An easier way to cut curved shapes in 2mm card.

I needed to construct several of the Scalescenes Low Relief Arches.

Some of the parts, including the arches themselves, need to be glued to 2mm card prior to cutting out.

I don't know about you, but I find cutting an accurate curve in hard thick card rather difficult with a craft knife. Arthritis in my hands makes this a rather painful task, and I'm seldom happy with the results.

It suddenly occurred to me that it should be possible to saw the cardboard using a fretsaw or a coping saw. Blades with fine teeth are cheap to buy. All that is needed is a small cutting table to support the piece being worked upon. It can easily be made from a scrap piece of plywood or MDF. Clamp or screw it to the edge of your workbench so that the cutting hole projects clear of the bench and away you go. The clamps or screws go at the top corners. The slot in the lower part allows the saw blade to enter the cutting hole without needing to disconnect it from the saw. The circular area is where the cutting is done. This hole can be any size you wish, but I recommend keeping is reasonably small - probably no more than 12mm - to provide maximim support for the cardboard.


 Fit the blade to the saw so that it cuts on the downward stroke as this gives the cleanest finish to the upper (printed) surface.

I drew a wavy line on a scrap piece of 2mm card and used that to practice on. Keeping the saw blade as vertical as possible will make the task easier.

Go slowly and gently and with a little practice, it should be easy enough to follow the curve you need.

Of course, if you are one of the lucky people who own an electric fretsaw, you've got it made!

I cheat, I let the plotter cutter do the work. Cuts any shape in card, plasticard, felt, balsa etc., also does embossing and engraving.

https://klicnkut.co.uk/product/knk-zing-air/

A useful tip Perry, cutting a neat curve in thick card is always tricky.

When do we get to see the results of your efforts?

Marty

I have used a device like a compass but with the pencil replaced by a blade, suspect that would need a number of passes to get through 2mm card, although it could be used to cut a groove which could then be more easily followed by a heavier knife.

http://www.hobbico.com/tools/hcar0230.html

…that's how I do mine, Mike, but for larger curves in hard 2mm board, plywood and aluminium I get out this gadget, a washer-cutter….True, one needs a carpenters brace to turn it but with keen attention to the sharpening [see what I did there…] it is very effective.



Incidentally when last in UK I saw an example of my 1930s Stanley ratchet brace in an antique shop window, albeit very polished and snazzy looking, a mere snip at £65…..

Poop-poop!

Doug

Nice gadget Doug. A carpenters brace I have… Now to find a washer cutter!

Marty

A good tip Perry.  :thumbs

I use a craft knife but, as you say, not very easy and my arches look like they've fallen ……………..

I do own an electric fret saw but find it extremely difficult to follow a line - it wanders all over the place.

I also have one of those old carpenter's braces Doug but normally, one is cutting an arch at the top of a window or doorway so cutting a circle is not possible - unless one joins the semi-circular arch to the "uprights" afterwards ………….:roll:

Perry,

You have got my mind wandering back!

I think I had one of those supports as a nipper for my fretsaw…along with the 'Hobbies' magazine and remember I made a station building and platform from tea-chest wood for my Hornby clockwork set. [big tea-chests 6d, small ones 4d, and don't tear your school pullover on the sharp metal edges when cutting it up…]

It came with a little metal thumb-screw to fix it to the kitchen table. Herewith a copy of the 1956 'Annual', Dad made me a garage building for my Dinky toys….Where has the time gone?




Doug

[user=1397]Dorsetmike[/user] wrote:

I have used a device like a compass but with the pencil replaced by a blade, suspect that would need a number of passes to get through 2mm card, although it could be used to cut a groove which could then be more easily followed by a heavier knife.

http://www.hobbico.com/tools/hcar0230.html

I have a compass cutter, but they are no good for arches that are not part of a true circle; eliptical arches cannot be cut using them.

I too had one of those Hobbies fretsaw workbench type things Doug - and reguarly bought the Hobbies magazine.

We must have been in a different era - my first fretsaw build was a pipe rack - made from scrap ply from somewhere.

We did use the tea chests - to store kindling which my father made us collect in the nearby woods along Harewood Avenue near Leeds.  My brother and I had to fill a box each but then we got to play "scouting and tracking" in the woods.  Father hid and we had to find him from "scouting" signs left along his route……………..

Good days they were - but probably only if you were a kid.  thumbs

Half of my life is spent cutting  cardboard and the other half is spent cutting out arches - the smaller they are, the more difficult to cut  but, not in styrene.

So, whenever I have a multitude of arches to cut out, I switch from card to styrene, use a pair of dividers and keep turning  until it cuts clean through the styrene. This, depending on the thickness of the styrene, takes several passes applying reasonable pressure with each pass.
Here is a typical arched bridge face cut in this manner out of Wills 2mm thick stone sheets.
Allan

 





 

Is that one of yours, Allan?

Wow!  Excellent work.  :thumbs

Great shot Allan. thumbs

I note that, of late, you seem to be using more styrene.  Is this because you prefer it to card or is it just "modern" ?  Also, what do you use to stick the styrene to card ?  I've usually found it's easy with a big overlap but any small surface areas don't bond too well. :roll::roll:

Hi Petermac

Best way I find to bond card to styrene is with either superglue or evostik impact.

Hi Max.

It was my hit at the Corris NG railway in Wales which means it's nothing like it ! Peter Kazer made a far better job of it but while he took 10 years to build his, it took 10 weeks to build mine - and it shows !

Will put more pics of it up on another thread later instead of hijacking this one !

Cheers.

Allan

I'll look forward to that, Allan.

Some months ago I went into our local Works Shop and found a Circle Cutter. According to the instructions on the back of the package it cuts circles from 12mm - 300mm in diameter. It comes with 5 blades, 3 pins and a 'Paper Protector'. I haven't used it yet so can't say how effective it is. It was only £1.99 and is branded as Craft Essentials. Hope that's of use.

Thanks Allan - I suspected it might be super glue.

I'm not totally sold on super glue.  Not its ability to glue, more my ability to keep it fluid in the tube once I've opened it ……………:roll::roll:  A bit like that expanding foam - unless I use the whole tube, the residue sets hard as iron.  Maybe I'm buying cheap stuff but then afterall, I'm a bit of a cheapskate ………………

Those circle cutters have the same problem as a compass cutter Mick. :roll:  Unless you're building a Norman arch, most are arcs of circles - usually with a very much larger radius than the width of the opening and not the full semi-circle.  You'd have to attach your arch to the "uprights" after you'd cut it.

I have seen objects used as archway formers - things like tin cans, cake tins etc which, if you can find something of the right diameter, work really well.

Having said that, you could probably make 2 or 3 of Perry's gadgets in the same time you spent looking for a likely tin …………………;-);-)     

Peter.

Never buy superglue in tubes. Biggest glue rip off of the century. Three drops at best, four if you're lucky.

Now I use superglue by the tanker load and use if for almost everything. No waiting yonks for things to dry, just instant rock hard joints instead thus speeding up construction ten fold.

However, 50 gram bottles of model shop superglue will knock you back six to eight quid depending on who's the greediest but I can get SILVERCILL thick, medium or thin industrial grade  superglue  at £2.25 a 50g bottle  manufactured by EUROCELL BUILDING PLASTICS, BIRCHWOOD WAY, ALFRETON,  DERBYSHIRE DE55 4QQ or go to their website.

Their 200ml cans of SUPERGLUE ACTIVATOR also comes at the same price as the glue and not ten quid a can from your friendly little model shop man who picks it up wholesail  from the manfacturers in his Ferrari !

And best value styrene? Slaters online jumbo sheets. Nobody comes close. Biggest styrene rip off ? Evergreen plastics and Plastruct but they've cornered the plastic section market so you have no choice but to keep them in the latest Roller every year   and a 50 acre villa in Beverly Hills.

Know your suppliers. Recognize the difference between profit and greed and cut your modelling costs in half.

Cheers.

Allan.

 

Some of the Chinese based Ebay shops have plastic tube and rod, square and round in sizes from about 1mm up to 10mm mostly in 50mm lengths, in bulk packs, example

48pcs Styrene ABS Round and Square Rod Pipes Architectual Accessories ABS00 | eBay

I bought one of these Chinese made plastics packs recently, excellent  value.
          Keith.