JB Weld or what

[backhertz]

JB Weld is an epoxy, I believe. An old timer showed me a trick one time with epoxy. We had to fill a hole which was not circular. He mixed up the epoxy and then added some alcohol to the mixture & stirred it up. He then poured it into the hole & the liquified epoxy completely went into every crevasse and when it dried a day or two later, a light sanding revealed a perfectly flat surface. I was amazed. He learned that during his apprenticeship at the Philadelphia Shipyard years ago. It's amazing what you can do with epoxy & a little alcohol.

[backhertz]

JB Weld is an epoxy, I believe. An old timer showed me a trick one time with epoxy. We had to fill a hole which was not circular. He mixed up the epoxy and then added some alcohol to the mixture & stirred it up. He then poured it into the hole & the liquified epoxy completely went into every crevasse and when it dried a day or two later, a light sanding revealed a perfectly flat surface. I was amazed. He learned that during his apprenticeship at the Philadelphia Shipyard years ago. It's amazing what you can do with epoxy & a little alcohol.

[JPG]

OMG! How big was the PO's pet gorilla?

My first thought was to insert a pipe on the inside to restrict any further deformation. However I do not think there is enough clearance at the top of the casting for a pipe with an id large enough to also clear the spring.

Second was was to form a 1/8" thick steel bar/plate on the outside where the clamp handle cams. I believe there is enough adjustment in the clamp screw to accommodate the extra thickness. If the formed bar extends above and below the hole I think it would be adequate without actually repairing the casting.

That camming of the clamp handle against the casting has always been an area of concern to me. Since it only takes a quarter turn of the screw after the mating parts are against each other and all further motion has been taken up, I have never encountered this problem.

I can see if the clamp screw was too tight, then excessive pressure on the clamp handle would happen.

[dusty]

OMG! How big was the PO's pet gorilla?

My first thought was to insert a pipe on the inside to restrict any further deformation. However I do not think there is enough clearance at the top of the casting for a pipe with an id large enough to also clear the spring.

Second was was to form a 1/8" thick steel bar/plate on the outside where the clamp handle cams. I believe there is enough adjustment in the clamp screw to accommodate the extra thickness. If the formed bar extends above and below the hole I think it would be adequate without actually repairing the casting.

That camming of the clamp handle against the casting has always been an area of concern to me. Since it only takes a quarter turn of the screw after the mating parts are against each other and all further motion has been taken up, I have never encountered this problem.

I can see if the clamp screw was too tight, then excessive pressure on the clamp handle would happen.

Your analysis is, IMO, right on.

I have worked JBWeld into the cracks, doing so from the inside. It flowed through the cracks quite freely. I have also checked to see if I could locate a washer under the cam. It appears as though that would work. The washer would do as you describe - distribute the pressure outward from the hole and taking all pressure off the peninsula between the two cracks.

I will do all of this and put the Shopsmith back into service knowing that I may have to break down and spend money on a replacement Headrest. Ohhh, spending money on broken parts hurts me to the core.

[JPG]

Not sure a washer is big enough. The surface where the clamp cams against is away from the hole. I believe the stress from the clamp camming is what caused the damage at the weakest point(the hole).

[dusty]

I think that a flat washer installed between the cam and the Mark V will reduce some of the stress that is applied to the cracked area but, as you say, will not eliminate the stress.

To reduce the stress, I plan first to make certain that the lock is never turned tighter than it needs to be. (I believe this is what caused the cracks to start with).

I am going to use a flat washer as well.

For a portion of the fix, I am going inside the Headrest. I plan to install a tube, over the spring, that will span that space and transfer at least some of the stress to the other side (where there is no hole).

Doing this is going to be a challenge because of the clearance issue pointed out earlier by JPG.

[JPG]

I think that a flat washer installed between the cam and the Mark V will reduce some of the stress that is applied to the cracked area but, as you say, will not eliminate the stress.

To reduce the stress, I plan first to make certain that the lock is never turned tighter than it needs to be. (I believe this is what caused the cracks to start with).

I am going to use a flat washer as well.

For a portion of the fix, I am going inside the Headrest. I plan to install a tube, over the spring, that will span that space and transfer at least some of the stress to the other side (where there is no hole).

Doing this is going to be a challenge because of the clearance issue pointed out earlier by JPG.

A pipe(tube) was my first thought, but I did not think there was enough clearance between the casting and the spring. I did not feel like doing a headstand to check out the clearance, so came to that conclusion by feel only. A pipe is probably too thick. Perhaps you could 'roll' one out of thinner steel. The sleeve that goes in the hole on the headstock side is about 5/8" and the spring is somewhat smaller(od). Maybe a bushing(s)?

[dusty]

A pipe(tube) was my first thought, but I did not think there was enough clearance between the casting and the spring. I did not feel like doing a headstand to check out the clearance, so came to that conclusion by feel only. A pipe is probably too thick. Perhaps you could 'roll' one out of thinner steel. The sleeve that goes in the hole on the headstock side is about 5/8" and the spring is somewhat smaller(od). Maybe a bushing(s)?

Your idea would certainly work especially if being done by someone who works sheet metal and has the tools.

I have all the tools to work wood. The only thing lacking may be skill and patience. I can over come the lack of skill by doing repeated attempts. I have made some measurements for going that way.

Then I got to thinking. What am I really trying to do. I am trying to fill that void that is behind the crack. Why should I not just block the holes and fill that void with epoxy. When it cures, drill a hole for the bolt and spring and I am done.

The hollow casting is now solid.

You can drill epoxy, right?

The void that I am talking about is seen in the last photo I posted in this thread. The epoxy would have to be about 1" thick to get above the hole. You can see one of the cracks in this image as well. There is another on the other side of the hole that is the same.

[JPG]

Your idea would certainly work especially if being done by someone who works sheet metal and has the tools.

I have all the tools to work wood. The only thing lacking may be skill and patience. I can over come the lack of skill by doing repeated attempts. I have made some measurements for going that way.

Then I got to thinking. What am I really trying to do. I am trying to fill that void that is behind the crack. Why should I not just block the holes and fill that void with epoxy. When it cures, drill a hole for the bolt and spring and I am done.

The hollow casting is now solid.

You can drill epoxy, right?

The void that I am talking about is seen in the last photo I posted in this thread. The epoxy would have to be about 1" thick to get above the hole. You can see one of the cracks in this image as well. There is another on the other side of the hole that is the same.

Got a 5/8" bit for drilling out the epoxy? Once you drill out to clear the sleeve & spring. you will have removed all the epoxy directly behind the smaller hole where the fracturing(or whatever) occurred. A washer(fender?) on the interior side of the smaller hole prior to filling with epoxy may be needed to provide a bridge between the epoxy and the hole.

I would look for bushings/sleeves/spacers/bearings with 5/8" id and a small od before trying the epoxy attempt.

All that being said, I think a flat(curved to match the casting shape(original) that extends both below and above the damaged area that is stout enough to prevent further stress on the damaged(jb-welded) area on the clamp handle side) is the simplest way to prevent both further damage and a need to replace it.

[dusty]

I have reevaluated the situation based on comments here. The object is to occupy the space in the current void behind the Headstock Lock cam so that the cracked area no longer takes all the stress applied by the cam.

My idea of floating that area full of an epoxy (JBWeld) would work I believe. But why can that area not be occupied by a block of wood that is fit "snugly" into the void area and accomplish the same objective.. The hole for the spring can be pre-drilled.