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Old Nov 11, 2011, 12:13 PM
Late for work again!
Gary Binnie's Avatar
Northampton, England
Joined May 2004
1,900 Posts
Mini-HowTo
Multiplex Center of Gravity gauge

Hi folks,

Not wanting to get into the whys and wherefores of balancing machines versus fingertips I'd like to share some info and photos on this particular balancing machine.

The product number is 69 3054 and is currently available (like all good things from Multiplex there may be a day when it isn't!!).

I built the thing in a couple of hours (there were some tea breaks!) and took some photos along the way. It might be a simple thing but I had read that some modellers have struggled with it and consigned it to the bin without using it.

I'm posting this in the sailplane section as that seems to be what it was designed for (and what I will be using it for mainly) but it can balance anything under 10 kilos.

GB
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Old Nov 11, 2011, 12:28 PM
Late for work again!
Gary Binnie's Avatar
Northampton, England
Joined May 2004
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Just noticed I spelt 'Centre' wrong! It's spelt the commonwealth way on the box!

The instructions are mostly clear and come in German, English, French, Italian and Spanish. They are downloadable from the MPX website if your dog eats them.

First job is to assemble the base, there were two minor problems here. Some of the screw holes were blocked (plastic flashing, easily opened up) and the foot bars were not gripped by the plastic triangles when screwed together. I added some tape to the insides of the slots to stop them slipping.

Next job is to glue the pivot caps together and fit them to the balance beam holders.
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Old Nov 11, 2011, 12:47 PM
Late for work again!
Gary Binnie's Avatar
Northampton, England
Joined May 2004
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The next step (fixing the graduated scale) is critical.

The stop pieces and trim weights are added, and pushed up to the centre part to find the balance point of each bar and establish a datum for the scale.

The instructions are not particular clear here (at least they weren't to me!!) so I trod carefully. A complaint I read is that there is friction in the pivot which makes finding the neutral point tricky. There is some friction so I balanced the beams off of the gauge using a drill.

Once the balance point is found a pencil mark is made 'adjacent' to the stop piece according to the instructions. It was not clear which side of the stop piece they meant to make the mark but it is on the side away from the centre piece.

What they are saying, in a round about way, is that the scale zero (which is not there because it stops at 30 mm!) should be in line with the pivot/balance point. Pictures might explain it better.

The centre pieces are then fixed to the bar with cyano.
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Old Nov 11, 2011, 12:54 PM
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United States, OK, Moore
Joined Jan 2006
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You spelled "center" correctly. And this device, if not in appearance, at least in service, is very much like this one: http://www.greatplanes.com/reviews/gpmr2400-man.html
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Old Nov 11, 2011, 01:07 PM
Late for work again!
Gary Binnie's Avatar
Northampton, England
Joined May 2004
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Last post in this 'mini-how to'.

I refitted the steel pivot pins with a smear of margarine on the plastic parts where they grip (believe Keil Kraft kits used to recommend this method of lubricating propeller thrust buttons on the rubber models). It does help to free them up.

A few sticky rubber pads on the feet and balance bars and that's it.

I placed my latest acquisition on the gauge (an early Multiplex Fiesta with built-up wings, but not entirely sure!) and it works nicely.

Contrary to the disclaimer at the shop I got it from it will go back in the box (just) if you don't glue the pivots on.

Hope this helps anyone who is thinking of getting one of these.

Cheers

Gary
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Old Nov 11, 2011, 01:20 PM
Late for work again!
Gary Binnie's Avatar
Northampton, England
Joined May 2004
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Quote:
Originally Posted by LVsoaring View Post
You spelled "center" correctly. And this device, if not in appearance, at least in service, is very much like this one: http://www.greatplanes.com/reviews/gpmr2400-man.html
Yep, much the same and a similar price. Don't know why but we seem to seeing less American products over here lately, I've often used the Dubro pull-pull cable sets but haven't seen any lately.

Seem to be seeing less British stuff as well come to think of it!!

GB
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Old Nov 11, 2011, 03:45 PM
Detail Freak
target's Avatar
Harbor City, CA
Joined Oct 2003
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I have one of these MPX balance stands. LOVE IT!

R,
Target
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Old Nov 11, 2011, 07:08 PM
cq cq de kr4is
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USA, VA, virginia beach
Joined Jan 2011
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Don't know why but we seem to seeing less American products over here lately,


GB[/QUOTE] china does a better job of munipulating the value of dollar than
obama and timmy g. do. and the oil cartell prices their oil by the power of the dollar,,,....my partial opinion as to why.
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Old Nov 13, 2011, 08:53 PM
Registered User
United States, TX, Houston
Joined May 2003
547 Posts
I had the Great planes balancer. I don't recommend it. The plastic rulers that tell how far from the leading edge to the CG slide and shift and are difficult to read. I threw mine in the trash.
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Old Nov 13, 2011, 09:01 PM
Detail Freak
target's Avatar
Harbor City, CA
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Quote:
Originally Posted by Hoot View Post
I had the Great planes balancer. I don't recommend it. The plastic rulers that tell how far from the leading edge to the CG slide and shift and are difficult to read. I threw mine in the trash.
+1

The MPX unit is much less rickety as well.
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Old Nov 14, 2011, 10:51 PM
R2R
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St Johns, FL, USA
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Quote:
Originally Posted by target View Post
+1

The MPX unit is much less rickety as well.
++1
I use the GP one without the rulers, and it works fine as just a balance stand. Measure your desired CG ahead of time and mark on some masking tape. Then use the stand to balance model until it balances on your masking tape mark.
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Old Nov 15, 2011, 12:12 PM
Will fly for food
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Bellevue WA,
Joined Dec 2003
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The Great Planes stand will hold a 15 lb airplane but not much more than that
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Old Jan 14, 2012, 05:51 PM
Gravity Test in Progress
United States, WA, Tacoma
Joined Jul 2010
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Quote:
Originally Posted by Gary Binnie View Post
A complaint I read is that there is friction in the pivot which makes finding the neutral point tricky.
If you look closely at the inside of the forks/tongs of piece #11 where the hole is for the pin you can see and feel a raised surface designed to be a "washer" to keep it centered between the piece #12. What I found on mine was that this made it too tight.
I trimmed these "washers" off using a sharp Exacto scapel and this made a big difference. It is now like a "jewel" movement.
This space doesn't have to be an interference fit, you don't need to worry about side to side motion here. With these "washers" trimmed off it is not going to affect the balance fore and aft of the CG.
You have to be careful though because if the scapel digs in you might just cut the tip off and that would ruin your whole day!

Also, the scale has got adhesive is on a paper backing. You do not need to glue it to the balance bar as you can peel it and stick it to the bar. What I would recommend is to peel a small section of it from the unmarked zero end and fold the paper under making a nice flat crease so that it lays flat underneath. Line up your 45 mark, lay out the length of the scale and hold it down in place. This allows you to get it lined up correctly along the bar while you press down at the zero end to start it sticking in the right alignment. Then you can lift the scale and begin pulling on the piece of paper out toward the end pressing it down along the bar as you go.
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Last edited by .Steve; Jan 14, 2012 at 08:32 PM.
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Old Feb 19, 2012, 02:37 AM
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JetMech2002's Avatar
United States, MO, Sedalia
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Does anyone have a source for these?
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Old Feb 19, 2012, 04:00 AM
Gravity Test in Progress
United States, WA, Tacoma
Joined Jul 2010
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Quote:
Originally Posted by JetMech2002 View Post
Does anyone have a source for these?
It is not carried on the Multiplex USA website.
I would be pretty sure Staufenbiel's here in Germany could order one for you and ship it. I didn't see it on there website either, but it would be easy for them to order for you.
I was just there yesterday and did not notice whether they had one, but I wasn't looking for one.
http://www.modellhobby-shop.de/Model...&t=3&c=39&p=39

Email them with the multiplex part number: 69 3054.
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