Cutting smooth curves for open-plan baseboard

[MarshLane]

Evening all,

I am in the process of building a small open plan baseboard for one end of my N scale layout.  It requires the track bed to be cut for two curves, and I'd like to try and get it as smooth as possible. I am using 3mm 3ply hardboard for the track base.  I have a jigsaw, but can anyone suggest the best way of getting a reasonably smooth curve?  I have tried previously drawing the curve and following it with the jigsaw and it ends up all short straight sides!  It doesn't have to be perfect, but I'd like it to look neat.  It is not a huge curve, width is about 3ft.

 

Any ideas?

 

Rich

[Penrhos1920]

Cut oversized with your jigsaw and use a sander or a flapper wheel in an angle grinder to get the smooth curve.

[PMW]

A jig on a router is the best way, but if you don't have a router then you can make one for your jigsaw. There are a number of ways you can make one, depending on your jigsaw model. The important thing is that the pivot point is directly in line with the blade. I have one something like this

 

https://www.youtube.com/watch?v=eKfMSZdytHk

 

If your jigsaw has holes in the sole plate you can simply use a bit of scrap ply. Draw a straight line on it, drill one hole slightly bigger than your blade then pin the jig in the center of your arc. Make sure your bit hole and pin are on the line.

 

[PatB]

For 3mm material at a constant radius, I'd think about something involving a (sharp) Stanley knife on the end of a string or a pivoted batten. Much quicker and cleaner than a jigsaw and sanding. I cut a lot of 3mm stuff (ply and mdf mostly) and never use a saw unless there are already battens or other complications already attached to the board. 

Edited October 25, 2020 by PatB

[Enterprisingwestern]

 

From experience, and this isn't the law, use reverse cut blades, ie, blades which cut on the downstroke, turn off the orbital action and go slow and steady round the curve.

As you are using thin sheet you will find a degree of whip occurs, I'd be inclined to put a sacrificial sheet underneath or use some Kingspan or similar foam sheet.

As previously mentioned, a trammel of some variety may help, but you will still have to counter the blades basic instinct to wander, so with jig saws I don't bother, only when using a router do I find a trammel useful.

 

Mike.

[polybear]

9 hours ago, MarshLane said:

 I am using 3mm 3ply hardboard for the track base.

 

I'd suggest that 3mm hardboard will end in tears over time, as there's a very good chance it will warp - unless this is going on top of something more substantial.  6mm ply would be a better bet. 

[doilum]

A thin SHARP blade will make it much easier for the jigsaw  to follow the line. I have built a layout from hardboard (it lasted much longer than expected)  but used ply for the track bed. Hardboard not only is liable to warp but doesn't take a pin easily.

Edited October 25, 2020 by doilum
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[ikcdab]

I have been doing just this thing,  but with 9mm ply on my oo layout (see link in signature, more postings there today).

Foloiwimg a marked line with a jigsaw is not difficult assuming you can see what you are doing and you cut alongside the line, not down the middle.

The truck is to able to draw a smooth curve first.

You can use thin, flexible bits of wood or plastic to draw long, these will form a natural curve. If it's a constant radius, then a bit of string, pencil and draw g pin works.

Or you can draw a curve using a drawing package on the laptop. Print it out and stick it on.

I use templot and get it to draw baseboard edges, I print out the templates, stick them down and jigsaw along the lines. A fine cut jigsaw blade is best. I have some that are designed to cut metal and they work a treat. Or a laminate blade that cuts on the down stroke. All give great cuts.

Ian

[MarshLane]

Thanks guys for the suggestions and help guys, much appreciated. In the true spirit of the A Team, I love it when a plan comes together!

 

@polybear - Yes normally I'd agree, but in this case to be honest, I have been keeping the cost down by using what was spare in the garage (all part of a grand plan to empty the place!) so where it is raised up, its being supported with some packing underneath, and its screwed to 2" risers every few inches.  One of the advantages is that  part of it will drop down a grade, and the 3mm thickness, allows some flexibility over the summit without it having an /\ effect.

 

Added to which, this is only a temporary layout - on one hand something to do, on the other hand a way of practising scenic ideas - and needs to be portable, so I am trying to keep the weight down while keeping it sturdy.  The whole thing will be replaced in 18-24 months by a bigger permanent layout in the new garage - hopefully! 

 

@ikcdab - Normally I use Templot and build the pointwork myself, but for this project I have used SCARM and Peco N pointwork for quickness.  The idea was just to run trains and practice the scenery, so I have relinquished on the track work a bit, I'll save that for the big project.  Trouble is I struggle to follow the line with a jigsaw, no matter how hard I try.  But the earlier suggestion from @PMW through the Youtube vid of locking the jigsaw to a central pivot point sounds the most logical thought.

 

Rich

Edited October 31, 2020 by MarshLane
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