It's also rather brittle and prone to shattering. Huh? Midwest Tungsten claims elongation at break from 8% to 14% for their range of tungsten alloys, with hardnesses from HRC24 - 28 and yield strengths from 85 - 90ksi. Hardly sounds brittle to me - certainly less so than hardened HSS or or tungsten...

Cliche perhaps but spaced steel plates/tungsten cored darts? I don't have any tungsten at the moment. It's rather expensive, you know... I do have a few inches of 1/4" tungsten carbide round, and a design for a sabot which should allow launching a 10g chunk of if at ~1100m/s. I also have a sabot ca...

I didn't know about the stress caused by reusing threaded parts - thanks for the heads-up. You may be oversimplifying something here - not quite sure what you're quoting me on. Regardless, it's generally good to not reuse them too many times. But if just reusing the parts is causing damage, and the...

I now have a reliable parting tool and a bandsaw, making it much easier to produce burst disks and integral shear skirt projectiles for this launcher. http://i813.photobucket.com/albums/zz59/ONKinetics/Stage1/DSC_1441.jpg This is an example, 0.024" thick, made of 7068-T6511 aluminum, with a rupture ...

First, to answer your question: what you're looking for doesn't generally exist as a standard part. There is such a thing as a "long hex nipple", but they generally only exist in smaller sizes, are 3-4" long, and the entire unthreaded section has a hex profile. I'm curious as to why using a pipe wre...

Even if it isn't a volumetric meter, post the meter volume and the chamber volume. Excessive meter volume in a manometric can result in an unexpectedly rich mix. In severe cases, too rich to ignite. A more likely scenario is poor mixing of the fuel, which can happen very easily in geometries like th...

Calcium carbide isn't a solid propellant, it's not the propellant at all. These designs are powered by the combustion of acetylene in air. Also, the rules don't have any restriction on solid fuels, it's solid or liquid explosives that are the concern. Even then, things are a bit unclear. Some solid ...

Reload time is irrelevant, accuracy is irrelevant, poor ergonomics are irrelevant. Can you hold it in your hands and fire it (once) at a person and do damage to that person? I think in most jurisdictions that is all that is required for the definition of a "weapon". If the device lacks any utility ...

The question here is really whether he's asking about maximum range or effective range. Obviously getting 400m effective range with a ball of any sort is a hard ask indeed, but simply reaching that distance is feasible, as I pointed out above. Also, I have to challenge your definition of a launcher ...

This all hinges on your definitions of "marble" and "firing range". If you mean "ball made of some kind of glass of less than 2" diameter" and "maximum distance to impact when fired over a flat, level surface", respectively, then yes, it is possible. Get HGDT and use its external ballistics calculat...

Looks like this is using an Arduino board... You're sure that the Arduino IDE you're using has the capability to talk to the 2560 board, right? Also, by the sounds of the material on the BQ site, the printer board might already have the firmware configured and installed, as it says the firmware is "...

I think there may be some confusion here - I just had a look at the Marlin project. You seem to be expecting a Windows program, but that's not what Marlin is - Marlin is printer firmware. Anyway, the project has a wiki here: http://reprap.org/wiki/Marlin You'll need to download it, configure it appr...

I just finished drawing the second stage, and am hoping for some feedback before I start building it. This drawing shows only the second stage components and some selected dimensions. The pump tube will thread into the 1"-32 threaded port at the left of the image, and the barrel continues on well pa...

I wouldn't try launching the dart in your picture without a sabot or some other support further up along its length. You risk destroying the dart in the barrel, and possibly tearing such a large groove along the barrel as to make it unusable. Take a gander at the HyGaC20 thread to see how this looks...

Thanks for the information. I'm guessing that you didn't actually end up catching the projectile this time around? What's your projectile situation with this cannon anyway? Do you have a lathe you can use for making projectiles from bar stock? You should be able to get at least 5 pounds up to 400m/s...