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Thread: Aftershock ... rc glider

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    Default Aftershock ... rc glider

    Figure rather than fill up the thread on my machine, I should start one down here for this project.

    Several years back a friend drew up a glider in CAD. We both drifted out of the hobby and it was forgotten. Well, I am back in, and want to make my own planes to fly.

    So I dug the files out, and picked up some wing plugs we made for it. Now I am getting busy.

    The plane was named the aftershock. It will have a 60" wing span. For slope flying. Fully molded composite glider.

    This is it in Rhino...

    Similar Threads:
    Attached Thumbnails Attached Thumbnails Aftershock ... rc glider-as60_01-jpg   Aftershock ... rc glider-as60_02-jpg  
    Wood neophyte.


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    Default Re: Aftershock ... rc glider

    First thing was setting up to make a plug of the fuse. The plug will be used to make a mold to make the composite fuse.

    So I cut a left and right half out of mdf. These will be aligned and glued together.

    Then I will soak the plug in think epoxy, and hit it with a heat gun. For those that do not know, this causes the MDF to soak up the epoxy. Then I re-coat it and heat it, a few times to get a good layer of epoxy soaked in. This gives a hard surface that can be sanded down real smooth. Most people will then paint it with a 2k car paint and sand and polish that. I will see how good I can get the finish with epoxy soaked mdf prior to determining if I need to paint it.

    Here is the first half cut. I clamped down a melamine board (shelf from home depot), sprayed it and my mdf with spray glue, enough to hold it, not enough that it's permanently attached. lol.

    Then I set up to cut down to that board. This allows me to cut one half at a time and then pull them up and glue them together. I guess I could have done something 2 sided and flipped it, but that seems like more trouble than anything.

    The other photo is the two halves together along with a fuse for a 40" w/s version I just cut and soaked in epoxy, and one we cut several years back. I have made some changes to how the horizontal stab will connect, so had to change them up.

    Attached Thumbnails Attached Thumbnails Aftershock ... rc glider-cce3337b-e08d-4293-a11d-af4a84ddcf03-jpg   Aftershock ... rc glider-e379ed3e-a07f-47c6-a02e-365bbe9d9d6c-jpg  
    Wood neophyte.


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    Default Re: Aftershock ... rc glider

    Nice indeed I have learned something about making a plug thank you gives me a lot of Ideas.



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    Default Re: Aftershock ... rc glider

    Sanding on the fuse started. Added some filler where needed.

    Attached Thumbnails Attached Thumbnails Aftershock ... rc glider-e426a100-576d-4b09-8139-d2d5a110d1af-jpg  
    Wood neophyte.


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    Default Re: Aftershock ... rc glider

    Cut vertical tail molds. Need to make a part to make sure the tail on the fuse is sanded to match. Thinking I might need to do these as plugs instead in order to get the sharp corners ... will see how it goes.

    Attached Thumbnails Attached Thumbnails Aftershock ... rc glider-dde969ab-42a8-4b8c-9873-90cfc732b428-jpg  
    Wood neophyte.


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    Default Re: Aftershock ... rc glider

    Cut and working on sanding the horizontal tail.

    Cut it out,
    Marked with marker to mark the low spots in the machining marks.
    Half sanded..
    Down to 3000 grit, getting there.

    Attached Thumbnails Attached Thumbnails Aftershock ... rc glider-0bc1754f-70f0-4861-8172-094af8286948-jpg   Aftershock ... rc glider-d942ce33-813f-4593-a7a0-99ec774a3c57-jpg   Aftershock ... rc glider-bf28ba10-4e5d-4c7d-b25d-8b4fc625352e-jpg   Aftershock ... rc glider-4e230dcb-ea1c-4a87-ad0c-15408dda85b4-jpg  

    Wood neophyte.


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    Default Re: Aftershock ... rc glider

    Vertical tail piece get's same treatment.

    Attached Thumbnails Attached Thumbnails Aftershock ... rc glider-2d159a7f-acb0-42dc-b62a-d5e00ba5f790-jpg  
    Wood neophyte.


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    Default Re: Aftershock ... rc glider

    Hello Arbo,

    Great job on the design and machining. I use to design my own thermal duration gliders and compete at the local and regional contests. I designed my own fuselage, carved my own plugs and vacuum bagged my own wings. When "Moldies" became more common and affordable, I stopped making my own gliders. I have not competed since 2007 but I still have all my planes and plan to get a few of my old DLG's going. I so wish I had access to a CNC machine then. Did you ever try using Jelutong for the plug material instead of epoxy coated MDF? What airfoil do you have on the wing?

    Marc



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    Default Re: Aftershock ... rc glider

    Had never heard of Jelutong, what would the advantages be? Is a, hmm, rg15 I believe, it's been a long time since it was designed. lol.

    Thanks.

    Wood neophyte.


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    Default Re: Aftershock ... rc glider

    Jelutong,

    Is a fine grained wood that is great for carving and working by hand. I use to use it for the Fuselage plug. Its what was recommended to my by other RC sailplane builders at the time. I then coated it with feather fill for the final sanding.

    Most of my slope racers and a few of my thermal duration gliders were RG15, but that was years ago and I would imagine there are better choices now. However its a great airfoil so why change. I will watch this thread to see how it progresses.

    Marc



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    Default Re: Aftershock ... rc glider

    Ah.

    No, years later, some of the same airfoils are still around and kicking. Rg14 and 15 are quite popular. Oh, you know, what, it's neither of those, it's a rk40. Just remembered that.

    Wood neophyte.


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    Default Re: Aftershock ... rc glider

    Should be able to get started cutting wing molds in corian tomorrow. 3d models of cuts below.

    For alignment in all the parts, I drilled in with .25 bn mill, will use .25 ball bearings, set in on one side, and out on the other. That will be for all molds I make.

    Wings will just have them glued in on one side since that is mold instead of plug.

    Attached Thumbnails Attached Thumbnails Aftershock ... rc glider-wingbotmold02-png   Aftershock ... rc glider-wingtopmold01-jpg  
    Wood neophyte.


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    Default Re: Aftershock ... rc glider

    Quote Originally Posted by Arbo View Post
    Should be able to get started cutting wing molds in corian tomorrow. 3d models of cuts below.

    For alignment in all the parts, I drilled in with .25 bn mill, will use .25 ball bearings, set in on one side, and out on the other. That will be for all molds I make.

    Wings will just have them glued in on one side since that is mold instead of plug.
    I've literally just tried my first casting attempt with a corian mold minutes ago funny enough, the finish detail was excellent, no sanding just some wax release spray. Unfortunately was not enough to get the fiddly little parts to release and ended up smashing the corian to get them out. Maybe casting flexible PU in a solid mold was a little ambitious to ever believe i could reuse the mold but the parts came out great was toying with engineering wax before the corian but was no where near as good.



    Look forward to seeing your wing take shape.

    Attached Thumbnails Attached Thumbnails Aftershock ... rc glider-img_0150-1-jpg  


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    Default Re: Aftershock ... rc glider

    Long ago I found that a well sanded/polished mold from corian, did not need anything but a few coats of wax to release hard parts make with epoxy.

    Wood neophyte.


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    Default

    Quote Originally Posted by Arbo View Post
    Long ago I found that a well sanded/polished mold from corian, did not need anything but a few coats of wax to release hard parts make with epoxy.
    Interesting, thanks for the tip!



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    Default Re: Aftershock ... rc glider

    Looking at your parts, it might take a bit of thinking to get them to release, if they are in a recess as it appears they probably are. Personally I'd have some parts where the side wall was down to the base of the mold, and just fill or build a wall with clay, so you can stick something in there to pry them out a bit. if that makes sense.

    Wood neophyte.


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    Default Re: Aftershock ... rc glider

    Quote Originally Posted by Arbo View Post
    Looking at your parts, it might take a bit of thinking to get them to release, if they are in a recess as it appears they probably are. Personally I'd have some parts where the side wall was down to the base of the mold, and just fill or build a wall with clay, so you can stick something in there to pry them out a bit. if that makes sense.
    yes i think you are right that would help greatly.

    Have you by anychance tried using a ball nose cutter with a radius to reduce the accentuation marks between passes in corian, i get these alot too using single flute down cut and ball mill without a ridiculous amount of passes, thinking a radius cutter might help but without going up in flutes i would image that would mean using a straight single flute with radius. Not sure how well these work in corian.



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    Default Re: Aftershock ... rc glider

    Unfortunately all I have done is shorten the overstep. I am down to 10% on a .25" BN. I still get them and it requires a good bit of sanding (and the paper clogs constantly). But corian cuts like butter if you have the speed and rpm's set right. I am cutting out one of the wing molds now, it's about half done at 2.5 hrs with a .25 BN, and I did not rough at all, straight to a finish cut, and the 'deepest' part on the tips, is about .75", i slow down my machine for the first couple passes that are full deep, but then put it back to 100% speed.

    Wood neophyte.


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    Default

    Quote Originally Posted by Arbo View Post
    Unfortunately all I have done is shorten the overstep. I am down to 10% on a .25" BN. I still get them and it requires a good bit of sanding (and the paper clogs constantly). But corian cuts like butter if you have the speed and rpm's set right. I am cutting out one of the wing molds now, it's about half done at 2.5 hrs with a .25 BN, and I did not rough at all, straight to a finish cut, and the 'deepest' part on the tips, is about .75", i slow down my machine for the first couple passes that are full deep, but then put it back to 100% speed.
    Yeah it's lovely stuff to cut, Infact probably my favourite material. you can go fairly fast with slowish rpm for some nice big chips. If you have the time (maybe not worth the wait for big parts) I find 1 or two very small step overs and step downs and a repeat 0 pass makes for close to a fine grit finish. Visually notice the effect better using black corian, the repeat pass removes the last of the white'ish grey material left and polishes completely back to black.



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    Default Re: Aftershock ... rc glider

    I guess it depends on what the total machining time would be. This piece, about 62" x 7.5" (at the widest) just took a little over 5 hours. Loads of sanding to do.

    Attached Thumbnails Attached Thumbnails Aftershock ... rc glider-609e4540-4c1e-418f-ac05-2578a8e74327-jpg   Aftershock ... rc glider-4cb68f45-2e11-47ed-97e3-54ece70fb704-jpg  
    Wood neophyte.


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