MK Dual Elavator Bellcrank & Pushrod?

[Brian Billings]

Troy, I hope I did not come across as bashing the Central Hobbies DEPS but I did have better luck with the Teflon cases. As I said, the system installed in my Majestic is soooooo smooth even with a slight bow in the rods. The one I am putting in the Impact has the hard plastic cases and they are not nearly as forgiving. I do remember when setting up the Majestic I had to cut the system apart and redo before installation because I wrapped the thread to tight. Either system will work fine ounce you learn the tricks. I love the way it functions when done and it eliminates any elev. tracking problems as long as the control horns are exact. 
No insult intended! Brian 
  ----- Original Message ----- 
  From: Troy A. Newman 
  To: discussion at nsrca.org 
  Sent: Friday, February 04, 2005 3:31 PM
  Subject: Re: MK Dual Elavator Bellcrank & Pushrod?


  Brian,

  sorry to hear you had some trouble with the guides on the DEPS.  We worked pretty hard on getting the system to be  easy to install and friction free. You are correct that any bending or curving in the system will cause it to bind up as stated in the instructions for the DEPS.  The Teflon sleeves have their own problems and what was happening is guys would wind the thread too tight on the Teflon sleeve and crush it. This would cause friction points along the length of the Teflon guide even it was dead straight. So the hard plastic guide kept this from occurring. 

  The key to both system is getting the pushrods at a straight shot to the control horns. NO bends no curves. If you install it this way it will be friction free. The right fuse exit location is so very important. I use a 4ft long straight edge to connect the dots from the servo connection location to the elevator control horn. I do this on both the side of fuse For the vertical location and angle and then the belly of the fuse for the fore and aft exit location. I use masking tape and project the lines to where I need to dremel the slot.

  This exit location will be very different depending on the location of the elevator servo up front and will also depend on the width of the fuse at the tail and where the elevator control horns are. So you need to have both mounted so you can align the rods to pass right by the connection points. No bending them over to it.

  A rough idea is my Supremes' have the exits about 10.5" forward of the elevator hinge line. A narrow fuse like a Focus of Temptation this exit will be slightly back further. The key is getting the slots in the right spot so it doesn't bend. 

  NOW some solutions I have heard of and never tried. Take the pushrods and slightly sand them with some 320 grit. "roll" the rod in your fingers....The ideal is not to sand diameter down but sometimes the pushrods can have some ridges on them from manufacturer. I think they are Pultruded (sp?) and this can cause some slight imperfections in the surface but I'm not sure.   I have seen  a  few of these with the CST rods. Never caused me any problems but I can see if the guides are curving it could.

  Next a little messy perhaps at first...Graphite dry lube like pine wood derby wheel lube works pretty good. Squirt a little in the tubes and the then install the pushrods. I heard of a guy doing this and he said it made all the difference. If you have to remove a glue joint on your pushrods to get it apart just heat the metal fitting up with a solder iron or a Bic lighter the glue will soften and you can remove the fitting. A little sand paper on the end where the glue was and the pushrod system will come right out of the guides from the front. Then deal with the guides and glue the ends back on. I recommend clean the old glue out of the hole. I use a drill...but be careful the titanium ends are very tough and you can break off a drill bit if you are trying to remove metal. I then use rubbing alcohol to clean it. Dry with a bic lighter and then glue it on again. Works fine.

  Next is sometimes you can get paint and crud in the tubes at the exits and this will cause some binding. Clean out the exit tube with a small round file....I have even used a long 2-56 pushrod threaded on one end to plunger the tubes and clear some debris.  I even saw one where the guy used some Thin CA to attach something and it ran down the CF rod and into the sleeves. It didn't glue it in place but it did cause quite a bit of binding. 


  I have not heard of guys having problems. Usually all you hear form this list and RCU is the bad stuff and rarely does the good comes through. I get tons of emails from guys that love it. I wondering if you try some of the fixes above and they solve your issue. I just installed this system on friends Angel Shadow and it works great! By the way Exits on it were about 11" forward of the elevator hinge line and they are a straight shot servo to the control horns.


  As for weight I just stuck the plastic tube guides on a scale and the Teflon guides as I have both. The Teflon one 4ft long was 6grams The Plastic one 40" long was 5grams....

  The 0.070" solid CF rods can't run unsupported for the length of the fuse. They will bow up when put under load. But inside the guides they are stiffer and more solid than any system I have ever seen or flown. This includes cables, MK, Dave Brown Fiberglass arrow shaft( the black one is fiberglass and not CF) And the CF rods  done like the Dave brown fork with a bushing support in the back. and supports in the middle too. The elevators get no differential between sides when under load and many of the other system do. This was the whole reason for using the DEPS system. Eliminate differential side to side and have a friction free slop free system that was light.

  Troy


    ----- Original Message ----- 
    From: Brian Billings 
    To: discussion at nsrca.org 
    Sent: Friday, February 04, 2005 11:33 AM
    Subject: Re: MK Dual Elavator Bellcrank & Pushrod?


    Speaking of the CF push rod set ups, I would like to share a little info. I just finished installing my second CF. elev. pushrod assem. in a Impact, the first was in my Majestic. In the Majestic I got the DEPS setup from CST seen here http://www.cstsales.com/CCPush-rodKits.htm
    This kit comes with a thin walled Teflon outer case and even with a slight bow or arc in the assem. the system remains Very friction free.
    For the Impact I purchased the kit from Central and it comes with plastic outer cases and these were difficult to get smooth and friction free, the slightest bend or arc made the movement very stiff and as a matter of fact, I could not even use them and ended up using hollow CF. rod for the outer case which worked very well but slight bends or arcs are out of the question. Just my personal experience, yours may differ.

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