24 replies to this topic

[dmeader]

First please let me say hi to everyone and thank you all for everything I have learnt from your knowledge on here. I have been in and out of pyro for many years as time is available. I have made very consistant bp of various grades prefected over several years of experimenatation. I used to be interested in model rocketry and would like to ret makng my owm motors.

After being let down with a tool I have decided to take to my lathe and make my own. Could any body help me with any technical dimesions needed plese. I would be looking to make a 12mm one to start and maybe up from there if thats successful. I will need to know my nozzle size and depth and how tall it should be. Does it need any taper on it. I know there is a science to all this but a start point will help. I have read several articles but want to be sure before making swarf.
Thanks Again Dale

[helix]

google "rocket sketcher"

[helix]

(double post)

Edited by helix, 05 December 2011 - 09:56 PM.

[dmeader]

Heard of that bug figgered it was something you need to pay for. Will take a look thanks.

[megabusa]

The free 'Rocket Tool Sketcher' is very good & you can download the exe file (or at least you used to be able to) so you can run it on your own PC.

If you select one of the presets, eg BP core burner & enter your tube ID, the tool will give you a good starting point.

I have only used the 1lb (19mm) & 3lb (25mm) designs from it. I kept the standard presets & they work very well.

One thing I did find was I needed very strong tubes, or to slow down the fuel fractionally.

I mostly now use 1lb rockets with my own tubes that are re-inforced with fibreglass tape during rolling, with a simple 6-3-1 mix.

These absolutely fly out of the launch tube so quickly that even on windy nights they go straight up !

[parabolic]

Heard of that bug figgered it was something you need to pay for. Will take a look thanks.

I also agree that the "rocket sketcher" is a fantastic program, if you want the stand alone exe file, pm your email and I will send you it. if you don't trust me for worry of a virus then you may find the file on the web,

Lee

Edited by parabolic, 06 December 2011 - 12:25 PM.

[dmeader]

What a brilliant little piece of software that is. Think I have everything I need there.
Only one question, I was going to use brass but would aluminium be a better option. I think to start with I will try using hammers made from hard wood until I know I have a tool that works. I can't see this being a problem.

[helix]

The aluminium/ brass question - did that relate to rammers or the spindle?

I've turned the spindles from brass or stainless steel and rammers from aluminium. I'm sure hardwood would be fine to begin with. You may need a long series drill bit to drill out the rammers if you are making a BP spindle.

[dmeader]

Brass or aluminium for the spindle. I'm thinking brass will be stronger and longer lasting. Ally is pretty cheap and easy to work so could make a few quick rammers, and so the project grows.

[Deano 1]

I use brass for the spindle and aluminium for the rammers. I used to use hard wood rammers until I made a press, they were fine with a mallet, but the press crushed them so I had some ali ones made.

[Peret]

Don't forget to turn a boss on the bottom of the spindle to secure it to a base! That part isn't shown by the sketcher tool. I had someone make me a tool without mentioning that it needed a mounting boss, so it came with a flat bottom and I had to drill and tap it to secure it down.

Also, not all stock alloys are made equal. Some aluminium and brass alloys are rather soft, and it's easy to bend the spindle by dropping it or putting the rammer in crooked. If you just buy a rod from a hardware store, you may not know what you're getting (and they may not know what they're selling). Here's a link to some materials information.

[dan100]

saorry for the bump.
how many people have made or use tools made with the rocket sketcher dimensions, i made some endburner tools and they work fine, im wondering if it is worth it making some 1 pound tools using standard dimensions provided, after being flamed on another forum for suggesting that was a good starting point and being told i dont know what im talking about i really dont know what to believe [ the guy does sell tools though so probably explains the attitude]
and if im right wasn't the rocket sketcher made by someone here?

dan.

[megabusa]

I used the standard presets on the tool sketcher for my 1lb core burners & it works fine. It also gives almost the same dimensions as my 3lb tooling, which I first made almost 30 years ago !

Within reason, you can get variations on the dimensions to work, you will just have to adjust your fuel mix accordingly.

I have a brass spindle with Ali rammers. The problem with Ali spindle & rammers is the rammer can sometimes get stuck as the Al binds to itself if the rammer goes too far on to the spindle. Brass or phsophor bronze give a little natural self lubrication.

[Deano 1]

I used the tool sketcher, I put in the tube dimension of the tubes I roled myself ( 17.5mm I.D. ) and it did the rest for me. I haven't got a lathe, but I turned the brass spindle on my pillar drill and I got a friend to turn the ali on his lathe, he was impressed when I gave him the print-out from the tool sketcher.

[dmeader]

I have to say I am totally sold on "Rocket Sketcher", one of the best tools I have come across in a long time. I have ordered the required materials and will hopefully have time over the christmas period to get started. Will post some picks when done. I plan to experiment a bit but what is the prefered method of producing the PB, should I bother with my ball mill or just screen it.