Robert Thomasson

  • Content count

  • Joined

  • Last visited

  • Days Won


Everything posted by Robert Thomasson

  1. The drill bit is a great idea!
  2. Can you adapt a posthole augur? Here is a company that seems to specialize in augur systems. Don't know what they cost or if they might be suitable for your purpose.
  3. Charlie Connell is the man when it comes to restoring and repairing stamp mills. I'm sure he'd be happy to answer any specific questions. I worked on the Donovan's Mill project in Silver City, NV with Charlie for a very short time, still learned a lot from him. Do you own a stamp mill? If so, we need pictures!
  4. Never seen one of these before, sure could use one.
  5. Sorry about the dead link. As I recall the drill was a Rube Goldberg type of contraption. The operator turned a crank and a series of hammers on a rotating wheel hammered away on the drill steel. The New Rock Drill Design thread title is sort of a joke.
  6. I use an MD-20. It doesn't have the depth of the regular pinpointers but it's very sensitive for checking crevices where other pinpointers aren't sensitive enough. Interesting that it's very sensitive to small gold but doesn't have much depth even for larger gold. Bob
  7. Not sure if this is still an active poll? My response is SDC-2300. Bob
  8. Really hard if not impossible to answer via the internet. You really need to get an experienced mining geologist out to look at your property first hand and follow his advice. Bob
  9. Jim, I found an old 1915 USGS Bulletin 601 on the National District by none other than Waldemar Lindgren himself. I don't think the National District has or is being heap leached, but I could be wrong. I have a friend who found a tennis ball sized rock in a Northern Nevada tailings pile that really set his detector off. It looked like a dull gray rock with no indication of mineralization. He took it home and cut it open to find that it was nearly solid electrum inside. It was a couple of weeks before he could get back out to the tailings pile and when he arrived there, the pile was completely gone. About Ryepatch, for some reason I'm just fascinated by the Eugene Mountains to the North. Spent quite a bit of time there, haven't found much but I keep going back. At least one tertiary paleochannel flowed through the Eugene Mountains. There are old workings in part of a channel there but I haven't found any reports of how much gold, if any, was recovered. And, of course there is Lunker Hill! Bob
  10. Chris, detectorists like you that have been detecting for many years were taught in the beginning to fill their holes. Now, there are so many people with detectors who haven't been taught and just don't care. Not sure what can be done about it, other than all of us taking a more vocal approach when we see people not filling their holes.
  11. This has been an issue for me for quite awhile now, this kind of lazy jerk does more than just make us look bad. With more and more people out detecting and leaving holes behind sooner or later there will be laws against detecting on public land and sad to say they'd be justified. We all need to start getting militant about filling holes. Bob
  12. Harry, That MFJ power supply was designed for Ham radios. They might draw 20 amps when transmitting at full load, but maybe only 1/10th of an amp when just turned on but not transmitting. Your pumps will only draw the current that they need from a 12V power supply. The "continuous" in the power supply description just means that the power supply is capable of supply 10 amps continuously, if it has to. Your pumps will only use the current that they need, even though more is available.
  13. A lot of the automatic car battery chargers have a built-in voltage sensor that detects the battery voltage. They won't put out any current unless they're connected to a battery. An older manual battery charger should work. Or you could buy a 10 Amp 12 Volt DC power supply but it might be expensive.
  14. Harry, Just wondering how the gear reducer is working out? I read this thread kind of late and I'm kind of concerned that the play in the shaft is going to affect the worm gear mesh. If it isn't adjusted right it can wear the gear pretty fast, especially at 3600 RPM. About the oil for bronze gears, some extreme pressure (EP) oil additives are corrosive to copper alloys. There is a test called ASTM D130 and non-corrosive oil will have an ASTM D130 score of 1a or 1b. That info should be on the label. Mobil SHC 634 is fine. The warnings about too much lube apply mainly to grease lubricated bearings. We always want to pack them completely full and it can cause overheating when the grease churns around in the bearing with no place to go.
  15. Sampson, Maybe it was intentional, there is an extra "g" in geology in your link above. Have to remove it to get the link to work. Bob
  16. Not sure if it helps any, here is a picture of the remains of a very old (1930's?) drywasher at the Ryepatch area of Nevada. As I recall, it had three bellows in parallel underneath it. Not sure how the conveyor system worked. Next time I'm near there I'll take some more pictures, but a lot of the parts are missing.
  17. What Chris said. There are lots of plans and threads on the various prospecting forums. Some of the plans are drawn by people who could never make a living drafting and it's hard to interpret exactly what the designer has in mind. There are some very good and reasonably priced commercial drywashers and although I'm an incorrigible DIY'er I think we should think twice before building one. I've never built one from scratch but I've totally rebuilt a poorly made DIY drywasher that I got from a friend. He either didn't follow or understand the plans. Most DIY machines are wood, since many of us already have woodworking tools. The main downside to a DIY wooden drywasher is that they are generally not as light and portable as an aluminum drywasher. If someone has a sheet metal brake or other means of bending sheet aluminum, then a DIY aluminum drywasher might be a good project. Building a drywasher is labor intensive and unless you already have the equivalent of a hardware store in your workshop, the price of parts adds up pretty fast. Depends on your individual circumstances and inclination whether it's worth tackling. One of the main reasons for building one rather than buying one is if you have some ideas or improvements that you'd like to try. Some areas that I think can be improved are: Hopper Design. It would be nice to have a larger hopper that will still feed the material evenly and in a controlled manner without either clogging or overloading too much material. I think some of the earlier wooden designs were better than newer models. Riffle Design. I think there's room for improvement or at least experimentation in riffle design and spacing. Vibration and Pulsing on Blower Drywashers. This could be optimized. Some of the commercial models vibrate horizontally and a vertical vibration is better. Flapper Valves on Bellows Drywashers. I see numerous configurations, some with a large single flap, others with several smaller flaps and some earlier designs with a separate air chamber. Seems like one or the other is better and some testing might be worthwhile. Bellows Stroke Length and Speed. Lots of different numbers being used and again some testing might be worthwhile.
  18. That's a good idea. I think it would be fairly easy to make some sort of a pistol grip with a short rod out of wood or other non-conducting material.
  19. Dick, What happened to Heathkit is that other manufacturers improved their circuits so that they were as good as Heathkit and low cost Asian assembly work made it so that we could buy very good quality electronic products pre-assembled for less than Heathkits. They hung on for awhile trying to sell wood furniture kits but I think they finally threw in the towel.
  20. There's a guy on another forum who did this using HDPE pipe, or maybe it was PVC. He cut a section of pipe into a slinky like coil and glued and screwed it to the inside of his trommel pipe. Can't prove it but I think HDPE is probably more abrasion resistant than steel and might last longer. Different story if heavy rocks make it through to the helix, they would deform HDPE pretty fast.
  21. Chris, that's understood and thanks for the explanation. I hope that Sampson Resources comes back. Decades ago I lived in what was then a small town with no radio station (Mammoth Lakes, CA). One of the local residents went to great expense and effort to get the proper equipment and licenses to start a station. After literally years went by he was finally all set up and ready to Rock 'n Roll. However, it turned out that advertisers wanted to decree what type of music the station played. So, he was faced with the choice of going out of business after all his effort, or playing what the advertisers wanted, which was very close to elevator music. Unfortunately it's the old case of who has the gold makes the rules and the advertisers have the gold. About the no advertising rule, it's a little bit vague. Advertising to me means a link to a product or service that I'm profiting from. In the recent case, I think he was just pointing out a product that he had no connection with, although there may be advertisers who sell similar products and this was a conflict. Maybe the rule could be re-worded to make it more specific and clear. Bob
  22. That's not surprising, as it's a term not commonly heard or used in the sheltered confines of academia. (What is the acronym, GD&R for "Grinning, Ducking and Running?") Seriously, I highly recommend "Fistfuls of Gold" as required reading for any serious gold prospector. Bob
  23. Harry, No, but I see that Ohio Gear is still in business and still makes the D3 series. I looked on their website but didn't find a pdf download shop manual. It might be worth a try to call them and ask. Not sure if posting outside links is acceptable here, but you can easily find Ohio Gear's website with Google. If it's bad bearings it might not be too bad of a job. If the gears themselves are no good you're very likely better off finding another gearbox. Bob
  24. Very interesting. I've seen students from the University of Nevada using the same or similar instrument mapping faults in my neighborhood. I was surprised they were using a hammer instead of an explosive charge. When I asked them about it they laughed and said they'd like to but weren't allowed to use explosives. From the video it appears that the hammer is the standard tool. I've also seen the geothermal energy companies using seismic tools for exploration but I think they use real explosives set off down a fairly deep well bore. Didn't know about the use of seismic methods to explore for tertiary channels. That is very interesting and there are lots of tertiary channels still to be discovered. Seems like it would take some skilled interpretation to identify an underground gravel channel. I wonder about the cost of a seismic system? I know that geophones are or were available used for pretty cheap, $5 or $10 each. I wonder about the cost of the monitoring hardware and software and it it's available used at a price a prospector can afford? I was pretty excited about hand held XRF devices 'til I found out the price... Bob
  25. The absolute best small trommel I've seen is a very professional DIY trommel designed and built by a fellow who goes by the handle of AZViper. You can find a very long thread on his trommel build by Googling for AZViper Trommel. Wish I had the patience to build one but I'm just too distracted with other priorities. - Bob