Stack cutting limit in hardwood?

[pjm699]

Greetings all, I am trying to cut some puzzles in hardwood (about 5mm each) where it is a pattern rather than a picture and half the pieces swap over to give a two tone end result.

This means I am trying to cut through 10mm of hardwood with a puzzle blade (Flying Dutchman) which is proving tricky - no matter how slowly I work the lower of the two pieces always has a chamfer on the edges (not a problem when I cut one piece) which stops me from swapping the pieces over at the end I assume this is because I am asking the saw to do too much in a hard wood - is this the case in your opinions or is there another lack of skill somewhere.

The idea is that they will end-up as coasters for a friend's new house. If I can't sort this out then they will have to be single timber puzzles but I would prefer there to be two timbers for interest. I will naturally put up a few images when I am done - they are following a series of paintings I did a few years ago. (I could only find a photo of one of the test pieces - sorry for the poor quality)

If you can imagine one of these but only made of 6 pieces and in two alternating woods then hopefully you will have the idea.
The circle which is cut is 85mm in diameter so all a bit fiddly as the pieces spiral more than in the test painting
As you can imagine, the pieces end up being quite convoluted.

Many thanks, P

 

[Gill]

The fact that your stack-cut pieces are not interchangeable suggests strongly that your table may be slightly tilted, so check that your table is square to the blade. You can do this easily by cutting part of the way into a block of wood, then reversing the wood and seeing if the blade still fits perfectly into the cut you have made. A tilt of less than 1/4 degree can make a huge difference, especially with large stacks.

Puzzle blades are very fine and will struggle with thicker pieces of wood, although they should be capable of cutting through 10mm of wood. Much depends on the type of wood, of course - 10mm of maple will be much more challenging than 10mm of sycamore. I suggest you cover the stack with low tack masking tape which will lubricate the blade as it cuts.

 

[pjm699]

Many thanks for that, I did check before cutting but it was fine - checked last night and it was a little off.
When you said cut a block - I cut an 18mm block is that thick enough for your test?
I did that with oak and it was absolutely fine - I shall try with a thicker piece tonight I guess the thicker it is the better the test as the distance of the error will increase with distance (thickness) - why do these things only become clear when it is too late?

I have an Axminster AWFS16 Fretsaw which has adaptors for the pinless blades which have a fair amount of sideways movement available when you put them in the saw so when I remove or replace the blade I can easily install it with considerable wonkyness. Perhaps this is the Cue for a new saw?!

The stack I was cutting was jatoba and beech - which I guess might also be a pretty heavy going task for the machine - I had also managed to get the grains at right angles to each other so that may have made for more fun - not sure on that though.

Images below of two single layers that I subsequently cut - the oak one is unfinished at the moment. I will make little frames for them from the stock they were cut from (like a child's tray puzzle) making them about 100mm square in the end and put another layer under them so they can be moved about easily.

Oak Parts (unfinished for assembly)

Assembled oak version (shocking quality - sorry) 85mm dia

Jatoba Parts in Order of assembly

Assembled Jatoba version - 85mm again

For some reason the jatoba version is much more tricky to assemble.
I am going to have words with the saw and try again with stacks as I think they will look nice.
I have cunning plans for some trickier versions as well.

Hope you like the pictures, Phil

 

[loftyhermes]

You're probably applying side pressure when cutting, this generally happens when the blade starts to dull, so you will need to change the blade more often, don't ask me how I know this, sideways pressure will give you a cut just the same as a tilted table

 

[pjm699]

Thank you for that information - I'm new to the game so that is higly likely -well I know I am doing it a little (which probably means a lot) I'm not sure the blade is dull as I used a few to see if the blade was at fault, sadly it looks like the error is all down to me. I broke a few getting to grips with tension and feed speed so I'm not sure they got a chance to dull! I will set it all straight again and see how I get on tonight,many thanks Phil