Broken back repair on my Sabrina doll

Technician · Post by **Technician** » Wed Sep 23, 2020 3:11 pm

Great thread! I'm going to go for the repair on my Bubbles this weekend if the stars align. It almost looks like if we were to remove that bracket piece from the bottom of the spine it could be welded to the 1/2 round repair tubing and then put back in with band clamps.
After I look at Bubbles I may even try the repair like yours, but with a couple plastic washers between the parts to make a spine that can turn to get that sexy "looking back over the shoulder" thing going on.
Thanks again for pioneering, I'll add my results here for others.

seagull · Post by **seagull** » Wed Sep 23, 2020 8:14 pm

Appropriate user name Technician

Siliconeman · Post by **Siliconeman** » Thu Sep 24, 2020 12:01 am

Technician wrote:Great thread! I'm going to go for the repair on my Bubbles this weekend if the stars align. It almost looks like if we were to remove that bracket piece from the bottom of the spine it could be welded to the 1/2 round repair tubing and then put back in with band clamps.
After I look at Bubbles I may even try the repair like yours, but with a couple plastic washers between the parts to make a spine that can turn to get that sexy "looking back over the shoulder" thing going on.
Thanks again for pioneering, I'll add my results here for others.

Thank you Technician, your input for this thread would be appreciated. Please keep us updated how it goes with your repair.

Cheers!

Sili

Wheezer · Post by **Wheezer** » Thu Sep 24, 2020 12:26 am

Many thanks for the thread !

Just opened up my Piper to fix an almost identical problem and came up with a similar solution. Based on your results I dropped the need for anti-rotation pins in the half pipe for my fix. Will probably go with adding JB weld to the pipes and four (4) hose clamps. I considered adding a thrust bearing to the saddle to allow side to side turning, but backed off of that. I would rather give up the side to side turn for a good solid back fix.

How has your clamp fix been holding up?

Great pics
Thanks!
... W ...

Siliconeman · Post by **Siliconeman** » Fri Sep 25, 2020 10:11 am

Wheezer wrote:Many thanks for the thread !

Just opened up my Piper to fix an almost identical problem and came up with a similar solution. Based on your results I dropped the need for anti-rotation pins in the half pipe for my fix. Will probably go with adding JB weld to the pipes and four (4) hose clamps. I considered adding a thrust bearing to the saddle to allow side to side turning, but backed off of that. I would rather give up the side to side turn for a good solid back fix.

How has your clamp fix been holding up?

Great pics
Thanks!
... W ...

Hi!

Yes, I had a look at your Piper thread and the break is identical with my SM175L.

My repair has been holding up very well and I have been tossing her around the bed.

What I could have done better is to glue the repair part (split pipe upper and lower parts) very well to the original pipe structure. This would give the repair more strength.

It is also very very important to tighten the repair bolt well so that upper part of the spine is not able to move in any direction.

Cheers!

Sili

Wheezer · Post by **Wheezer** » Fri Sep 25, 2020 2:05 pm

Siliconeman wrote: Hi!

Yes, I had a look at your Piper thread and the break is identical with my SM175L.

My repair has been holding up very well and I have been tossing her around the bed.

What I could have done better is to glue the repair part (split pipe upper and lower parts) very well to the original pipe structure. This would give the repair more strength.

It is also very very important to tighten the repair bolt well so that upper part of the spine is not able to move in any direction.

Cheers!

Sili

Great to know its an identical problem!

But a quick question about your doll - that is about the two back joints above the break.

In my situation they are VERY hard to move, but I wondering if that is not a problem. They might need to be fairly stiff to prevent flop when all the parts are assembled.
In your case how stiff were these joints before the repair?

I don't want to fall into the trap of redesigning and fixing a "problem" component that is only the item performing as it was originally designed.

Thanks!
... W ...

Siliconeman · Post by **Siliconeman** » Fri Sep 25, 2020 3:03 pm

Joint above the breakage point was VERY stiff. And I think that is why the break happened.

Wheezer · Post by **Wheezer** » Fri Sep 25, 2020 3:13 pm

Thanks ... same problem.

Mine was locked solid since I think the original owner forced it and kept pushing leading to failure. I got it moving by careful applications of banging it with a ball peen hammer. So now it's straight again. And moves ... with some effort.

But yours was tight also. And after the repair she now seems to have an acceptable range of motion. So I am coming to the conclusion that the repair to fix the broken joint may not have to extend to replacing the stiff joint. If yours works and bends reasonably with a stiff joint that is good news.

I REALLY do not want to get into the effort and potential debris issues involved with removing all the welded nuts and bolts in the joints.

Many thanks!
... W ...

seagull · Post by **seagull** » Fri Sep 25, 2020 9:06 pm

Avoiding debris in doll material, smart move 'cause once it gets in there it is there to stay
Packing around the skeleton repair section with cloth can reduce the amount of debris getting in there but if using a power tool, kinda risky

Filing by hand and using a magnet is the easiest way to remove metal and manage debris

Wheezer · Post by **Wheezer** » Fri Sep 25, 2020 10:40 pm

We all agree - no debris ! (Is that the TPE Doll Repair School chant ??)

For the drilling I am going to place a LOT of protective material around, down and under. Think of a surgical drape times three. As an added precaution I will place a number of Neodymium "super magnets" (wrapped in cloth) ringed around the drill site. Maybe attached to metal protective can, gotta test it first. Those should collect any flying bits. Especially if the can is tall and gives me a containment tower.

Right now the plan (hope) is that a firm back joint is not a deal breaker. In that case it is only a case of drilling one hole in the doll parts and dramatically reducing potential debris issues.

On to other tests in progress.

Cheers!
... W ...

Technician · Post by **Technician** » Sun Oct 04, 2020 12:49 am

Bubbles' back is officially fixed, thank you Siliconeman for a great repair thread!

Bubbles was broken exactly the same, but her pelvis frame section is "U" shaped so I didn't have the option of using the lower pipe half and my upper was only about 3" long.
I also loosened the pivot bolt (which is about a 7/16" grade 12.5 hardened bolt that had the nut welded to the bolt) so adjusting her back will require less force.
My parts were:
3/8" X 1" bolt
3/8" nut
(2) 1 1/2" hose clamps
1" X 6" galvanized nipple
I cut Bubbles open and found the damage, there's a layer of what I believe to be fiberglass Mat in there saturated with tpe all around the spine.
After cutting out what I had to so I could get to everything I got 2 combination wrenches on their bolt and broke it free, that was a bitch, I had hoped to pull the piece out and weld it to my pipe but the piece wouldn't let go of the spine even without the bolt so I opted to leave it in place and tighten the bolt back up a little less than what it was when I started.

: 20201002_215454.jpg (1.35 MiB) Viewed 1032 times

I cut the threads off both ends of the nipple, before doing the slit cut, and dressed up the edges on my wire wheel.
Then got her torso elevated with a rolled up towel so her spine could get where a drill could get to it, I forgot how unfriendly stainless is about being drilled through, but I remember well now.

: 20201003_001744.jpg (2.37 MiB) Viewed 1032 times

My plan "B" if welding failed was to use a castle nut and pin so I drilled a through hole in the bolt where it should have been, unfortunately I decided to add a washer to the bolt end to make it easier to turn and was only able to see half the hole so plan "C" was drafted on the fly to just make it ungodly tight.

I skipped the zip ties and went right to band clamps and tightened.

: 20201003_013900.jpg (1.06 MiB) Viewed 1032 times

Cleanup was tedius, a magnet got some chips because the hinge was steel, but the stainless of course is non magnetic. For me sticking masking tape to her and peeling it off seemed to work best.
Since I removed the fiber cloth that kept the joint out of contact with the TPE I cut a little Ace bandage to replace it before pasting the hole with Xylene and closing it up.

: 20201004_000527.jpg (1.44 MiB) Viewed 1032 times

Today there was still a spot the xylene hadn't melted back together so I redid that little part, if theres a noticeable scar I'll use my hot air rework station to dress it up.

Siliconeman · Post by **Siliconeman** » Sun Oct 04, 2020 1:41 am

Great work Technician!

Now be careful with her, although healed she is not like she used to be!

Cheers!

Sili

Technician · Post by **Technician** » Sun Oct 04, 2020 2:56 am

Thank You!
I'm actually thinking about not being careful though, there's a few things at play.
I'm just finishing an AI on a very small computer as a doll computer prototype so at some point she's getting opened up again for installation of the computer, batteries, sensors, and more so I'm laying out an articulated spine for her at the same time.
Using her like normal now could expose a weakness that I can address later.

Wheezer · Post by **Wheezer** » Sun Oct 04, 2020 4:19 am

Great suggestions and (almost) worked on my Piper. Made pipe parts to fit and then (DAMN!) the hip pipe was bigger than I thought. Oh well, just do it again with a larger pipe

For what it's worth the Piper back repair is a bit more challenging since they used hip bigger pipe, but a smaller hip pipe length and (still) they must have hired the same bad welder. The support portion that goes on the underside also has to deal with a 25mm bolt welded to the bottom of the hip pipe for some unknown reason. Just another hole to drill to clear it.

The shorter hip pipe only allows me to use two hose clamps, but I found some in the parts bin that should work well. They are Mikalor Supra W2 stainless clamps. Other places make similar style clamps. They are exceedingly strong due to a solid band, unlike the worm gear clamps. Tightening is with a solid screw which should not give as easily as a worm great. Plus when you tighten you don't get a protruding band. You might want to look at these if you are doing a future back repair.

: New_SS_clamp(600).jpg (60.56 KiB) Viewed 1022 times

Now to make another set of repair parts in the morning.
Cheers!
... W ...

Technician · Post by **Technician** » Sun Oct 04, 2020 11:54 am

That's a good idea going to the other style clamp!

On mine the weld was not at fault. I think what's happening it the heat from welding fatigues the pipe, then just being stressed back and forth breaks the pipe at the weak spot. Siliconeman's pictures look the same to me.
They really should be a heavier pipe in that spot.