Should I bother with a fuselage jig ......

[toto]

So ....... the debate shall rage ..... A fuselage board ....... or not ..... that is the question.

 

As many may be aware, I have just recently built a model building board with a Sundeala top surface to accept pins and assist in the building of model kits. I'm sure that it will be well used and pay its way. it is currently being pressed into service in the building of my very first model ... the Tony Nijguis Sky 40.

 

Its been asked if I have a Fuselage building board which the answer is no .... at least not yet anyway. I had been considering making such a beast utilising the popular SLEC gridded paper ( as you will see below shortly ). 

 

However, as mentioned, I had been considering it to the point that I went out and bought the beginning of what would have been my choice of construction materials for it ...... as follows.

 

The SLEC gridded paper with self adhesive backing ....

 

 

this measures 1.2m x 370mm .... call it 1.2 x 0.4m

 

Stainless steel right angled brackets ( as vertical supports ) which measure 100mm x 120mm and I have 18 of these.

 

 

these are very rigid and don't bend when pressure is applied.

 

 

M5 x 35mm wing bolts ....

 

M5 Captive nuts

 

6mm washers

 

and my own addition to this build .....

 

 

A perspex cover sheet ..... which I appreciate that you can't see through the protective packaging which measures 1.2m x 500mm

 

I would need to add a base board of 18mm thick MDF as per my build board and a couple of stand off legs as per the build board. All in all a 1220mm x 610mm standard size sheet would easily do the job.

 

My plan would be to cut the MDF to suit the SLEC grid and stick the grid down. Cut the perspex to size and lay over the grid paper. Secure the perspex at each corner with a screw through into the MDF to keep it all fixed. Bore through the holes as pre-marked on the grid paper ( and the perspex ) to take the 5mm wing bolts ( making any additional holes as think necessary ). I would drive the captive nuts into the underside of the MDF but not before making say a 5mm deep countersink with an appropriate sized forstner bit ..... a bit like this one .....

 

 

The above would see the captive wing nuts countersunk into the underside of the board for a neater job.

 

Once done and the captive nuts driven into place ........ feed wing bolts through the brackets and into the captive nuts. These can be slackened in order to move the brackets to suit.

 

The question is ........ is the work required worth it for this particular model ..... or do I go off the straight as shown in the models plan of the fuselage.  ....... any comments etc as always ..... very welcome ..... but sooner rather than later.

 

Just thought I would through this out there for discussion.

 

cheers

 

toto

 

[Don Fry]

What’s the Perspex do, Toto?

[toto]

The perspex was just really to act as something to protect the grid when brackets are constantly being moved around on the top of it. It can only add rigidity as well. It doesn't need to be added at all if there is any disadvantage though.

 

toto

[GrumpyGnome]

Probably overkill for the model you are currently building.....

[toto]

I do tend to agree with you grumpy .... It was my original thoughts.

 

the fuselage in the SKY 40 seems to be made up of a basic few " composite parts " as opposed to a fuller build that has all the bracing pieces formed and glued together separately.

 

 

In my mind .... there is less potential for things to shift or move anywhere.

 

 

A fuselage jig as such is a good shout for building fuselage's as such and more so where you have all the individual diagonal and vertical braces holding say 6mm square stock uppers and lowers together. I think Tony's design was done in mind to make it easier to achieve a " square " or " straight " fuselage without the intricate nature of a more traditional build.

 

I think the suggestion of having a fuselage build will rage on from modeler to modeler in general and I am of the belief that they are worthwhile having ...... I think the fact that I have bought most of the materials to build one proves that but maybe just not for this model.

 

I hope I wont be made to eat my words. 😄 another one of these ..... " I told you so " moments.

 

decision made.

 

toto

[Caveman]

Toto, my take on this, ditch the Perspex, it's not needed. A 1200mm long board should be adequate for 40 size models.

 

For the Sky40, which is, to some extent self jigging due to the interlocking nature of its design, a jig probably isn't needed, but build the fuselage over the plan to ensure that when you draw the tail in both sides bend equally in order that you don't build a banana 😀

 

When you come to make other models where the formers don't interlock with the sides then a jig comes into its own.

 

In general a fuselage jig is one of the most useful bits of tackle you can have. This is mine in action, I couldn't have made this fuselage straight and true without it.

 

 

GDB

[leccyflyer]

Agree with the above, the persex is unecessary complexity, but a fuselage building jig is one of the best bits of kit that you can have. Highly recommended.

[David Davis]

I wouldn't be without mine. It's the best investment I've ever made in modelling kit.

 

 

[gangster]

9 hours ago, leccyflyer said:

Agree with the above, the persex is unecessary complexity, but a fuselage building jig is one of the best bits of kit that you can have. Highly recommended.

Yes I agree. I had my last sSLEC jig since the mid 80s. Certainly no need for the Perspex. It was built on a piece of contiplas. The only reason I replaced it was as a result of a house move and packing was a nightmare. Have got another one now

[EvilC57]

I wouldn’t be without mine. And as others have said, don’t bother with the Perspex. Although I have used a sheet of thin polythene before, to stop the fuselage under construction from sticking to the jig - especially if using cyano.

 

[Jon H]

Given the square nature of the model you are building i would skip it. I dont have one and am yet to build a banana so i question their usefulness personally. In your current case, just build the forward box section then pinch the tail together after it is all solid at the front end. Sighting down the fuselage will clearly show any deviances from straight. If you are short of squares, cd cases are excellent stand in's and they also double as reusable epoxy mixing trays, which is handy. 

 

While it is always important to strive for accuracy its not critical down to the thou. I know a chap who was going to scrap an entire wing as plan shrinkage caused one wing panel to be about 3/8-1/2 inch shorter than the other and it was going to be all out of trim and blah blah blah. I recommended he fly it before burning it and to the surprise of no one (except him), it was fine. 

 

I have also found over the years that measuring certain things (like wing tip to tail) is a total waste of time and you can just look at it to tell if its straight. Its very obvious when something is bent or out of alignment so dont loose too much sleep trying to measure everything to the Nth degree of accuracy as you will simply go insane. 

 

 

 

 

[leccyflyer]

Looks like a no-brainer in this case, given that toto has bought almost all of the components to make a building jig. I certainly wouldn't be without mine and I have previously built a banana by just eying it up over the plan and trusting on tape to hold the rear end together in the right place. The thing about the jig is that it holds the work in place, nice and secure, whilst the glue is curing. If using wood glues you have a nice leisurely set up time, you can check everything is square -mark a centre line on each former, make sure the centre line of the jig grid lines up with them, make sure that each pair of uprights are aligned to be offset from that centre line by the same amount. Check with your squares and then the work is supported throughout the setting time - that's the basic function of a jig, to hold things in the correct position during assembly. If you don;t use the jig then you just need to come up with an alternative means of holding everything in the correct place - you're essentially making a makeshift jig anyway.

[Andy Stephenson]

Putting the wing nuts underneath will be a real bind when it comes to the fine adjustment of each of the brackets. You will need to see the top side whilst tightening the nuts underneath, much easier to have them on the top.

A jig isn't always necessary with some builds but it is essential with something like this...

[kc]

A fuselage jig is the way to go!

The way I use the fuselage jig is to first mark centre line of each former, assemble the fuselage 'dry' ( without any glue)     centralising the centre marks on each former over the centre line of the board.   Then gradually moving all the brackets to achieve perfectly accurate alignment.     Then remove all brackets ONE SIDE ONLY leaving the other side bolted down.     Take the fuselage apart and apply glue.   Replace in jig moving the removed brackets back into place pushing onto the fixed brackets which makes alignment easy.    Leave for glue to FULLY set before moving - 24 hours for PVA or aliphatic.

 

You mentioned Super Phatic setting time somewhere -   I found it takes 24 hours to set hard.   The low time mentioned are just not enough.   Try a sample on scrap wood and see!     Moving a fuselage before it sets really hard can cause a bent or weak fuselage.

 

[Cuban8]

I've had my fuselage jig for well over 30 years - have resurfaced it with cork as discussed elsewhere. I bought it from the now long defunct South Yorks Models and it's been an absolute boon - solidly made with very substantial brackets etc.

Must say that I had to read Jon's posting a couple of times to make sure I wasn't misunderstanding it. True, we don't need to build to full size aerospace specifications but I think it's nice to at least strive for the best accuracy that one can attain and go about it as best as we can.

I disagree that "measuring is a waste of time" because although the Mk1 eyeball is pretty good generally, people's perception does differ and measuring  can highlight  other errors that just simple eyeballing might miss IMHO. I always measure and check my builds to within an inch of their lives including inclinometers to check rigging angles.......not because I'm paranoid, but it just gives me confidence that I haven't missed anything that might catch me out later.

If you can do that all by eye then that's fine - no big controversy, whatever works for the individual.

 

Edited October 6, 2023 by Cuban8

[GrumpyGnome]

The fuselage in question is sooooo simple, a jig is complete overkill........................ yes, a good idea for more complex builds.

[Simon Chaddock]

I to basically agree with Jon-Laser Engines.

Over the years I have build quite a number of balsa models and as suggested if there is a basic box section to start with then careful use of the Mk1 eyeball works well.

The same technique can be very useful in detecting warps and twists that can develop over time and from repairs.

 

No harm in using a jig but being old scholo I do an eyeball check on anything I have built and also a 'comparison' check if there are two indentical components.

 

 

  

[Tom Gaskin 1]

I've had my SLEC jig for some time now and find that it really comes into its' own during a re-build! Getting the 'jigsaw' straight is so much easier.

 

Tom

[Jon H]

35 minutes ago, Cuban8 said:

I've had my fuselage jig for well over 30 years - have resurfaced it with cork as discussed elsewhere. I bought it from the now long defunct South Yorks Models and it's been an absolute boon - solidly made with very substantial brackets etc.

Must say that I had to read Jon's posting a couple of times to make sure I wasn't misunderstanding it. True, we don't need to build to full size aerospace specifications but I think it's nice to at least strive for the best accuracy that one can attain and go about it as best as we can.

I disagree that "measuring is a waste of time" because although the Mk1 eyeball is pretty good generally, people's perception does differ and measuring  can highlight  other errors that just simple eyeballing might miss IMHO. I always measure and check my builds to within an inch of their lives including inclinometers to check rigging angles.......not because I'm paranoid, but it just gives me confidence that I haven't missed anything that might catch me out later.

If you can do that all by eye then that's fine - no big controversy, whatever works for the individual.

 

 

I am not suggesting you dont measure anything, just certain things. 

 

The classic wing tip to tail measurement is a total waste of time as a tiny build error can be multiplied many times due to the distances involved. Say the tip of one wing is 1/4 inch longer than its mate, and/or the wing half a degree off perpendicular. this will cause a measurement difference to the tip of the tail. But you line it all up with equal measurements and to your surprise the tail looks crooked and measures as crooked when you take its centreline to its tip. So you straighten that out but now the tip to tip measurement is wrong....etc

 

Just forget it, as long as its all basically straight it will be just fine. In my case with largeish WWII fighters i will not be worries about a few mm of deviation on an 80-90 inch wing. It will make no difference to the model at all and will be completely invisible. 

 

We also make models from wood, which can change dimension as it wants, and even laser cut parts are hand finished so are not identical. We then pin them to a paper plan by hand and move forward with the build. Anyway the point i am trying to make is that the way we build models is inherently inaccurate and so the final result will also be inaccurate. While we would like these inaccuracies to be as small as possible they will crop up and for the most part do not matter. If the error is small enough that you cannot see it, it is unlikely to cause any problem for the model in the air. 

 

More specifically on fuselage jigs though, i build too quickly to mess about with the stupid thing. I find they get in the way of the build, take up loads of space and are generally a complete inconvenience. As i am yet to build a banana without one i do not see what value they bring to the table, especially on a simple build like this. 

 

 

 

 

[toto]

A quick note for Andy,

 

I am putting the captive nuts underneath. The wing nuts will be as everyone elses ..... on the top of the bracket for access to adjust. 

 

Thanks for raising it. If I have stated otherwise it's been an error.

 

Cheers

 

Toto

[john davidson 1]

Even with slab sided fuselages errors can occur, when I first started with depron slabs  a banana resulted so had to throw it away and got out the Slec jig

[Geoff S]

I wouldn't be without my SLEC fuselage jig. I've had it years and built many models using it, including a boat hull.  It's not just handy to get a straight build but as a means of jigging the parts and holding them in place as the glue sets. Of course, you can manage without one. It's just easier with it.

[kc]

You might want to consider the 'screw in'  type of M6 captive nuts sold by Screwfix.   They are inserted into a hole with an allen key and sink flush with top or you can insert underneath  ( also flush ) for more strength.   A few inserted into workbench means you can fix any sort of accessory or jig etc on worktop and remove to leave a flush worktop.

[Erfolg]

We all seem to agree that the Perspex is not essential. However why not if that is what you want to do, for me overkill.

 

My jig is not even a SLEC offering.

 

Others may think my own is crude. My jig is made from Ply,  what appears to 15mm, 3 ply. Due to its relative instability I have 1.5"* 1" PAR side rails and few cross rails.

 

I drew various coloured lines along its length, the whole lot then varnished.

 

The fastenings are SS nuts pocketed into the rear surface. Which were pulled into the  under side of the board having  countersunk the holes, then Cynoed around the edge.

 

My brackets are simple pieces of ply, with some routed bits of wood re-enforcement. The brackets held in place with SS cap heads (5 mm), with SS washers

 

I do not use my jig often, although in use at the moment.

I have a wing board built in a similar daily use manner (it is mostly on top of the jig board) which is in mostly daily use.

 

Both from of cuts, costing, nothing in reality. Crude compared to what is proposed.

 

An aside, since my Cataract operation, I use cheap spirit levels more than ever, I do not see close up things with the same accuracy as previously. I also do not seek thou accuracy, if I was still capable of such things.

[kc]

Screwfix call the captive nuts  "Insert Nuts"   50 for 5.99    Too heavy for wing bolts I reckon but great for workbench.