Steel guitar maker looking for die

Good morning all!

My name is Matt and I own Mule resonator guitars. My hundredth guitar is coming up and I wanted to do something different. Dan Auerbach of The Black Keys had sent me his 1935 Dobro to check out after I sent him a Mule. It had some really cool metalwork. I'm looking to have a die made to stamp a wedge in brass for underneath the fingerboard.

I'm just winging it. I've been winging it since I started. It's proven difficult to get past the front desk of places with this idea.

I've attached pictures of what I'm trying to do. The material will be .025 half hard brass. Very low volume. This will be done for guitar #100, and I imagine I would maybe do 50 of these my whole life. Because of this, I was told about a company that 3D prints dies for stamping metal that can do it cheaper that machining.

I have a DXF, SLT, and DWG of the wedge itself drawn by a CNC guy in solidworks

I have zero experience with any of this stuff. I'm just a guitar maker. Something I had read that airplane guys do is rubber pad pressing. Just the male side of the die on guide posts pressed onto the brass into the pad. Think that's something we could do here? I have the rubber pad that was recommended for such a thing. I would make the press to use, perhaps a 50 ton car jack in a frame.

I also had the idea that this wedge would be machined on a 1/2" plate. The plate woul dhave four 1" holes in the corners for alignment. The female side of this die (if necesary) would have the same holes in the corners, and the wedge would need to be .025 (the thickness of the brass) larger than the male edge

I know this may be a bit different than what you are used to doing, I appreciate your patience. If there is something I can do to make it easier, let me know.

Also, if you do this kind of thing and would take on doing this project, send me an email or private message.

Matt

Are you trying to replicate the result shown in the second pic? What's wrong with the press jig shown in the first pic? For a one off, seems like that would work fine. Is that what you want/need to make? The jig?

Cool guitjo by the way...

Brent

Sounds pretty simple to me. Just make the two sides of your forming die out of around 1" steel plate and dowel them together at the back corners to give you enough throat to get your brass sheet in. I don't know much about forming dies but I wouldn't think you would need more than a 2 ton jack for .025" thick brass. What are the dimensions of the formed area?

Looks like a fun project. As a hobby guitarist Im intrigued by your post. Metal stamping dies, are not necessarily my forte, but I have done quite a bit of plastic and composite mold making. If you'd like I would be willing to work, in exchange for one of your finished guitar.. or some other reasonable trade. feel free to private message me, if you're interested.

Yup! Trying to make the part that is in the second picture. That press is not mine, it's one from Terraplane guitars. Great guitars, but I don't believe they are still in business.

I'm looking for some confirmation about the dimensions of the male and female sides of the die. I have the male side drawn, If I know what to do fro the female side I can just say "MAKE THIS" which is what it sounds like every place wants.

A location might help.. For jobs like that, best to find a local contact... Hopefully someone here can help. As far as guiding the punch/die.. Used diesets, similar to the pic are cheap. For a simple die like that, a used set will work fine.

Make just the female cavity portion of the die. Use 1/2" thick 80Duro urethane for the "pusher".
Many years ago, I developed the Bonny Doon Engineering Hydraulic Press that is now being manufactured by a friend of mine in Taos, NM. It is marketed through Rio Grande Tools.
The nice thing about this is that you don't have to mess with clearances, etc.

Lee (the saw guy)

I have that rubber as I was originally looking at rubber pad pressing. I originally had it n my to make the male die, press that onto the brass with the rubber pad underneath.

To use just the female part, what would the die on top look like? I'm having trouble seeing in my brain what would push the rubber into that cavity. Wish I had a hydro form press!

I'm in Michigan. I've done some asking around and I get "We usually make car parts! Thanks!"

Matt

The press just pushes against the urethane pad and it flows like a liquid essentially hydroforming the part. You know the pot lids that are bulged so the lid is larger than the pot OD and they have an edge that fits in the pot? Well they draw the lid with straight sides put the urethane slab inside and press it which bulges the sides out, and the urethane shrinks back and falls out ready for the next part.

Along the same line I just hydroformed a 12" diameter x 1" deep dome in 316 SS 0.12" thick using a $149 pressure washer to supply the pressure. Two of them bolted together make a housing that holds about 1 quart of water.

I doubt that 3D printing a mold this simple is cost effective. 3D printing of molds pays when the mold is complex enough that machining it would be tough to machine. Heck I could do the die for this part on my homebuilt CNC!

Definitely the rubber pad press option. Simple cheap and easy compared to a stamping die.

PM'ed, check your messages.

Just to show how the urethane moves metal, here is a short video. It shows the metal being shoved into a cavity by using the urethane only. There is no shape to the urethane, just the restraints created by the shape of the opening.

Silhouette Die Kit with Two Silhouette Die Plates

I have not affiliation with Rio on this, as I sold the business several years ago.

Lee (the saw guy)

You guys are the bomb! I was really hoping the rubber pad was the way to go when I started hunting around online. Luckily I got your second opinion after talking to that fella on the phone. Now I know what I need to have done on the drawing, and will go from there. BOOM. THanks.

For that, you don't even need anything as hard as a steel die for 50 of, you could probably get away with a good dense hardwood or my go to favourite a lump of acrylic.

The rubber based hydro-forming is great, you can use male or female dies, you only have to ever make one side and the rubber does the same job as a follower - clamp - pressure plate on a drawing die, i do a fair bit of rubber die formed parts, lots of simple domeing and lots of bits like in your pic. Its a very easy process and you really don't need steel dies at all. You do need some nice rubber blocks, some times simple frames to help constrain them and also some times some packing under them in certain spots to help get depth easier.

Only real trade off compared to steel dies is the effort taken up by compressing the rubber, hence its a fair few more pump strokes on a manual hydrulic press than it would be with steel dies, that said the ease of tooling more than makes up for it.

Doug, the aircraft style presses i have encountered were not presses like most would consider them, more a diaphragm type device in a frame with a pump to energise that rubber diaphragm at up-to a thousand bar. Yeah, thats truly vast tonnages considering the area some of thoes had!! The bits though are truly beutiful and come out with out so much as a scratch or wringle, which is pretty incredable considering the forces they have had to endure.

A lot of what i have done has easily exceeded your 1500psi too, i know some of my 3mm alu bits i did were north of 10Kpsi and to do that the rubber very much had to be contained. At these pressures rubber flows akin to water and will oze out of even small gaps

Some point i need to find some far harder rubber too than what i have been using, i need some urethane, but its hard - expensive here in the uk.