A short video of the new RSM control system

[Mike Griffin]

I wasn't really sure of where to post this but I thought you all would be interested  in this.  Eric Rule at RSM is now offering this for a control push rod system upon request.  I think Eric now has the prices posted on his Vendors Corner section under new products.  The Carbon Fiber tube is just a standard 3/16" OD tube.  The ball links and the stainless steel ends are what are so unique and innovative. 

Mike

[James Holford]

woohoo no more soldering sleeves on music wire for me!!!

[Mike Griffin]

Yes it eliminates that too James.

Mike

[Rick Bollinger]

Mike
 That's a good looking set-up. What is the weight of one end with the ball joint?

[Mike Griffin]

Mike
 That's a good looking set-up. What is the weight of one end with the ball joint?

Rick I will weigh one today and post it..

Mike

[Mike Haverly]

Those ball joints work great until they don't anymore.  I've seen them fail.

[Randy Cuberly]

Those ball joints work great until they don't anymore.  I've seen them fail.

What were the conditions of the failures Mike.  Was it in model airplanes or some other environment?

Randy Cuberly

[Mike Haverly]

In an airplane, at VSC.  Ask John Callentine (I think), and there are others.  The stick and wear out.  They're probably OK for sport flying or light duty, but I wouldn't trust it in a full boogie PA model.

[Mike Griffin]

In an airplane, at VSC.  Ask John Callentine (I think), and there are others.  The stick and wear out.  They're probably OK for sport flying or light duty, but I wouldn't trust it in a full boogie PA model.

Hi Mike

Thank you for bringing this to our attention.  We are in the process of contacting John and see if he can confirm that is was in fact this particular type of ball link he was using and if it was this type, under what conditions and when this failure occurred.  We take this very seriously and want to verify what happened.

Thank you again for your input and we will get back with you shortly.  I have also relayed your message to Eric Rule at RSM.

Regards,
Mike

[Mike Griffin]

In an airplane, at VSC.  Ask John Callentine (I think), and there are others.  The stick and wear out.  They're probably OK for sport flying or light duty, but I wouldn't trust it in a full boogie PA model.

Mike can you please give me the year you are talking about at VSC?  Thank you

Mike

[Mike Haverly]

You know, I can't verify for sure that it was John.  The year was 2007.  I don't think you will find many serious competition fliers use those ball joints for the reason I described.  It has been the topic of more than one conversation on the west coast.  Some fliers have used them and swear by them, other swear at them.  Part of the problem in Tucson is the low humidity and heat. 

[JohnCallentine]

Glad to report it wasn't me. But I seem to remember someone having one of those balls pop off.

[Mike Griffin]

OK, I have never been to VSC but Eric goes about every year so I am forwarding all of this to him for him to review.  So far all we have is something vague and I want to see if we can trace this back. I am not doubting anyones word but this supposedly happened 10 years ago and nobody seems to know who it happened to.  At this point we don't even know if it was the same type of ball link or what may have been done in the construction of them over the last 10 years.  I really don't think Eric Rule would put something on the market that was flawed in any manner. 

Thank you all for your input.

Mike

[Allan Perret]

My suggestion for Eric would be to just sell the pair of right and left hand 4-40 adapters and let builder supply his preference of end fitting.

[Mike Haverly]

It happened to a high profile pilot and I have an idea, but hopefully he'll pop up.  From California, I'm sure.  Thanks John for clearing that up.  I remembered you had an accident with a new airplane just as I arrived, must not have been the ball joint.

[Randy Cuberly]

I can tell you that nylon is not a good material of choice for use in dry hot climates.  The Nylon matrix is highly dependent on water for strength.  If it drys out over time it becomes brittle!

Could be part of a problem.

I am very interested in the stainless steel end fittings that slide over the 3/16 carbon shafts, with opposite threads and would like to obtain some!  They could make life easier!

Randy Cuberly

[eric rule]

First, a note of thanks and congratulation to Mike Griffin........ Another in the long line of excellent videos, Mike. You have become very good at this and I thank you on behalf of those of us who love to get new information  on products and construction "how to". Your videos are short, to the point and provide great data. Thank you for doing these.

Second, to Randy Cuberly.........I just sent off some of the "cup end" fittings to you. Give them a try and let me know what you think of the idea. You are one of those guys that I listen to so your comments will be appreciated.

Third, regarding the failure of ball links....... I am old enough to understand that not every product in the market is perfect and will never break. To the best of my knowledge I have never seen or heard of a ball link breaking. That is not to say that it has never happened- only that I have never seen this nor heard of it. I am certain that over the past 10-11 years millions of ball links have been sold and used on millions of model aircraft. I have not heard anything about them breaking and causing model aircraft to crash. If this were a regular occurrence surely we all would have heard rumors of this happening.

That being said; however, I never want to offer a product that is defective! If anyone knows who the person is who was supposed to have crashed in 2007 at the VSC due to a faulty or broken ball link please let me know. I want to speak to this person and find out exactly what happened to cause the crash, what brand of ball link he was using. What size of link was it. Did the link pop off the ball. Did the link brake or did the ball brake?  Without specific data all we currently have is a comment about seeing a crash and thinking or hearing that it was caused by a ball link. If anyone has some solid facts please get in touch with me.

Regards
Eric Rule

[Mike Griffin]

Thank you Eric.

Mike

[john e. holliday]

I'm going out on a limb on this as I think it was our stunt friend from the NW, Randy Powell.  If I remember right he left a plane in Tuscon with some one to keep for him.  I don't think either of them thought of the temp changes on what they would do to control components.  I also believe the plane went in on a practice while he was getting it retrimmed and or loosened up.  I think he stated the controls got very stiff and he tried flying the plane before loosening them up a bit.  Now don't hold me to this. Maybe Randy wil;l come on here and tell about the plane he lost at VSC.

I do know that some of the cheaper balls I've had would get stiff if not worked a lot or flown consistently.  I use Dubro 4-40 ball links all the time now.

[phil c]

RC car stuff uses a lot of ball links.  I think most of them are now using glass reinforced polyester, not nylon.  Poly doesn't absorb much water and is much more dimensionaly stable.

I'll try and get one and burn it to check.  Nylon smells like burnt hair.  Polyester just smells like smoke.

[Motorman]

blank

[Mike Griffin]

To answer these questions about weight, the only scale I have that measures in grams will not even register when I put the parts on the scale.  I do not own a sensitive scale that will register some thing that light.

Mike

[Randy Powell]

I like the pushrod ends, but wouldn't touch that type of ball link. As other's have said, I've had them fail.

[Mike Griffin]

I like the pushrod ends, but wouldn't touch that type of ball link. As other's have said, I've had them fail.

Randy are you the one who was using this type of ball link shown in my video that crashed at the 2007 VSC because it broke?

Thank you
Mike

[Randy Cuberly]

lol, I do the same thing cutting CF rod. Some smells like polyester resin and others smell like epoxy. Doesn't seem to make any difference in stiffness.

I like the idea of the one step glue on rod end but they look heavy and, is Stainless steel 4-40 strong enough for the full sized ships?

MM

The question of stainless steel screw strength depends a lot on the type of stainless used.  That said my guess would be that these are made from 300 series stainless (Just a guess) which is about 15 % lower in tensile strength than heat treated carbon steel like the type used in typical Allen Head cap screws.  My opinion is that it would be similar to the strength of the titanium ends sold by Central Hobbies but Titanium is subject to intergranular stress corrosion when used in continuous stress conditions!  I have had two such titanium rod ends fail.  Examination with a scanning electron microscope (can't tell you where that was done or I'd have to kill you)  , showed the failure was due to said intergranular stress corrosion in a small section (screw threads) likely due to improper heat treating!  UUhhhh I did work for a local Aerospace Company for a long time!
At any rate titanium is probably not the best material for small section screws.  It's my opinion that stainless steel may be a better material to consider.  Calculations for a small section screw made of 316 stainless show a nominal strength that should be more than adequate for the type of loads we would see in a stunt ship.  There is of course some guess work involved in such an opinion as to control loads etc. but the margins are large enough to support the opinion!  There are of course many other things to consider in such a situation, such as machining errors and assembly methods that can not be easily controlled in a purchase situation.

Some testing of the rod ends would go a long way to making the opinion more solid!

Randy Cuberly
PS:  One of the rod end failures was on my Road Runner during practice at VSC several years ago!  The ball links in that situation were DuBro links and were not involved in the failure!

[eric rule]

For those folks who are interested in weight I tried to weigh one of the fittings. Was unable to get a reading as my scale will not register that low. Ended up putting 20 of the fittings on the scale in order to get a reading. Twenty of the fittings weigh only 2.5 grams. That translates to each fitting weighing only 0.125 grams. Kind of insignificant weight at best when I've seen folks who stress about every 1/10th oz in the wood they use put 20 oz finishes on their models.

Randy Cuberly is absolutely correct about titanium (he would know if anyone does). I considered using aluminum but was concerned it would not be strong enough so decided to go with 300 series stainless steel.

To those folks who worry about which type of ball link to use I would suggest you consider purchasing only the fittings. Then screw whatever ball link you prefer on the ends. That way you will get all of the benefit of the push rod system and be using a ball link that you are comfortable with.

[FLOYD CARTER]

The ball links I have used are the black Nylon type using a separate 4-40 screw through the brass ball part. 

I test each ball link before use, because I have found some to be too stiff to use, even with oil and exercising the ball connection.

The ball configuration allows for slight mis-alignment without binding.  They have never failed me.

Floyd

[Mike Griffin]

For those folks who are interested in weight I tried to weigh one of the fittings. Was unable to get a reading as my scale will not register that low. Ended up putting 20 of the fittings on the scale in order to get a reading. Twenty of the fittings weigh only 2.5 grams. That translates to each fitting weighing only 0.125 grams. Kind of insignificant weight at best when I've seen folks who stress about every 1/10th oz in the wood they use put 20 oz finishes on their models.

Randy Cuberly is absolutely correct about titanium (he would know if anyone does). I considered using aluminum but was concerned it would not be strong enough so decided to go with 300 series stainless steel.

To those folks who worry about which type of ball link to use I would suggest you consider purchasing only the fittings. Then screw whatever ball link you prefer on the ends. That way you will get all of the benefit of the push rod system and be using a ball link that you are comfortable with.

I agree Eric and if you look up in the thread, I could not get a reading on my scale either and I even screwed the ball link on to add a little extra weight and still could not get a reading. 

Mike

[Fred Quedenfeld jr]

Well   Well
How much are the end fittings
How do we purchase he fittings???
Fred Quedenfeld AMA 58609

[eric rule]

As requested I have posted details of the push rod system along with prices for each component in the RSM Vendor's Corner.