write about your clearance and radii ammounts?

Also what type of steel did you use for the tooling? Just standard 1018?

You could probably also improve the wrinkling by use a set of presses.. so that you bend it in stages

Hi Belwar, major props go to Jonson, who showed it could be done. My "tool" has evolved, and if I ever get the free time, probably would benefit from being rebuilt from scratch, but right now, hey it's working and turning out acceptable stuff. It is made of .500" regular low carbon steel (its not even cold rolled), i've put probably 40-50 pieces through it with no wear other than giving it an occasional polish with some 320 grit. Nickel silver is pretty soft stuff. Clearances vary, but are in the range of .005 - .010" per side subtracting the thickness of the .020" N-S material. I started out with .016 N-S, but either because the material was too thin, or clearances too large, wrinkling was excessive. Just changing to .020 made things a lot nicer. Radii are about 1/16" on the edge of the male tool, about 1/8" at the entry edge of the female. Having a set of radius gages really helps to get these even, it is hard to do by eye along. All the radii were started by hand with a die grinder, and then polished with a sanding drum in a dremel.

I'm using a black moly grease, and lubing it up every 5 pushes or so. it does seem to help.

Also, standard procedure for this type of tool in industry is to have a "cover plate" which hold the blank flat as it is drawn into the die. I tried that, but never got it to work. It just raised the press force enormously, and started tearing corners off the parts. If you get it to work, let me know how :-)

Oddly, I did find through experimentation, that if your clearance is too large in a corner, the material, instead of being drawn in, just gets torn off. That was completely unexpected from my point of view.

[David King]

Great work so far Marku. I'm wondering if using a free-machining leaded steel like 12L14 would further help with the corners, it's quite slick under high pressure.
From what I understand they often use chromium steel in this application as it polishes up nicely and is incredibly wear-resistant
Is the nickel silver sheet you get "dead-soft" i.e. fully annealed?
How hard is it to knock the die apart again to get your part out?

[marku52]

I don't think 12L would make a difference, except in that it would make making the tool faster, that stuff cuts like butter. I haven't seen a hardness spec from McMurray, but this stuff moves like it was dead soft or near to. It flows pretty well.

I don't take the tool apart, then I'd have to re align the top and bottom halves, I use a puller into a threaded hole in the male punch. Works fine.

[Joe Gwinn]

...which just tells me that there is a real art to designing these tools....

That's exactly right. Notice that the first drawing had a clamp plate.

[Joe Gwinn]

Also, standard procedure for this type of tool in industry is to have a "cover plate" which hold the blank flat as it is drawn into the die. I tried that, but never got it to work. It just raised the press force enormously, and started tearing corners off the parts.

The springs that push the clamp plate against the NS sheet are too strong.

[jonson]

Just caught this thread as I'm not on here too much these days as I'm busy like all else keeping my head above the water. If through anything i've placed on this site before gets one person making their own parts then that would be enough, but it looks like more through Marks efforts are gonna do the same.
Well done Marku you can go to the top of the class for this.
What Joe said is right that a hold down plate helps with the wrinkly bits and doesn't need to be tight. with your mill recess the existing plate to take the blank about 15 to 20 thou deeper than the nickel thickness and make a top plate with a slightly oversize hole for the punch to pass through. Experiment with the corner cuts as this is where the can gets stretched the most so a lot less material is required there. PTFE spray, dry machine lubricant or even a piece of black rubbish bag under the nickel also helps. Other than that Bro it looks like you got it nailed and once again well done.
I hate paying exorbitant prices for bits knocked out in the far east and sold by UK and USA suppliers which is why I decided to make my own covers.
Vacuum formed plastic covers, Flatwork and Bucker pickup rings etc. Just a bit of imagination and a few dollars and your there.
Bucker rings now from allparts are about £4 or $8 a pair. Thats £200 for 50 sets the wrong damn colour. A 1kg can of RTV silicone rubber and a 2kg of fast polyurethane resin plus colour paste is about £50 and that will give me about 60 sets the right colour. The fact that they have that silly Gibson M number on the inside is neither here nor there, but we all have our silly little foibles.