Refurbing a Scroll Saw

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Tore into the upper assembly today. Discovered a couple of surprises. A few wear problems also.

Got a surprise damage! This is under the lower arm.
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Apparently the PO allowed a loose screw to get trapped.
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Badly worn roll pin. Attached tensioning rod to lower arm.
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Broken spring.
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Extra washer. I think PO added it because the threads are jammed in the arm preventing full tightening.
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More next post

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Continuing upper assembly disassembly.

I think the PO added a 'silencer'.
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Exploded parts collection.
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Shade tree bushing press.
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I decided to replace the bronze bushings and 'shafts' since the arms had side to side play. The wear was mostly to the bushings. They are 5/8" x 13/16" x 1" flanged bushings. Found some at 'MSC'.

The roll pin that connected the air pump shaft to the lower arm will be replaced also. No where near as worn as the tensioning rod pin.

The tensioning rod is worn at the roll pin bore and is also bent. Apparently that part is no longer 'available'. I do hope that upgrading to the newer blade tensioning will be an option. I assume I will need a different(new version) tensioning rod.

Last but not least is a 'shopsmith' logo 'decal' that is long gone.

Will call Mon AM to see what my options are.


Gold painting comes next while waiting on 'parts'.

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I decided to not describe goldie parts painting and will let following pix show them instead.

Well the bushings arrived and SURPRISE!!! Although all other dimensions are 'correct', the flange thickness is twice the original.[ATTACH]13166[/ATTACH]

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Bushing 'Arbor'. The sawdust gremlins who reside on the floor stole the keyed washer which I DID use when modifying the bushings.

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I first roughed out the flange with a 1/2" skew then filed(while turning) and finished up with a small jewelers file. I got very close to the dimensions of the originals(so close I will not say since I do not believe it myself).

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A little more accurate press than the shade tree one.

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Finally the flange was seated fully since the other end of the bushings is proud of the opposite side of the arm.

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The bearings arrived and replacing them was still easy in spite of their newer condition. The looseness is I am sure due to the original bearings slipping both on the shafts and the bearing bores.

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Notice the inner end where the shaft rode on the bearing. Due to both the wear and looseness, I decided to use locktite blue sparingly as I installed them(all 6)(inner and outer races) into the lower assembly. Since this was done as previously described, I will not repeat it here. However I did align the two counter weight gears with no tooth offset. I decided I probably allowed them to slip while disassembling since I did push in on the left shaft prior to the 'off tooth' pix.

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The smaller connecting rod bearings were a tight fit. The inner race is tight against the arm/cam when the shouldered screw is tightened(no locktite needed).

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I used a nickel to position the bearings close to the center of the rod casting.

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Sneak preview

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And again! Both pix taken prior to bearing installed in base.

[nuhobby]

Good lookin' Goldie Scroll, Red!

Prior to this posting I never noticed the gentle "bow" in the lower blade-holder. Of course I don't have a SS scroll-saw (yet).

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Good lookin' Goldie Scroll, Red!

Prior to this posting I never noticed the gentle "bow" in the lower blade-holder. Of course I don't have a SS scroll-saw (yet).

Top one is the same same casting although it is machined differently. It is mounted inverted so the 'bow' is concave downward.


P.S. This project is currently on hold. Awaiting shafts and tensioning rod, spring and roll pins from Dayton.

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Decided to get the new version of the tensioning rod. Dave did not know how they differed, but I figured if it wouldn't work, I could always get the update kit. Turns out I could 'make' it work.

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The old and new tension rods are almost the same. The old one has a relief on the knob end and a 6-32 tapped hole to secure the center part of the knob. The larger portion(3/8") is longer, but is not 'functional'.


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The new tension rod is slightly longer than the old one and is threaded all the way to the end and does not have a tapped hole in the end. As I will show later, adding 1/4" between the tensioning sleeve and the bottom of the adjustment knob compensates for the different positioning of the knob further out on the tension rod end.


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The original roll pin was severely worn so I measured the pin and the hole(both new parts) and found the hole to be .212 that a .187 roll pin goes into. I decided to do two things differently. 1) use a hardened dowel pin(0.187) rather than a roll pin. 2) Shim the hole. I added 3 layers of aluminum pop can between the pin and the outside of the hole in the tension rod. That decreased the hole diameter by about 0.018. Since the rod needs to rotate on the pin, that is all I dared shim it.


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The pin hole was packed with grease to provide lubrication. I believe the original was also. I believe the extreme wear to both the tension rod hole and the roll pin was due to the amount of play between them. The roll pin hammered the tension rod hole as the saw was operated. The creased side of the roll pin increased that 'slop' as it wore down. The opposite side suffered little similar wear.

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Since the dowel pin was shorter(.750) than the roll pin(.875), the pin does not extend to the outer ends on the hole in the lower arm. I centered the pin in the arm hole and used blue locktight on both ends. Strange lighting used so the arm though gold, looks 'coppery'.

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The old parts were used with the new tension rod. 5 3/16" flat washers(1/4" hole) were added as a spacer.

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The knob on the new tension rod is about 1/4" further away from the pivot end than the old tension rod as shown by the mark on the paper.


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5 3/16" flat washers provided about 1/4". This places the outer knob in the proper position relative to the center knob. The center knob is a detent for the outer knob. The outer knob applies pressure against the tension sleeve and spring.


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The PO had marked one of the knob 'lines' with red nail polish. I kept that, but also whitened up the remaining 15 'lines'.

By tightening the center knob against the end of the tension rod, I think it will stay put. If not, there is that blue stuff! The center and outer knob must be kept close to the original positioning relative to each other since a ball bearing and spring inside the outer knob that presses against the detent grooves on the inner knob. If the outer knob is screwed down too far, the ball bearing drops into the outer knob.

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The lamp added by PO was included. I added a Heyco grommet where the power cord entered the top of the right side. The grommet effectively grips the power cord so an additional strain relief is not needed. I decided to mount a magnet that the po used to hold the blade spacer and allen wrench that one needs to use the scroll saw in the hole he had drilled for a cord clamp. Pix of magnet is a couple posts down.

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The small boss near the top had a hole in it and I tapped it to 6-32 so as to provide a grounding point for the power cord. External tooth lock washer both above and below the terminal. The paint was scraped off the boss so the lock washer did not have to penetrate that. The outer sheath of the power cord was removed since there is precious little room for it and the air tube.

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The lamp wires and the air tube were snaked through the right side. Keeping them in position while attaching the arm cover was a PITA, but it eventually got done. Too many potential pinch points to ignore!

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The web that the wires and air tube must pass through in the arm cover was deepened to make room for them.

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Not easy to see, but I inserted a short piece of the power cord outer sheath over the wires as they entered the arm cover. The wires and air tube were routed as shown. I added disconnect terminals to the lamp wires.

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The arm cover with the wires covered and the air tube passing through the cover.

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Continue by inserting the upper arm, spring and center shaft(spacer).

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This is out of sequence, as the single screw securing the arm cover to the right side has to be done before routing and covering the wires and air tube in the cover as shown in the previous post.

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Slip the upper arm into the arm cover and into the right side.

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Install the upper arm shaft and secure it from the outside end with the flat washer, lock washer and screw. It must be inserted through the arm bushing and into the bore in the right side. The second screw securing the upper arm cover can be installed and tightened through the hole in the arm. I aligned the cover mounting tab to square it with the top of the right cover, and pushed the cover firmly against the right cover while tightening the two screws.

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The tension spring was attached to the upper arm. Note the positioning of the loop on the end of the spring.


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The center shaft(actually all it is is a spacer) is inserted and secured as the upper arm shaft was.