Vintage setter modification

[JoshNZ]

I bought an old bandsaw setter off an auction site last month for pennies, thought I might be able to put it on a bench and power it with a motor, has a bunch of adjustment all seems to be within scope of what we use, except for the pattern..

It is left-right-left-right. An input wheel with 2 lobes on it for the teeth setters and 2 lobes for the pusher. So, push-left tooth-push-right tooth-etc...

Before I drop it in the trash I wondered if anybody had any ideas to modify it to left-right-centre pattern. Looks like a deep rabbit hole to me but just in case I'm missing something obvious I thought I'd ask.



 

 

[Ljohnsaw]

Do the lobes on the wheel just do the advance?  Is there an internal cam that does the setting?  Does it have just a single lobe?

[JoshNZ]

Correct lobes on the big outter wheel advance the pusher, twice per rev.

Internally there is 2 lobes, must be 180 degrees opposite, and offset from eachother, one each of them per rev.

[Ljohnsaw]

OK, so I understand how it works.  The internal lobes, were they turned on the shaft or at they set with some set screws.  That is, are they adjustable?

[JoshNZ]

That's a good question. Suppose either way I could turn them off or remove them and turn some lobes that were adjustable..

[Ljohnsaw]

I'm thinking if you make two lobes that are 120° apart on the setters and change the big wheel to have three lobes for the advance it will work.  Great find!  Might have to make the advance ones steeper on the push side since the timing of the setters is tighter.  Just a guess.

[JoshNZ]

Sounds like a rabbit hole to me 😆I'll have to dig into it a little and see what the lobes look like.

The lobes on the front wheel would be tricky, they're on the edge of the wheels circumference rather than axial lobes like a cam shaft. I can't think of any way you'd make those easily

[customsawyer]

I don't think I would mess with the lobes. The left right is beside each other the same as our blades are. Just adjust the length of stroke so it will advance three teeth at a time.

[JoshNZ]

Left and right setters are directly opposite each other. That's possibly an idea though, to make new arms offset the length of the tooth pitch and advance 3 teeth

[JoshNZ]

Just one lobe inside and removable as suggested, don't know why I thought seperate lobes. You must've pulled a few machines of this age apart @ljohnsaw .

Makes it a bit trickier, two lobes would cause each tooth pusher to move twice per revolution. I could hope the pushers wasted cycle lands out in thin air above the gullet somewhere.

Could I just add a steep lump on the advance cam between the two existing on one side, for a skip push..

???



 

[Ljohnsaw]

Hmmm.  I was hoping for two, offset cams.  But your idea might work.  Easy enough to test.  Can you mount up a blade (or a broken piece of a blade) in it, crank it a few strokes and just before mid-set, give the advance a shove?  If the teeth clear the setters, I think you have a very simple solution!

[JoshNZ]

I can't see any reason that wouldn't work what you're suggesting above. If I could figure out a way to manufacture a new face style cam like this, I could tighten everything up, no reason the pushing can't happen quicker?

How the heck did they build something like this before CNC existed.

I can only think of finding a hooring great thick walled piece of pipe about the same size and draw the path around the wall, try and freehand it ???.

For an old machine it sure came apart easy, everything is beautifully oiled. The pins that the pusher arms pivot on are an interesting design, one end of the pin just tapped into a bore on one side of the casting but the other side is an oversized hole with a thread. A part with the opposing bore on the inside and a thread on the outside is then screwed in over top of the pin end, and a lock nut overtop of that is snugged up against the casting. I assume it makes the bore replaceable if play ever develops (but only one end...?) Or perhaps somehow removes slop by tightening further, can't quite see how that'd work though.

Pretty neat looking but of equipment anyway




 

[Ljohnsaw]

One word, Bondo! ;D  Or, you could make a form out of duct tape and fill it with JB Weld?  In either case, lay on a strip of tin for a better wear surface.

[Alligator]

It appears you need a three stroke cam instead of a 2. 3D printed one would test that theory pretty easy. Or something tha would give 3 strokes per revelotion. A set right - set  left - and - pass that doesn't set. If I understand the setter operation right.

[Ljohnsaw]

The more I thought about it, it will be pretty difficult.  The setting cam is probably 90° offset from the advance cams.  The timing is probably pretty tight between the advance and the setting.  The only "easy" way I can see to do it is to have a solenoid in line with the advance mechanism that gets fired somehow to do an advance right after one.  It would require modifying the backside of one of the advance cams to drop back immediately to retract the pusher so the solenoid can fire to double advance.  Or so I think...

However, it would be pretty neat to have the parts pictured laying on some graph paper like some 1/4" or 5mm grid.

[JoshNZ]

I had a play around with another cam today, I first put it in in the same orientation the last one came out and face palmed myself, seemed completely stupid and impossible at that point.

The wheel is cast so cam is secured by set screws, one requiring a spanner, one a screw driver and one an allen key ( :D) meant I could rotate it and try different timing.

So now each setter is retreating before the pusher begins to shift the band, and the pusher is retreating before each setter touches the tooth, but only just. Theres stuff all in it!

Maybe 3 hours spent on it now, it'll need a motor and sprocket and bench with blade support arms. Still wondering if the hole is too deep.

Seems to have every kind of adjustment you could think of all over it, I'm sure it could be made to work to some degeree