britishrocket's bipropellant GOX/ethanol thread

[Johansson]

Looking good!

[britishrocket]

Thanks Anders!

Here are some more photographs of the progress of this tool so far:-

I decided against welding the parts together. Instead I used two part epoxy. Before I bonded the parts, I drilled the three 120 deg spaced M5 clearance holes to fit the mounting to the rotary table:-








The next thing to do was to bond the parts, which I did using two part epoxy. I left the parts clamp in the milling vice for 18 hours. Not really required, but I was a bit paranoid about it all!








After the epoxy cured I milled the access slot for the coupling. Here is the mounting trial fitted to the table. You can see the coupling peeking through it's window:-

[britishrocket]

Mechanically, the rotary table project is near enough complete now. All that remains is to make a small hand wheel for the rear shaft on the stepper. This will enable manual operation of the table if required.

I drilled the four holes in the square portion to mount the stepper. I made these M5 clearance in the end. I wasn't keen on tapping into aluminium, and I used M5 screws with nyloc nuts and washers to secure the motor.

Here is a photograph of the motor as fitted:-








At this point I made a full test of all the functions, moving the table under power. The system worked perfectly. Here is another photograph of the completed mounting attached to the table. Two of the 3 M5 fixing screws can be seen just behind the coupling, and the 4 M5's to secure the motor are in the foreground:-









I have ruggedised the stepper motor flying leads with 6mm expanding braid sleeving. I secured this at each end with adhesive impregnated heat shrink. I'm not sure yet if this is the best solution, and I may alter it in the near future. I will most likely opt for a small junction box on the motor with a sheathed cable exiting this. At any rate, the present arrangement will be fine for now. I terminated the stepper leads with a locking connector. This will prevent the stepper being inadvertently disconnected whilst being driven.

Here is a photograph of the rotary table with motor and ruggedised leads:-









And here is a shot of the connector with it's threaded locking sleeve:-










The fifth pin on this connector is not used. I am now working on building the control and drive electronics into a die cast box. In order to do this, I am having to make a few minor modifications to the LCD/keypad and stepper drive boards. Principally this involves making them a bit more low profile. The LCD/keypad board will need to have the contrast preset potentiometer moved from the front to the back of the board. There are also one or two headers that are in the way and can be removed. These are normally used for accessing other Arduino I/O pins. As this is a production device, they won't be needed. With regard to the stepper driver board, I am going to remove a couple of capacitors and add lead extensions to them so that they can lie flat. I'm also going to remove the screw terminals for the control inputs and stepper drive outputs, and solder these leads directly to the board. This saves about 9-10mm in height, which may not sound much, but will make all the difference in fitting the unit into the case.

The minimum number of push buttons for the front panel would be five. These being UP/DOWN, LEFT/RIGHT and SELECT. I did a few trial panel layouts and they all looked rather cluttered. You all know that I like the odd recycled component or two. Searching through my stock of useful parts, I found some spring return to centre SPDT switches. So I can use one each of these for UP/DOWN LEFT/RIGHT and one push button for select.


Here is a photograph of one of these switches:-

[britishrocket]

Mechanically, the rotary table project is near enough complete now. All that remains is to make a small hand wheel for the rear shaft on the stepper. This will enable manual operation of the table if required.

I drilled the four holes in the square portion to mount the stepper. I made these M5 clearance in the end. I wasn't keen on tapping into aluminium, and I used M5 screws with nyloc nuts and washers to secure the motor.

Here is a photograph of the motor as fitted:-








At this point I made a full test of all the functions, moving the table under power. The system worked perfectly. Here is another photograph of the completed mounting attached to the table. Two of the 3 M5 fixing screws can be seen just behind the coupling, and the 4 M5's to secure the motor are in the foreground:-









I have ruggedised the stepper motor flying leads with 6mm expanding braid sleeving. I secured this at each end with adhesive impregnated heat shrink. I'm not sure yet if this is the best solution, and I may alter it in the near future. I will most likely opt for a small junction box on the motor with a sheathed cable exiting this. At any rate, the present arrangement will be fine for now. I terminated the stepper leads with a locking connector. This will prevent the stepper being inadvertently disconnected whilst being driven.

Here is a photograph of the rotary table with motor and ruggedised leads:-









And here is a shot of the connector with it's threaded locking sleeve:-










The fifth pin on this connector is not used. I am now working on building the control and drive electronics into a die cast box. In order to do this, I am having to make a few minor modifications to the LCD/keypad and stepper drive boards. Principally this involves making them a bit more low profile. The LCD/keypad board will need to have the contrast preset potentiometer moved from the front to the back of the board. There are also one or two headers that are in the way and can be removed. These are normally used for accessing other Arduino I/O pins. As this is a production device, they won't be needed. With regard to the stepper driver board, I am going to remove a couple of capacitors and add lead extensions to them so that they can lie flat. I'm also going to remove the screw terminals for the control inputs and stepper drive outputs, and solder these leads directly to the board. This saves about 9-10mm in height, which may not sound much, but will make all the difference in fitting the unit into the case.

The minimum number of push buttons for the front panel would be five. These being UP/DOWN, LEFT/RIGHT and SELECT. I did a few trial panel layouts and they all looked rather cluttered. You all know that I like the odd recycled component or two. Searching through my stock of useful parts, I found some spring return to centre SPDT switches. So I can use one each of these for UP/DOWN LEFT/RIGHT and one push button for select.


Here is a photograph of one of these switches:-

[britishrocket]

I am back in the UK, and I have lately completed the automated rotary table. As mentioned in the last post, the electronics were made more compact by stacking the boards together.

The boards and power supply were then mounted on the front panel of the die cast box, not before the rectangular holes for the LCD and two menu scroll switches had been milled out.

The stepper drive socket was fitted to the side of the box. The mains lead enters via a strain relief gland.

Once completed, the box was connected to the stepper on the rotary table. A full functional check was successfully carried out. Here are some photographs depicting the stack up of the boards, the internal arrangement of the power supply and electronics, and the completed system in it's entirety.

















Now that this tool is complete, attention can again be turned to the development of the tube bundle chamber concept. The material for this has been ordered, so look out for more updates.

[britishrocket]

Greetings All,

Been a while since I've posted here, but I now have the metal to make a start on the tube bundle thrust chamber concept. I have obtained a cutting stand for my 4 1/2" angle grinder and I'm building this up to form a jig to cut the tubes to accurate length.

I will get around to posting some photos here in the next few days, in the meantime if you'd like an update please visit my blog at britishreactionresearch.blogspot.co.uk

Thanks!

[Richard OConnell]

Welcome back! I look forward to seeing what you've been up to

[britishrocket]

Thank you Richard,

At the moment I have a lot of ideas but very little substantial to show for it. I tend to find that a large amount of theoretical and practical research has to be done to give a small step forward.

It is not so much the hard work that is tiring, more the constantly reaching for the thing that seems perpetually just out of one's grasp.

[britishrocket]

Happy New Year to everyone...

Currently still tooling up to attempt the tube bundle design. New blog post, please check it out.

All the best,

Carl.

[britishrocket]

It has been a while...the aluminium tube bundle engine is happening. Stay tuned for further details.

[britishrocket]

New post on my blog regarding the heat treatment of aluminium weldments. This is pivotal to the development of the aluminium engine. You can read it at:-

www.britishreactionresearch.blogspot.co.uk

Cheers,

Carl.

[britishrocket]

Tested the pottery kiln that I intend to use to heat treat aluminium. Measuring the temperature inside with a thermocouple, it took about 30 minutes to stabilise at 530 degree C.

Will post in more detail on the blog once I get chance.

Carl.

[britishrocket]

It's been a while. Just want to wish all who post here a Merry Christmas and Happy New Year.

More here and on the blog next year.

Carl.

[britishrocket]

Nozzle emerging from a piece of 6082 T6 bar in the Harrison.

[racket]

Good to see the project is still progressing :-)