Here is a list of all the postings Four stroke Fred has made in our forums. Click on a thread name to jump to the thread.
Thread: Mc Donald Model tractor |
12/05/2022 01:02:47 |
Usually winter in Australia in our area brings a large high in the weather pattern and this results in stable weather, blue sky and it is relatively dry but not this year. Queensland has had rain and more rain and this means the out door foundry can not be used and we have to wait for the next dry spell. Over the last couple of weeks I have been modifying both the pattern and core boxes for the engine. There was not a great deal to be done on the pattern as that works quite well but I did enlarge the water outlet on the top of the cylinder to give a smoother flow to the thermo siphon cooling system. The core box has been refined to give more metal when machining the bore and thus reducing the water passage volume. The original core box was in four parts but I have now decided to make it in six parts to ease the withdraw of the sand core. The 3D printer is now working over time as each of the six parts takes approximately 9 hours to make. Having now received advice and having consulted doctor goggle I realise that there is more than just make a runner and pour in the molten metal into the flask. I will give this area and the venting much more consideration and take care to 3D print the correct shape and size of runners, risers and vents. Being an amateur in the field of foundry work and trying to produce a difficult casting means that there is a very steep learning curve but this is a self inflicted problem that presents a challenge and that is just one of the joys of our hobby. Fred |
23/04/2022 09:31:47 |
Thanks to Jon,Pat,Roger and Diogenes for your comments and pleased to hear that you enjoy reading the progress on this project. I have been working on this model tractor for the past 3 years - time flys by quickly when your having fun and it’s good to share opinions and comments with like minded friends. When one visits an exhibition you see the finished models but it doesn’t show the effort and time that has been used to create them. This thread has been a record of both success and failures and even now I am not sure what the outcome will be! The runner height could have been lower. The speed of the pour could have slower. The temperature of the melt may have been to high. The last casting is usable but the school report would have read “ could do better” and with this in mind I may have another attempt. If at first you don’t succeed you just keep trying! Fred.
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22/04/2022 10:15:22 |
Today we cast another crankcase- still not perfect but I will have to wait until tomorrow to see if the inside of the water passage is o.k. I have machined datum faces to keep things square but still have to bore out the cylinder and top of the cylinder barrel which will reveal the water passage. Photo shows “ as cast” but the casting has now been cleaned up and partially machined. Fred |
19/04/2022 08:48:04 |
Fred. |
16/04/2022 09:54:26 |
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09/04/2022 07:42:45 |
Sorry about the double up Fred. |
09/04/2022 07:42:07 |
Over the last week I have spent time on redesigning the crankcase patterns and core boxes. One the the unforeseen problems is the alignment of various parts of the model when the dummy engine was placed in position. For example on the full size tractor it is very difficult to measure parts like the engine length and the front mountings as there is no straight line due other bits being in the way! It isn’t until a “ dummy engine” has been made that these discrepancies manifest themselves and have to be corrected. It’s all about that never ending learning curve! I have decided to make the second crankcase pattern in 8 parts and use a chemically bound sand for each part. The 3D printer will be working overtime as all 8 pattern parts will take in excess of 67 hours to produce but that does leave me time to design and make the special casting boxes and to sort out that part of the process. With the last tractor ( Saunderson &Mills) I made it took 8 weeks to perfect the casting of the cylinders and that did not include pattern and core box making. This tractor seems to be following the same path but the end is just around a very long corner. It’s a case of you made the problem you solve it! Fred. |
09/04/2022 07:40:30 |
Over the last week I have spent time on redesigning the crankcase patterns and core boxes. One the the unforeseen problems is the alignment of various parts of the model when the dummy engine was placed in position. For example on the full size tractor it is very difficult to measure parts like the engine length and the front mountings as there is no straight line due other bits being in the way! It isn’t until a “ dummy engine” has been made that these discrepancies manifest themselves and have to be corrected. It’s all about that never ending learning curve! I have decided to make the second crankcase pattern in 8 parts and use a chemically bound sand for each part. The 3D printer will be working overtime as all 8 pattern parts will take in excess of 67 hours to produce but that does leave me time to design and make the special casting boxes and to sort out that part of the process. With the last tractor ( Saunderson &Mills) I made it took 8 weeks to perfect the casting of the cylinders and that did not include pattern and core box making. This tractor seems to be following the same path but the end is just around a very long corner. It’s a case of you made the problem you solve it! Fred. |
Thread: Sugden Special Castings |
25/03/2022 00:31:37 |
Hi Nicholas, Twelve years is a long time to wait! Did you locate a casting and have you made the engine yet? |
Thread: Mc Donald Model tractor |
24/03/2022 22:08:11 |
Thanks for the comments from those who are following the progress on this model and good to hear that you are making a Diesel engine Roger ( what is it?) They do present a real challenge but that’s what makes life interesting. The Mc Donald did not use a cartridge type start. The flywheel has a retractable sprung loaded handle and the engine is “ rocked” until it bounces of compression and fires up. I hope the model will do the same but I expect there will be teething problems and I will just have to try to solve them one at a time. Fred |
Thread: Sugden Special Castings |
24/03/2022 21:28:20 |
Good Day Bill, I have an original casting for the Sugden Special that I have had in store for at least fifty years and would be willing to part with it! I had intended to make it but at that time I had neither the skills or equipment and yes I live in Australia. Fred. |
Thread: Mc Donald Model tractor |
24/03/2022 06:10:59 |
Fred. |
24/03/2022 05:43:43 |
Fred. |
15/03/2022 20:38:17 |
Good Day Roger Fred |
15/03/2022 08:19:29 |
These are the 3D drawings of the cylinder head with the injector on the top and the hot bulb on the under side. The top photo shows the hot bulb and special peg spanned and the lower part of the combustion chamber all made from steel.I may need to experiment with more hot tubes of various thicknesses and lengths but will have to wait until the rest of the engine is made to test what will actually work. The match box gives some idea of scale. The next stage is to make 3D patterns for the main part of the head and then cast them in aluminium. Fred |
15/03/2022 08:08:44 |
12/03/2022 09:12:10 |
Thanks for your comments. After all this time and effort there is no guarantee that it’s going to work but it’s good fun trying and a great learning process. Fred. |
12/03/2022 07:09:34 |
This is the injector pump with the cover removed to show what is happening inside. The brass fittings are one way valves that allow fuel in from the tank and then pumped out to the injector nozzle. As the cylinder is almost horizontal gravity is used to seat the ball valves with small 12 BA pins used to prevent them from “ jumping” to far off the seat similar to the check valves used on model steam locomotives.The handle on the right controls the amount of fuel being pumped to the injector and is connected by levers to the drivers end of the tractor. The knurled part holds an “O” ring in place to help form a seal between the 1/8” piston and cast iron cylinder. I now have to start to think about the cylinder head and that will be a really interesting part to design and make but that for next week! Fred.
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07/03/2022 01:19:08 |
Fred. |
18/02/2022 07:49:09 |
The photographs show progress on the governor. I still have to add the spring adjusters and test to see what speed the cast iron weights throw out to the outer limits. The eccentric is made from bronze and will have a steel eccentric sleeve/ rod when it is made. Having studied the injector pump arrangements on the Lanz I now understand how it works - the outer eccentric gives the pump stroke and the inner concentric one gives the advance/ retard but I have made mine as shown on one of the sets of drawings for the Mc Donald. If I find after test this does not work I will have to change the design. The reason for choosing this is because there is very little room for two eccentrics and there are less parts to make! The next part to make is the injector pump. Fred.
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