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Best way to cut cut .01 over on 1.5” diameter tubing 4’ long

kssnagger

Plastic
Joined
May 9, 2013
Location
ks usa
What’s the best way to repair 1.75”x1.5” tubing 4’ long, they are for oilfield pumps so if I can figure it out could potentially be hundreds or thousands of them to do. Basically they have plungers that run through them and they get grooved and it causes them to slip the fluid and stop pumping but they sell oversized plungers. So I would like to be able enlarge the barrels so they can be reused. Some are brass, some are stainless. I would like to be able to do .01, .02, and .03 over 1.5”. What kind of tooling would you use boring bar, reamer?
 
You dont do it in lathe you need a hone...Phil

And that is what the OEM is using, a hone.

Not to be a kill joy but I think you will have a very hard time breaking into this niche business and competing with the OEM.

This is one of those applications that the initial cost of the barrel becomes very insignificant to the overall pump replacement/installation cost.

Just realize that the OEM is using a multi spindle horizontal hone, so they are doing multiple parts per hone stroke in addition to having everything else to put the pump together.

If you have this all figured out and can make a decent profit with a single spindle hone as an aftermarket supplier, than great,go for it.
 
A guided boring bar is a possibility, but it will take a lot of setting up and messing about to make it work, ............and there's every chance stainless will require a completely different set up to brass.

So please, no offence intended, but going by the sort of questions you have asked, I'd suggest that maybe such a method / project is not for you.
 
Are there areas on each end that are original diameter, with the working area in the center uniformly oversize? Or are there grooves in each end at the reversal of stroke and the rest of the barrel close to original size? If you just have to bore each end out to fit oversize seals a suitable sized lathe should do. If it needs rework full length, I'd think scrapping the barrel and replacing with new would be a better option. I just don't see that many dollars of material there to justify much expenditure for rework.
 
Usually the ends of the barrel are true where the cups don’t run but where the cups(plungers) run it’s grooved on one side or the other. It has to be true for the full length of it so it will carry fluid without slipping it, so you have rework the full length of the barrel. They cost about $200 apiece, so it adds up pretty fast if you can rework them. They also sell oversized cups of .01, .02, and .03 over so someone is reworking them.
 
Usually the ends of the barrel are true where the cups donÂ’t run but where the cups(plungers) run itÂ’s grooved on one side or the other. It has to be true for the full length of it so it will carry fluid without slipping it, so you have rework the full length of the barrel. They cost about $200 apiece, so it adds up pretty fast if you can rework them. They also sell oversized cups of .01, .02, and .03 over so someone is reworking them.

What machine shop capabilities doo you have ?
 
I would think that you could use a skiving machine to cut them to size the fastest. Depending on surface finish requirements you could get a skiving/burnishing tool.
 
Usually the ends of the barrel are true where the cups donÂ’t run but where the cups(plungers) run itÂ’s grooved on one side or the other. It has to be true for the full length of it so it will carry fluid without slipping it, so you have rework the full length of the barrel. They cost about $200 apiece, so it adds up pretty fast if you can rework them. They also sell oversized cups of .01, .02, and .03 over so someone is reworking them.

IME reworked / conditioned etc etc parts are worth at the most 50% of cost of new (folk tend not to pay anymore)

So we'll take $200 , halve it = $100, out of which has to come machine time, tooling and set up costs, tooling replacement etc etc

Time lets just say 250 rpm (most jobs like that the speed guide goes out the window) and you can get the finish you need at 0.005'' / rev = 1.25 '' / min or <> 38 mins cutting time per pass @48'' long.

Now again lets just say a machine shop charges $50 / hour ..............you will soon be in a situation where there will be precious little of the $100 left to make the job worthwhile.

Of course YMMV, BOTOH, the above comes from someone who over 50 years ago almost grew up reconditioning parts.
 
If you are running any kind of piston seal a honed and/or burnished finish will be needed. Reaming then honing or ball burnishing would work if you can keep size.

Ed.
 
IME reworked / conditioned etc etc parts are worth at the most 50% of cost of new (folk tend not to pay anymore)

So we'll take $200 , halve it = $100, out of which has to come machine time, tooling and set up costs, tooling replacement etc etc

Time lets just say 250 rpm (most jobs like that the speed guide goes out the window) and you can get the finish you need at 0.005'' / rev = 1.25 '' / min or <> 38 mins cutting time per pass @48'' long.

Now again lets just say a machine shop charges $50 / hour ..............you will soon be in a situation where there will be precious little of the $100 left to make the job worthwhile.

Of course YMMV, BOTOH, the above comes from someone who over 50 years ago almost grew up reconditioning parts.

Except I’m going to use the end part so it’s worth $200 to me and my labor is me so pretty affordable. Also I can use about 100 barrels easily every year so 100x$200 is a significant operating cost.
 
What material?

Some of them are forged. There is a lot more technology in that 4ft. piece of pipe than is realized.

The surface finish is down in the 20micro finish from the one vendor I am familiar with.

I do not see how the OP has any hope of making money on this. Even if they could have a sell price of $200, that is only 4hrs. total of shop time. The OEM has a fully automated process and spits these out in minutes. The OP has an old manual lathe that is far from an ideal process and still a honing operation will be required.

At a minimum, the OP needs to stop thinking of this as a lathe job and think more in a least cost process path to do these parts.
 








 
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