Repair bent or twisted crankshaft. DA 150
11-26-2014, 09:27 AM
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I straightened crankshafts from smaller engines like the Zenoah 20cc, 38cc and a MVVS 26cc gas. I did not open any of them. If the crankshafts are not bent too strong, you can go the same way.
Instead of the prop, you mount an absolutely flat steel-or aluminium plate. Remove the spark and mount the engine to some kind of test stand. Then put some measuring-clock to your plate. Logically, your measuring results will be more precise, the bigger your radius from center of your engine becomes.
Start turning the plate slowly and watch the clock. Don`t damage your device, if the clock can not show more than one or two millimeters of moving !!!
The image shows the repair of one of my two Zenoah 20cc. The clock was a type, showing one millimeter in a hundred parts. As you see, the radius don`t need to be huge to receive precise results. In this example, I had about 80mm.
Well, I remember, I grabbed the plate with my two hands and put the shaft in shape again. I think, it was bent about something less than one millimeter. This should be the limit at a radius of 80mm !!!
I was able to reach about one or two hundreds of a millimeter. Keep in mind, that the crankshaft is running in ball-bearings. According to this fact, don`t try to reach the zero-point. You can only become crazy, trying the mission impossible. And the material of your crankshaft will thank you, not to be bent twenty times even to the other side. It had enough stress from our crashes or somrthing.
In my case, my machine met the model of my own club-buddy, flying in front of public, finishing a small french event in May 2009. That f....... audience gave us a big applause...... but that`s another story.......
My 20cc was sent to Toni Clark first. I bought it there in 2008. Toni`s companion Gerhard Reinsch called me back late in the evening to tell me about the damages and the repair costs. They would have been 10 euros less than the price for a new engine. The main reason for this, was the ignition box. It has kinda dome, which the cable is screwed onto. The dome was broken off completely from the box, nothing left.....
So I wanted the engine back, the way it was.
And this engine is still running. And it is the engine, that has more hours than any other of mines. Of course, I had to buy a new ignition. But this was by far cheaper, than a new engine.
In case of your DA 150, you need a bigger plate. But you will realize, you are able to bring this shaft in shape!!
If you first testrun your DA, have a close look at the running at idle speed. Can you bring it down to the rpms you had before the damage???
If not, or if the idle is not really stable, your front bearing could have suffered too much from the damage. Possibly, It can still do its work for years. But it could be a pressure-leak now, such as the first generation cylinder gaskets from DA85 or 170.......
I compared my fixed engine to an absolutely new one by mounting the same prop to them and measuring the movement of the prop-tips. To my surprise, I had less movement with my fixed engine.
Also make sure, that the crankshaft is not turned in itself, as it can occur hitting the ground with a two or more cylinder engine. Of course, I don`t talk about dead stick hittings. There you have almost no risk, turning the shaft in itself.
If you are able to change the front bearing yourself, don`t be afraid of replacing all the gaskets by a high-temperature silicone. If you don`t want to replace the cylinder gasket, fearing a too high compression or changing the timing of your DA, make an aluminium-dummy and mount it with silicone.
Pics show a DLA58
If you want to do the same, start with the rear half of the crankcase!!
Mount all parts such as the isolator, reed-block, carb eventually venturi to it. Be aware that the two bolts are not screwed to far inside the case, otherwise you will block the shaft with them or scratch it.
Give this unit some minutes to dry and look inside. If there was too much silicone moving inside, that could prevent the reeds from working freely. Just pull it out with ease.
Use a type of silicone, not damaged by fuels or acids. Most of them stand temperatures of 250°C currently and 300°C short times. Really enough for our purposes.
I hope, I could help you, wish you safe flights!!
Pedro
Instead of the prop, you mount an absolutely flat steel-or aluminium plate. Remove the spark and mount the engine to some kind of test stand. Then put some measuring-clock to your plate. Logically, your measuring results will be more precise, the bigger your radius from center of your engine becomes.
Start turning the plate slowly and watch the clock. Don`t damage your device, if the clock can not show more than one or two millimeters of moving !!!
The image shows the repair of one of my two Zenoah 20cc. The clock was a type, showing one millimeter in a hundred parts. As you see, the radius don`t need to be huge to receive precise results. In this example, I had about 80mm.
Well, I remember, I grabbed the plate with my two hands and put the shaft in shape again. I think, it was bent about something less than one millimeter. This should be the limit at a radius of 80mm !!!
I was able to reach about one or two hundreds of a millimeter. Keep in mind, that the crankshaft is running in ball-bearings. According to this fact, don`t try to reach the zero-point. You can only become crazy, trying the mission impossible. And the material of your crankshaft will thank you, not to be bent twenty times even to the other side. It had enough stress from our crashes or somrthing.
In my case, my machine met the model of my own club-buddy, flying in front of public, finishing a small french event in May 2009. That f....... audience gave us a big applause...... but that`s another story.......
My 20cc was sent to Toni Clark first. I bought it there in 2008. Toni`s companion Gerhard Reinsch called me back late in the evening to tell me about the damages and the repair costs. They would have been 10 euros less than the price for a new engine. The main reason for this, was the ignition box. It has kinda dome, which the cable is screwed onto. The dome was broken off completely from the box, nothing left.....
So I wanted the engine back, the way it was.
And this engine is still running. And it is the engine, that has more hours than any other of mines. Of course, I had to buy a new ignition. But this was by far cheaper, than a new engine.
In case of your DA 150, you need a bigger plate. But you will realize, you are able to bring this shaft in shape!!
If you first testrun your DA, have a close look at the running at idle speed. Can you bring it down to the rpms you had before the damage???
If not, or if the idle is not really stable, your front bearing could have suffered too much from the damage. Possibly, It can still do its work for years. But it could be a pressure-leak now, such as the first generation cylinder gaskets from DA85 or 170.......
I compared my fixed engine to an absolutely new one by mounting the same prop to them and measuring the movement of the prop-tips. To my surprise, I had less movement with my fixed engine.
Also make sure, that the crankshaft is not turned in itself, as it can occur hitting the ground with a two or more cylinder engine. Of course, I don`t talk about dead stick hittings. There you have almost no risk, turning the shaft in itself.
If you are able to change the front bearing yourself, don`t be afraid of replacing all the gaskets by a high-temperature silicone. If you don`t want to replace the cylinder gasket, fearing a too high compression or changing the timing of your DA, make an aluminium-dummy and mount it with silicone.
Pics show a DLA58
If you want to do the same, start with the rear half of the crankcase!!
Mount all parts such as the isolator, reed-block, carb eventually venturi to it. Be aware that the two bolts are not screwed to far inside the case, otherwise you will block the shaft with them or scratch it.
Give this unit some minutes to dry and look inside. If there was too much silicone moving inside, that could prevent the reeds from working freely. Just pull it out with ease.
Use a type of silicone, not damaged by fuels or acids. Most of them stand temperatures of 250°C currently and 300°C short times. Really enough for our purposes.
I hope, I could help you, wish you safe flights!!
Pedro
11-26-2014, 09:34 AM
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I straightened crankshafts from smaller engines like the Zenoah 20cc, 38cc and a MVVS 26cc gas. I did not open any of them. If the crankshafts are not bent too strong, you can go the same way.
Instead of the prop, you mount an absolutely flat steel-or aluminium plate. Remove the spark and mount the engine to some kind of test stand. Then put some measuring-clock to your plate. Logically, your measuring results will be more precise, the bigger your radius from center of your engine becomes.
Start turning the plate slowly and watch the clock. Don`t damage your device, if the clock can not show more than one or two millimeters of moving !!!
The image shows the repair of one of my two Zenoah 20cc. The clock was a type, showing one millimeter in a hundred parts. As you see, the radius don`t need to be huge to receive precise results. In this example, I had about 80mm.
Well, I remember, I grabbed the plate with my two hands and put the shaft in shape again. I think, it was bent about something less than one millimeter. This should be the limit at a radius of 80mm !!!
I was able to reach about one or two hundreds of a millimeter. Keep in mind, that the crankshaft is running in ball-bearings. According to this fact, don`t try to reach the zero-point. You can only become crazy, trying the mission impossible. And the material of your crankshaft will thank you, not to be bent twenty times even to the other side. It had enough stress from our crashes or somrthing.
In my case, my machine met the model of my own club-buddy, flying in front of public, finishing a small french event in May 2009. That f....... audience gave us a big applause...... but that`s another story.......
My 20cc was sent to Toni Clark first. I bought it there in 2008. Toni`s companion Gerhard Reinsch called me back late in the evening to tell me about the damages and the repair costs. They would have been 10 euros less than the price for a new engine. The main reason for this, was the ignition box. It has kinda dome, which the cable is screwed onto. The dome was broken off completely from the box, nothing left.....
So I wanted the engine back, the way it was.
And this engine is still running. And it is the engine, that has more hours than any other of mines. Of course, I had to buy a new ignition. But this was by far cheaper, than a new engine.
In case of your DA 150, you need a bigger plate. But you will realize, you are able to bring this shaft in shape!!
If you first testrun your DA, have a close look at the running at idle speed. Can you bring it down to the rpms you had before the damage???
If not, or if the idle is not really stable, your front bearing could have suffered too much from the damage. Possibly, It can still do its work for years. But it could be a pressure-leak now, such as the first generation cylinder gaskets from DA85 or 170.......
I compared my fixed engine to an absolutely new one by mounting the same prop to them and measuring the movement of the prop-tips. To my surprise, I had less movement with my fixed engine.
Also make sure, that the crankshaft is not turned in itself, as it can occur hitting the ground with a two or more cylinder engine. Of course, I don`t talk about dead stick hittings. There you have almost no risk, turning the shaft in itself.
If you are able to change the front bearing yourself, don`t be afraid of replacing all the gaskets by a high-temperature silicone. If you don`t want to replace the cylinder gasket, fearing a too high compression or changing the timing of your DA, make an aluminium-dummy and mount it with silicone.
Pics show a DLA58
If you want to do the same, start with the rear half of the crankcase!!
Mount all parts such as the isolator, reed-block, carb eventually venturi to it. Be aware that the two bolts are not screwed to far inside the case, otherwise you will block the shaft with them or scratch it.
Give this unit some minutes to dry and look inside. If there was too much silicone moving inside, that could prevent the reeds from working freely. Just pull it out with ease.
Use a type of silicone, not damaged by fuels or acids. Most of them stand temperatures of 250°C currently and 300°C short times. Really enough for our purposes.
I hope, I could help you, wish you safe flights!!
Pedro
Instead of the prop, you mount an absolutely flat steel-or aluminium plate. Remove the spark and mount the engine to some kind of test stand. Then put some measuring-clock to your plate. Logically, your measuring results will be more precise, the bigger your radius from center of your engine becomes.
Start turning the plate slowly and watch the clock. Don`t damage your device, if the clock can not show more than one or two millimeters of moving !!!
The image shows the repair of one of my two Zenoah 20cc. The clock was a type, showing one millimeter in a hundred parts. As you see, the radius don`t need to be huge to receive precise results. In this example, I had about 80mm.
Well, I remember, I grabbed the plate with my two hands and put the shaft in shape again. I think, it was bent about something less than one millimeter. This should be the limit at a radius of 80mm !!!
I was able to reach about one or two hundreds of a millimeter. Keep in mind, that the crankshaft is running in ball-bearings. According to this fact, don`t try to reach the zero-point. You can only become crazy, trying the mission impossible. And the material of your crankshaft will thank you, not to be bent twenty times even to the other side. It had enough stress from our crashes or somrthing.
In my case, my machine met the model of my own club-buddy, flying in front of public, finishing a small french event in May 2009. That f....... audience gave us a big applause...... but that`s another story.......
My 20cc was sent to Toni Clark first. I bought it there in 2008. Toni`s companion Gerhard Reinsch called me back late in the evening to tell me about the damages and the repair costs. They would have been 10 euros less than the price for a new engine. The main reason for this, was the ignition box. It has kinda dome, which the cable is screwed onto. The dome was broken off completely from the box, nothing left.....
So I wanted the engine back, the way it was.
And this engine is still running. And it is the engine, that has more hours than any other of mines. Of course, I had to buy a new ignition. But this was by far cheaper, than a new engine.
In case of your DA 150, you need a bigger plate. But you will realize, you are able to bring this shaft in shape!!
If you first testrun your DA, have a close look at the running at idle speed. Can you bring it down to the rpms you had before the damage???
If not, or if the idle is not really stable, your front bearing could have suffered too much from the damage. Possibly, It can still do its work for years. But it could be a pressure-leak now, such as the first generation cylinder gaskets from DA85 or 170.......
I compared my fixed engine to an absolutely new one by mounting the same prop to them and measuring the movement of the prop-tips. To my surprise, I had less movement with my fixed engine.
Also make sure, that the crankshaft is not turned in itself, as it can occur hitting the ground with a two or more cylinder engine. Of course, I don`t talk about dead stick hittings. There you have almost no risk, turning the shaft in itself.
If you are able to change the front bearing yourself, don`t be afraid of replacing all the gaskets by a high-temperature silicone. If you don`t want to replace the cylinder gasket, fearing a too high compression or changing the timing of your DA, make an aluminium-dummy and mount it with silicone.
Pics show a DLA58
If you want to do the same, start with the rear half of the crankcase!!
Mount all parts such as the isolator, reed-block, carb eventually venturi to it. Be aware that the two bolts are not screwed to far inside the case, otherwise you will block the shaft with them or scratch it.
Give this unit some minutes to dry and look inside. If there was too much silicone moving inside, that could prevent the reeds from working freely. Just pull it out with ease.
Use a type of silicone, not damaged by fuels or acids. Most of them stand temperatures of 250°C currently and 300°C short times. Really enough for our purposes.
I hope, I could help you, wish you safe flights!!
Pedro
Last edited by pedroaleman65; 01-08-2015 at 02:23 AM.
11-26-2014, 01:11 PM
#29
11-26-2014, 04:50 PM
#32
Well, that is an interesting way to check tracking and I will try that. I usually use a dial indicator on the prop hub itself to check runout. If a person used your method, you could check for tracking as well. A prop hub can run true in runout, but if it is not square as well, it will not track perfectly.
I also think .003 runout is excessive, and I try to shoot for less than .001".
AV8TOR
I also think .003 runout is excessive, and I try to shoot for less than .001".
AV8TOR
11-26-2014, 05:07 PM
#33
It may be best to use a PM (private email) to contact some person for help on certain things. Sometimes a lot of others jump in & make a mess of the whole works. Just saying.........
11-26-2014, 06:48 PM
#34
One thing that occurred to me as I was at the field today was that from what I have read, the OP says that he has checked the hub with a dial indicator? He also said that the spindle shaft has runout. It could be that it's the spindle shaft that is bent and not the crank. I had this happen once on a 3W 170 and it offsets the prop slightly and the engine shakes like hell. The spindle is fairly soft and was easily straightened in a lathe.
11-27-2014, 02:39 AM
#36
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Hummmmmmmm thats interesting I have been here all of the time and have fixed so many twisted cranks I have forgotton.
FYI Speedracer the factory considers .003 total run out to be within specs. I think that is a joke I try to get mine to run with in .0001. So maybe the factory is not always the best after all.
FYI Speedracer the factory considers .003 total run out to be within specs. I think that is a joke I try to get mine to run with in .0001. So maybe the factory is not always the best after all.
With a .0001 dial indicator that only reads to .200 total I am very sure. Yes a G-62 crank is one that twists as well and can be twisted back to run straight.
It is not the size of the crank that makes it wobble when turned, it is the fact it is out of alignment with itself.
What happens is when a prop strike happens the front of the engine stops at once ,since the crank is not a solid piece and pressed together with pins the rear half tries to keep turning for just a fraction of a second twisting the back part of the crank and making it out of align. Some cranks are pinned and that can be fun too although there pinned they to can still twist as a rule those I won't even touch.
Sometimes a mill vice can be used, while others need to be in a lathe just depends on how severe the crank is out.
How the straighten a twisted crank well the first thing a person needs is a good dial indicator preferable a .0001 read but a .001 will work I heard of some using wooden V blocks a brass dowel and a hammer. Myself I use a little more expensive tool called a lathe or milling machine. As for how I do it .well lets just say I do it and leave it at that. I was taught by a master 40 some years ago, when we used to rebuild crankshafts for bikes and snow machines, not like today where they just toss um out and replace with new.
Want to have some real fun try doing a 6 cylinder boat engine, it will drive a person nuts.
It is not the size of the crank that makes it wobble when turned, it is the fact it is out of alignment with itself.
What happens is when a prop strike happens the front of the engine stops at once ,since the crank is not a solid piece and pressed together with pins the rear half tries to keep turning for just a fraction of a second twisting the back part of the crank and making it out of align. Some cranks are pinned and that can be fun too although there pinned they to can still twist as a rule those I won't even touch.
Sometimes a mill vice can be used, while others need to be in a lathe just depends on how severe the crank is out.
How the straighten a twisted crank well the first thing a person needs is a good dial indicator preferable a .0001 read but a .001 will work I heard of some using wooden V blocks a brass dowel and a hammer. Myself I use a little more expensive tool called a lathe or milling machine. As for how I do it .well lets just say I do it and leave it at that. I was taught by a master 40 some years ago, when we used to rebuild crankshafts for bikes and snow machines, not like today where they just toss um out and replace with new.
Want to have some real fun try doing a 6 cylinder boat engine, it will drive a person nuts.
11-27-2014, 06:00 AM
#37
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I have seen so many of the lesser grade engine's have a fairly straight set up on the crankshaft only to have a prop hub that has run out or the prop hub nut has run out, so far as .008 -.009 of an inch. I like to take a skim cut across the face on the hub after I know the crank is straight and maybe re knurl it if necessary. This all depends on what type of a hub and setup the engine has. If the prop hub hold down nut is bad I make a new one to replace it with. While I have the crankshaft set up in the lathe I assemble the whole unit, prop hub and nut with a dummy prop of course then torque it to specs, then do the final machining on the prop hub bolt. Seems to work for me just fine. as far as a slight run out of the prop hub say .001 - .003 it is so close to the center of things it is not hardly worth messing with for that small of a deal, but again you can take a skim cut on it. Different props and spinner back plates or over tightening can change things, but as a rule not to much unless there really hosed up, With the exception of over tightening that cause some real run out issues as far as tracking go's. There is and old saying ,There is several ways to skin a cat so please by all means use the method that suite's you and return's good results.
11-27-2014, 10:06 AM
#39
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happy Thanksgiving everybody. I took a lot more measurements and as far as I can tell 1 crankshaft is twisted at one of the rod pins. The other crankshaft is bent at the end of the shaft where the prop hub attaches.
11-27-2014, 11:07 AM
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Hummmmmmmm thats interesting I have been here all of the time and have fixed so many twisted cranks I have forgotton.
FYI Speedracer the factory considers .003 total run out to be within specs. I think that is a joke I try to get mine to run with in .0001. So maybe the factory is not always the best after all.
FYI Speedracer the factory considers .003 total run out to be within specs. I think that is a joke I try to get mine to run with in .0001. So maybe the factory is not always the best after all.
11-27-2014, 11:30 AM
#41
I would agree that the lesser amount of runout in the crank assembly its self would be less wear and tear on the bearings, it would take so little as far as prop/spinner balance and torque to nullify it with respect to vibration. I have no idea if my current 150 has ever been back to DA or not as I have only had it for 6 months. I do however know it is 13 years old and runs very smoothly although I think it's time for a carb rebuild. It sat for 8 years before I got it and all I did was take it apart, soak the soft parts in gas for a bay and blow the passages out. Video of my Extra is 15 min in.
[h=3]DVRC Open House Rev 1 - YouTube[/h]
[h=3]DVRC Open House Rev 1 - YouTube[/h]
► 25:12► 25:12
www.youtube.com/watch?v=Wj9VFMz0uI8
Oct 20, 2014 - Uploaded by Nigel Watson
Higher resolution video of the DVRC Open House, October 18th, 2014.
Oct 20, 2014 - Uploaded by Nigel Watson
Higher resolution video of the DVRC Open House, October 18th, 2014.
11-27-2014, 12:10 PM
#42
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my idea was very simple. I thought about simulating, what had happened to bend the crankshaft. And in most cases the breaking of the prop causes the damage. No matter, if you crash after a deadstick or with the engine running. It is always one of your prop-blades bending the shaft by breaking. The damage is bigger, if you had a Mejzlik or Biela mounted. These props are not only loading your engine more than others, they can also harm it heavier by its stability.
My method is kinda reset, of what happened. And if the damage is not too big, it can be a cheap way. If you use a real big plate, you don`t even need the clock. Put a needle to the plate and watch with your eyes the changing distance while turning. You can also hear the needle touching the plate less, while turning and straightening the shaft.
Of course you have more control of what your doing, using the clock!!! I was working as an industrial mechanic and had to straighten lots of steel shafts after the hardening. Otherwise they would have jumped off from the grinding-machine later.
The ball-bearings can take really hard knocks, because this happens so incredibly quick. The karate way, I would call this.
I have made experiences with dealers, getting their money not only by selling engines. A series of stupid repairs will also fill their pockets, if the customer is a beginner being fooled very easy. Sad to tell you this......
And I would not tell you things, I haven`t done and tested practically by myself.
My method is kinda reset, of what happened. And if the damage is not too big, it can be a cheap way. If you use a real big plate, you don`t even need the clock. Put a needle to the plate and watch with your eyes the changing distance while turning. You can also hear the needle touching the plate less, while turning and straightening the shaft.
Of course you have more control of what your doing, using the clock!!! I was working as an industrial mechanic and had to straighten lots of steel shafts after the hardening. Otherwise they would have jumped off from the grinding-machine later.
The ball-bearings can take really hard knocks, because this happens so incredibly quick. The karate way, I would call this.
I have made experiences with dealers, getting their money not only by selling engines. A series of stupid repairs will also fill their pockets, if the customer is a beginner being fooled very easy. Sad to tell you this......
And I would not tell you things, I haven`t done and tested practically by myself.
11-27-2014, 12:42 PM
#43
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I am not sure of belonging to the knowledgeable people. Until now, I made only good experiences with this US-forum. I found this crankshaft-thread by accident.
Your language is not mine, but I was taught from my cuban friends, that the modellers are a huge international family spread all over the world. So, struggeling for english or spanish words is always worth the time.
In a german forum I was offended personally by a dealer. I wrote about a damaged ignition he sold me with a new engine. The 11th flight of my machine had therefore been a free flight, ending with tons of luck and little damages.
I was not bashing this brand of engine. I showed everyone, how to make a winner of excellent pieces, that were only suffering from bad gaskets or silicone comming out.
I gave all informations to the producer, doing the work that had to be done by the dealers. There are lots of black sheeps in any nation, looking for the fast money.
Your language is not mine, but I was taught from my cuban friends, that the modellers are a huge international family spread all over the world. So, struggeling for english or spanish words is always worth the time.
In a german forum I was offended personally by a dealer. I wrote about a damaged ignition he sold me with a new engine. The 11th flight of my machine had therefore been a free flight, ending with tons of luck and little damages.
I was not bashing this brand of engine. I showed everyone, how to make a winner of excellent pieces, that were only suffering from bad gaskets or silicone comming out.
I gave all informations to the producer, doing the work that had to be done by the dealers. There are lots of black sheeps in any nation, looking for the fast money.
11-27-2014, 04:08 PM
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11-28-2014, 07:05 AM
#46
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DirtyBird that question is not worth the type to explain. Most everyone knows the truer something can spin the less harmonics it has and also the less run out. Extend things out farther and the more wobble you will have.
When a manufacture makes a crankshaft they mass produce them and don't have the time to finish aligning the crank assy. As a rule .003 will allow the engine to run but hurt's the over all performance and longevity of the engine.
The factory also knows that the parts being used are not perfect and can vary slightly. So what they come up with runs and works. Some may be dead on while others can be off a little, so they have a tolerance to hold and the last I was told was .003.
Also when I said .0001 that is as close to perfect as possible I can do, it is also not always obtainable due to the parts at hand, the holes can be off as much as .002 in those case's you get it as close as possible. But a good set of counter balances and straight parts the .0001 is very realistic.
When a manufacture makes a crankshaft they mass produce them and don't have the time to finish aligning the crank assy. As a rule .003 will allow the engine to run but hurt's the over all performance and longevity of the engine.
The factory also knows that the parts being used are not perfect and can vary slightly. So what they come up with runs and works. Some may be dead on while others can be off a little, so they have a tolerance to hold and the last I was told was .003.
Also when I said .0001 that is as close to perfect as possible I can do, it is also not always obtainable due to the parts at hand, the holes can be off as much as .002 in those case's you get it as close as possible. But a good set of counter balances and straight parts the .0001 is very realistic.
11-28-2014, 08:37 AM
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Thanks Pope, I posted some details in another thread "DLE55 prop size". And in my profile you see some pics, also the smaller brother "Raudilio" ....this here is "Raudilio grande". Feel free to ask for more in a PM. I have to respect the rules of the forum, not to be completely off topic. But I can tell you, I took pics from every building step. I also made some promotion by flying at different events, because some people were interested in machines like mine.... at least, I could not get any concrete order... but there could be bigger problems, than these.......
Pedro el Aleman
Pedro el Aleman
11-28-2014, 10:59 AM
#49
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DirtyBird that question is not worth the type to explain. Most everyone knows the truer something can spin the less harmonics it has and also the less run out. Extend things out farther and the more wobble you will have.
When a manufacture makes a crankshaft they mass produce them and don't have the time to finish aligning the crank assy. As a rule .003 will allow the engine to run but hurt's the over all performance and longevity of the engine.
The factory also knows that the parts being used are not perfect and can vary slightly. So what they come up with runs and works. Some may be dead on while others can be off a little, so they have a tolerance to hold and the last I was told was .003.
Also when I said .0001 that is as close to perfect as possible I can do, it is also not always obtainable due to the parts at hand, the holes can be off as much as .002 in those case's you get it as close as possible. But a good set of counter balances and straight parts the .0001 is very realistic.
When a manufacture makes a crankshaft they mass produce them and don't have the time to finish aligning the crank assy. As a rule .003 will allow the engine to run but hurt's the over all performance and longevity of the engine.
The factory also knows that the parts being used are not perfect and can vary slightly. So what they come up with runs and works. Some may be dead on while others can be off a little, so they have a tolerance to hold and the last I was told was .003.
Also when I said .0001 that is as close to perfect as possible I can do, it is also not always obtainable due to the parts at hand, the holes can be off as much as .002 in those case's you get it as close as possible. But a good set of counter balances and straight parts the .0001 is very realistic.
So make it better if you like. I think you will find it makes little difference to the overall performance
11-28-2014, 11:09 AM
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Well, I don`t know if I understood the meaning of your question. With a smiley I could take it as a joke. Bent crankshafts are normally the results of flying accidents, crashes, collisions, bad landings...... Even the profs sometimes have to go through this