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Building Tips and technical articles. => Building techniques => Topic started by: Mike Griffin on August 25, 2016, 10:55:04 AM

Title: Using a magnetic building board
Post by: Mike Griffin on August 25, 2016, 10:55:04 AM
This is a wonderful way to build a wing.  This is a wing for Mikey Pratts Primary Force

Here is the link where you can buy the magnets


http://www.magnetsource.com/airfieldmodels/
Title: Re: Using a magnetic building board
Post by: Mike Griffin on August 25, 2016, 04:36:16 PM
1/2" X 1/2" leading edge and trailing edge sheeting now installed.
Title: Re: Using a magnetic building board
Post by: john e. holliday on August 26, 2016, 11:55:51 AM
I have one of the first magna jig boards that was used a couple of times.   But I question you on your bell crank mounting.   Is it back wards? ???
Title: Re: Using a magnetic building board
Post by: Fredvon4 on August 26, 2016, 04:01:20 PM
I actually prefer the BC (using the hi low offset 3 or 4  inch version) with Push rod inside

This causes the up line, for a bottom mounted Elevator horn, to be the front control line... pull line/Push rod for up  but this is just me and I learned it really does not matter

With combat planes the stab/elevator horn is usually on top so UP line is in front...easy to remember

About magnet building... I invested in this method a while back and use the crap out of it even for 100% profile building...I never did invest in all the holding fixtures  but do use a Pat king carbon rod wing jig WITH the magnets... and a set of laser triangle squares from Walt....Now if I could just have the eye sight to select a truly straight piece of wood I might get a warp free straight wing

BTW my magnet set came from a supplier WITH holes and two metal side plates on each of the 100 magnets.... many are used without the plates as they are easier to slide around...but for setting ribs square, I use the side plates as they can BOTH hold the rib square, and if pinched tight, hold it upright in height for CA or real good gluing

Title: Re: Using a magnetic building board
Post by: Mike Griffin on August 26, 2016, 08:34:23 PM
Doc I have several planes with the bellcrank mounted that way.  They fly fine

Mike
Title: Re: Using a magnetic building board
Post by: Larry Renger on August 27, 2016, 11:01:31 PM
Could you give a close up of exactly how the magnets grip the ribs? Nifty construction technique but not quite clear
to this bear of feeble fbrain. (See Winnie the Pooh)

Do you have 2 different sizes of magnets stacked, or a passive spacer between the two main magnets to grip each rib?   ::)
Title: Re: Using a magnetic building board
Post by: RknRusty on August 27, 2016, 11:41:27 PM
Doc I have several planes with the bellcrank mounted that way.  They fly fine

Mike
On my recent Twister build, it would have allowed me to put the pushrod exit hole on the inboard side, keeping the rods and links away from most of the exhaust stream. I decided to just mount it normally and now I regret that decision. They do work just the same either way.
Rusty