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Old Oct 27, 2015, 05:16 PM
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New Dynamax conversion kit in the making

V1 Kits now available as shown in the picture below
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Pricing/availability info:

--Version 1 (V1) Short Centerbody--
-Price: $130 shipped
-Machined Hub and V1 Motor mount as shown in the picture below for any 50mm motor with an 8mm shaft and mounting hole diameter between 25 to 30mm.
-2x6-32 Machine screws for the long stators
-2x6-32 nuts
-3xM4 set screws
-1xM5 spinner screw
-4xM4 socket head screws for the motor
-80g and 150g Emery cloth to adjust motor shaft OD
-50mm heatsink and 3grams of thermal paste
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How to disassemble your old Dynamax fan:
Dynamax fan disassembly (15 min 14 sec)



Here are the assembly videos:

Grinding down motor shaft:
HET 800-73-590Kv motor shaft sizing (3 min 29 sec)


Fan assembly:
Dynamax EDF conversion V1 Kit (23 min 51 sec)


Stock Dynamax running on 14s on a 590kv HET motor:
Dynamax with HET 800-73-590kv motor on 14s (4 min 38 sec)


Eagle Tree data log of 14s run:
Dynamax 14s 590kv eLogger data (3 min 40 sec)


12s run
Dynamax 12s HET 590kv with thrust tube (3 min 51 sec)

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-Development history
For those of you who have not been following the Scorpion Dynamax thread, I am currently working on a new conversion kit that will work with any existing 10mm or 8mm motor. My primary reason for going this route was to remedy a poor shaft design on the scorpion motor but in the process, I realized that we can use much of the stock Dynamax fan to include the original motor mount and convert them to an electric setup.

The prototype as shown below is being machined this week and I am hoping to have video and data available by next monday. Since I will be constructing this version primarily for the Scorpion 5035-700Kv motor, the initial production run will match the prototype below. As soon as I am confident in the new hub and shaft, I want to expand the options for folks looking to use their old Dynamax fans with other motor brands (HET, NEU).

So, i'm listing some options below to get an idea of what motors people are most interested in using. I plan on having several options available. Here is what i'm thinking right now with approximate prices (subject to change). Again, nothing is for sale just yet.

Option 1: Scorpion 5035-700Kv conversion kit- Will include new solid 10mm shaft, new rotor hub, 10mm shaft retaining collar, set screws, and spinner screw. Based on some initial estimates, price should be around $150 or lower if the demand exists for a larger production run.

Option 2: HET 800-68-685Kv or 590Kv- Will include bolt on mount for the motor that will utilize the stock dynamax stator hub, a new rotor hub, 8mm to 10mm sleeve for the smaller shaft, shaft set screws and spinner retention screw. I'm estimating around $200 for this setup.

Option 3: NEU 19xx series: Same as HET setup but with a different motor mount. Pricing should be similar to option 2.

Option 4: individual parts as desired for your own setups.

Once again, nothing is for sale just yet. I simply want to know what people are interested in. If all goes well, I am looking to have at least option 1 available in about 30 days with the other options before the end of the year. If there are any other good motors that I am not aware of, please let me know and I will see what I can do.
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Old Oct 28, 2015, 01:00 PM
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I'd be interested in one for either the Neu or HET motors. Have a Dynamax waiting for a conversion that uses the existing center body....
Can you please explain the drawing you have posted a little more?
Jim
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Old Oct 28, 2015, 03:49 PM
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Jim,

Much like yourself, my main motivation for designing this was to utilize my 4 year old dynamax. Its a shame to let such a good fan collect dust. The HET setup will come second as it's a more affordable motor than the NEU. What you are looking at in the picture is a new hub for the dynamax rotor. This hub replaces the stock dynamax rotor hub that is well hidden under all the blades. The 3 black screws you have on the front face of the stock rotor will go into the 3 holes you see on the face of this hub with the stock washer. This hub has a 10mm hole through the center vs. the stock hub that is not compatible with any electric motors.

Since the HET comes with an 8mm shaft, I plan to use a sleeve that will have an ID of 8mm and an OD of 10mm which will allow for the use of a motor with a 8mm shaft. The HET will attach to fan with an aluminum motor mount that will be press fitted and screwed into the stock stator hub. I will post some more 3d renderings soon but I hope this helps. Thanks for the input.

Quote:
Originally Posted by Lear45 View Post
I'd be interested in one for either the Neu or HET motors. Have a Dynamax waiting for a conversion that uses the existing center body....
Can you please explain the drawing you have posted a little more?
Jim
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Old Oct 28, 2015, 04:20 PM
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I'm sure you know this, but when it comes to shaft fit, etc. it really needs to be close tolerance.
Maybe even a 'heat to fit.' I look forward to your progress.
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Old Oct 28, 2015, 04:47 PM
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Yep...agree with you 100%. the sleeve will be an interference fit and heat will be required. Stay tuned.

Quote:
Originally Posted by Lear45 View Post
I'm sure you know this, but when it comes to shaft fit, etc. it really needs to be close tolerance.
Maybe even a 'heat to fit.' I look forward to your progress.
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Old Oct 29, 2015, 01:37 PM
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Having one of Tam's rotor hubs in hand I can say that his is a lap fit. If you watch his installation video the shaft hole is less than 8mm. He hooks the motor up with a bare shaft and then runs it at a relatively low rpm while holding a scotch brite pad on the shaft. Checking the fit frequently between shaft and hub. Also there are no flats ground on the shaft. Just the 3 set screws tightened equally.

Par,

Have you considered offering your hub with an 8mm hole and the set screws on the motor side? And instead of a 10mm shaft offer a motor adapter that fits inside the Dynamax stator housing to mount a HET motor? Similar to the one Ed shows in his post here:

http://www.rcgroups.com/forums/showp...9&postcount=76
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Old Oct 29, 2015, 02:24 PM
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Steve,

I have seen the video you are referring to. Someone else also mentioned leaving the flat spots out. The only reason I am including then on the 10mm shaft is because the machine shop said it will cost next to nothing for them to do it. I think it will also provide a a little more security.


I also considered having an 8mm hub produced. Perhaps you can shed some light on this topic but since the HET 685kv motor has a relatively short shaft, 3/4" if I'm not mistaken, is there any adverse effect on the motor since the rotor hub hangs well past the end of the motor shaft? My thought was that a well fitting 10mm sleeve on the motor would be a more solid setup. This would also allow me to keep the same hub design along with a couple of other components, which would save some cost. Having a 10mm/8mm sleeve machined is relatively cheap. I will purchase a HET motor next month to start testing this out and I will go with the cheaper option as both will likely work equally well.

As far as the motor mount goes, my plan is to do exactly what you said. It will fit inside the stock black motor mount and the HET will simply bolt to that. It will be similar to what Ed did. I'm going to work on getting some 3d renderings done this weekend.
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Old Oct 29, 2015, 02:57 PM
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The sleeve adds unnecessary tolerance. Also your sleeve would have to have set screws as the HET motor shafts aren't going to be long enough to reach the set screws as you have your adapter drawn now.
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Old Oct 29, 2015, 09:43 PM
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Quote:
Originally Posted by SteveC68 View Post
The sleeve adds unnecessary tolerance. Also your sleeve would have to have set screws as the HET motor shafts aren't going to be long enough to reach the set screws as you have your adapter drawn now.

The sleeve will be an interference fit that will use set screws. I think the tolerances are manageable but if they are not, I will simply go with an 8mm hole in the hub with set screws on the back side of the hub. Can't know until I try it!
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Old Oct 30, 2015, 02:34 AM
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Looking forward, about the hub idea you have.
Only my motors have a 8mm shaft.

Yesterday i received my own design center motor mount.
The idea was to use the tamjets hub. But sadly it isn't available anymore. So need to look an other solution
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Old Oct 30, 2015, 08:07 AM
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Quote:
Originally Posted by Par_18 View Post
The sleeve will be an interference fit that will use set screws. I think the tolerances are manageable but if they are not, I will simply go with an 8mm hole in the hub with set screws on the back side of the hub. Can't know until I try it!
What is the concentricity tolorence that you have? What is your machine shop capable of? The fit is only half of the machining process. You have to make sure your centers are aligned as well. So the sleeve increases the error of the centers being offset. Without the sleeve you only have to align the centers of 2 circles. With the sleeve you have to align the centers of 4.
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Old Oct 30, 2015, 02:29 PM
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Quote:
Originally Posted by SteveC68 View Post
What is the concentricity tolorence that you have? What is your machine shop capable of? The fit is only half of the machining process. You have to make sure your centers are aligned as well. So the sleeve increases the error of the centers being offset. Without the sleeve you only have to align the centers of 2 circles. With the sleeve you have to align the centers of 4.
I am not a machinist nor a practicing engineer. The shop I am working with supplies turbine blades and the equipment they have is more than capable of producing a shaft. I tell them what I want and they produce it to whatever tolerance is needed to make it work like I want. Like I said, I can't know until I try it. If it doesn't work, then I'll try something else.
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Old Oct 30, 2015, 02:40 PM
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Quote:
Originally Posted by Hoeby View Post
Looking forward, about the hub idea you have.
Only my motors have a 8mm shaft.

Yesterday i received my own design center motor mount.
The idea was to use the tamjets hub. But sadly it isn't available anymore. So need to look an other solution
Those are some nice looking hub's. My idea is slightly different in that the new hub will only encompass the preexisting aluminum ring in the stock Dynamax hub. I plan to hold the new motor mount/hub in place by first press fitting in place and then by using 4 stator blade screws. The stock screws will be a little too short but this is an easy fix. From a cost perspective, I think this is the cheapest way to go because it will be extremely simple to machine. I'm hoping to have it on the test stand in about 3 weeks.
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Old Oct 30, 2015, 04:36 PM
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Originally Posted by Par_18 View Post
I think this is the cheapest way to go because it will be extremely simple to machine.
I think you are right about this.
And easy to place do for anyone who already has a dynamax.
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Old Nov 08, 2015, 12:27 PM
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Update-

I received my first new machined rotor hub which will work with any motor that has a 10mm shaft. My main reason for designing this was to fix the poor design of the Scorpion 700kv motor that is specifically sold for a dynamax conversion. I plan to make this hub available with a 10mm shaft for any outrunner that uses a 10mm shaft.

If guys want to use this with an 8mm shaft, you can either wait for the second version that I have in the works at the moment or I can have a hub machined with an 8mm hole. Going with your own 8mm shaft, you will need to find a way to use the stock spinner, if needed. Also keep in mind that the shaft will need to be of a minimum length in order to fit entirely through the new hub. I currently have the system assembled and ready for testing. The weight increase with the new hub is minimal and I will post exact numbers later in the week when I disassemble it to weigh all the components. Here are some pictures and a short video of fan running with the scorpion 700kv motor on 8s.

https://goo.gl/photos/hqsVMueRcosK6VDS6
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