Cutting plywood

[SvenglishTommy]

I am about to make some new washboards and have ordered, at much expense, some 12mm teak plywood for the job. I am not that skilled a woodworker and am hoping to get some tips on getting a nice clean edge when cutting the ply to size. I have been experimenting with some mahogany ply I have already and am having difficulty get a good finish.

I am limited pretty much to using a jig saw, or perhaps a hand saw, and so far the best results I get are with a fine metal blade at high speeds, followed by a light run over with a plane. I still cant manage to stop the ply chipping a bit though.

Any tips?

 

[Appleyard]

Score first with a sharp stanley-type knife,and make your cut just "outboard" of the score. A hand saw will give you more control and a better cut than a jigsaw. Make sure it is sharp.Score front and back if you want a really clean cut. Have a go on a scrap bit first.

 

[tillergirl]

Cut a Japanese Pullsaw, about £14 or less from Screwfix. Best saw you'll ever own and give you the finest cut possible.

 

[chasroberts]

If you clamp some offcuts or bits of cheap ply on either side of the teak ply and cut through all three with your jigsaw, the teak ply in the middle will come out perfectly.

Chas

 

[Appleyard]

This works but can be a bit awkward with a large sheet of ply,as the offcuts tend to flex and will not prevent splinters. Also it makes it difficult to accurately cut to the original line.Better to score the ply as I originally said..foolproof.

 

[Cliveshep]

Jamesmar is correct, cut through the face veneers with a sharp "Stanley knife" just outside (say 1.5 to 2mm) the cutting line, complete the cutting with your jigsaw with a medium or cross-cut blade, not one with the big teeth which rip up fibres. Plane back to the line with a sharp plane, electric or hand, finish off with a sander if you need to round off edges, otherwise leave the sander alone. When planing around a curve, allow to plane "over" or in the direction of any grain, not against it. Likewise, cutting with grain lessens fibre rip up.

 

[fisherman]

Remember you can get jigsaw blades with teeth that cut on the down stroke; this gives a clean top edge, but still tears the underside.

 

[SvenglishTommy]

Thanks for the tips. I did try scoring first, but could not work how I would get the scores exactly the same on both sides as I am using the old washboards as templates rather than measuring exactly. There is a curve on the top washboard, so take it I should have the grain running vertical so I can plane the curve across the grain.

 

[Blueboatman]

You dont really need to score the back surface when using normal 'fine cut'jigsaw blades.
Unless the curve on the top washboard edge is really tight a la Van de stadt or Macwester it is better to do one continuous cut with the jigsaw .
What you really want is an orbital action jigsaw with adjustable speed,set not too fast.And a new blade.The saw will pull itself along the cut with very little effort.
When planing however you may wish to plane from the ends in to stop the corner tearing out.
It is well worth sealing the finished boards with epoxy before you varnish them.to permanently seal the end grain edges.
If you make a mistake and make em too small you can always epoxy a strip of solid wood along the edges,this has the double advantage of taking any knocks whilst protecting the end grain plywood.
I am probably making it sound harder than it really is.Enjoy!

 

[Robin2]

I used to get jigsaw blade for a Black and Decker saw that cut going up AND down. They were really great. Fast as well as clean. I have a Bosch saw now and I have not found similar for it. I don't know if the up and down type are still available for other brands -but well worth looking for. In any case make sure that, whatever blade you use it is cutting INTO the good side - usually means having the wood face down with normal blades that cut on the upstroke. I would not use the orbital action for fine work across the grain.

 

[Appleyard]

[ QUOTE ]
Remember you can get jigsaw blades with teeth that cut on the down stroke; this gives a clean top edge, but still tears the underside.

[/ QUOTE ] Not much good for this job then!!!

 

[dur]

I'm with those who score the line with a knife then cut outside the line (I use a hacksaw blade in the jigsaw, running slowly). Then take it back to the line with a sharp low angle block plane. If you don't have the block plane it is worth getting one and for this sort of work (Axminster tools do one for £15.00).

 

[VicS]

[ QUOTE ]
I'm with those who score the line with a knife

[/ QUOTE ] Me too. That's how you should always mark across the gain when sawing timber, ply or otherwise.

I sometimes mark a double line and cut between them if I am cutting a number of pieces from the same sheet or length.

Ideally you should use a "marking knife" but heaven* knows where you would buy one these days. It is only sharpened on one side so that the side against the straight edge is flat.

*Heaven and Google of course!

 

[Pye_End]

I havn't tried the scoring technique but will next time.

Also of limited woodworking skill, I have found that masking tape top and bottom and a hand saw for me has given the best results.

 

[VicS]

[ QUOTE ]
hand saw

[/ QUOTE ] Yes i am a fan of hand tools. You really need to be able to sharpen your own saws though, unless you go for the modern "hard point" ones. My best saw was my Grandfather's !

'O'level woodwork from the days when they taught proper woodwork!

 

[Pye_End]

It was a shame that our school did not do woodwork. I bought a jigsaw thinking it would make up for my lack of skill/experience, but eventually came full circle when found it didn't - even with ply! Of course it does seem easier working with decent wood, and B&Q only sell pine in the shape/size you want!

And then of course there were the polytechnics....

 

[gandy]

All good advice, but practice on scrap first before you risk your expensive material.

 

[ean_p]

I've recently asked this question of a local shipwright as to how he can cut a good clean and straight line with his jigsaw and yet I can't with mine ........his answer was that his jigsaw ( a high end Bosch) had access to good blades where as my jigsaw (also a high end Makita) did not .......he can cut a locker access top easily and true....mine the bottom of the blade wanders all over. I work in the machine tool industry now and know that cut quality on timber depends on ( yeah wait for it!!!) tool rigidity more than any other factor all other things been equal . so if you want a good cut with a jigsaw buy a Bosch and Bosch blades......

 

[richardandtracy]

Don't forget that a cheap circular saw can be bought for £25 at Screwfix & possibly B&Q, and they'll give a nice straight cut with little chipping if you keep the feed rate low. A really cheap one will last a couple of years too.

I always find that wandering is my biggest problem with a jigsaw. The chipping is avoided by very low feed rates with a metal cutting blade & highest cut speed. Reduce wandering by running the saw next to a batten, but even then the blade will tend to wander - and the thicker the stack of ply the worse the effect is. My Makita jigsaw is just about worn out and the blade wanders badly - after 17 years & literally miles of cuts through wood, ply & steel. Finally, for a straight cut, get rid of the pendulum action, it allows your hand to move slightly each cut.

Regards

Richard.