I can buy a hub-hub ABS coupler at the home stores (etc.) but they don't carry repair couplings. Can I ream out the stop to make my own?

no, you may not, as each side of the coupling is TAPERED and designed to allow full 'seating' of the pipe only when solvent cement is applied (acts as a lubricant/solvent when 'wet')

the taper is precision 'machined' to form an actual 'weld' by applying PRESSURE at the base

a 'properly made' joint is as strong as the pipe itself

theoretically

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Are ABS repair couplings really tapered? I don't think so.

correct - that is precisely why a 'repair coupling' (for ABS or PVC or CPVC or any other solvent welded plastic pipe) is garbage

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

The repair couplings are not tapered. I know I can take a repair coupling and slide the entire coupling onto the pipe without a lot of struggle.

On the other hand, a regular coupling is tapered from the edges towards the center, which is why you can't easily push a pipe all the way in till it bottoms without primer and cement. For this reason if you just remove the ridge in the center, you still cannot use it like a repair coupling, to slide it over one pipe, insert the joining pipe, then slide it half way over the joining pipe.

You can do that with a repair coupling, but due to its non tapered nature, the joint will not be as strong.



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Can you use a shielded "no-hub" coupling instead?

Thanks for the great answers. I hadn't known about the tapering. I can use a shielded no-hub coupling - but they're more expensive and look temporary, rely on torque - 60 lbs!, which seems like a lot. The application is venting, and all the pipes have lots of support - I wouldn't think strength would be an issue. That so many stores don't sell them must mean something.



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The torque is 60 INCH lbs, not FOOT lbs.

what it meansis that not many people use them and they are a "PITA" to use properly.



Edited 1 times.

[www.google.com]

[pimmedia.winsupplyinc.com]

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Whoops! 60 ft-lbs would have been exciting. 5 seems reasonable.

I haven't found anybody in town that has them, even special order. An Internet search turns up a page for them at home depot, but they're unavailable. I suspect that DIYers screwed up so often that making a buck on them isn't worth the hassle of unhappy customers, even if it is the customers' fault.

I downloaded Nibco's catalog, and Genova's and Charlotte's.

I never realized that couplings were tapered either...makes sense though now that you explain it. This also explains why every time I have tried to use a plastic repair coupling it's leaked and I've had to cut it out and use a Fernco banded coupling.

I also thought that the glue-in coupling looked more "professional" than a Fernco, but I've gotten over how it looks, I'm all about no leaks!! Also why the real pros don't use these glue-in repair couplings.

The other problem besides the lack of taper is that the repair coupling pushes all the glue out of the way as you slide it into place, so you never really know how much glue is left in the joint.

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Not a plumber by trade but a fierce DIYer