Gap Tooth Repair

[matthewsx]

My new to me Bolton 13x40 has a gap tooth.



This piece fell off during transport but I was able to recover it from the freeway rush hour traffic.




The lathe was dropped on it's face prior to me getting it and the crack wasn't obvious when I went to inspect it. So, seeing that this isn't the worlds best machine to begin with I figure I'll just try to reattach it from where it came off. Thoughts so far are to mount a thick steel plate to the front of the bed and this piece with bolts and maybe add some strong epoxy once I've got it lined up well.

But I'm open to suggestions.

John

 

[markba633csi]

The way I would probably approach it would be to clean the parts thoroughly, epoxy them back together while fitted in place on the lathe, then remove it and add some type of reinforcing plate across the break, after milling a flat area and drilling some new holes. Then epoxy and bolts. Don't try brazing or it will warp like crazy and you'll never get it to fit again. Cold repair only.
-Mark

 

[matthewsx]

I’m hesitant to remove what’s left of the gap as it seem well aligned and already glued in there by some kind of filler material.
Also my mill is just a little thing that isn’t really up to working with something like this.

John

 

[ErichKeane]

Wow, amazing that you were able to find the thing! Thats great news!

I more or less agree with Mark.

I'd definitely start by drying to epoxy it together, avoiding getting any on the bolts. I think you DO need to remove the other side, otherwise you're not going to get a good mount for a plate. I don't think you need to mill a flat, you should be able to do it with a set of files, though it'll take way longer. Then, just take a plate of mild steel (top and bottom maybe?)and bolt it in.

Alternatively, there are devices known as 'stitch' kits, its basically a piece of metal shaped with a bunch of bulbus shapes, that you then hammer into a bunch of drilled holes. For a full break, you have to do something like ~14 seconds here:

See this image for an explaination: https://www.metalockinternational.org/metalock-onsite-stitch.html

The nice part is the kits have a drilling guide, so you can do this with just a hand drill.

 

[ErichKeane]

Some additional info on lock-n-stitch:

They refuse to list prices on their website, but: http://castingrepair.locknstitch.com/viewitems/lock-kits-2/lock-kits#
for the cross-stitch kit. You can then use the pin kits: http://castingrepair.locknstitch.com/viewitems/l-series-pin-mini-kits-2/l-series-pin-mini-kits
For the areas in between.

 

[matthewsx]

Some additional info on lock-n-stitch:

They refuse to list prices on their website, but: http://castingrepair.locknstitch.com/viewitems/lock-kits-2/lock-kits#
for the cross-stitch kit. You can then use the pin kits: http://castingrepair.locknstitch.com/viewitems/l-series-pin-mini-kits-2/l-series-pin-mini-kits
For the areas in between.

Looks interesting, one problem I see is there’s not enough flat area on top of the smaller piece.

john

 

[ErichKeane]

Looks interesting, one problem I see is there’s not enough flat area on top of the smaller piece.

john

Maybe? I cannot really tell. First, no reason that couldn't be flattened a little. Second, the smallest lock-n-stitch is only 1 inch long. Presumably based on the design you could get away with < 1/2" on each side.

That said, if he's willing to break up the body filler on the other side, the right answer is likely to pull that out and do whatever repair you'd need like this from the bottom.

ETA: Just after posting that, I saw this: http://castingrepair.locknstitch.com/viewitems/l10-l15-5-locks/l15-5-locks

Looks like their shortest one is .793". So ~.400/side? Maybe a little more doable?

 

[Cooter Brown]

Clamp a block in the middle and braze it back together.....

 

[pontiac428]

I support the cold repair. J-B Weld has worked wonders for me. I broke a bolt flange off a carburetor that I repaired with J-B, which was a weak cantilevered joint, and I daily-drove that pickup for 15 more years without incident. In terms of cross-section, that was a tiny repair compared to yours, so I imagine that would be strong enough for any forces it sees on the ways. Sometimes the simple solution is a good one, but I do understand if you don't want to use glue as a permanent repair on your lathe bed.

I think the most correct repair would be brazing, but this casting is a really poor candidate for that. Re-grinding or scraping the gap piece would certainly be necessary. It might be worth it to re-manufacture the part from a single piece of steel if you've got to do it, since you'll be doing an equal amount of fitting as you would with the hot work option.

 

[matthewsx]

As a sailor I have a lot of respect for modern epoxy, if it doesn't work the worst that will happen is I have a lot of scraping grinding and sanding to get back to the original metal. I think a call to the Gougeon Brothers might be in line here, their West System products haven't failed me yet.

John