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Bos Model Claw (by Johan Bos aka Pfuf)


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Bos Model Claw

By Johan Bos

Available from Johan Bos (Pfuf) for € 75,- (Adjustable arm not included)





With the sudden surge of WW1 biplane models, the ‘need’ for a tool or jig to hold all those wings in place in order to align them and apply the rigging without damaging your model became imminent. We saw the Aeroclub Biplane assembly jig for instance. It allowed to carefully set the jig to the right angle of attack and make sure everything lines up. See photo as used by Paul Thompson:




And we also saw a whole range of wooden laser cut examples like this one from JHmodels:




Thus far I’ve managed to restrain myself. Mostly because these jigs only serve one goal: rigging a ww1 biplane. Since I build a lot of ww2 subjects as well in a wide variety of diameters, I’ve been holding back until something more flexible and versatile came along.


I have seen our fellow forum member Pfuf (or Johan Bos) working with a self designed and machined contraption which allows him to turn, bank, twist the model in all directions, while a the same time not blocking his working area too much. When he messaged me and told me he was en route to produce and market his contraption I knew I had to have one…


The device

I’m not calling Johan’s invention a jig, because that would not cover all the bases. I’d rather call it a claw. It sits on a flexible arm (not included in the set) and grips rounded hooks carefully around the wings or fuselage without damaging the model.




Let’s start with the arm.

This is an important part of the ModelClaw and was not fabricated by Johan. It’s a technical tool that you might find in a specialized store for lab-workers or engineers(?). It’s produced by NOGA. An Israeli company that produces high quality holding systems. It serves as a weight and steady base on which to work from. The heavy foot contains a magnet that can be turned inside with a knob: releasing and engaging the magnet when placed on a metal area. Let me say here that the weight of the foot is sufficient to carry a single engine 1/32 plane. It even holds my He219, unless you off centre the claw too much. Half way up the arm there is another know that secures the entire arm when turned tight. When turned loose the entire arm turns limb, allowing the model to be positioned in any desired pose. This is a feature that I love most of the Claw. It enables you to detail and weather paint the underside of your model, twist the knob, and lets you work on the sides. Pretty cool. The price of this part (NOGA arm) alone retails for 104 US dollars. Important to state is that this part is not included in the ModelClaw set. You can get the NOGA one or a cheaper chinese alternative.


At the end of the arm there’s a hole where the base of the claw is clamped in. And this is where the real fun starts…




The Claw

Johan designed all the parts that make up the Claw in 3D software and had the parts machined. When you unpack the box it resembles Meccano in a lot of ways. The main components consist of U-beam rails, flat 90 degree hooks, support frames, mounting blocks and a selection of nuts and bolts. From this point you can do two things. Look at the manual and examples of Johan’s constructions on the forum. Here for example. And he also made a movie demonstrating the ModelClaw:



What you can also do is look carefully at your model at hand and get creative. In the end we’re all modellers aren’t we? Depending on what type of plane you’re building you can find places where you want the ModelClaw to grip. Especially considering the places you want to reach and not let the ModelClaw block your working area. The only tool you’ll need is a Philips screwdriver and you’re good to go.







I think the most common way to build your Claw is to start with the main beam that runs parallel with your fuselage. Then you can decide where to place a cross beam and 90 degree angle supports that hold the actual hooks. A special support frame is also supplied to support the tail or rear fuselage of your plane.





When the model is in place you can loosen long soft plastic screws to release the hooks. Enabling them to twist and extend. Place these over the wings and fasten the screw. This can be done by hand and you don’t need a screwdriver for this. Since ho hard pressure is applied to your model, you don’t have to be afraid your surface will receive damage.






I have used the ModelClaw for a few weeks now for my He219. The wings on my 219 are still loose (not glued) but the ModelClaw holds everything in place. Enabling me to align tail, wings, fuse and other parts until I’m happy. As soon as I reach painting stage I’ll place the He219 in the claw to allow me careful work on the mottling and weathering.


Since I am now a little side-tracked by the Ar234, I might alter the jig a little to accommodate my Arado.



Conclusion / Verdict

I think we have all experienced damage to our paintwork by handling the model with our bare hands. Trying to lay our model on it’s back on a improvised stand in order to paint the bottom. Snapping off a radial or wheel well door when trying to reach a difficult spot and missing a hand. That’s where the ModelClaw proves it’s worth. We have seen similar solutions on the market before but they are limited in their use and flexibility. I don’t think a model can be too small or too big (just remember to attach the magnet to a solid metal area) to use with the ModelClaw. Johan Bos is clearly a clever engineer that puts his talents to use of the modeller. In first place himself and it’s up to us to profit from his inventions if we like.


From 1 to 10 I’d rate this set a 8. A tool that will add comfort and ease to the bench.


Very highly recommended



Our sincere thanks to Johan Bos (Pfuf) for the review sample. To purchase directly, send an e-mail to Johan Bos: bosmodelbase@Hotmail.com




If (and only if) Johan reaches 50 pre-orders the ModelClaw will see production. You will receive a parts list, instruction manual and all the parts you need. Remember: the arm is not included. You can order it for 75 euro’s or a cheaper version from around 25 euro’s. The ModelClaw itself costs 75 euro’s.



Jeroen Peters

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  • 4 weeks later...

Jeroen, I'm very much interested in this claw do you happen to know what size NOGA base arm that Johan used I found a place here to purchase them but want to make sure it's the right one if and when I do recieve my CLAW.



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  • 3 weeks later...
  • 2 years later...

Love that thing, thanx for showing. (edit: just seen that this is an old thread, but my biplane-question remains and is enhanced to "what are the users thinking"-questions)

Actually I'm loking for a "Jig", a solution for all my large scale planes and found JH Models and Vertigo ones. I prefer metal to acrylic or wood for theese kind of tools, so I was amazed seeing this one by BOS and tend to go that way.

One thing I couldn't see in the review and in the video is the ability to rig a biplane with a properly alignment of both wings. I would be interested if there is a possibility.

Cheers Rob

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