egkb

How do I make the slots in the Cathead?

32 posts in this topic

Hi All,

 

I have a question and hope I've asked it in the correct place..

How do I make the 'slots' for the sheeves in the Cathead's, I understand the 'drilling 2 holes and joining the holes' method, alas it is the 'joining the 2 holes' that is causing the problem with this method.  I have even considered marking where the 'slots' go then cutting the end off the Cathead level with the outboard edge of the slots, then either sawing or filing down to the inboard end and gluing the 'cut-off' end back on.

 

Any and all suggestions welcomed, including the 'Forget about them and go for a pint instead' method !

 

Incidentally, my carpentry skills wouldn't pass muster (I just about know what a saw is :) ) so please please take this into account.

 

Thanks in advance,

 

Eamonn

Apologies to Moderators if this is in the wrong section

 

 

Share this post


Link to post
Share on other sites

Good day Eamonn.

 

First, the forget about it and go for the pint only works once. Sooner or later those catheads will be back before you so best to just deal with 'em :)

 

I do have wood experience although lots larger than these little boats but a cathead with slots was a first for me too. I drilled two holes at each end, and another two inbetween. I then found some really thin, really thin I say again, sanding cord. It is like a thread with abrasive stuck to it... and I inserted that in one hole and slowly pulled up and down from the first hole to the second and so on until I had a slot. The first time it looked poor, second time it looked average and by the time i was done I was satisfied. Next time, probably even better,... maybe ;)

 

So, there you go,,, the way i did it. :P

augie, EJ_L, egkb and 1 other like this

Share this post


Link to post
Share on other sites

I have some very small carving chisels. I make 2 holes and then cut out the wood between them to represent the sheave spaces. Looks pretty good, but I also really like the sanding cord idea, if one could find the right diameter.

EJ_L and egkb like this

Share this post


Link to post
Share on other sites

Thanks Randy and HSM for getting back so quickly.. really like the Sanding Cord method, and the idea of leaving some wood behind to represent sheeves (though on re-reading I think I may have mis-read your suggestion HSM but my mistake might work too:) ) I shall try both and see which works for my limited ability (might even be able to combine both suggestions and use the 'cord' to sand down to a fake 'sheeve' Hmmmm might be on to something there)

 

Thanks again guys

 

Eamonn

Share this post


Link to post
Share on other sites

First connect the tool holes by defining the slot....you can do this by cutting some shallow lines with a sharp blade from one hole to the other.  This will help keep the slot neat with some sharp edges as you remove the material between the two stop cut lines.  Sharp chisels and small rasps or files are a must as well when trying to round off the sheave.

 

Chuck

 

simsheave.jpg

 

simsheave1.jpg

 

fixedblocks1.jpg

 

 

 

Share this post


Link to post
Share on other sites

I have had lmiited success with the drill holes method.  It depends on the hardness of the wood and the scale you are working in (and if you can drill straight!).  I usually opt for cutting the end off (or cutting to length minus the end cap), making the slots (easier with three sides exposed) then putting a cap on.  For the cathead this also helps if you are planning on decorating the end piece.

 

On my Druid I had to do this for my chesstrees and was very successful with the cutting out and putting a cap on.  It is a case by case basis.

 

Cheers,

Mark

Share this post


Link to post
Share on other sites

Thanks Chuck,

 

This is exactly the result I had in mind by combining the methods of Randy and HSM (even though I mis-read him), I was thinking of feeding the Sanding Cord through both holes and gently pulling it back and forth.. I shall put those needle Files and small chisels on my 'To Get List'.

 

Model Ship World rocks

 

Eamonn

Share this post


Link to post
Share on other sites

Hey again Mark, fancy meeting you here :)

 

The 'cutting the end off' was the direction I was heading prior to discovering MSW as drilling straight was indeed an issue.. but I think it is about time I learnt to do this skill and at least try to live up to the standards on display here, there is this chap bashing a 1850's clipper called the Lady Anne that I'm following, and his standard is to be envied :) so it's time to up pick up my abilities I think.

 

E

Share this post


Link to post
Share on other sites

I find that drilling half way through on one side and then flipping it over and drilling from the other side works well.  The bit will meet in the middle and it is easier to keep the hole straight.  You also dont get any ragged edges where the bit works through the other side.

egkb, fnkershner and druxey like this

Share this post


Link to post
Share on other sites

Thanks again Chuck, am looking forward to giving these a go in the next few days, I won't require the cathead until then (and other deck furniture has to go in place before I can determine it's exact placing, my model didn't come with comprehensive plans, just sometimes vague photos and text which can leave a lot to be desired, fun though as long as I plan ahead... learned that the hard way!)

 

Eamonn

Share this post


Link to post
Share on other sites

Eamonn,

 

I use Chuck's method.  If you drill from both sides you get perfectly centred holes and if you've gone a bit astray the problem will be in the centre of the work and not showing on the outside.  For filing out the slot to make the dummy sheaves I use watchmakers round escapement files.  If you go to a jewellers supply shop you'll find them down to really tiny sizes.

 

John

egkb likes this

Share this post


Link to post
Share on other sites

Thanks for that John, seems to be the way to go. A friend of mine dropped in a very very fine bladed saw (think he called it a jewellers saw) to join up the drilled holes, so I have lots of great ideas to try out.

Wish me luck :)

 

Eamonn

Share this post


Link to post
Share on other sites

Hi All,

 

Thanks for all the advice, I used a combination of the above suggestions i.e. Drilling, sawing, chiselling and filing! Phew

 

Result is by no means perfect, rather ragged by the standards on display in MSW, but sure we have to start somewhere (that's my excuse... and I'm sticking to it)

That said I'm fairly pleased, and if any of my friends look too closely and comment they'll get a 'flick around the ear' :)

 

Eamonn

 

post-5925-0-10087400-1377858658_thumb.jpg

Share this post


Link to post
Share on other sites

Very nice work, Eamonn.  Just remember - the only standard on here that matters is that to which your own skills and experience allow you to achieve.  These came out quite nicely, though. 

 

Please pardon me for not digging around - what vessel are you building?

pythagoras and egkb like this

Share this post


Link to post
Share on other sites

Hi Wayne,

 

Thanks for the 'vote of confidence', The model is a 1:46 Bounty that came as part of a 'Building the Bounty' weekly magazine spread over 2 years (about 13 years ago) if you rummage about in my post 'New to MSW' circa 20th Aug you will find a few pikkies of her, I am on the masting at the mo. I recently picked up the Sherbourne kit and the comparison in build information is staggering (Sherbourne had actual Plans for a start, Bounty has photos & text, which at first sounds great until you need to get down to the 'nitty-gritty' of where stuff goes and how it interferes with later stuff, am convinced they used photos from at least 2 different builds to create their instructions, makes life very interesting though) :)

Thanks for the inquiry Wayne, and all the likes posted.

 

Eamonn

kevin56 likes this

Share this post


Link to post
Share on other sites

There you go, Eamonn, piece of cake, really! ;)  :)

 

John

Share this post


Link to post
Share on other sites

Hi John,

 

In a word... 'AAAAAAAAAAAAAAAAAAAHHHHHHHHHHHHHHHHHH' :)

Am curled-up rocking back and forward in a darkened room as we speak making gurgling sounds.

 

Eamonn

 

Thanks again for all the help and encouragement folks.

DelF likes this

Share this post


Link to post
Share on other sites

Hi Eamonn, 2 other methods not mentioned above are:

1. don't drill any holes but laminate thin strips of wood together and leave a slot or two where you want the sheaves to be.  You will need to clean up the lamination after the glue dries, but you will have perfectly squared slots.

2. if you have access to a mill, then that will give you square sides whose corners can be easly cleaned by filing.

 

Actual sheaves can then be installed. 

If your scale is small, then Chuck's method is the better.

 

Good luck and have fun.                       Duff

WackoWolf, egkb and Beef Wellington like this

Share this post


Link to post
Share on other sites

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

WackoWolf likes this

Share this post


Link to post
Share on other sites

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.

egkb and mtaylor like this

Share this post


Link to post
Share on other sites

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.

egkb, mtaylor, Canute and 1 other like this

Share this post


Link to post
Share on other sites

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

Altduck, Canute, mtaylor and 1 other like this

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites

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

 

https://www.youtube.com/watch?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 ...

jud, donrobinson, Canute and 2 others like this

Share this post


Link to post
Share on other sites

www.amazon.com/Uxcell-Hollow-Square-Mortiser-Chisel/...

This is more like I was thinking about.

jud

Canute and mtaylor like this

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.