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A question for al you users of scroll saws


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I have an old (brand new ) 2 speed 16" Delta Scroll saw model 40-560 That i purchased 20 years ago. I have used the saw as manufactured perhaps 3 times and even on the low speed thought it was rather challenging to get a smooth cutting action. so I mostly used the jewelers saw because of the much smoother control. What I am looking to accomplish is to use jewelers blades in a scroll saw in order to be able to cut both wood and metal with a little more precision than I can presently achieve by hand.

 

My question relates to the action of the blade which seems to not move up and down in a vertical mode is this a common condition of scroll saws? I only discovered how much this moves off vertical when deciding to make this tool work without power so that I could slow it down more, and work with both hands on the work.

 

I took off the motor and all the electrical parts and jury rigged it up on a metal frame I had kicking around, I used a rope

 

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to a foot lever to pull the saw blade down

 

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and a tension spring to pull it back up, the geometry of the arms is the issue.

 

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even with the rather disconcerting motion of the blade essentially in a back and forward motion as the blade goes up and down the ultra control with my foot pedal made cutting some very small parts manageable and far easier to control than when under power.

 

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Michael

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 I  have an old (at least 50 years) Craftsman saw.  In those days the motor pulled the bottom of the blade down and a spring pulled it back up.  But as Mark said the arms on yours, although keeping the blade tight, cause the blade to move back and forth.   You might want to replace the motor with a DC motor so you can adjust the speed, with a rheostat, and also give your foot a rest.

 

Bob

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You might want to replace the motor with a DC motor so you can adjust the speed,

 

Bob the only part that I have now decided to keep is the base casting and the tilt table. I machined up a piece of 3/4 inch thick aluminum scrap I had in the scrap box  to fit to the cast iron base this entailed drilling a few holes so that I could bolt it up. It took a while figuring out how to hold the odd shaped casting but it all worked well in the end.

 

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This next picture shows the new slide block attached to the casting. the rod that slide up and down is a polished 3/8 roller from and old scanner. at the top end I silver soldered a U shaped frame bent up from some 1/4 x 5/16 bar steel I heated it to cherry red with the propane torch in order to accomplish this.

 

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a side view, just to the left you can also see that the 5/16 x 1/4 bar has a 90 degree twist so that the wide dimension become vertical for the U portion of the frame. A spring from the spring scrap box was shortened to act as the return up.

 

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The grey steel frame has been set aside to be used for another purpose and the base of an old treadle sewing machine has been dragged back into service as the power source for the new powered jewelers saw. presently as a test to check out the principle the bottom hook of the slide is connected to the front of the treadle with a bit of 1/4 inch line.

 

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This arrangement seems to work quite well and there4 is a great deal of control on the speed which is much slower anyway., the flywheel effect of the sewing machine large belt drive is a bonus.

 

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From the end the overall profile, all that is left to do is add the blade holders for the top and bottom the bottom one will be threaded into the steel bar just in front of the slide, the top one will function the same way as the small jeweler saw that I made some time ago.

 

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I will place a new full top over the sewing machine one I might move the saw to the left so that I can take advantage of the treadle drive for a belt driven tool in the future.

 

All a bit Heath Robinson but I had not used the sewing machine in twenty years, and I have others anyway. I use the jeweler's saw a lot and this will be just another version of a great saw.

 

Michael

 

 

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Thanks Michael for a very good thread! I have exactly same old Delta scroll saw, and have never been happy with it. I have tried to use it during the years for only 2-3 times, but have never succeeded very good. I have thought that the problem is with me, not to be able to use it correctly, and have always liked more of the manual jeweler's saw.

But now that I read your thread I noticed that it is the saw, not the man, where the fault is. So I have to follow your way and make the same modification as you did. But I still try to have it motorized, and use a proper dc motor with a good and cheap Chinese motor controller, with which you can adjust the speed almost to zero and still keep the motor torque reasonable.

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Hi Bob and Mark, Yes a bit outside the box so to speak. Mark you are correct the whole U shaped piece moves up and down vertically the trick is to make sure that the blade is set vertical as well I am still working on that

 

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The use of the saw feels a lot different than a regular jewelers saw so I am unfamiliar with the fell of it , I will probably stick to the hand one for metal but I think that for some of the woodwork there is definite potential. Still a few kinks to work out but it feels quite promising.

 

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Tomorrow is another day.

Oh yes and thank you all for looking in and the likes

 

Michael

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A new direction is under way.

 

First I cut off the top part of the U arm this will be the foundation of a new deep hand held jewelers saw

 

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this left the slide bar with the clamp for the blade for the bottom of the blade this will be fixed to the foot pedal with a solid arm link to keep the bottom slide with a positive motion both up and down

 

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I put the frame part for the arms of the original saw back on the base. and will add in a piece of aluminum u channel 1 1/2 x 3/4 with 1/2th inch wall section inside this is a piece of birds eye maple that will be fixed with the ability to slide forward and backward with a micro adjustment to ensure the blade is vertical.

 

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The top of the blade will clamp to a slide inside a metal support that will be sprung loaded to pull the blade up.

 

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Michael 

 

 

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Thanks for all the likes and feedback.

 

I have read that one has to fail a number of times before the final device/tool/modification/invention works well. I can attest to that comment.

The geometry of our human ability to use a hand tool efficiently and skillfully belies just how difficult it is to replicate those movements to accomplish the same work in a different way.

 

The ongoing work on the saw has given me pause to think about the actual motion of the saw blade when fixed into a mechanical device that is mechanically operated versus the action imparted by the human arm and hand.

 

I can now understand why the manufactures have used parallel arms, it allows for a consistent tension on the blade, which the sprung loaded top spring does not, at least in the configuration where the blade is tensioned with a compression spring.

 

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If the bottom slide comes up and the top slide is unable to pull up the blade..... yes it bends and snaps I did this a few times with older blades, increasing the tension on the top spring which I tried does not work either just as many blades snapped.

 

I have used the top blade capture device from the original saw and fitted it to some 3/8 rod with a 4x40 screw sleeved to fill the larger hole in the original arm.

 

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I have also fitted a linked arm to the bottom slide that ensures a smooth up and down that is a constant and positive motion.

 

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I am now going to fit a new U arm between the top and bottom slides keeping the top slide housed in the top arm above the new U arm this will allow for a constant tension on the blade which needs to be set so that there is a slight angle forward from the bottom to the top the combination of these two conditions will improve the action I think. Teh top slide will also keep the top part of the U arm in a more guided position with no wobble.

 

Tomorrow we will see.

 

Michael   

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Michael, when you were using the rope to pull the blade down the only force moving it back up was the spring pulling from above.  By replacing the rope with the solid bar it is possible to push up the bottom of the blade faster then the spring can pull up the top.  This brakes the blade.  Put the rope back to not break the blades.  Ideally there should be a large coping saw where the arms move straight up and down without pivoting from the back.

 

Bob

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I just got back for an overnight in the city, Bob your comment about the rope versus the solid link makes so much sense, The other comment about a large coping saw is basically where i was going next with the top guide to keep the top of the saw in line without the spring.

I'm off out to the shop now to sort this next part out.

 

Michael

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Smooth as silk

 

I fabricated a strong lightweight arm from some 1/2inch aluminum plate I did not have anything wider than 5 1/4inches so had to make do with a slightly narrower height that the 6 that would have been optimum.

 

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I made it as light as I could, I probably could have made it a bit lighter but this arm is lighter than the original steel one and is much more rigid. it is clamped to the bottom slide bar with a couple of 4x40 cap screws.

 

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There is about 1/8th adjustment fore and aft on the top slide both for the blade and for the guide block.

 

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The cut through some 1/4 inch maple was very smooth and I felt that I had good control.

 

Now to polish it all up and finish off the clamps for the top arm.

 

Michael

 

 

 

 

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Michael, that is a really cool modification you made to your old saw. I have the Proxxon saw that was in the link and I use it a lot. It is a bit noisy and I still have trouble getting the tension on the blade correct when changing blades, but other than that I like it. I do have an old treadle sawing machine in the basement however, so now you have me thinking on how I could repurpose it.

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Thank for all the feedback and likes.

 

The saw works as well as it probably can. and is smooth.

 

The bottom line is that I prefer to use the hand jewelers saw, I did a number of cuts this afternoon the same shape using both types of saw, and with different materials.  For me the hand saw works better, and faster plus I can feel the cutting.

 

Metal is much easier with the hand saw.

 

So this experiment is concluded for now.

 

I have always preferred a band saw for long curved cuts. I can put a 1/4 inch blade on the big 20 inch band saw but a smaller saw would be good . the three wheel type are good for a small bench.

 

We all learn to use different tools and also have our preferences. This was a good learning experience and taught me quite a bit about the pluses and minuses of scroll saws.

 

Michael

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  • 2 weeks later...

One of my issues with the foot to hold down the work from lifting was that it was just far too large and cumbersome, so I machined up a new one from Bronze and polished it I realized that i did not need it to be sprung like the original.

 

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I wanted to be able to control  the area more tightly and might even make a couple of different feet

 

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I am now able to cut a close edge all I need to do now is practice using the saw.

 

Michael

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