New marquetry tool/machine

[Arron]

This is tool that I've made for marquetry work. Its an old design, I've seen it around and admired it many times for its simplicity.

Basically, its scrap mdf, a metre long piece of brake line bent in a U shape, a drawer slide, a spring, a scroll saw blade and a few nuts and bolts.

I liked this design as soon as I saw it because:

- it looked like something I could make in a couple of hours. Most of the hard work is done by someone else (whoever made the drawer slide). Good for me as I didnt want to spend a lot of time and money making something as I'm not that keen on marquetry really, I just do a bit every now and then to enliven an otherwise dull object. It did indeed take about two hours to make excluding gluing time.

- it seems technically right to me, in that the deflection imparted by the user working the mechanism is dealt with immediately below the blade, not somewhere back along the shaft as seems to be the norm with the other designs I've seen.

I've included a shot of the first piece I've done with it, which apparently is a little Mayan monkey image. Dont be too quick to judge the potential of this tool by this piece, it was the first cab off the rank and I was still tinkering, trying different blades etc and not particularly worried about accuracy.

When I bought the drawer slide I actually bought two, intending to set one up below the blade and one on an adjustable arm above the blade. I thought it would need the extra stability, but now I'm not certain that it does. It may be the combination of the effective suppression of deflection below the blade and the short stroke length of the 115mm blade is enough. I'll try a more demanding piece and see what can be done with it as-is and I'll post the result (probably in a week or two).

The really nice thing about it is that its gentle. Using 1.3mm veneer there was no breakages and (best of all) no need for tape :D:D. If I see a breakable-looking bit coming up, I just slow down and go stroke by stroke. I already prefer it to a scroll saw.


Cost and materials:
1000mm brake line offcut - $15 from a local automotive shop.
One pair 300mm King Standard drawer slides (Bunnings) $12. Only one used so far.
1 spring (Bunnings) $4
Pinless scroll saw blades. Say 30 cents each from USA.
MDF - I used scrap but you could get it out of a $12 sheet
Various bolts and screws

cheers
Arron

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[BernieP]

Arron, that is incredible can you please post some more instructions and photos, would really serve me well!
Cheers
Bernie

[Evanism]

Love it.

Just 2 questions.... :). Can we have some photos on how you attached the blades and which blades did you choose for this piece?

[Arron]

A couple of days ago when I did the original post on this device I was a bit ambivalent about it. Now I'm seriously fond of it. The thing that made the difference is that I've converted it to foot operation. This is great because not only does it allow me to use both hands to guide the work but it eliminates the accuracy-destroying shoulder stress that comes from having to work a handle. It also allows me to square my body up to the direction of blade travel. The foot pedal is just a piece of string going down to floor level. I hook my foot in and away I go.

If I need to use the handle, I still can, I just point my foot upwards and grab the handle.

Leaves me wondering why I messed around with a scroll saw and didnt build one of these ages ago.


Anyway, to answer your questions:


Just 2 questions.... :). Can we have some photos on how you attached the blades and which blades did you choose for this piece?

I use Flying Dutchman pinless blades. Currently I'm using 2/0 as I've run out of almost everything else. Given a choice I'd probably use size 2 or 1 for fairly simple stuff as a bigger blade will track better and give smoother curves. The 2/0 is good where there are lots of sharp corners and for organic forms.

The way I mount the blade is to give it a forward rake of about 4mm. This means with each stroke the blade bites into the timber between 1 and 2mm depending on the length of stroke. Probably not the canonical way of mounting a blade but I like it.

There is a photo attached of how I attach the blade. Rough, but works very well.



Arron, that is incredible can you please post some more instructions and photos, would really serve me well!

I've attached a couple of photos. You can see more photos of someone else's versions here http://lumberjocks.com/projects/29694 . The changes I made were to provide a wider, more stable base, reduce the size of the tabletop and blade-frame as I cant see myself ever doing a metre-long piece of marquetry, make the blade angle adjustable as different size saw kerfs require a different bevel angle, and move the centre of thrust directly under the blade by using a small round furniture knob.

What this is basically is a home-made fret saw trapped in a purpose built table with a stabilisation mechanism provided to minimise deflection. In my original photo it looks like the blade-frame functions as a spring but it doesn't; it moves up and down without distortion as the operator moves the handle up and down.

The blade-frame is a long U shape. The very end of the lower limb is attached to the top of the drawer slide plus it has the lower blade-holder very close nearby. The upper limb simply has a blade holder at its tip. Mine is all just bolted together as I cant weld.

A drawer knob is provided to manually move the assembly down, and a spring moves it back upwards.

The table is just a square box approx 300 x 400 x 130mm, or whatever size you want depending on the type of things you make. The front and back of the box are largely cut away to allow the blade-frame to travel up and down.

You can see the table top has a lot of parallel Lines. These I use to keep the direction of blade travel in front of mind. Especially useful after you've done an internal corner and are about to restart down a straight.

The drawer slide is mounted to a couple of pieces of mdf which have two wing nuts to allow the blade angle to be adjusted. In the photo its at 8 degrees, which is fine for a 2/0 blade. It will go up to 12 degrees which is good for a #2.

The slide is a King Slides 300mm 'standard' draw slide. These come as 3 parts which fit inside each other. The innermost part has a bit too much wobble in it so I removed that and just used the outer two parts.

The spring is a Century Spring Corp C-163, which seems to have about the right action. I have attached it awkwardly to the outside of the knob as it was an afterthought.

My foot-operation mechanism is just a piece of string tied around the knob, and with a loop just above floor level.

The hole in the table through which the blade works should have been much smaller, to give more support around the blade when cutting fragile pieces. I will need to remake this.

I'm still tossing up whether it needs stabilisation for the upper limb of the blade-frame. Answer is probably no, but I might try it anyway.

Its all pretty rough I guess - but I have over 40 homemade jigs and fixtures that I use for woodwork and I'm way past making them pretty.

I hope this answers your question, otherwise ask away.

cheers
Arron
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[BernieP]

Thanks Arron makes it a lot clearer, however may have to ask more as I begin making it.
Cheers
Bernie

[joe greiner]

Excellent.:2tsup:

I don't think you need to remake the top with a smaller hole. I made a zero-clearance top (not an insert) for my bandsaw from a sheet of polycarbonate about 1mm thick. It covers the whole top, it's slippery (sort of), and it's clear so any markings under it are visible. I ordinarily just tape it down, but a better fastening is pending. You'd probably want to make the fastening fore-and-aft adjustable to allow variation in the blade angle.

Cheers,
Joe

[Arron]

I havent had much time to use this toy since making it but I have made a few small improvements.

I found in Masters things called hansa wire stop nuts and realised they would make good connection fittings for pinless blades https://www.masters.com.au/product/900043198/champion-hansa-wire-stop-nuts. Photo attached. I couldnt find any 5/32 whitworth thumb-bolts or wing-screws so have made up my own.

They work very well - quick, secure, tool-less.

You need to make sure the screw which fixes the stop nut to the arm penetrates to a point just inside the hole through the centre - otherwise the tip of the blade will be bent and mangled when you do the wing-screw up. When properly fitted, the blade is actually clasped between tips of the fixing screw and the wing-screw.


Then I made a foot pedal. Just 3 pieces of timber and a hinge. The pedal is returned to the top of its travel by the spring already fitted to the blade carriage. Getting the amount of travel and minimizing foot fatigue is just a matter of getting the right spring tension, and changing the length of the string using an adjustment fitting. A rough prototype but very smooth and pleasant to use.

cheers
Arron

[BernieP]

Thanks Arron every bit of info helps.

Cheers
Bernie