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How do I make the slots in the Cathead?


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31 replies to this topic

#21
egkb

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Thanks D, another clever method to add to my list.. the more I think of this method the more I like it (especially if you are painting the Cathead as that would cover up the Laminate.. so to speak !)

 

Have a great New Year.

 

Eamonn


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#22
Mike40

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This is a very easy job for a scroll saw. Just drill the two holes, insert the scroll saw blade and cut first on the far edged of the first hole to the second and then repeat on the other side and  you are done. I think every model builder and woodworker should have a scroll saw. They are VERY handy tools to have for so many different tasks.


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Mike,

an American living in Norway

 

 

Current build:  Galley Washington - 1:48 - Scratch POF - NRG plans

 


#23
jbshan

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If you are not going to be using actual sheaves, but leaving some of the wood in the slot to simulate them, try drilling your two holes each than shaping as if there were a sheave in there using a 'reamer'.  This is a small, tapered, four-sided drill bit sort of thing that you merely twirl along where the sheave should be.  It won't grab like a drill and you can shape it fairly precisely.  You will be putting line here, so make it deep enough so the line can curve around as if there were a sheave down in there.  It isn't as aggressive as a file, and is less severely tapered; you can also use a reamer to clean out drilled holes without enlarging them too much.


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#24
Chazz

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You can also put a coping saw blade in a pin vise and saw the slot directly between the drilled holes.  They come in many sizes, even round ones that will cut in any direction.

 

Chuck Ward


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#25
wefalck

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If the cat-heads are to be painted, one can also build them up from layers, leaving a space for the slot. The sheaves then can be added later.

 

Btw, the reamers mentioned above have five sides not four, at least those that you normally get from watchmaking supply houses. A four-sided reamer would not cut, but just dig in.


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wefalck

 

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#26
jbshan

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wefalck, I'm not sure of the intended use, but mine all have four sides.  They came from a hobby shop.


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#27
wefalck

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I was talking about this kind of broaches or reamers:

 

image.jpg

e.g. from https://www.eternalt...g-broaches-set.

 

They come in sets of different sizes up to 2.5 mm I think.


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wefalck

 

panta rhei - Everything is in flux

 

 

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#28
jud

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Reamers need 5 or more cutting edges to prevent being forced into the material and cutting, breaking or jamming. Often you will find reamers with 5 or more cutting edges not symmetrical in their cutting edges around the center, 'odd spacing to prevent chatter'. There are drilling devices made to drill square holes in wood, never have seen any small enough for model applications, they are high speed drill bits within a square cutting guide with chisel corners.

jud


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#29
wefalck

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Yep, this square-hole drilling or rather milling devices always fascinated me. There is a nice animation on YouTube:

 

https://www.youtube....h?v=L5AzbDJ7KYI

 

It's a bit like a Wankel rotary-engine ...

 

However, the slots in the cat-heads do not have to have sharp corners at all. I gather on the prototype one would drill two holes at the ends and then chisel-out the wood in between. Using a fret-saw, a scroll-saw or a filing-machine would be closest to the prototype. In small scales there will be limits due to the width of the saw-blades that would need to fit through the hole at one end.

 

Another option would be to use a reasonably precise drill-press as morticing-machine. Grind a chisel-edge onto the drill you used for driilling the end-holes and chuck it up the 'wrong' way around. With this you can nibble away the material between the holes. If I had to do this, I would use my hand-shaper, even though it would somewhat cumbersome for small model work.

 

If you have a lathe with a hand-lever tailstock, you can use this in the same way, with added advantage that you have very controlled feed for the morticing operation through the top-slide of the lathe. You would need to devise a way to fit a vice on the cross-slide, perhaps with a vertical milling slide.

 

As these deep, narrow slots are recurrent machining problem, also in the production of blocks, one may want to construct a small morticing machine for that purpose ...


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wefalck

 

panta rhei - Everything is in flux

 

 

M-et-M-72.jpg  Banner-AKHS-72.jpg  Banner-AAMM-72.jpg  ImagoOrbis-72.jpg

#30
jud

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www.amazon.com/Uxcell-Hollow-Square-Mortiser-Chisel/...
This is more like I was thinking about.
jud

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#31
WackoWolf

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Thanks for the YouTube link.


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Wacko
Joe :D

Go MSW :) :)

#32
JerryTodd

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There's also lamination, especially for things that will be painted. 

 

con20150505a.jpg

 

con20150505b.jpg

 

con20150504b.jpg

 

con20150504e.jpg


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