# Machining big pipe.



## Flyinfool (Aug 5, 2021)

This will be interesting.
I have to c'bore the ends of a piece of 5" sch 120 pipe that is about 70 inches long.
That the pipe is 5.563 OD with a .500 wall. I need to C'bore the ends to 4.510 dia x .500 deep.
Each pipe weighs about 160 lbs.
I have a 13 x 40 lathe but the pipe hangs past the end of the bed, the surface is also to rough for a steady rest and this will be used in a pressure vessel so the OD can not be turned smooth for the steady rest.
I have a mill, 70 inches is to long to hang off the side of the table. Not enough space between the spindle and the floor to get a boring head in there.
This will be an interesting one to figure out.


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## benmychree (Aug 5, 2021)

Sounds like it is too big for the available machine tools.


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## rabler (Aug 5, 2021)

Align the mill off the end of the tailstock end of the lathe, with a center or such mounted on the mill table?
Haven’t done that myself but IIRC both Keith Fenner and Abom79 on YouTube have done variations on this


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## matthewsx (Aug 5, 2021)

Best plan would be to find a suitable machine and transport the material there. Don't mess around with pressure vessels if you don't have the gear or expertise, the results can be very, very bad....

John


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## Jimsehr (Aug 5, 2021)

Flyinfool said:


> This will be interesting.
> I have to c'bore the ends of a piece of 5" sch 120 pipe that is about 70 inches long.
> That the pipe is 5.563 OD with a .500 wall. I need to C'bore the ends to 4.510 dia x .500 deep.
> Each pipe weighs about 160 lbs.
> ...


If the OD is 5.563 and you take 2 times the wall thickness 1 inch you end up with 4.563 . That is larger then your bore size of 4.510.


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## MrWhoopee (Aug 5, 2021)

Time to get that right-angle head for the mill.


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## DAT510 (Aug 5, 2021)

Not sure if there’s a solution here, but this guy has some really creative solutions for machining large pipe and cylinders. I really like the chuck he made for his tailstock.



			https://www.youtube.com/c/CuttingEdgeEngineeringAustralia


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## Norseman C.B. (Aug 6, 2021)

At the shipyard I used to work at we used an internal adjustable spider set back enough to do your bore and dialed in to spec
while on the live center, had to get creative with the tooling a lot but it worked out..............


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## Alcap (Aug 6, 2021)

What brand / type of a mill ?  Or could you possibly set the pipe up on the saddle and use the steady rest to support the opposite end with the tail stock removed , might have to smooth out for sliding  .


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## mmcmdl (Aug 6, 2021)

MrWhoopee said:


> Time to get that right-angle head for the mill.


Easily done on a BP with a right angle head .


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## jpackard56 (Aug 6, 2021)

Jimsehr said:


> If the OD is 5.563 and you take 2 times the wall thickness 1 inch you end up with 4.563 . That is larger then your bore size of 4.510.


? Gotta agree, with those demensions you have to remove more than you have to start with ?


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## jmkasunich (Aug 6, 2021)

Agree with others that a right angle head on the mill would be best for this.  But if you don't have one... 

Do you have a boring head and a follow rest?

Put the boring head in the lathe spindle.  Mount the follow rest to the saddle.  Put one end of the pipe in the follow rest and clamp it down tight so it won't rotate.  Remove the tailstock and support the far end of the pipe on an adjustable height roller (like woodworkers use for table saw outfeed).  Bore by feeding the carriage and the non-rotating pipe toward the spindle and the rotating boring head.


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## MrWhoopee (Aug 6, 2021)

jmkasunich said:


> Agree with others that a right angle head on the mill would be best for this.  But if you don't have one...
> 
> Do you have a boring head and a follow rest?
> 
> Put the boring head in the lathe spindle.  Mount the follow rest to the saddle.  Put one end of the pipe in the follow rest and clamp it down tight so it won't rotate.  Remove the tailstock and support the far end of the pipe on an adjustable height roller (like woodworkers use for table saw outfeed).  Bore by feeding the carriage and the non-rotating pipe toward the spindle and the rotating boring head.


The follower rests I'm familiar with, unlike a steady rest, only have two bearings, behind and above the stock. However, I like your thinking. It suggests something like a large vee block bolted to the carriage and adjusted to center the tube on the spindle. 

There's more than one way to skin a cat bore a tube.


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## jmkasunich (Aug 6, 2021)

MrWhoopee said:


> The follower rests I'm familiar with, unlike a steady rest, only have two bearings, behind and above the stock. However, I like your thinking. It suggests something like a large vee block bolted to the carriage and adjusted to center the tube on the spindle.
> 
> There's more than one way to skin a cat bore a tube.


Good point about the two rollers - I had a bit of a brain fart there.  Vee block would work if the carriage has provisions for attaching it, and if you can shim or otherwise get it to the right height.

A follower rest could work if you used a ratchet-strap or something to pull the work back and up towards the two rollers.  That would also serve to prevent it from turning.  And the adjustments built into the follow rest might simplify centering the tube on the spindle.'


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## Flyinfool (Aug 7, 2021)

Jimsehr said:


> If the OD is 5.563 and you take 2 times the wall thickness 1 inch you end up with 4.563 . That is larger then your bore size of 4.510.





jpackard56 said:


> ? Gotta agree, with those demensions you have to remove more than you have to start with ?



You are both correct, That is what I get for trying to remember numbers. 
I need to make the c'bore 5.047 dia and then put a 3:1 taper from that dia to the original wall thickness to avoid a sharp corner stress riser. This is to to match the wall thickness of a 5" SCH 40 pipe. so that there is room to use a backing ring to weld on the next fitting All of the rest of the system is SCH 40 pipe.

I have a Tree 2UVR mill. I have seen OLD catalog pics of a right angle head for it but have never seen one available anywhere at any price.

These are for a manifold, the heavy wall is not needed for strength, it is to satisfy the minimum thread engagement for a 3/4 NPT hole. I will have to drill and tap almost 750 of the 3/4NPT holes in these pipes. I expect to wear out a few drills and taps. There are 30 to 32 holes per pipe but there are 24 pipes to do.

All welding will be done in a proper shop by a certified welder that makes pressure vessels for a living, I only design pressure vessels for a living, Even though I am able to weld, steam pressure in not something I would trust my welding skills for.


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## matthewsx (Aug 7, 2021)

Didn't mean to offend by my earlier comment, clearly you know what's required here.

It sounds like you might need to do some tool shopping 

John


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## MrWhoopee (Aug 7, 2021)

Flyinfool said:


> I will have to drill and tap almost 750 of the 3/4NPT holes in these pipes. I expect to wear out a few drills and taps.


Not to mention your arms.

What is the due date, and do you have help?


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## jpackard56 (Aug 8, 2021)

Is there a shop you would trust to facilitate the taper portion and then return items back to you for the 3/4 NPT ports and finish ?
I've worked with gas/oil and sometimes each piece has a serial # and only approved shops and certified welders with inspection with documented paper trail can do any work. 
Thinking out load...this might be hard to send to another shop for taper which brings you back to machine shopping (probably soon) 
Sounds like a great opportunity for new equipment, let us know you resolution !


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## Eddyde (Aug 8, 2021)

Perhaps a clamshell lathe like this could help: https://www.ebay.com/itm/164986986416?hash=item2669fd9fb0:g:tU0AAOSwQldhA4Cp 
They are made for external beveling of pipes in the field but it looks like it could be easily modified to cut internally. I think the company that makes them rents the units as well.


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## jmkasunich (Aug 8, 2021)

Flyinfool said:


> ... I need to make the c'bore 5.047 dia and then put a 3:1 taper from that dia to the original wall thickness ...





Flyinfool said:


> ... There are 30 to 32 holes per pipe but there are 24 pipes to do....


Those two bits of information change things a bit.

The taper means it won't be at all simple with a boring head (unless you have an automatic boring head, which are kinda rare).  That strongly favors setups that rotate the work instead of the cutter.

And the 24 pieces make cobbling up something out of junk simultaneously less attractive ("you mean I gotta do this craziness 24 times?!") and more attractive ("all this effort can get divided over 24 workpieces").

Here is some more craziness...  Do you have two lathes?  Can one of them be moved?  put them tail to tail, and remove both tailstocks.  Lathe 1 holds the workpiece in a chuck and rotates it.  A steady on lathe 2 holds the working end of the part, and lathe 2's carriage makes the cut.  Use the compound for the taper.

A variation on that theme that only needs one lathe - do you have access to one of these pipe threading machines?  Remove the tailstock from your lathe, put the steady on the tailstock side of the carriage.  Figure out how to prop up the threading machine at the right height (strap it to forklift forks?) so that it can support and rotate the pipe from the far end while the steady supports the near end and you machine using the carriage.


(don't try this at home kids!)


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## AmericanMachinist (Aug 9, 2021)

You said the OD can't be turned for a steady.  Can you add a spider around the OD and run a steady using that?

Then maybe a mandrel of some type that is mounted in the lathe headstock and expands into the ID of the pipe, but with enough clearance to cut the counterbore?   Sounds very far from ideal, but maybe?


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## KyleG (Aug 9, 2021)

Could you make the “reducer” section separately and then weld it to the rest of the pipe? I.e. split off the last few inches of pipe, do your turning, and then have one additional weld made per part?


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## nnam (Aug 9, 2021)

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 Ignore this, maybe harder than I thought.

Probably source it out or use spider idea above are good options.


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## camarint (Aug 9, 2021)

I do not think that welding it back is a good idea


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## KyleG (Aug 9, 2021)

camarint said:


> I do not think that welding it back is a good idea



Why not?


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## Flyinfool (Aug 9, 2021)

I may have a line on a bigger lathe I can use for a day. Fortunately only 12 of the 24 need this fancy C'bore. Hopefully I can get them all done in 1 day. This may be a good excuse to spring for a tapping head. I always wanted one but could never justify the expense.


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## Flyinfool (Aug 9, 2021)

jpackard56 said:


> Is there a shop you would trust to facilitate the taper portion and then return items back to you for the 3/4 NPT ports and finish ?
> I've worked with gas/oil and sometimes each piece has a serial # and only approved shops and certified welders with inspection with documented paper trail can do any work.
> Thinking out load...this might be hard to send to another shop for taper which brings you back to machine shopping (probably soon)
> Sounds like a great opportunity for new equipment, let us know you resolution !



I do have to maintain traceability on the material. It all has to be certified material, there are no required certs on the machining. As long as the material is marked and the cert stays with the material, all is good.


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## Weldingrod1 (Aug 11, 2021)

3/4" NPT is going to explode most tapping heads!

Sent from my SM-G892A using Tapatalk


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## sdelivery (Aug 12, 2021)

Weldingrod1 said:


> 3/4" NPT is going to explode most tapping heads!
> 
> Sent from my SM-G892A using Tapatalk


Not if you pick the correct tapping head and adjust the release pressure.


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## MrWhoopee (Aug 12, 2021)

sdelivery said:


> Not if you pick the correct tapping head and adjust the release pressure.


$2k for this tapping head that MIGHT be able to drive 3/4 NPT:


			https://www.mscdirect.com/product/details/89489801
		


Then you need a gear head DP with #4 MT spindle and the horsepower to drive it.
A good sized radial DP might be a better choice.

I would definitely get a 3/4 NPT reamer for this job.

I hope this job wasn't under-bid, or is at least T&M.


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