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I did a video of Top Dead Center and was able to reproduce setting with just a rod.
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Happy Friday
Ok,
Balanced prop. I had to add a lot of urethane to this prop as the hub was way out of balance after drilling the holes. The opposite side of the hub also had to be sanded a bit. This is an inexpensive prop so you get what you pay for. Cut the start off attachment off of an old prop washer and checked for ballance. This prop washer was manufactured to use a t shaft type starter but in the clockwise direction. I could not cut a chamfer on the edge to mimic the standard 150 washer because I could not hold onto the piece on the lathe without the correct vice. Assembled the prop and torqued. ( Check torque specs from DA Manual posted previously). Now I have to figure a way to anchor the stand in the garage because it is cold and have snow in the yard. I will start in the garage as soon as I figure a safe way to do it. My shop is messy, I have to clean it. |
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An easier way to gain weight on the hib of you prop is to use sticky back fuzzy side velcro. Usually a 1" sq will do wonders. Any hub imbalance can be rectified by applying medium CyA to the velcro, then spraying some accelerator on the super glue. Then, depending on how your test stand is built, cinder blocks make great ballast. |
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Thanks for the input!!!!! |
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Merry Christmas and Happy Hanukkah
Started the engine this morning. The initial start is very good. The temperatures unlike engine 1 are equal in both cylinders. It is to be seen if the temperature stays the same when at full throttle. The engine seems to have less vibration and is smoother.
The idle had to be re-set because the temperature is so cold and as the engine heats up I had to adjust the low needle setting . The engine would not repeat low idle until it wormed up to 75C. The air cooling baffle mounted on the test stand was removed to get less air across the cylinders. I will get a video going as soon as I can. Got to 5200 RPM with room to go. I have to run a couple of tanks at 3000 Rpm before opening her up. I added ballast to the leg of the frame and the frame still wanted to move on the concrete. I am not thrilled running the engine in the garage. A hole bunch of leaves were sucked into the garage with the door open, Man this engine moves some air!!! Have a safe Christmas and a healthy New Year!!! |
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Update
Hi all.
Last few months have been difficult in that I have been dealing with poor health. As in all things, life happens. This plus the cold has slowed down my work to finish this project. Our RC Brother GHoffman , who is probably the most knowledgeable engineer I know, and a good friend, shared this thread with me to keep me company during my convalescence. As I have said to him, "I have way to much time on my hands". His reply was to send me a primmer on two stoke engines. I would like to pay it forward and share it with you. Although technical, it is written with the layman in mind. This pamphlet contains everything we have been talking about. If you look at this article and carry out some of the calculations, you will see that DA has engineered a very reliable engine. It also goes into tuned pipes and how they work and every aspect of 2 stroke engines. http://www.2strokeengine.net/gordonj...rshandbook.php Thank you Brother Hoffman |
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Funny story: Dr Gordon Jennings who wrote that was my hero. One day I found a bunch of his papers in the college library and brought some back to the dorm. I went in to tell my friend and they were parting (and I was sober at that time) so they all thought it was hysterically funny and from then on my nickname was “Gordon”.
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Incidence Meter
Today, I found an incidence meter app , and downloaded it to my phone. I fabricated a small clip and attached it to the engine hub and a camera tri-pod fixture to attach the camera, This app can be used for both wing incidence as well as engine timing application. I posted the app address and 3d printed wing incidence fixture on Tom Wheeler and Ronald Wlosinskis Kap-Aero build thread. Please visit this thread as these two guys have some serious talent. Attached is the STL file to do the 3D print of the phone holding fixture. The author requested this be used for personal and not commercial sue only.
Please be aware that the phone mounting clip is only an example. It is only intended as a quick method to test the inclinometer app on the engine hub. http://rcsoaringpictures.free.fr/3D_...denceMeter.zip https://play.google.com/store/apps/d...inometer&hl=fr |
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DA150 Disassembly Procedure
Hi All.
It has been a while since I have done any work on the 150's. 2020 was quite the year. I am sure we would all like a do-over I never did get to tune the engines properly, I got a little frustrated and I kind of lost interest. As soon as spring hits, I will get back on it but in another thread looking at just the carburetor and the fuel air mixture. Looking back on my work, my engines never achieved the correct running temperature . 85 C is not hot, which leads me to believe I was too rich Last week I looked at this thread and made a few changes in some posts that were not clear. Among these changes is the disassembly procedure. I think a couple of things must be clarified. DA150 DISASSEMBLY PROCEDURE Using an old prop or a prop drill jig, drill prop bolt holes into a bar 12:x2"x 3/16 " thick. . Drill at least a 5/8" hole in the middle of the bolt holes to allow a socket to be used to take off the prop spindle. The bar has two functions:1 is to allow leverage against the socket wrench for removing and assembling the spindle, 2, it is used to provide a counter force when removing the hub. Drill the holes far enough from the edge of the bar to give you enough space to use an edge as a leverage point; Screw the bar onto the prop hub Using a wrench and socket, remove the prop spindle. Place the engine into the press resting the attached bar across two members. You will need a press that has at least 14 inches of height clearance. Apply heat evenly using a torch to the prop hub and expand the aluminum. Hub should release with minimal force- do not loose the key or dowel Screw two bars into the top piston heads mounting holes and level engine across two members Attach hollow nut or pipe on top of the shaft to use as a sacrifice. Avoid pushing on threads as much as possible. Apply heat to the case body evenly. and quickly . You do not need to measure the crank case temperature . Instead, while heating, slowly rock the press lever applying and removing pressure. When the loc-tite melts, the shaft will release easily. You do not need tons of force. use heat expansion to help out. Remove the bottom of the shaft by placing a bar in between the counter-weights. Straddle the bar onto two members. Use two 8 inch bolts or bars and a plate to put pressure on the lower crank case. Heat the bottom crank case and push it out. The bottom bearing needs to be removed with a blind hole bearing puller. Apply the blind hole puller to the bearing expanding the puller jaws with its mandrel. Attach a slide hammer to the mandrel. I used a threaded rod and a pipe. Turn the bottom of the crank case upside down onto two wooden members. Heat the bottom case with a torch and using the slide hammer pull out the bearing. Remove the top bearing by placing bearing edges across two members. Use sacrifice nut on top of the shaft and press bearing out. The intermediate bearing is harder to press out. Normally one would use a two component bearing puller to get underneath the bearing. Remove the dust/shield bearing cover and place the bearing edges onto members. Place force on the crank shaft, and heat the inside of the bearing. The bearing presses out when the loc-tite melts Do not overheat!!. Do not heat the shaft, het the bearing. The top and intermediate bearing have the same inside diameter so you have to press out the intermediate bearing past the top bearing journal. Use care not to damage or bend crank arms while pressing out bearings Pictures can be found in posts:13,18,43 and 64. There were two engines. Well, that is all for now. Thank you all |
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I have found no heat is needed at all. With a puller, the hub will come off pretty easy. If it feels a little stubborn, you could talk the puller screws with a small hammer but I have never needed to to that.
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Heat will affect grain structure of polarized materials , depending upon grain density structure the gauss level will diminish There are small digital gauss meters on the market that are affordable if one doubts the gauss levels Had a new 3W strait out of the box with issues , when all was said and done it was the gauss level of the trigger magnet to be the issue , gauss levels were significantly different from the new hub to another new hub The G man didnt want to hear about this untill I showed the data , this was a first for him As we know .... any thing is possible when an engine is not happy |
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United States, OH, Berlin Heights
Joined Jul 2006
5,961 Posts
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Pullers do work no matter how hard the hub is to come off.Even on tapered shafts they still come off, with a pop sometimes.Only place I use heat is on cases during bearing install,they just drop in no worry about alignment.
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Hub Removal No Heat
I appreciate the concern from the response on hub removal. and I agree with you all that heat is not necessary.
Therefore , I consulted with higher powers, Brother Hoffman that is, and we came up with this process for removal. I was over thinking that I would need a pulling device of some kind until I was shown the light . This is why this forum is fantastic. I removed the spindle, and attached a old prop drill jig upside down, and screwed it into the hub. The nub that guides normally into a prop, is now used for pushing against the crank shaft tip. Tighten the screws and the hub comes off. Man...you have no idea how good it is to have this dummy engine to work on. Thank you all for helping out!!! |
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