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loose nut
09-25-2014, 06:17 PM
I need to machine both ends of a piece of 1 1/2" pipe two accept roller bearings for a axle.
My plan was

1 - to put a temporary center in the end of the pipe (I don't have a bull nosed center), with a center drilled in it, for the tailstock support, my lathe doesn't have a big enough spindle bore to take the pipe.

2- with one end in the chuck and the other supported by the temp. center to turn the OD of the pipe, at the end, for the steady rest.

3- mount steady with outboard end of pipe on it.

4- face and bore the end to fit the bearing.

5- turn end for end and repeat.

Now why this won't work. Pipe isn't round or straight inside or out, at least not by machining standards. While I may get the ends square and bored perpendicular to the faces, it is extremely unlikely that this method will result in the axis's of the bearings, once installed, being inline let alone parallel. Because of the inaccuracies of pipe, putting a temp. center in the pipe won't put the tailstock center inline with the center of the pipe so all machining will be off center.

Any ideas on how to do this right.

Lew Hartswick
09-25-2014, 06:25 PM
Use DOM tubing.
...lew...

JRouche
09-25-2014, 06:31 PM
Center and hold the pipe with a temporarily modified follower rest. Mount a boring tool in the four jaw chuck so its off center and sweeping through the bore dia you need. Support the loose end of the pipe in the steady rest.

Dunno? Just thinkin out loud :) JR

Lu47Dan
09-25-2014, 06:37 PM
Use DOM tubing.
...lew...
+1
In my experience, BIP is not the easiest material to machine. It is kind of gummy.
If I was going to build your project DOM tubing would be my choice also.
Dan.

MrSleepy
09-25-2014, 06:38 PM
If you had a cathead..you could eliminate step 1 ... just centre it of the cathead using the steady rest as step 2 .

You could add the extra step of creating a steady rest bearing surface ,so you could remove the cathead , then re centre and machine the actual bearing surfaces.

Hack admission: I have in the past used an old geased up tailstock mounted chuck as a three prong bull nose...while machining the steady rest bearing surface at the chuck end...but it wasnt for anything important.

Rob

Bob Ford
09-25-2014, 06:52 PM
Use a four jaw chuck. A steady rest and the center you made for the end of the pipe. Set up the pipe in the four jaw the other end supported with the center. Adjust the four jaw so the pipe runs near true. Turn a band on each end of the pipe that is the same size for the steady. Install the steady at the chuck end and adjust to fit, now move the steady to the tail stock end. It should fit the band without adjusting. Remove the tail stock and bore for the bearing. Reverse the pipe in the lathe. Put the steady on the band at the tail stock end. Adjust the four jaw so the the band now at the head stock is running true then bore the tail stock end to size.

Bob

loose nut
09-25-2014, 07:22 PM
DOM tube is out, it is a project for a friend and he gave me pipe.

lakeside53
09-25-2014, 07:26 PM
+1
In my experience, BIP is not the easiest material to machine. It is kind of gummy.
.


I have the opposite experiences. BIP is quite ductile and machines beautifully -almost mirror like. I use carbide and a fairly high sfm.

brian Rupnow
09-25-2014, 08:13 PM
Cheat!! Bore both ends a few thou oversize. Get a shaft that is a good fit to the i.d, of the bearings. Coat inside of bored recesses with Loctite, drop bearings into place and immediately insert the "alignment" shaft. Let cure 24 hours. Works like a charm.

J Tiers
09-25-2014, 08:59 PM
I have the opposite experiences. BIP is quite ductile and machines beautifully -almost mirror like. I use carbide and a fairly high sfm.

I'm in the "it's kind of gummy" camp..... never got a mirror finish on pipe or 1018 without grinding. You must have that thing spinning fit to take off.

SGW
09-25-2014, 09:03 PM
Put a center in both ends, and turn between centers with a lathe dog to drive it.

lakeside53
09-25-2014, 11:37 PM
I'm in the "it's kind of gummy" camp..... never got a mirror finish on pipe or 1018 without grinding. You must have that thing spinning fit to take off.

1000-1250 rpm, 3/4 BIP made in korea (from Home depot!). it does not turn like 1018... way way better. I don't know if all BI pipe is like this, but what I have in my shop is.

darryl
09-26-2014, 12:17 AM
Pipe is not round- true. But by machining a press-fit disc with a bored center hole, you'll get it averaged to a central point about as well as can be. If you don't use too much pressure, the pipe won't distort much, and your bored hole will be about as close to center as you'll get. Machine a stub to fit the bored hole and hold that in the tailstock however suits- a chuck would be fine. It may or may not be inline with the lathe axis, but it won't matter much. Machine the OD just until all the original surface has been cleaned away.

When you reverse the pipe and use the same disc, that end will center pretty much exactly like the other end did. Machine the OD there. If you want to be critical, reverse the pipe once more and recut the OD. The spindle chuck will be holding onto a machined OD at this point, and the pipe will be as wobble-free as you'll get it. Once you'd done machining the first OD again, remove the disc and turn the spindle slowly. Whatever wobble you see, tap on the 'high' side of the pipe until it turns wobble-free. At this point set up your steady rest and machine the ID.

Loosen only the upper steady rest arm and reverse the pipe, machine the other ID. Those bores are now going to be about as inline as you'll get. The shaft that is supported in the bearings may not be totally centered within the pipe, but it will be centered to the machined OD portions. If the OD of the whole length of pipe needs to be centered, then you'll have to machine it. But I doubt that will matter. If pipe is the chosen starting material, you will have done the best that can be done with it.

RussZHC
09-26-2014, 05:34 AM
Don't know this might really "solve" your problem, my "solution" was to start far away from size i.e. pipe that was far thicker wall and larger than needed OD enough so that I knew several boring and external passes could both be made before getting close to size. I guess effectively I was putting the tube shape I needed within the walls of the material I had so that even if out of align it still fit.
It then became a matter of getting an interior and exterior surface machined by repeated flipping of the part (could not machine any surface fully due to holding material), using one then the other surface as "true", two external and two boring passes and it was within reason (I was working towards the "spindle" of a welding positioner, needing to maintain as large a bore as possible so no vital measurements and still fit the bearings on the exterior, the OD important as to fit).

IMO the suggestion about establishing a running surface for a steady rest and the working from there is what should be done, I just did not think about it (if I am thinking about it correctly, at the very least it would add accuracy to the method you describe by allowing the interior plug to be fit more exactly re: alignment to axis)

Lew Hartswick
09-26-2014, 08:59 AM
DOM tube is out, it is a project for a friend and he gave me pipe.
Well! If he had given you a tree stump would you try to use that? :-) In some cases the "offered"
or "supplied" material just isn't suitable. :-)
...lew...

ironmonger
09-26-2014, 09:15 AM
How about reversing your thought process,,, build a v block to clamp the od of the pipe and bolt it to the compound in place of the toolholder, mount a boring bar in the chuck and bore the pipe.
If you are close to the correct ID my blacksmith side votes for machining a tapered swage a few thou undersized, heat the end of the pipe and drive the swage in, and the shrink fit the bearings in place. I either event, I would use a shaft to align the bearings as they were pressed into place.

As far as 'gummy' pipe is concerned, the only pipe that fits that description is wrought iron or 'Byers' pipe. It can be identified by a spiral red stripe... or if that is worn off by the crappy threading characteristics. Never had a problem threading pipe with the exception of an occasional inclusion. Using ark cutting oil, sulphated if available will yield excellent results.

see:
http://www.oatey.com/brands/hercules/products/oils-lubricants-and-hand-cleaners/cutting-oil/dark-cutting-oil
delicious! :p

paul

Rosco-P
09-26-2014, 09:19 AM
Well! If he had given you a tree stump would you try to use that? :-) In some cases the "offered"
or "supplied" material just isn't suitable. :-)
...lew...

If I wasn't busy and if the piece was short enough, I would line-bore it on the horizonal mill.

Get yourself some t-shirts made: "I'm a Machinist, not a Magician."

gzig5
09-26-2014, 10:31 AM
The way I have done this in the past...
Cut work piece over final length, mount in 3jaw chuck, face end, bore bearing seat, bore minor ID if desired.
Remove work piece from chuck and either create an expanding arbor or turn a sacrificial arbor to press the work piece onto, registering on the bearing seat you have created.
Mount part onto the arbor you have created (use tailstock to press on if needed), face end to correct length, bore bearing seat, true OD if desired. Light cuts may be required depending on the mounting method.
Remove part from arbor and go enjoy the beverage of choice. The seats on the end should be square to each other and in line because your arbor was turned in place without removing it.

Old Hat
09-26-2014, 10:44 AM
Well! If he had given you a tree stump would you try to use that? :-) In some cases the "offered"
or "supplied" material just isn't suitable. :-)
...lew...

+1


If I wasn't busy and if the piece was short enough, I would line-bore it on the horizonal mill.

Get yourself some t-shirts made: "I'm a Machinist, not a Magician."

+1

A knee-mill has four mysterious bolts that when loosened, allow the head to be swung to the left
till your pipe can extend below the table surface. Bore, flip, bore, done.

My T-shirt Idea is:

He can do it Faster?
.........Great!.......
Then take it to him,
and I'll warm up the
... ... Dynasty ... ....

Lu47Dan
09-26-2014, 10:49 AM
I have used pipe in the past and had it machine alright, but the vast majority of it did not like to be turned. I have tried various speeds and feeds on the bad pipe without success. Older American made pipe seems to turn better than the new stuff. I did use some recently that surprised me in how well it turned.
But if I could get or would have had DOM in stock I would have used it instead. Less problems and less time invested in it.
This is just my machining experience with BIP.
Dan.

TGTool
09-26-2014, 02:56 PM
A knee-mill has four mysterious bolts that when loosened, allow the head to be swung to the left
till your pipe can extend below the table surface. Bore, flip, bore, done.



Can you elaborate on how you locate the pipe when you flip it? I can certainly get two bores of the right size that way but have some uncertainty whether the centerline of each will be coincident and/or parallel.

Apropos of the boring mill setup, I have used a between centers boring bar on the lathe with the workpiece clamped to the crosslide. It introduces some other problems (centering on the workpiece and making sure it's parallel to the ways) but it does guarantee that both end bores will be exactly in line and with a little twitching they can be exactly the same size.

MrSleepy
09-26-2014, 03:20 PM
A knee-mill has four mysterious bolts that when loosened

Does Loose Nut have a milling machine .. ?..

loose nut
09-26-2014, 07:50 PM
Not a knee mill or a horizontal, I have a small home shop, not a big fab shop, so line boring or other ideas requiring equipment I don't have are out, hence the use of the lathe. As far as making it out of a tree stump, no I wouldn't but as far as pipe, well I'm not going to buy a piece of DOM tube (even if it is available locally, which it might not be. Country area not near a big city) for him so it is what I would use.

Rosco-P
09-26-2014, 08:45 PM
What about saying: No. No, I can't make it from this piece of water pipe you have. I can make it from DOM tubing, if you are willing to pay for the material. Even schedule 80 pipe would be a better starting point. Sometimes you can't make a silk purse from a sows ear, not matter how much of your time your willing to waste.

darryl
09-26-2014, 11:44 PM
It is for an axle, not a precision spindle. Chances are it will be more than adequate for the job, and chances are it will be 'typically German over-machined' at that, even if it's detectable that the bores aren't precisely in line with each other. Ball bearings have more than enough tolerance for any 'off axis' misalignment that this proposed method would give.

Rosco-P
09-27-2014, 12:03 AM
It is for an axle, not a precision spindle.

I think everyone reading and commenting on this thread figured that out. Yes, for a simple axle. Carry on, tilting at windmills Don Quixote.

mike4
09-27-2014, 12:15 AM
If its just for an axle ,why not grip it in the chuck use a steady ,just for safety, and machine one end to finished dimensions , assuming the chuck is a four jaw flip the pipe/axle over and machine the other end to finished size.
Easy and quick , I and others here have made our own tyre carriers for workshop use to allow one person to change truck tyres etc .

Material used was common garden variety gal or black pipe.

Michael

loose nut
09-27-2014, 02:08 PM
Just heard back from the guy I machined the pipe for (machined as stated in first post) and he said it worked fine. Thanks.

Old Hat
09-27-2014, 05:39 PM
Can you elaborate on how you locate the pipe when you flip it? I can certainly get two bores of the right size that way but have some uncertainty whether the centerline of each will be coincident and/or parallel.

Apropos of the boring mill setup, I have used a between centers boring bar on the lathe with the workpiece clamped to the crosslide. It introduces some other problems (centering on the workpiece and making sure it's parallel to the ways) but it does guarantee that both end bores will be exactly in line and with a little twitching they can be exactly the same size.

Sorry, I've sort of scaled down my thinking automaticly without realising it.
Often when doing large work on floor-bars, it's just assumed that quallification cuts (indicatable areas)
need to be cut on a part. At times even requiring a set-up that acheives nothing else
but the formation of a patch in line with another patch, or perhaps a full length or full width witness cut.

The pipe would have needed something along these lines, indicatable, or rested on the witness in a V-block etc. etc.
===========

If cuts are not allowed but are needed, temporary pads are tacked on for these cuts
and removed when done.