Open Day Hot Air Engines

One of the reasons of the lack of updates on here was the work on the Stirling engine for my university design module. I had a few problems with getting it to run properly, and ran out of time for tweaking at the end, so decided to fit an electric motor. As well as the main engine, I decided to make a cut away version as shown on the left showing the basic operation of a Stirling engine.

The two models won the £50 cash prize as voted for by the 30 odd other groups on the same course!

The Engineer.

An Apology...

Just thought we'd let you know that we are still here! Both of us have been very busy as of late doing various non fun things! Work, exams and coursework - the usual. We both have one or two interesting things to post up at some stage, it's just finding the time! Still, the intention is for normal service to be resumed in about a months time! But between now and then, we will try and get one or two things posted up here to tide you all over!

In the meantime...

MBI

Bearing Puller

As part of my uni course, we have to complete a two day workshop tutorial, one day on manual machines, the other on CNC machines. The view taken by the uni is to get an 'experience of the people we will manage do', personally, I think it is far more important than that, and that a manager shouldn't be given the job until he has spent a decent amount of time in each section of the works.

Anyway, we had to construct this bearing puller - it's quite a smart little project I feel. The tolerances it had to be made were within +/- 0.5mm - so quite a bit of margin for mistakes there! The main body was made on a big CNC Bridgeport milling machine which was quite a smart piece of kit...could squeeze one into my workshop I am sure! It was a very enjoyable couple of days to spend in a workshop full of old Bridgeport milling machines and old Colchester lathes getting my hands dirty as a distraction from all the mathematics and materials science I'd been doing!

The Engineer.

Mousetrap Car

Some uni work again! Recently, as part of our Mechanics module (Newton's Laws and all that) we were set the task of building a small car powered by a mouse trap to traverse a distance of 5m as fast as possible. Each car was to be built out of 3mm MDF and powered by a spring from a standard mouse trap given to us - everything else was up to us. With CAD software and the laser cutter available, it was decided to take advantage of this, making everything in 3D, assembling it and then laser cutting the wooden components. Little work was actually needed to make the car - cheating I know, but c'est la vie!

Anyway, a 5m track was laid out, with a light sensor at each end, these were connected to a computer and were used for measuring the time taken to traverse the track. A computer program was set up to calculate the minimum time a car should take to run the 5m based on the weight of each car and the engine stored in a control spring...this showed quite a considerable fluctuation in the spring constant of the supposedly identical springs!

Anyway, after this, using various bits of data from the test, and other assumptions made, a set of calculations had to be done to calculate velocities, accelerations and times for the movement of the car. I did these calculations using Excel, with which you are able to produce a rather snazzy spreadsheet where changing one piece of data such as the weight of the car, alters everything!

By the way, after hating Excel for the last 18 years of my life, I have discovered the joy of these snazzy spreadsheets and have introduced The Carpenter to them, who now uses them for calculating information for organ building.

The Engineer.

Bass-ically i finally got back to my own work!

Well its been a hectic past couple of weeks with "proper" workload so I haven't posted much, still today whilst playing my somewhat beaten up semi restored double bass, I decided I needed to get back on with its restoration. So I cut some pine strips to re make the missing (broken off) decorative beading on its edge. I also worked some glue into a body crack to stop further propagation.

I cut some pine to match the body thin enough to bend to the required curve, and glued them into place holding them down with a few dress makers pins, a useful asset for this sort of work. Once thats dry i'll slowly work the it back to a matching bead and it should look nice again!

The bass itself is probably about thirty years old, it was my teachers old school bass and has been through the wars! I recognise it'll never be a Stradivari example but a little work and it should be a charming example showing its war wounds but with an aged dignity.

The Carpenter

Micro Power Generation

With all this eco-waffle you keep hearing about, the term micro-generation pops up quite a lot, but I don't think something quite of this scale is what is meant! Something here we didn't make, but I thought would be interesting to post none the less - it's a 'Ministeam' generating plant manufactured by Lutz Heischler in Germany. I picked this up, missing it's crank pin and piston for £7 at Steam Toys In Action 2013 up in Leicester. I got onto my good friend Phil at Forest Classics who sorted those bits out for me, and while I was at home the other weekend, I assembled it and tried it out. I was pleasantly surprised by it's impressive performance.

The Engineer.

Stirling Engine III

I took the Stirling engine home for the weekend do do a bit of work on it. I planned to make the displacer cylinder and piston, which I got done but also managed to get a few more bits done including assembly of the crankshaft support assembly.

The displacer cylinder was made from an old sump syringe that I cut in half, the base is from an old brass plate I had in the scrap box, I think it looks rather smart, the firebox will be built up under this. The displacer piston is made from some 2" diameter brass tubing I picked up at a car-boot sale. Everything is silver soldered together, which was made far easier by my new larger gas torch which I use to pile heat into the whole component, using my smaller one to focus on the specific area of the job.

The Engineer.

Stirling Engine II

Had a chance today to put all the Solidworks drawings into the laser cutter...and this popped out...

I made the holes in the supports undersized for a tight press fit for the roller bearings I am using.

I am taking it home this weekend to manufacture the displacer and power cylinder, so disassembled it, leaving me with a flat pack hot air engine!

The Engineer.

Stirling Engine

Been quite busy with other things recently, but thought I had better post something, a university project for a change.

Since the start of the course, we have been working on a design for an eco-friendly boat (not by choice...don't get me started on the lack of interesting engineering occurring these days!) and have elected to go for a bio-gas powered Stirling engine as our main power source with waste heat recovery from a thermo-couple. Anyway, we have a presentation day towards the end of the year where we set up a stand, we get marked and visitors from industry come and view our design proposals. It was decided we needed a working Stirling engine on the table!

Here at MBI, we aren't big fans of planning our projects, but with the laser cutter at my disposal, some degree of planning had to be done! I started doing the frame components in Solidworks for putting into the laser cutter - it's not a proper assembly of components, there are no axles or bearings and the cylinders are missing, but as these will be made by hand, I didn't draw them! The assembly was really just to check all the tabs and cut outs lined up correctly.

The Solidworks drawings should be fed into the laser cutter tomorrow, and a kit of parts for a Stirling engine should come out!

The Engineer.

An iMEADiate success?

Ayup chiefs the mead is done!! The good news being it doesn't taste half bad, it's not an overly sophisticated flavor I'll admit, but what can one expect for a bung-it-in-a-jar beginners recipe. It has some depth of flavor to it, you can deffinatly taste the orange that went in, as well as that classic mead taste.

Overal a great success me rekons! Some nice bottle labels and heat shrink caps finished off the job nicely. I think I may make two batches next time!

May your belly be warm and your flagon empty, until next time...

The carpenter.