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Feb 16, 2012, 04:16 AM
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DIY make a mini scroll saw on the cheap


Having just taken up building boats, and also making planes, I wanted a way to make cutting out the forms easy and quick..

I tried using a coping saw and a jewellers saw, but they gave me problems or just took too long..

Cutting the shapes needed 3 hands, two to guide the saw and one to hold the work... Unfortunately my space is very limited, no workshop or even a work bench..
I looked at power tools but they were either too big or too expensive to justify buying...

So I thought to make it myself
Last edited by davereap; Feb 17, 2012 at 06:27 AM.
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Feb 16, 2012, 04:17 AM
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The basics...
1.....The blade has to move up and down, and be held under tension or firmly between two clamp fixings

I have used two pairs of fibre gass rods with the clamps fixed to them... they are fixed into some 2x4
Last edited by davereap; Feb 16, 2012 at 04:27 AM.
Feb 16, 2012, 04:18 AM
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My first thought was for a vibrating saw so I used a small motor with a filed cam to move the blade....this didnt work

Note because both ends of the systen are sprung the force must act to power the cutting stroke, and the return is made by the spring of the material..

whist the motor was vibrating the blade there was no cut made and the motor was not up to the job..likely there was not enough power and movement?
Last edited by davereap; Feb 17, 2012 at 06:29 AM.
Feb 16, 2012, 04:18 AM
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With the previous setup not working I decided to more copy a scroll saw, using a more powerfull motor and imparting more movement to the blade..... this setup worked fine
The motor I used is an old brushed speed 400... with a gearbox... pre brushless days, so not being used for flying...
Control is through a brushed ESC worked from a servo tester and 4.8v battery..
Main power ..an old 9.6v nicad from pre lipo days..
All the bits apart from the servo tester were never being used..
Last edited by davereap; Mar 14, 2012 at 05:33 AM.
Feb 16, 2012, 04:19 AM
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notes on the above..

I put the shaft close to the axis on the white wheel... the further out it goes the more up and down you will get... it might also impart some sideways movement... but this is not a bad thing because the cutting edge of the blade is oriented sideways in my version by mistake... any sideways movement is effectively rocking the blade in the cut.. much like a jigsaw movement, as well as pulling it up and down

both ends of the blade are fixed into blocks on the sprung rods.. to get the blade moving it must be pulled, the shaft rotating around the axis will pull the chord up when it goes to its highest point, this moves both sets of rods upward as it is pulled and then the spring in the rods will pull the blade back down as the shaft goes to its lowest position.

Important.. must note ..pulled not pushed... because both ends are sprung and the blade is thin, pushing on either set of rods will not work.. all that will happen is you will flex and wreck the blade... under a pull all the parts are under tension and the blade is kept straight
Last edited by davereap; Feb 17, 2012 at 12:39 AM.
Feb 16, 2012, 04:27 AM
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and more.. The concept works well, but there are a couple of points where it can be improved..

1.. I would like it to cut on the downstroke.. then the table will resist the woods movement under the cut.. rather than having to hold it against the pull upwards..

2 ....the Ali table wants to be adjustable for height.. so it can be moved to use other sections of the saw blade, when one spot gets a bit blunt

neither is a major issue, the blades are very cheap and it is not a problem holding the work part in place for the cutting

I would however like to get the motor and control bits all down below, and all in a neat box
Last edited by davereap; Feb 17, 2012 at 12:06 AM.
Feb 16, 2012, 03:08 PM
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Ward Hagaman's Avatar
Very ingenious! Thanks for shaing!
Feb 16, 2012, 11:21 PM
KE your cub.
Curare's Avatar
Very cool, however I cant help but feeing that the time that would have taken you, if you considered $ per hour of your time, you'd have been able to buy a scroll saw!
Feb 16, 2012, 11:57 PM
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As I said I needed a small unit, because ive very limited space... also I have the time to mess about making one, being retired, and it was made out of various unused old rc bits and scraps of wood so the only cost was some blades.. even those were purchased previously to fit a jewelers saw handle
I do enjoy the making, I make my own designs rather than purchasing a kit, its so much more satisfying and cheaper by far..
when you have the time, but dont have a surplus of cash its the way to go...

I did find a smaller unit .. but I couldnt find it available for sale in the UK.. and it would have been over 200$... so I made this gadget in one morning... then corrected it in the afternoon to make it work..
can I really justify spending 200$ to cut out a few boat forms...not a chance

cost wise..yes, you are correct, if I were working full time I could have earned enough to purchase a cheaper scroll saw... unfortunately I would still lack the space to put one into....

next there are a couple of improvements to think about...With a bit of thought this can be reduced in size and made neater
Last edited by davereap; Feb 17, 2012 at 12:53 AM.
Feb 17, 2012, 01:08 AM
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Note on fitting the blades...

The blade needs to be held under tension... this keeps the blade straight and it cuts more acurately...
so fit the end near the chord , the top end first, then bend the lower rods upward while you fit the bottom end nice and tight.. when the rods are released the blade will be held nicely taught...

don't forget the teeth must be set to cut on the pull stroke, that determines which way round the blade is fitted..
Feb 17, 2012, 01:18 AM
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Note on performance...
I went round my flying buddies to cut a load of forms on a big scroll saw(16" type).. My small cutter is much quieter and its speed of cut is very favorable.. cutting 1/10 ply on his and 1/16 on mine the time is much the same..

ease of cut.. my finer thinner jewelers blades are easier on the sharper bends..
noise..his needs ear protection used..
Accuracy.. both are fine


update .....just been cutting some of the 1/10 ply and it seems just as fast to what I remember of my buddies scroll saw....
Then my old nicad run out of juice... so they will need a few cycles to do any good
Also the top pulley systen is wearing out..but that was expected as its only using very thin soft plastic parts
With the wear in the top end the chord has gone slack... this must be kept tight to stop blade flex, it can now bee seen vibrating about......next an Ali top end set, ive got some bar stock that will do..
Last edited by davereap; Feb 17, 2012 at 04:53 AM.
Feb 17, 2012, 05:07 AM
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Quick demo on some balsa
note the top chord is loose here because of the ware on thin plastic gears at the top...
The chord does need to be under tension so the blades keeps straight when its going up and down..here the blade is flexing a bit too much
.
quick cut demo1.AVI (0 min 24 sec)
Feb 17, 2012, 12:50 PM
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rcav8r2's Avatar
Very crafty indeed. I'd say it's priceless
Feb 17, 2012, 11:39 PM
B for Bruce
BMatthews's Avatar
Davereap, I commend your tenacity and ingenuity. It's always nice when you do something like this that works out well for you.

Just a thought. One reason the regular electric scroll saws are the size they are is to get the depth in the throat. Most of us are willing to accept the size of the saw to have the ability to swing larger sheets of stock around without fouling the back of the arm too easily. It tends to avoid the need to do a rough cut to get something that'll fit and the waste of material that accompanies this roughing out.


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