Advice about a Jet BOS-5 bobbin sander

[worn thumbs]

A while back I bought a used Jet BOS-5 bobbin sander and it had spent most of its life in a school workshop.I had to conclude that the pupils regarded woodwork as a punishment as there had been quite a lot of abuse and it has taken a bit of time to deal with the effects.I can sort of understand that a left hand thread on the base of the bobbins might not be too obvious and I have to live with the rounding off of the flats of the hexagons-there is just enough left thankfully.The remaining defect is one for which I am seeking advice;when the bobbin is moving up and down it tilts forward going one way and then backward going the other way.Not by a huge amount-maybe 3mm total movement at the top of the larger bobbins and there isn't obvious slop in the mechanism.I suspect there is a track for guiding the machine somewhere in the base and I wondered whether anybody here had found a similar situation and cured it.

 

[sunnybob]

http://content.jettools.com/assets/manu ... man_EN.pdf

 

[worn thumbs]

Thanks for that link,I have downloaded the document for closer study.It isn't immediately obvious what guides the vertical motion but I will at least have a guide as to what goes where if I totally dismantle the machine as I fear I will find myself doing.The other thing that became apparent from the documentation is that I have nothing like a full set of bobbins.If anybody knows of a source of replacements for the smaller sizes I would be very interested.I don't doubt that they can eventually and at considerable cost be bought from a spares stockist.What would be better from my point of view would be to find somebody who has had to scrap a machine or had some kind of really severe damage and who has a few redundant bobbins as it would realise a bit of cash for them and save some for me.

 

[Hot stuff]

There is a worm gear and associated connecting rods and pins that turn he motor rotation into vertical motion.
I have a Charnwood one that had similar symptoms and was jamming on the down stroke, turned out to be a bent bolt holding that lot together. It's a simple enough set up when you see it, not much to go wrong really.

 

[sunnybob]

Just to play devils advocate here, are you sure you have enough need for this to spend the time and money?
Last year I bought the record bobbin sander, and have to admit I think I wasted my money. Even though almost all of my stuff is curved and sanded I rarely use this machine because it only sands about 2" high. Try to sand anything taller and you just get deep grooves from the top of the bobbin.

 

[worn thumbs]

I have to thank you for the guidance and encouragement.I took the drive out of the case and investigated,since it was a small amount of movement there was nothing major staring me in the face.Then when I looked closely there was more play at the bottom of one of the links than the other and when I removed the link,it was clear that the pin it was driven by was loose.I peened the head of the pin to tighten it up a bit and it has brought about a good improvement.Not total perfection,but close enough for almost any job to come out OK.I will try and attach some images to illustrate the parts that weren't quite right.





Finally,the seriously abused spindle.



Things learned;don't drop the motor assembly on your thumb while lifting it out of the case.