Unsupported Compound Cuts

[Gill]

Compound cuts can be very challenging. The normal procedure for this sort of work was described a couple of years ago in this rather rambling thread. The big problem with using this technique is that once all the cuts have been made on one face, there's nothing to hold that face steady while the other face is cut. Of course, by taping around the block you can add a lot of support, but there's still going to be movement.

A project I've been working on recently calls for very accurate compound cut pieces which stand on a flat base. I considered using the traditional technique but decided to use a different method instead. Working on the principle that inaccuracies are usually due to the piece moving inside the block because there is nothing to support it, I decided to 'nibble' cut the workpiece so that the part of the wood that is being cut is always supported by wood which has yet to be cut. This meant cutting a small section at the top of the piece, rotating it through 90 degrees and cutting the same amount of wood on the adjacent face, then rotating it back and cutting a bit more, gradually working down to the base. I took a photograph of this:

Normally, a scroller would squeal at the sight of so much wood being removed from directly around the area of cut! But there was no movement of the central workpiece because it was still supported - not by the surrounding block of wood but by the wood which had yet to be cut.

The cutting progressed until I had left only the curved section at the base of the block on each face uncut. Then I completed the cut on one face so that it could move freely:

The block was then rotated through 90 degrees again and I held it in a simple clamp made from offcuts of MDF. At this point, the only way the workpiece could move within the block was sideways but putting it in the MDF clamp prevented sideways movement. I didn't clamp it too tightly because I didn't want to compress the wood as I made the two final cuts.

Let's go back to the first photograph. If you look carefully at the base of the block, you'll see that I made some pilot cuts which were just deep enough for me to be able to insert the teeth of my blade. This photograph emphasizes those cuts:

As I tightened the clamp around the block, I positioned a blade in these pilot cuts to ensure alignment. Knowing that the blade could still travel in these cuts despite the block being clamped reassured me that I hadn't over-tightened the clamp.

Then I made the two final cuts with the block clamped in position. When the clamped was removed, my 'creation' emerged, cut more accurately than I could have hoped for using the traditional technique.

Sorry if the pictures aren't too clear. I have difficulty taking photographs when working with such small pieces.

Gill

 

[keithhickson]

Gill as a complete and utter novice, but one who has been to vauious shows and exhibitions may I saw WOW :shock: If there was an emoticon for the Wayne's World "We're not worthy" this page would be full of them!!!!!

 

[StevieB]

Nice demo Gill, the pictures are fine - any more details on the project? Looks like a possible chess piece?!

The object you are cutting lends itself to this technique since there are multiple points on the form which lend themselves to the cut being interrupted. A curved surface may be a little more difficult to do this on I imagine since a stop in the cut would possibly show?

Steve.

 

[CHJ]

Excellent result Gill, no wonder you have been quiet around here of late.

On the finishing front, if this is the same project, soaking pieces in a slightly diluted cellulose sanding sealer or application of low viscosity CA before final finishing may help protect any fine detail or across grain weakness.

 

[Gill]

You guys are very kind. What I like about compound cutting is that it isn't terribly difficult but impressive results can be achieved even by a novice.

I quite agree with you, Steve, that this technique isn't suitable for every type of compound cut. For instance, unless you were prepared to create an artificial base which could be removed later, it certainly wouldn't be suitable for the Christmas decorations I referred to earlier. Nevertheless, there's a surprising number of compound cut patterns which do have flat bases and I think this technique is a powerful weapon to have in a scrollers armoury for just such occasions.

If the example I've demonstrated looks suspiciously like a chess piece, I'm happy. Although I've got another project underway that's soooo far behind schedule as to be embarrassing, I just couldn't resist trying out this new compound cutting technique when it occurred to me. Diana Thompson's produced some delightful compound cut chess patterns and His Lordship has always wanted a chess set so it seemed like the natural thing to do. I've cut about 75% of the chess pieces so far but progress is painfully slow because I no longer have as many opportunities for woodwork as I once had. Nevertheless, here's a "Work In Progress" picture - it's Diana's "Woodworker's Chess Set".

Thanks for the tip about sealing the wood before applying the finish, Chas. It echoes a suggestion somebody else made, so I'll definitely follow your advice.

Gill

 

[StevieB]

=D> I like that! Very nice indeed, particularly the Queen- would love to see it finished! Are you doing the other side in a different timber - Walnut, Mahogany? or from the other post going for a stain on one side to make them darker?

With your skills a nice marquetry board to go with them could be a next project!

Steve.

 

[Taffy Turner]

Gill,

:tongue9: :tongue9: :tongue9: :tongue9:

Wow - I am absolutely blown away!!

That is absolutely awesome - both the design and the execution!

Just when I think I may be getting the hang of this scroll saw lark, you go and show us something like that, which puts me in my place!

I would love to see the finished results.

Regards

Gary

 

[Anonymous]

Blimey Gill - that is superb work, bravo =D> =D> (hammer)

 

[alanjm]

Very good Gill, nearly makes you want to learn to play chess. ..but if you strated playing, the chess pieces would only remind you that you have another 'little' cutting out project that you could be getting on with.
Regards
Alanjm

 

[Gill]

It's likely that a marquetry chess board will turn up underneath the chess pieces eventually . I've never made one before and often thought it would be nice to have a go.

I'll probably use a light antique stain on the light chess pieces and an ebonising lacquer to produce darker ones. However, before I apply any finish I intend to cut some more compound projects which I can experiment on until I'm happy that my chosen finish will work. I'd hate the finish to 'go wrong' on the chess set and then have to find a way to recover the situation.

Gill

 

[DomValente]

Very, very clever and very lovely Gill.

Dom

 

[stevebuk]

lovely stuff gill, following with great interest..

 

[StevieB]

Gill, I was going to ask whether you could list the other patterns available for me as I know someone who would love one with a gardening theme. Lo and behold a quick google search and I have ordered the book for a mere £3 as there is indeed one. Not sure whether I will be up to cutting it, especially before xmas but you have given me the inspiration to have a go so many thanks for posting as you did!

Steve.

 

[Gill]

Hi Steve

I quite fancied cutting the gardener's chess set too, but I'm worried his Lordship might say, "If you're that keen on gardening, you mow the lawn next time" .

Getting the book for £3 was quite a bargain; well done! I actually scaled down the plans a little (I don't want a big chess set) and used a #3 skip tooth blade instead of the #5 that Diana recommends. At one point I tried using ordinary blades but they just didn't cut effectively - you really do need skip tooth blades. Compound cutting is surprisingly addictive and I wouldn't be at all surprised if you were to finish your set much quicker than you anticipate. It's quite magical when you've finished all the cuts and the waste wood falls away to reveal the secret within.

Gill