Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[Martin (Admin)]

 
That's some update!

Thanks Alex, a good read.   

[IKB]

Hi Guys,


Quick update, designed up a new sturdier mounting which consolidates the gearbox with the motor mounting plate, eliminating the requirement for standoffs and seems much more appropriate for a unit producing 5Hp 

More updates as they happy


Alex

[hopeitfloats]

any build progress on the latest design

[IKB]

Hi Hopeitfloats,


There is indeed and I had completely forgotten to post anything, I printed the new motor mount and tested it on the lake back on 18/10/18, it works really well, the new mount holds the motor solid as a rock, which gives the drive a very smooth operation now and that brings this part of the build to a bit of a conclusion


But worry not, the jetdrive will return in a new guise, I do have some plans for a fully 3D printed hull with twin integral drive units, there is also the small matter of the pneumatically actuated KaMeWa style reversing buckets to finish, unfortunately this all takes time and parts cost money, both of which are in very short supply at the moment, as I have sold my house and in the process of packing my life away into boxes ready for the hopefully imminent move to the new house, which has, among other things, a very nice brick built workshop 
This does however mean that my current ShedShop is also in the process of being packed away, so I am limited to smaller, more portable projects, so I have gone back to my Arduino programming and picked up a project I started a while ago, that being a fully self contained AUX RC system for my models, this will work alongside my normal transmitters, but gives a degree of customisation and expandability that you just can't get anywhere else


Alex

[hopeitfloats]

that's one very neat motor mount

[IKB]

Hi Hopeitfloats,


Thanks, I am very pleased with how the mount turned out, it is rock solid and building in allen key holes makes it all the more user friendly


Alex

[IKB]

Hi Everyone,


Just a quick update, a lot has happened this year already, I finally moved into a new house with my partner and our dog, after being in the house for a couple of months, I was just about at the point where I could restart project work, (like the jet drive) when at the beginning of the month, the company I have spent the last nine years at went into administration, so currently focusing on finding another job
But fear not, I have plans for more jet boat adventures, just might take longer for them to hit the lake than last time! 

Hope you are all well and enjoying the sunshine at your respective lakes when it does appear

Alex

[hopeitfloats]

sorry to hear about your job loss alex. been in the same position myself. its not nice but hope all works out well and you can get back on to your build.

[IKB]

Hi Hopeitfloats,


Thanks for the message, hopefully it will all sort itself out sooner rather than later


Alex

[IKB]

Hi Everyone,


Quick update and this time progress has been made! 


This time I have been continuing the development of the pneumatic system that powers the reversing bucket, the latest hurdle to overcome was just how to regulate the amount of air generated when demand was at zero, as the system can only store so much and after 30 Psi, all of the Lego pipe connections are prone to failure, so ideally some sort of pressure relief valve would be used to enable the compressor to run continuously at a low speed
One solution would be to use an electronic pressure sensor and something like an Arduino to turn the compressor on and off, but after an initial scout around the internet for a suitable sensor, I gave it up as a project within a project too much and decided to go for something a little more old school, namely a Mammod style pressure relief valve mounted in a custom Brass housing I made at work one lunch time
The valve is easily adjusted and initial testing shows good results


Alex

[martno1fan]

Great work but a bit of advice as regards the hull design , it needs chine rails(where the sides meet the actual ride surface this will do two things first it will allow the boat to run more stable to keep straight and to also turn better it will also and this is important stop water riding up the sides of the boat as its doing on yours which is causing massive drag and soaking everything above deck as in the video .

[IKB]

Hi martno1fan,


The hull is very much a compromise I agree and the bow section was added to help streamline the airboat style hull, when this mod was made I added spray rails to the sides of the hull, which helped quite a bit


I completely with your assessment and the new hull, when I get around to building it, will have proper shape, chine rails etc


Alex 

[IKB]

Hi Everyone,


Well, amidst all of the craziness that is going on in the world at the moment some good has to come of it, I am fortunate enough to be able to work from home, this means no commute, which means extra potential for ShedShop time! Let's make some progress 


So I have decided to continue working on the pneumatic system for the KeMeWa style reversing system, I can make pressure, the reversers can use it, there is pressure relief, the only thing I don't have is some way of remotely actuating the system from the handset.
A while back I was pondering the problem and came across the following solution by a guy on YouTube called: Ivan Krajča, his video can be seen here:https://youtu.be/7xTvVCuuXMc It is a really nice simple design which I have now made my own version of, the first attempt has proven that the geometry works well, but the interface between the servo and the valve needs some refinement, I have animated the CAD so you can see how the issue of the servo having a much wider throw than the valve is over come: https://youtu.be/V-lYxRJNIKU

Alex

[derekwarner]

Alex.......if you find the semi oscillating valve faces difficult to maintain and or loose pressure, the radio controlled model truck [1/12 scale?] fraternity use an extensive variety of pneumatic cylinders, motors....and spool valves ...the later being R/C controlled


The spool valve sealing [leak free] characteristics have natural advantages


Derek

[C-3PO]

Hi Alex,

Good to see you have been able to pick this project back up - I have followed your posts and fascinated by the whole project.

I look on from the sidelines with admiration at your exploits with 3D printing and pneumatics.

Look forward to your future updates

C-3PO
 

[warspite]

Hi,
 I read with interest that you wanted to control the compressor to the tanks, i.e. when it got to 30 PSi it would switch to running the compressor at a non load until it was needed again.


Maybe I am a little puzzled at this as I don't have experience at controlling compressors, does switching the power off do the same, i.e. if the tanks are empty and the compressor starts up, it will fill past the 'minimum required to operate' point and then on to the full point, if the power switches off, does the tank remain full until it is used and it gets to the 'minimum required to operate' point again and the compressor power comes on filling up the tanks again and so on, assuming that there is a one way valve to prevent leakage back through the compressor.


I was thinking would something like the item shown in the link help, as the pressure in the device passes a point it clicks, two would be needed, one for the upper pressure limit and one for the lower limit, though on reflection there is only one of these needed if as shown, the pressure is attained and the switch activates, the compressors power goes off, when the pressure drops the switch starts again and the compressor kicks in, it's finding a way to keep the power off until the lower level is reached, or does that matter, does the amount of air used drop the pressure below a set amount that the compressor would have to come on again anyway, i.e. 1 or 2 amounts of compressed air is stored in the tanks.


https://www.justfans.co.uk/differential-pressure-switch-300-ip54-p-1263.html?gclid=CjwKCAjwhOD0BRAQEiwAK7JHmL3c0Dt3mjd3Ew-cMrdTHi2fkrxmtj9ZWY5hAZG4oU1Hjh9y_oFkiRoCPFAQAvD_BwE

[IKB]

Hi Everyone,


Thanks for the recent comments, it is great to be back and making some progress again, answers to your questions below:

• Derek - Good suggestion, but for the time being I have not found the valve leaking to be an issue
• C-3PO - Thanks, always good to have you along
• Warsprite - I get where you are going with your explanation, I considered some form of electronic sensing / control a while back and decided that it was more of a project within a project than I wanted to do at that point, hence why I went with the option to have the compressor running slowly, but continuously, the system pressure is then regulated using a re-purposed Mamod safety valve

Hope to have more updates soon


Alex

[IKB]

Hi Everyone,
Quick update, so I have tweaked the design of the 3D Printed parts and reassembled the unit, it is still not perfect, but hey, when is anything we make?

Little video of it actuating the reversing mechanism on my jet boat: https://youtu.be/-_pZTagLMc8
Alex 

[IKB]

Hi Everyone,


Going through some old videos and came across the film I made from the last jet boat run on 05/08/18!    Arguably the most successful run to date, 12S @ 5HP, enjoy!


https://youtu.be/v3LzNfdkx-Y


Alex