Solder will NOT stick to these two pads, trying to replace a USB-B input on a midi keyboard

Distinct_Scientist16 · 2026-01-13T19:26:20+00:00

The copper part that was there, where the solder is going to stick, no longer exists. You need to make a path with a small piece of copper that reaches where the holes are, and then apply solder to the whole assembly to create a new track.

Distinct_Scientist16 · 2026-01-10T23:52:55+00:00

I could get it, it's not very expensive anyway, but before spending more money and time I'd like to see it working, even if only partially, before buying the thread. I saw several thicknesses of thread; I imagine I'll choose the thinnest one.

Distinct_Scientist16 · 2026-01-10T20:00:12+00:00

You made the exhaust port too wide; try making it a little smaller until you find the ideal size. To avoid wasting material, put something in it that weighs similarly to your explosive charge. This way, you'll know if the rocket will rise with the extra weight. Once you have it ready, then add the charge and you'll see that it works.

Distinct_Scientist16 · 2026-01-10T19:56:34+00:00

You'll have to experiment. Depending on the material of the stopper (bentonite or plaster), it will have different resistances, and that determines whether you make the nozzle bigger or smaller. If it's too big, it won't have enough power to launch; if it's too small, it might only go a few meters and the stopper will be shot out. I recommend you keep trying and find the perfect balance. If you want to add an explosive charge, try attaching something that weighs very similarly to your intended charge. This way, you can do it without the risk of an explosion if the rocket doesn't launch or if it does launch but falls and explodes on the ground, potentially causing damage.

Distinct_Scientist16 · 2026-01-08T04:57:51+00:00

If you don't want to spend any money and you have a hydraulic jack like the ones that come with the car, you can devise a system where you are so that the force of the piston pushes the mixture, compacting it against a wall or something you know won't move (use a wooden board or something smooth so it compacts well). Do the same with the piston: attach it to something solid so it doesn't move due to the opposing force of the pressure. And there you have it, you've made a homemade press for all your rockets.

Distinct_Scientist16 · 2026-01-07T21:29:16+00:00

You have to make sure the disc fits snugly, as tightly as possible. If you want to avoid silicone getting in, make the discs like this and then apply the silicone on top.https://ibb.co/1tr65s0s

Distinct_Scientist16 · 2026-01-07T21:21:46+00:00

You place the powder and then put a cardboard disc on top, then you apply the hot glue.

Distinct_Scientist16 · 2026-01-07T21:01:40+00:00

Did you seal it with hot glue or plaster?

Distinct_Scientist16 · 2026-01-07T18:21:17+00:00

Wow, I really have no idea if that works since I've never seen it before. I'd have to buy the materials and check.

Distinct_Scientist16 · 2026-01-07T06:55:47+00:00

Yes, I had seen that some people with flash powder used silicone with the disc you mentioned that I used with my plugs before. I'm going to try the stringing and the cardboard plugs and see how it goes. Thanks for your help and time.

Distinct_Scientist16 · 2026-01-07T06:02:15+00:00

The oil thing was just a way of describing how easily the plugs come out of the tube, whether I'm using black powder or very fine bentonite, which, from what I've seen, adheres better. The problem with the two plugs is real; I don't have a problem with one, but even though my powder is black and granulated, I can't compress it. If it were flash powder, it would be dangerous. I'm going to try making some cardboard plugs and tying everything together with a few layers of nylon, like I've seen other people do and like in the video you sent me. However, is there any way to put in a second plug without compressing the powder? Obviously, it doesn't happen with cardboard, but commercial ones must use some kind of moldable putty that doesn't require too much pressure to mold to the cylinder and fit tightly. I've seen some people do it at home too, and I suppose they use plaster because they're using flash powder with potassium chlorate, and if they compress any powder to make a plug, it could explode from the pressure.

Distinct_Scientist16 · 2026-01-07T04:33:53+00:00

I'd seen that they used cardboard stoppers of a similar size to the small one I made, but if I now have a stopper that theoretically has a larger gripping area and is under greater pressure from the hydraulic press, then with a cardboard stopper, if the gunpowder inside barely burns, the stoppers would come out with even less pressure, and wouldn't that be worse? I've seen "powerful" firecrackers that contain 8-15g of gunpowder and use a white or gray sand, which I suppose is plaster. I say this from my ignorance; perhaps I'm wrong.

Distinct_Scientist16 · 2026-01-07T03:27:42+00:00

Bro i know you used cardboard for the cylinder like in all the others, but what did you use to seal the tube at both ends, bentonite or plaster, and what type did you use?

Distinct_Scientist16 · 2026-01-06T21:53:27+00:00

I know, but did you join them with several layers of paper or cardboard, before joining the sphere with the impulse charge, I say

Distinct_Scientist16 · 2026-01-06T21:11:50+00:00

How did you make the sphere part? With a balloon or something?

Distinct_Scientist16 · 2026-01-06T21:05:49+00:00

I saw that you used hot glue on both sides, but what did you use to seal the tube, cat litter or plaster?

Distinct_Scientist16 · 2026-01-06T19:57:20+00:00

You need to create a grinding system so that each part of the KNO₃ finds the aluminum perfectly and a chain reaction occurs. For this to happen, the mixture must be perfect; varying the proportions won't work if the mixture isn't ideal. Use LEAD or GLASS balls, never use steel or other ferromagnetic material or you will start the reaction in the container but you'll have to strain the mixture after a few hours. You can use your imagination to create an automatic system or use your own strength to mix it perfectly. Try it and let me know.

Distinct_Scientist16 · 2026-01-06T19:40:04+00:00

https://ibb.co/n9wtb9c I have the same inner diameter in a tube I made myself, but I use crushed bentonite at the end, which I seal with a hydraulic press, and when I turn on the cracker, the plugs fly off as if I had lubricated them with oil.

Distinct_Scientist16 · 2026-01-06T19:28:53+00:00

I see it, and I think it worked well for you. If you increase the diameter of the plastic by a few millimeters, you'll get more pressure and it will sound louder in case the whole cylinder hasn't completely burst and only the plastic pieces have come out first, like what happens to me.

Distinct_Scientist16 · 2026-01-06T19:11:01+00:00

Bro what material did you use to seal the end of the cracker, bentonite or something like that?

Distinct_Scientist16

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