Cutting 1/8" ply

[Robin Kearney]

Hi all,

im looking for some advise please, the current build requires some 1/8" ply formers to be cut out, mostly straight edges but with a few notches and corners cut off.

I've built a few things from plans, but nothing has required any ply thicker than 1/16", which I happily cut with a Stanley knife. What is the best method of cutting thicker ply? Power or hand tool recommendations would be good, what with the house mose I'm not overly flushed, so I expect a hand saw will have to suffice for the short term!

r.

[John Tee]

A hand held fretsaw will do the job nicely. Available from most toolshops and hardware stores quite cheaply. A variety of blade s are available to suit different materials. Next step up is an electric fretsaw, but it is not always easy to cut straight lines with one.

John

[Chris Bott - Moderator]

For hand tools, fret saws and razor saws work well.

A fret saw will go round curves well, but it's often best with these, to cut slightly oversize and sand back with a square edged sanding block.

A razor saw cuts straight lines better but isn't very deep so needs to be held at a very shallow angle.

[John Olsen 1]

The general idea with saws is to have something like three teeth inside the material at once. If you hold a normal fretsaw blade up against 1/8 ply you will find that the teeth are really a bit coarse. See if you can find some jewellers saw blades. These have really fine teeth and will cut fine plywood very nicely. Being pretty small they are fairly delicate but with care you will get a lot of service out of them, and they are not expensive. The fine teeth don't break the edge away so badly either.

One thing that sometimes helps with ply is to stick sellotape along the cut underneath. This helps stop the saw pulling the edge away.

For long straight cuts you can still use a Stanley knife.

John

[stuey]

I found that a large sized hacksaw blade worked well. It has fairly fine teeth and was better than my old razor saw.

[Biggles' Elder Brother - Moderator]

Going down the saw route try an abrafile. Fits in either a hacksaw or a fret saw frame. Not as fast as a saw to cut but very fine control and it cuts in any direction - up/down/sideways. Its basically a very thing circular file in a saw frame. Unfortunately not easy to get these days sadly - I bought a job lot some years ago and still have some - an internet search should unearth a supply.

BEB

[Braddock, VC]

Use the ruddy stanley knife with a new blade and the multiple cut route with a steel straight edge for the straight cuts and cut v. slightly oversize on round bits.

I've just put a 4mm marine ply floor down in a bathroom to lay vinyl on and a genuine stanley blade will do about 16 feet of cutting before it needs changing i.e. both ends of the blade total.

To get through 4mm ply took about 6 multiple cuts, but please ensure that there is something between the ply and the table also keep your finger tips away from the edge of the steel rule whilst cutting.

For small ply parts on planes eg ribs and formers, I prefer this to using my band saw as it is quite possibly more accurate.

I also have a fine toothed pull saw, about a tenner from screwfix that cabinet makers use and this (when I can find the blurry thing) gets used on thicker ply. (I think they are called japanese pull saws btw, I don't know if that's because the japs invented them or because the teeth go the other way).

[Reno Racer]

I Use a hand fret saw or my PROXXON fret saw machine. For larger straights, i've even used a jigsaw for the straights, then use the fret saw for tabs, corners etc. (obviously for larger scale)

[kc]

I agree with Braddock's methods. But if the formers have straight sides I would use a saw to cut a length of ply for all formers, then a jack plane or smoothing plane to get a straight edge on one side. If several formers are same width then use the plane to get a parallel edge at the right width. Then shape the curved top with a fretsaw, then saw off each fomer to length using a pullsaw. Any shaping is best done with a Permagrit block. All you really need is the Wedge Permagrit block.

Look for secondhand wooden or steel woodworkers planes at boot sales etc. If you can find one for a pound or two a little work with an oilstone will produce a good cheap tool. Avoid split wooden bodies.

Same source might produce a hand fretsaw, coping saw or a jewellers saw. When using these make sure you insert blade as a pull saw ( teeth point to handle  and use a fretwork Vee.

[kc]

[kc]

[Robin Kearney]

Thanks for all the responses gents.

Ive fetched a fretsaw from a local B&Q today, I'll give it a go tomorrow night.

Thanks for the pictures of the Vee, KC. I'd heard them mentioned but had never seen a picture, nice to have it confirmed it looks pretty close to how I imagined!

[kc]

The Vee is really just a piece of 4 x 2 with a stout ply top. The top bar is optional and gives a step to hold a spar etc to cut to length, while the groove was an idea to hold wire etc for hacksawing. The extra bar at base stops it wobblying in a vice or Workmate and is suitable for working seated at a Workmate.  I found that this is best used in a mechanics vice which is higher up, so can be used standing. In this case it needs to be a swivelling mechanics vice or you need the narrower part to grip in a small vice.

Whilst you are at it make a bench hook too of traditional design. Or my improved type which enables a G cramp to hold the work if required also sits either way in a Workmate or carpenters vice.

Note that fretsaw blades vary greatly in quality, the cheap ones are brittle and snap easily, best quality ( Neill/Eclipse or Sandvik etc) are much more forgiving. Also best to get a selection of teeth sizes. For the fine ones check teeth direction with your fingernail, teeth point to handle to make a pull saw. Same with Coping saw use as pullsaw - not all woodwork text books state this but it make a big difference in whether the saw cuts in a straight line or runs off!

Edited By kc on 14/04/2013 12:36:19

[kc]

[kc]

[Robin Kearney]

Thanks again KC, that is very useful to know.

 

I improvised a clamp and got to work with a couple of ply formers with my new fretsaw, I'm amazed at how easy it was. I remember really struggling cutting ply with a coping saw years ago, I now think it was far to coarse for the job, certainly much more coarse than this fret saw.

 

One less thing to worry about in future.

 

r.

Edited By Robin Kearney on 19/04/2013 22:28:07