GoodAmount

My favorite detector/coil setup by far is the GPZ with X-Coils 8” - I’ve found many ounces with that little coil. It hits on the tiniest pieces at good depth, but also goes surprisingly deep on larger nuggets. I mostly hunt rocky terrain where the bigger coils I’ve got aren’t maneuverable enough, so they don’t get much of a look in.

I’d put my bets on VLF-like multi frequency/6000-Geosense approach, but with multiple concurrent ZVT timings plus Algo-like discrimination. You can be guaranteed Minelab will have developed highly complex algorithms to match the capacity of current chipsets to get the most out of the machine in deep, hot, variable ground. I wouldn’t even mind if it was heavier than the Algo or 6000. I’d be surprised (and disappointed) if the 8000 doesn’t reinvigorate old patches and open new ground like the Equinox 800 did for relics, coins and small-gold hunting.

Yep, you’re right. I didn’t weld it straight across though (see previous post). If I was doing repairs as a business for customers, I’d be sure to go through a rigorous process, but given my pick is a big DIY experiment anyway, I’m happy to leave the result in the lap of the gods. Plus, I’ll just make another one if it breaks. I’ll be surprised if it does though - it feels pretty robust.

The tip of my pick was already a bit of a stub so I ground it down to a V profile and matched the back end of the new tip to suit. I figure by adding more surface area to the join perpendicular to the sheer line it’ll give it a bit more strength. There was no gap between parts, but I beveled the edges to give the weld some bite. So far so good - I’ve been out with it a few times since and the tip is holding up super well and keeping its edge.

I didn’t quench or temper the one shown in the picture. The source of the welding heat was away from the tip, so I didn’t worry about it. I’m happy to just see how it goes and if I’m having difficulty keeping a keen edge I’ll just weld on another tip and spend some time hardening and tempering it.

Gold Digger picks are awesome. Those Supersede picks are awesome too - I love that the parts bolt on and are replaceable (I’ve done the same thing with my DIY-build pick an it’s worked out super well). I’d recommend welding on a new tip if you’re only replacing the sharp end of the tooth, given bolting it on will interfere with its travel into the ground. Bolting an entire new tooth at the handle collar will work great, but you’ll be throwing away good steel in the process.

Honing down a triangular pick head can be laborious if you’re wanting to maintain its triangular shape. I’ve just retipped my pick with a new section of carbon steel from a trailer leaf spring. It was getting pretty stubby in the tooth and becoming difficult to get through the ground, particularly when hunting heavily surfaced areas where you need to bust up slaty bedrock. In those situations it needs a well honed point and a decent wedge profile to break up the rock without sending it flying. I welded on a small arbitrary 60x18mm parallel-edged tip section and ground a relatively oblique taper on the end with an angle grinder. I reckon I’ll get a year or so of easy regrinds to maintain its shape before needing to replace it again. I took it out for a test run two days ago and it sure rips through slaty bedrock like a champ. It’s slightly too long in the tooth at the moment, but it’ll only be a couple of sharpens before it’s the right length.

I use rubber ties like these (thanks to Howard of QED fame). They’re grippy, easily removed and reusable.

I’m doing a solid infill, but it’s never quite solid given the extrusion profile is circular and there’s gaps between strings. It’s possible to over-extrude material to reduce the gaps, but I’m using a Stratasys machine/slicer that doesn’t give me that option. Printing parts ‘airy’ is good for keeping their weight down though. My nozzle diameter is the standard 0.4mm and layer height is 0.25mm. I’m super interested to hear how you go. And yes, bring on the Star Trek replicator. 👍

@jasong Amazing Goo is a good lightweight option. Do you just apply it around the rim? I’ve seen it done like this, but the centre of the coil housing still gets pretty scuffed up. Annealing in salt is a great idea. I might give that a go before trying hot water - I think it’ll maintain shape integrity better. I went out for a swing this morning with a fresh skid plate on to a spot where it would get a hammering on bedrock. Below are pics of how it looked after the session (I did reasonably well 🙂). I’ll track the rate of wear and see how long it lasts over the next few weeks - I’ll be heading out most days, so it’ll rack up hours quickly. I think with the extra material thickness around the leading edge it’ll last longer than a styrene vac formed part, but not sure how it will compare to an abs-pc mix equivalent. Regardless, I can just print another one for a fraction of the price if it does wear out fast. 👍

…just don’t use cloth tape - it will leave adhesive on your coil when it comes time to replace it.

I just use pvc duct tape (pictured in my earlier post in thread). Works a treat.

You could certainly play with the angle of the lip to give the skid plate a tight fit. Or just globally scale the whole part for a tight fit according to the extrusion tolerances of your 3D printer. The coil housing will have a bit of draft on it anyway, so given there’s a perpendicular inner wall on the skid plate file, it will have the same effect. I’ve uploaded the stl btw if you want to mess around with it. I love the idea of a flexible skid plate that lips up over the top of the coil like a sock. I’ve never had much luck printing TPU though - it’s very temperature sensitive and I end up with either a globby mess if it’s too hot or a part that delaminates easily if not hot enough. Getting the right balance is tricky. I’ve been wanting to design a two-part clam shell version where the top shell protects the top of the coil cover when scraping the scoop over it, but I was planning to just make it out of ABS. A flexible one would be great though. I usually anneal parts with a heat gun, but it’s better to do it in a more controlled way. I’ve had a few disasters where I’ve melted parts in the oven beyond recovery, so I’m reluctant to do it that way until I have an industrial oven with better temperature control. I haven’t tried hot water - I’ll give it a go. 🙂

This is the profile section I'm currently using, working on the premise that I can 3D print plastic volume where I need it and taper it down where not required. This means I can reduce overall weight while increasing wearability. 3D prints are inherently lighter anyway as the density of plastic is reduced given there's micro air gaps between the extrusion lines, whereas a typical vac-formed part comes from a 'solid' sheet of material. I've been finding if the fillet on the leading edge is too small it catches on rocks, so I've left it fairly generous. For printability, I've had to leave an intersection between the base and the leading edge for better printability, but it doesn't seem to catch on rocks much and it smooths off relatively quickly. I'm testing a few different profiles to see if I can get lighter weight and better performance for both for wear longevity and slipperiness through the terrain. I'd be interested in your thoughts - I'll add an stl to the downloads section for anyone to try.