New DIY Rocket Tooling Complete!

[NightHawkInLight]

Here's my third recent attempt at tooling, I think I've got the design just how I want it:

 

 

The top portion of the tooling comes off with the spindle. Two screws with the heads cut off keep the top aligned with the others.

 

The end of the threaded section is mushroomed to prevent the rear nut from coming off. This allows you to grip the forward nut and twist the spindle out of the rocket.

 

I can't ram any rockets tonight, but I rammed a nozzle in just to see how well the nuts pulled the spindle out. Worked great. The real test will come tomorrow night!

 

This project was a great way to welcome my new drill press into the shop! My new favorite toy

 

Total cost for tooling was under $10 for the materials with enough left over for about 5 more sets.

Edited March 28, 2011 by NightHawkInLight

[Updup]

Looks pretty nice. Just a few questions though:

 

1. Whats your bolt made out of? Most are steel right?

 

2. You don't have the usual nub to keep the tube centered, I guess your rammer will do the centering for you, but if it does, why does every other set of tooling I've seen have that nub?

 

3. What drill press? I'm half tempted to get my own, but I would want to save up for a nice one (Do you think thats worth it?) and I still need to get one of your shirts.

[NightHawkInLight]

I couldn't wait:

 

 

Looks pretty nice. Just a few questions though:1. Whats your bolt made out of? Most are steel right? 2. You don't have the usual nub to keep the tube centered, I guess your rammer will do the centering for you, but if it does, why does every other set of tooling I've seen have that nub?3. What drill press? I'm half tempted to get my own, but I would want to save up for a nice one (Do you think thats worth it?) and I still need to get one of your shirts.

 

My spindle is steel. It was made out of a 3/8" threaded rod. My rammers are wood so I have no fear of sparks.

 

That's exactly right about the rammer centering the tube. It works just fine. I think the raised spindle on other tooling is both to center the spindle as well as prevent the tube from raising when ramming the nozzle. I have had that problem on other tooling I have made and have needed to hold the tube down tightly for the first few blows. I didn't have a problem on this tooling making the above rocket.

 

My drill press I bought used, a Central Machinery benchtop model. It worked great for me today. I've wanted a drill press ever since I was 12 years old, I just never was willing to pay for a new one. I really don't know if it's worth it or not to buy a high end model, I hear the low quality ones will allow the bit to drift.

[Mumbles]

The standoff present on most tooling also has the advantage that it allows divergent nozzles to be created. Most importantly, it recesses the nozzle, which helps to prevent blow out. It's similar to why the heads on wooden whiskey barrels are recessed as opposed to just attached at the mouth.

[NightHawkInLight]

The standoff present on most tooling also has the advantage that it allows divergent nozzles to be created. Most importantly, it recesses the nozzle, which helps to prevent blow out. It's similar to why the heads on wooden whiskey barrels are recessed as opposed to just attached at the mouth.

Ah, that does make sense. in that case I may add one if I have any trouble.

[dagabu]

If I may add to your sentiment Mum, thrust curves show a significant advantage to having a divergence that keeps with the de Laval concept. The extra tube caries on the phenomenon further down the thrust stream and captures lost thrust redirecting it to carry the motor further. At least in theory

 

A de Laval nozzle (or convergent-divergent nozzle, CD nozzle or con-di nozzle) is a tube that is pinched in the middle, making a carefully balanced, asymmetric hourglass-shape. It is used to accelerate a hot, pressurised gas passing through it to a supersonic speed, and upon expansion, to shape the exhaust flow so that the heat energy propelling the flow is maximally converted into directed kinetic energy. Because of this, the nozzle is widely used in some types of steam turbine, it is an essential part of the modern rocket engine, and it also sees use in supersonic jet engines.

-Wikkipedia

[dagabu]

Ah, that does make sense. in that case I may add one if I have any trouble.

 

No problem HNIL, just cast a divergence from epoxy filled with sharp sand and it will slip off the spindle as well when you pull the spindle off. I am not sure how to remove the insert though... Let me get back to you on that one.

[NightHawkInLight]

If I may add to your sentiment Mum, thrust curves show a significant advantage to having a divergence that keeps with the de Laval concept. The extra tube caries on the phenomenon further down the thrust stream and captures lost thrust redirecting it to carry the motor further. At least in theory

 

A de Laval nozzle (or convergent-divergent nozzle, CD nozzle or con-di nozzle) is a tube that is pinched in the middle, making a carefully balanced, asymmetric hourglass-shape. It is used to accelerate a hot, pressurised gas passing through it to a supersonic speed, and upon expansion, to shape the exhaust flow so that the heat energy propelling the flow is maximally converted into directed kinetic energy. Because of this, the nozzle is widely used in some types of steam turbine, it is an essential part of the modern rocket engine, and it also sees use in supersonic jet engines.

-Wikkipedia

 

A venturi, I know the concept, but I wasn't sure how much of an effect the reverse cone on the outlet would have on thrust in reality. I may have to do some tests.

 

http://en.wikipedia.org/wiki/Venturi_effect

[dagabu]

Some tests show 20% improvement but that is with a bell shape, not a straight wall like we use.

[Updup]

Some tests show 20% improvement but that is with a bell shape, not a straight wall like we use.

 

Well I'm glad to hear that, I was starting to feel cheated giving away some of my tube to "The centering standoff" Happy to hear it does more.

 

NightHawk, do you have any machined tooling? I'd be interested to hear the comparison between your homemade set vs. a genuine set of aluminum or brass.

 

 

Also, I'm sure this will be demonstrated by your next video, but did you put the threaded rod on your drill press and use that as a sort of vertical lathe? I've heard of people doing that (Not with rocket tooling) and there is actually a part sold that attaches to the working plate of your drill press and is basically another chuck (That the right term?). I did a little research and some people were saying the bearings of a drill press weren’t meant for the horizontal pressure. What do you guys think? Depends of the drill press quality or the bearings should be abused like that no matter the quality of the drill press?

 

 

[dagabu]

Littlemachineshop.com has M2 tapered chucks for drill presses and you can buy machinists vices if you wanted to simulate the cutters on a lathe. For our use, I prefer an angle grinder while the bolt is chucked up in the drill press and a file to dress it up after wards. I do agree that steel bolts are hazardous and that you should change over to a nonsparking metal some time but I still have and use my 20 year old steel bolt spindle from time to time.

[NightHawkInLight]

 

Well I'm glad to hear that, I was starting to feel cheated giving away some of my tube to "The centering standoff" Happy to hear it does more.

 

NightHawk, do you have any machined tooling? I'd be interested to hear the comparison between your homemade set vs. a genuine set of aluminum or brass.

 

 

Also, I'm sure this will be demonstrated by your next video, but did you put the threaded rod on your drill press and use that as a sort of vertical lathe? I've heard of people doing that (Not with rocket tooling) and there is actually a part sold that attaches to the working plate of your drill press and is basically another chuck (That the right term?). I did a little research and some people were saying the bearings of a drill press weren’t meant for the horizontal pressure. What do you guys think? Depends of the drill press quality or the bearings should be abused like that no matter the quality of the drill press?

 

I don't have machined tooling. This is the first decent set of rocket tooling I've had. To make the spindle I put the threaded rod in the chuck of a battery operated drill and tapered it with my bench grinder. I then smoothed it with 100 grit sandpaper then with 400 to finish it off. I think a drill press would work fine as a lathe, and some are actually sold under the name of a lathe/drill press combo. Just adjusting the belt to a slower speed would probably work just fine. It would be very difficult to get a smooth taper on a rocket spindle by hand I would expect though.

 

Dag, do you really believe it's dangerous to use a steel spindle if none of the rammers are steel, or even metal? I haven't heard of any accidents. I wouldn't ram Ti into a comp over a steel spindle, but otherwise I don't see where there would be a problem?

[dagabu]

The problem actually comes from the removal of the spindle, not the ramming. Mild steel (bolts and the like) oxidize easily and create iron oxide. Iron oxide on the spindle means that there is now pitting and that the comp will now be sticking into those pits and making even more friction then from steel alone which is significantly more then most nonferrous metals like SST and brass to begin with.

 

Even if the spindle is "clean" the pours in mild steel are gigantic in comparison to SST and Aluminum, and that is why it will not take a shine like them. Friction is your enemy when it comes to spindle removal and you want the spindle to POP off as easy as possible, with as little friction as possible.

 

It sounds like you have a method to pull the spindle straight out of the tube, that great! It is something that should have been incorporated into commercial spindles all along.... but no body is going to pay an extra $50.00 for it

[NightHawkInLight]

My spindle is extremely pitted just from grinding. On previous tests I worked hard to get my spindles very smooth, but for this one with the nice removal system I didn't work quite as hard at it. I simply coated the spindle slightly with wax. There's really nothing that could give me enough trouble that the nuts wouldn't be able to remove the rocket easily. If friction is really that much more of a danger I'll simply be sure to wax up the spindle good before each use. As well as not holding the rocket while removing the spindle. Both of your hands need to be on wrenches anyway.

 

My primary concern is I really want to share a good way for my youtube viewers to make budget tooling. I believe wax should be plenty to prevent dangerous amounts of friction and corrosion, but if there really is a serious concern I certainly don't want to recommend it. So far it sounds like an easily avoidable issue with wax, and perhaps simply a hypothetical or potential danger that has not actually resulted in any accidents. Not that I want there to be a first time, but if the issue with steel is easily compensated for, it is certainly easier for the average individual to find threaded steel rod than Al. Also, this design would likely wear out quickly if made from Al. I don't know that the threads would hold out.

Edited March 27, 2011 by NightHawkInLight

[dagabu]

IMHO, "safety should never be moneys bitch". SST bolts are available and so are brass bolts. Sparking materials just shouldn't be used if there is an alternative available. If It were OK then Firesmith and Wolter would make tooling from steel.

[NightHawkInLight]

IMHO, "safety should never be moneys bitch". SST bolts are available and so are brass bolts. Sparking materials just shouldn't be used if there is an alternative available. If It were OK then Firesmith and Wolter would make tooling from steel.

Money wasn't the primary issue, it's availability. I don't even know where you would find threaded Al rod, if they make it at all. I hadn't thought of brass, I'll have to make a brass spindle for the video.

[dagabu]

Google Threaded aluminum rod or "fasco threaded brass rod", lots of choices available.

[NightHawkInLight]

I picked up a threaded brass rod on my way home today and have already completed my new spindle. The brass was very easy to work with, and having practiced my method on several others before arriving at this design it took no time at all and came out great. I believe I put a very even taper on it, though I really won't know for sure till I use it. I finished it off with 100, 400, then 600 grit paper which really gave a good shine. The brass is soft enough that I think it may even be possible for someone to sand the threads down with a sheet or two of 80-100 grit sandpaper with the rod chucked in a drill, which would be great news for someone without a grinder. I have another pound or two of 60/30/10 granulated and drying now so I should be able to test things out in an hour or two. Here's a few pictures:

 

Threaded rod next to old spindle:

 

Closed threads to prevent the nut from spinning off when removing rocket:

 

Post grinder:

 

Sanded and finished:

 

Btw, sorry to whatever mod had to move this. I don't think I ever realized there was a section for tooling.

Edited March 28, 2011 by NightHawkInLight

[Updup]

Very nice shine on that tooling! Do you have any idea on how you are going to add a stand off to it? I'd be interested to hear what you've come up with.

 

Also, the tooling section got added last night, it's new [=

[NightHawkInLight]

Very nice shine on that tooling! Do you have any idea on how you are going to add a stand off to it? I'd be interested to hear what you've come up with.

 

Also, the tooling section got added last night, it's new [=

 

I don't think I'm going to worry about a standoff, at least not for a while. If I were to make one I would just use a short piece of 3/4" dowel core drilled and sunk/glued into the top layer of wood. I'd add a little slope to it with a grinder. I might also consider a chunk of Al or brass rod rather than the dowel.

[Mumbles]

Yep, the section is new, no problems. I've never had to bulk move anything, but it's almost easier than moving a single thread actually. This whole section took me less than 30 minutes to make and populate.

 

The brass sure looks good. Hopefully the tooling works well too.

[WonderBoy]

That looks like a pretty nice and easy way to make spindles NHIL. Recently I've been using SS cap screws. I just cut off the hex head and turn a taper into the smooth shaft. Then you don't have to mess with the threads down the whole rod. Edited March 29, 2011 by WonderBoy

[dagabu]

NHIL, use Mothers polish and you will get it even brighter.

 

http://www.pyrobin.com/files/100_2025.jpg

[NightHawkInLight]

That looks like a pretty nice and easy way to make spindles NHIL. Recently I've been using SS cap screws. I just cut off the hex head and turn a taper into the smooth shaft. Then you don't have to mess with the threads down the whole rod.

I've thought about that also, but there are a number of reasons I decided on the threaded rod. First is because I'm keeping more threads than what they give you on a standard bolt. I also like being able to take the nuts off the spindle side. The last thing is I want the 3/8" threaded section for durability, but I wanted the spindle itself to be much smaller. It's easier to sand down 1/16" of thread than 1/16 of solid brass rod. It would be easier to just use a bolt for someone without a grinder though.

 

That looks great Dag!

[dagabu]

Thanks NHIL, it sure will pop off the spindle if you brighten it up some more. I really like your idea for removal, I am going to try an all aluminum design, can you spare some details?