Mitre boxes and razor saws for fine cut'n'shut work

[Compound2632]

I've been looking around for tools for doing cut-and-shut work on Ratio and Slaters plastic carriage sides in 4 mm scale - where one of the key requirements is to be able to make accurate cuts at right angles to the long side of the moulding. There are a variety of fine razor saws or long blades around - Zona, X-acto, etc., but I'm unsure about the mitre boxes I've seen - I sespect they're mostly designed for wider blades, so won't give a reliably square cut.

 

Any suggestions gratefully received.

[Enterprisingwestern]

 

Linear ball bearing slide rails with a blade attachment system, also useful for sanding accurately.

 

Mike.

[doilum]

7 minutes ago, Compound2632 said:

I've been looking around for tools for doing cut-and-shut work on Ratio and Slaters plastic carriage sides in 4 mm scale - where one of the key requirements is to be able to make accurate cuts at right angles to the long side of the moulding. There are a variety of fine razor saws or long blades around - Zona, X-acto, etc., but I'm unsure about the mitre boxes I've seen - I sespect they're mostly designed for wider blades, so won't give a reliably square cut.

 

Any suggestions gratefully received.

I would be wary of using any mitre box for this job. Use a set square and a blade to score an accurate line and then cut with either a razor saw or piercing saw. I have a sheet of thin ply with a hard wood strip down one side that fits exactly under my cutting mat. This allows me to ensure that my flat set square and the material remain true.

[teaky]

There was another similar thread recently: https://www.rmweb.co.uk/community/index.php?/topic/156761-mitre-box-help-please/

 

My own research led me to a Zona 500 32tpi fine kerf deep cut razor saw & T-SA37/240 thin slot mitre box.  However, I didn't take it any further, so it is still on my round tuit.  The two suggestions above give further food for thought.

[Compound2632]

9 minutes ago, teaky said:

There was another similar thread recently: https://www.rmweb.co.uk/community/index.php?/topic/156761-mitre-box-help-please/

 

My own research led me to a Zona 500 32tpi fine kerf deep cut razor saw & T-SA37/240 thin slot mitre box.  However, I didn't take it any further, so it is still on my round tuit.  The two suggestions above give further food for thought.

 

Many thanks for pointing me to that thread and my apologies to Steve @Londontram for not having spotted it.

[ikcdab]

I've never been really happy with mitre boxes, I just don't think they hold the saw true enough. Better to scribe a true 90° line and cut/file precisely to that. You'll get a better result. 

Ian

[Il Grifone]

I've never been able to get mitre boxes to cut true. The saw always seems to w*** about in the slot.

I clamp a steel straight edge to the workpiece against a firm backing and cut against that using an X-acto saw (as fine as possible - and as new as possible for precision work). Try to cut away too little rather than too much. then finish with a file.

 

For heavy work I use a mitre saw. Mine came from B & Q IIRC (usual disclaimer), but I couldn't find one last time I looked. (It could do with a new blade.)

[hayfield]

On 22/09/2020 at 10:45, doilum said:

I would be wary of using any mitre box for this job. Use a set square and a blade to score an accurate line and then cut with either a razor saw or piercing saw. I have a sheet of thin ply with a hard wood strip down one side that fits exactly under my cutting mat. This allows me to ensure that my flat set square and the material remain true.

 

I totally agree with this advice, I cut and shut some Ratio coach sides, I used an engineers square and a fine tooth X-Acto saw blade (with the correct handle) I inherited some cheap imitations, which were binned due to very poor quality. Use originals

 

Cuts made on door joints

[Compound2632]

9 hours ago, hayfield said:

Cuts made on door joints

 

Just so - ideally.

 

Thanks to all who have convinced me to stop looking at mitre boxes and start looking at a new engineer's square - my current one is getting a bit rusty and gunky, having got glue on it too many times.

[ikcdab]

20 minutes ago, Compound2632 said:

 

Just so - ideally.

 

Thanks to all who have convinced me to stop looking at mitre boxes and start looking at a new engineer's square - my current one is getting a bit rusty and gunky, having got glue on it too many times.

Ah, an excellent distraction activity, clean up tools. Fine wet and dry, thin oil, bit of metal polish, and it's as good as new.

[hayfield]

1 hour ago, Compound2632 said:

 

Just so - ideally.

 

Thanks to all who have convinced me to stop looking at mitre boxes and start looking at a new engineer's square - my current one is getting a bit rusty and gunky, having got glue on it too many times.

 

 

I have two, one is a 2" (ideal for coach sides in 4mm scale the other is a 4" one

[Clive Mortimore]

Hi Stephen

 

First thing, check that the vertical items like doors and paneling are square with either the top of bottom of the coach side. Use the one that is best as you datum for marking out. Using your square and a fine point on a pencil mark where your going to cut using the flat part of the coach side. Continuing the marking on the tuck under the pencil will wander. If scoring using a square the blade will also wander.

 

I am lucky I have a six rule that has enough give that it will follow the contours of a coach side. If you do not then use a strip of brass with a know straight edge which will take the contour of the coach side. Line your straight edge with your pencil mark, a few strokes with a sharp craft knife blade, scalpel etc and then snap the coach side along the score line.

 

Clean up any burrs, reassemble your jigsaw of bits to the required widow and door arrangement. Bung in the filler were needed.

 

I find even with razor saws the width of cut they make is too wide. Scoring and snapping I do not end up with a side 1 mm too short, OK I do but that is normally a wrong measurement in the cutting. 

Edited September 23, 2020 by Clive Mortimore

[doilum]

A sliver of Microstrip can be used to compensate for the material lost to the saw. The trick is to reassemble the parts against a steel straight edge just like building a Kirk kit.

[hayfield]

10 hours ago, Clive Mortimore said:

Hi Stephen

 

First thing, check that the vertical items like doors and paneling are square with either the top of bottom of the coach side. Use the one that is best as you datum for marking out. Using your square and a fine point on a pencil mark where your going to cut using the flat part of the coach side. Continuing the marking on the tuck under the pencil will wander. If scoring using a square the blade will also wander.

 

I am lucky I have a six rule that has enough give that it will follow the contours of a coach side. If you do not then use a strip of brass with a know straight edge which will take the contour of the coach side. Line your straight edge with your pencil mark, a few strokes with a sharp craft knife blade, scalpel etc and then snap the coach side along the score line.

 

Clean up any burrs, reassemble your jigsaw of bits to the required widow and door arrangement. Bung in the filler were needed.

 

I find even with razor saws the width of cut they make is too wide. Scoring and snapping I do not end up with a side 1 mm too short, OK I do but that is normally a wrong measurement in the cutting. 

 

 Clive

 

I agree with you that even with razor saws the cuts could be slightly wide.

 

I copied what others have shown in these pages, that is to cut slightly off center on the waste side of a door line, finding the 2" engineers square the easiest tool to keep the extra fine saw blade at 90 degrees, also having the correct handle also helps in controlling the cut

[Compound2632]

Thanks all once again - RMWeb at its most useful. Nothing like putting forward a wrong idea to get the right answer! 

 

I do think, though, that interested RMWeb members should perhaps club together to buy @Clive Mortimore, the doyen of cut'n'shut, a can of Halfords grey primer.

[ianLMS]

Similar question but referencing how to cut a curved aluminium coach roof squarely? I used my metal mitre box and razor saw and it was well off square by the time i finished. 

 

Any suggestions as i dont recall seeing a curved engineers square anywhere so i can scribe a true line?

 

Thanks

Ian

[doilum]

42 minutes ago, ianLMS said:

Similar question but referencing how to cut a curved aluminium coach roof squarely? I used my metal mitre box and razor saw and it was well off square by the time i finished. 

 

Any suggestions as i dont recall seeing a curved engineers square anywhere so i can scribe a true line?

 

Thanks

Ian

Some very careful measurement from one end to draw the line over the roof. Follow the line carefully with a piercing saw to create a score line before attempting to cut through. If the surplus is scrap I might be tempted to use the chop saw or even band saw leaving a fraction to clean up with a file.

[Il Grifone]

23 hours ago, ianLMS said:

Similar question but referencing how to cut a curved aluminium coach roof squarely? I used my metal mitre box and razor saw and it was well off square by the time i finished. 

 

Any suggestions as i dont recall seeing a curved engineers square anywhere so i can scribe a true line?

 

Thanks

Ian

 

This might be a case for the mitre saw. The beast is rather large for the job, but careful cutting and cleaning up should leave it nice and square. Bow-end carriages are going to be a bit of a problem however. (Multiple diagonal cuts?)

 

The standard reel type rule would bend around the roof.

[doilum]

4 hours ago, Il Grifone said:

 

This might be a case for the mitre saw. The beast is rather large for the job, but careful cutting and cleaning up should leave it nice and square. Bow-end carriages are going to be a bit of a problem however. (Multiple diagonal cuts?)

 

The standard reel type rule would bend around the roof.

Bow ended?

Cut overlength and shape with a Dremel to finish with a file.

[kandc_au]

On 22/09/2020 at 19:45, doilum said:

I would be wary of using any mitre box for this job. Use a set square and a blade to score an accurate line and then cut with either a razor saw or piercing saw. I have a sheet of thin ply with a hard wood strip down one side that fits exactly under my cutting mat. This allows me to ensure that my flat set square and the material remain true.

Hi doilum,
Would it be possible to post a pic please?
Khris

[hayfield]

I know this may be very obvious but many of us keep cutting tools far to long !! It is far easier to make a straight cut with a sharp tool than one going blunt, this goes for razor saws, files and of course knife/scalpel blades

[Compound2632]

11 minutes ago, hayfield said:

I know this may be very obvious but many of us keep cutting tools far to long !! It is far easier to make a straight cut with a sharp tool than one going blunt, this goes for razor saws, files and of course knife/scalpel blades

 

I'm forever forgetting and using a recently-changed blade on card, which is a sure way of blunting it. I tried having a card knife with an old blade and a plasticard knife with a nice new sharp blade but since they were in identical handles, it didn't really work out.

[doilum]

5 hours ago, kandc_au said:

Hi doilum,
Would it be possible to post a pic please?
Khris

Apologies for the state of the bench. Other non modelling projects have taken over recently. The square came from a budget tool shop many years ago. The scales were very blurred but it was square and cost about a quid. I also have a larger 60x40 cm square which is useful for woodworking. For marking out I rely on accurate engineers steel rulers. The base was made from scrap and the whole thing used to fit into a brief case if I was taking my modelling on a trip.

[Compound2632]

@doilum, thanks, that's informative, since I was envisioning an engineer's square.

[doilum]

I should have mentioned the need to start by squaring up the sheet of Plastikard. They have nice straight edges but are rarely square.