How would YOU measure these final plumbing cuts?

[Schulks]

Hello! Last time I plumbed I had about 20 extra couplings...

How would you measure these final cuts for my drain lines?

I was going to try and use this plumbing video which uses math to solve for the length of pipe. But I am not sure how accurate it will turn out!



Does anyone here use math for cuts instead of a measuring tape?

 

[troublemaker]

Maybe I’m a caveman, but I honestly hold the elbow in line and measure. The unions make that one simple, as you aren’t try to glue a 45 mid pipe. It’s PVC, it’s a little forgiving, a 16th here or there isn’t even going to be noticed.

 

[Kingsley_Reef]

Licensed plumber here just eyeball it cut your pieces long dry fit and adjust and dry fit again eventually you get really good at it hahaha

 

[Schulks]

Alright, I will give that another try.

My previous/first plumb job, I had some leaky unions and had to heat the pipe to bend it a bit.

I think I can do better this time.

 

[Kingsley_Reef]

Alright, I will give that another try.

My previous/first plumb job, I had some leaky unions and had to heat the pipe to bend it a bit.

I think I can do better this time.

Yeah just make sure there’s no stress on the pipes when dry fitting everything should fit nicely with no bending ratcheting pipe cutters will make your life easier and give you clean cuts take your time cleaning and glueing give it time to cure youl be fine

 

[Schulks]

Yeah just make sure there’s no stress on the pipes when dry fitting everything should fit nicely with no bending ratcheting pipe cutters will make your life easier and give you clean cuts take your time cleaning and glueing give it time to cure youl be fine

Thanks for the tips. I am using my miter saw for pristine cuts in 2 seconds. It is nice.

Is there a trick to dry fitting? I can never get the pipes to go in completely before adding primer and cement.

 

[Kingsley_Reef]

Thanks for the tips. I am using my miter saw for pristine cuts in 2 seconds. It is nice.

Is there a trick to dry fitting? I can never get the pipes to go in completely before adding primer and cement.

Not really just got to muscle it

 

[UncommonSense]

I used this recently to get precise lengths for expensive clear sch.40… it does take some careful thinking though!

https://www.omnicalculator.com/math/triangle-45-45-90

 

[Schulks]

I gained the courage to glue some drain lines today. The primary drain came out perfect but the emergency drain is a bit too long, I believe.



Edit: after 1 coupling it lines up way better.

 

[Schulks]

Another segment completed.(all glued)



Now for the final level.. (none glued)



Im stumped atm!

Edit: I also figured out why everyone uses threaded bulkheads instead of slip. I had to get a ratcheting cutter because my miter saw can't reach the back of the tank. slip bulkheads are not removeable with 90s right by them.

 

[UncommonSense]

Now for the final level.. (none glued)



Im stumped atm!

Either use two 45 elbows in a row to make things 3D, or…

Shorten pipe length to have wye and 45 elbow touching socket to socket, shorten pipe going in to bottom of wye slightly too, aligning UV plumbing better… Increase pipe length out of trueunion valve; either side!

 

[Schulks]

Either use two 45 elbows in a row to make things 3D, or…

Shorten pipe length to have wye and 45 elbow touching socket to socket, shorten pipe going in to bottom of wye slightly too, aligning UV plumbing better… Increase pipe length out of trueunion valve; either side!

hmm, this is not tight fitted but how does it look?



I'm not sure where to start. I think I will just tight fit things and then start cutting and gluing one thing at a time.
It would look really nice without all these couplings i foresee.


Edit: there will also be a union on the main return line.

 

[UncommonSense]

hmm, this is not tight fitted but how does it look?
I guess I will go back and fit things together really tight then start measuring and cutting.

It would look really nice without all these couplings i foresee.

There are some couplings designed to do multiple jobs, but you’re already using many of them!

I typically like to chamfer the exterior of the pipe’s cut edge on my bench grinder before test fitting to make things easier, but you typically just want to measure socket depths and account for that in pipe lengths where you can!

For example; where you want to attach that 45elbow above the wye; use a tiny little 1” length of scrap pipe as a placeholder to get those two fittings together socket to socket! This allows you to rotate the 45 elbow while holding it in final position! — you’ll have the final length of pipe cut to the exact length of both fitting’s socket depths for final assembly, of course… just make an indexing line from fitting to fitting for final alignment, and swap the 1” placeholder pipe for the final pipe right when you glue up!

This technique can be used anywhere where you want to get things to final test-fit, then still be able to take them apart easily after, just measuring the length of pipe between each pair of fittings, and adding the depth of each fitting’s socket to the length for the final pipe! (I recommend using cheap white pipe for slightly undersized mock up plumbing)

Note: not all brands of fittings have sockets of equal depth! Don’t assume they’re all the same, always check!

 

[Schulks]

There are some couplings designed to do multiple jobs, but you’re already using many of them!

Sorry, I mean joiner couplings because I am going to measure poorly and have to make a few corrections lol

I typically like to chamfer the exterior of the pipe’s cut edge on my bench grinder before test fitting to make things easier, but you typically just want to measure socket depths and account for that in pipe lengths where you can!

For example; where you want to attach that 45elbow above the wye; use a tiny little 1” length of scrap pipe as a placeholder to get those two fittings together socket to socket! This allows you to rotate the 45 elbow while holding it in final position! — you’ll have the final length of pipe cut to the exact length of both fitting’s socket depths for final assembly, of course… just make an indexing line from fitting to fitting for final alignment, and swap the 1” placeholder pipe for the final pipe right when you glue up!

This technique can be used anywhere where you want to get things to final test-fit, then still be able to take them apart easily after, just measuring the length of pipe between each pair of fittings, and adding the depth of each fitting’s socket to the length for the final pipe! (I recommend using cheap white pipe for slightly undersized mock up plumbing)

Note: not all brands of fittings have sockets of equal depth! Don’t assume they’re all the same, always check!

I have a union to add on the main return line so I wont have to line up the elbows. That just leaves measuring correctly.

You are verifying a lot of what I have been figuring out. I am measuring every socket and adding it all up to calculate cuts and it is moving along. Hopefully these pieces are done by tomorrow.


Thanks for all your help again!


oh and I have this nifty tool for chamfering. It is working nicely.

 

[Schulks]

This segment is pushed together really tight.



Should I just start measuring cutting gluing and then remeasuring as I go?

 

[UncommonSense]

This segment is pushed together really tight.



Should I just start measuring cutting gluing and then remeasuring as I go?

I only see one possible change to make it tighter; that would be using a street (aka “spigot”) style elbow goin into the UV sterilizer, like so!

That’s up to personal preference, of course!

You look ready to go otherwise! The 45 elbow above the wye on the return line that’s currently joint to joint could be made 1/8-1/4” longer/taller, lining up the return plumbing perfectly!

 

[Schulks]

Ahh, you're right! I already have a street 90 in my parts but i already glued that elbow. Woops.

And I am going to tight fit the primary return after gluing this segment. There will be a union where the pipes are not lined up. maybe a gate valve too depending on space.

 

[UncommonSense]

Ahh, you're right! I already have a street 90 in my parts but i already glued that elbow. Woops.

And I am going to tight fit the primary return after gluing this segment. There will be a union where the pipes are not lined up. maybe a gate valve too depending on space.

Ah well!

You have space for both a gate valve and a union; gate valve knobs can point any direction; you’ve probably noticed that I like mine sideways!

(Here’s a bonus tip for style points: if plumbed to plan for it; you can have your plumbing/gate valves hidden behind a thin sheet material like plastic, with the gate valve stem(s) poking through the plastic! — This means the valve itself is hidden, and all you see when examining the sump cabinet is a knob sticking out of a wall!)

 

[Schulks]

Finished that piece and am working on the final segment !

It is too tight to fit any blue pipe here :<

 

[Schulks]