R018 Low Relief Arches - Best way to cut out?

[Tony Davis]

After some success with the low relief warehouse and the goods shed I have started on the Low Relief Arches kits. I have hit a stumbling block inasmuch as I am cutting the curve of the arch "freehand" and I am not terribly happy with the results. With the straight edges I can use a ruler, but obviously this is not usable on a curve! Has anyone come up with a way of cutting the arch using some sort of guide, I did think of  a pencil on a string to impress a guide line - would that be the best option.

 

Regards

 

Tony

[amdaley]

Hi Tony.

Try a compass.

[Tony Davis]

Hi Tony.

Try a compass.

Thanks, I will give that a go.

[Dr.Glum]

Hello Tony,

I hit the same snag. My solution was to use an Olfa cutter which can cut constant radius arcs. The printed outline on the Scalescene's sheet isn't constant radius, but there's enough height in the brickwork above the arch and below where the horizontal ledges will come, to get a higher arc to fit. Mark out the centre-line of the arch, put the pin of the cutter about halfway up and set cutter arm length to reach a corner. By a bit of trial an error, you'll find a height and radius (cutter length) that just meets the corners and eats into the plain brickwork the minimum amount.

That's how my arches were done.

http://www.rmweb.co.uk/community/index.php?/topic/7090-railway-arches-and-workshops-plus-girder-road-bridge/ has photos of the process and gives my distances.

Cheers, Tony G

PS my other post about arches was http://www.rmweb.co.uk/community/index.php?/topic/4578-railway-arches-with-workshops-underneath-with-lighting-4mm-scale/

[Tony Davis]

Thanks Tony

 

Great thread BTW - really inspirational

 

regards

 

Tony

[Job's Modelling]

I draw and cut a line from the top of the arch to the bottom.

In this way I have to cut two half arches.

I carefully follow the line, and cut the arch very slowly. I repeat this until I have cut the arch.

For my this works very well. 

 

I also liked threads of Tony G.

 

Regards

 

Job

[Tony Davis]

Hi Job

 

Having been consistently impressed by the quality of your work I will give that method a go.I presume you would use a fairly small point knife, like a scalpel blade, rather than one of the cheap snap - off type?

 

Thanks

 

Tony

[Job's Modelling]

Thanks for the compliment, Tony.

 

I use a small snap-off knife of a good quality using a new blade.

Going along the arch is, for me, like driving my car through a difficult curve. I try always to look a little bit forward, where do I want to go to.

 

I also use a good quality card.

 

Let my know if it worked out for you.

 

Regards,

 

Job

[RAF96]

My tip in addition to those above is to proceed with light cuts.

Any attempt to heavy through in one cut will be a recipe for disaster.

Rob

[Campaman]

Further to Jobs great tip, and Rafhaaa96's which I was just typing as the post came, I do the same as Job but actually cut more segments, depending on the size of the arch, once cut a quick rub round with sandpaper smooths things off.

 

Again depending on the thickness of the card being used either the smaller type of snap off knife or my scalpel, the trick is running the blade round hard enough to cut, light enough so that you can steer it, and I have found that a thin stiff blade works better.

 

I got craft knife set from Wilkinson's craft range, it included two round handles (Xacto style), blades and a pair of tweezers, the larger of the two handles has a nice sharp, pointed stiff blade that is very good for cutting arches and circles as it is somewhere between the snap off blades and the scalpel.

[Tony Davis]

My tip in addition to those above is to proceed with light cuts.

Any attempt to heavy through in one cut will be a recipe for disaster.

Rob

Thanks - this is something I have already discovered :-(

[Tony Davis]

Further to Jobs great tip, and Rafhaaa96's which I was just typing as the post came, I do the same as Job but actually cut more segments, depending on the size of the arch, once cut a quick rub round with sandpaper smooths things off.

 

Again depending on the thickness of the card being used either the smaller type of snap off knife or my scalpel, the trick is running the blade round hard enough to cut, light enough so that you can steer it, and I have found that a thin stiff blade works better.

 

I got craft knife set from Wilkinson's craft range, it included two round handles (Xacto style), blades and a pair of tweezers, the larger of the two handles has a nice sharp, pointed stiff blade that is very good for cutting arches and circles as it is somewhere between the snap off blades and the scalpel.

I did invest in a Swan Morton set but am a bit reluctant to use the scalpel blades as the heavy card is very good at blunting them, the blades are expensive, the snap off blades are cheap and so am I! We do have a Wilkinson's not too far from here so I will drop in and see if they sell replacement blades for their own brand set, then I can use those in the swan morton handles. I have discovered that the cheap snap off sets, at least the one's that I am using, tend to "catch" the edges of the paper when cutting curves. They seem fine on the straight cuts though.

[Metalhip]

I get my scalpel blades here,usually get them next day and don't think that they are particularly expensive.

 

http://www.scalpelsandblades.co.uk/

 

A scalpel blade lasts a good while if you use a piece of 1000 grit wet and dry on a solid base such as a piece of wood or steel offcut and use it as a strop for the blade.I threw the last one away after the shape eventually went through too much sharpening.

 

Allan

[Campaman]

I get my scalpel blades from Amazon, around £6-7 for a box of 100, remember you don't need them to be sterile.

 

I also have a small sharpening stone that I use when cutting card with them (Poundland do a set), I also keep older blades that are not so good for fine stuff, to rub over with the sharpening stone for use with card, and they only get thrown once they are well and truly done for, usually they end up being used for carving plaster and similar tasks before they are completely dead, and then I may grind a shape in the end for scraping plastic....

[allan downes]

Hi Tony

 

I know what you mean about trying to cut circles freehand - anywhere but the marked line - and the tighter the arch, the worse it gets!

 

What I do is to close pierce around the inside of the arch then seperate the waste and clean up the edges with fine sandpaper - or you can try 'rocking'  the knife around the arch as opposed to trying to pull the knife around - a technique that's easier to demonstrate than it is to explain!

 

Or of course you could try using a propper circle cutter -  otherwise known as a compass cutter although I've never used one my self so therefore I offer a  disclaimer in case you cut your fingers off!

 

Allan.

[Removed a/c]

I used curved nail scissors. Get the paper into the middle of the scissor and feed it in rather than snipping it with the ends. 

[Tony Davis]

Hi Tony

 

I know what you mean about trying to cut circles freehand - anywhere but the marked line - and the tighter the arch, the worse it gets!

 

What I do is to close pierce around the inside of the arch then seperate the waste and clean up the edges with fine sandpaper - or you can try 'rocking'  the knife around the arch as opposed to trying to pull the knife around - a technique that's easier to demonstrate than it is to explain!

 

Or of course you could try using a propper circle cutter -  otherwise known as a compass cutter although I've never used one my self so therefore I offer a  disclaimer in case you cut your fingers off!

 

Allan.

I have tried sandpaper in the past but found that it shredded the grey board I was using