reguarding turning between centers

[Bullshop]

John242
Thank you thank you thank you, I just cant say thank you enough!!!

[theperfessor]

Do you have a South Bend lathe manual? I think I have a scanned version of it somewhere that I could put on a CD or USB drive and send you. Some of it is specific to certain model features but most of it is just darn good basic information on how to do basic lathe operations.

Let me know if you're interested.

[David2011]

Am I missing something? The center can be on a faceplate or it can be in a chuck, or it can fit into the taper of bore of the lathe head. If the center is in the chuck, you must center it. Some faceplates are built centered (fit on to the mounting provision for the chuck), some fit into chucks and must be centered, some centers fit into tapers in the lathe head bore. The barrel bore is centered by the center, you can make and use a spud in the bore with a center drilled hole to fit the center and protect the bore. The other end goes on the tailstock center, also with a spud preferrably. Tighten the tailstock center against the work and the bore is centered. Run a dog in the slot on the faceplate or against the chuck to provide power to the piece. This "dog" is the teardrop shaped hole thingie with a bolt to tighten to clamp to the work, and a 90 degree "dog"leg to fit into the faceplate slots.

Leftiye,

There are several sets of correct but confusing information presented here.
1. You would only need to center drill if turning barstock on centers.
2. The method that discusses dogs in T-slots on the faceplate is for irregularly shaped objects, like a rectangular block that needed a round shape machined internally or externally.
3. If you're machining a barrel blank or other tubular item that already has a hole down the center you would turn it in the live and dead centers as described, using a lathe dog to drive it. The cool thing about turning on centers with a lathe dog is if you're threading, you can remove the workpiece from the lathe and return it without losing your indexing as long as you return the dog to the same slot or stop. Goodsteel described a great way to make a dead center on the fly. If the lathe bed is too short to accommodate the barrel between centers with the center in the chuck, then you will need a dead center that fits the spindle's tapered bore. That will give you several more inches between centers.

"How to Run a Lathe" is still in print and available at Brownell's. It's a bargain at $7.95: http://www.brownells.com/books-video...prod18158.aspx

David

[David2011]

OK Good!!!! I am beginning to get it. When I got the lathe with the tools I noticed there was a dead center that fit the MT of the tail stock but with it there was a sleeve that fit over the dead center that changes it to a larger MT that at this point I am assuming will fit the head stock.
Another thing mentioned here was to run the bent leg dog against the chuck. I had woundered about that. So if done that way will that eliminate the need for the face plate?
That brings up another question for me, what is a straight leg dog for?
I do appreciate all the help and hope you wont get sick of me asking. I am sure I will have many more questions.

Hi Bullshop,

The fit of the dead center in the tailstock without the sleeve is common. If actually turning, you would need to use the live center in the tailstock so it's free to spin with the workpiece. The dead center turns with the spindle and lathe dog so it doesn’t have to be able to spin.
There are two options for the dead center. One is Goodsteel’s excellent method of making one from barstock in your chuck. That method will make the most accurate possible dead center. If you remove it from the chuck and later re-use it, you would need to cut a new taper to true it up but that should only take a light pass or two. With that method you would drive the lathe dog with a chuck jaw.

The other method is still very good; just not as close to perfection as making a dead center in the chuck. That is to remove the chuck, clean the spindle taper and dead center as described in another post, seat the dead center and install the slotted faceplate to drive the lathe dog. The dead center doesn’t transfer torque to the workpiece; it just holds it in the centerline of the spindle so it doesn’t need to fit super tight in the spindle. It will get tight enough on its own.

Be sure to put a piece of ¾” ply over the ways to protect them from the chuck or other accessories falling when you change them out and keep the fingers above the center of heavy parts.

Hope this clarifies a bit.

David

[Bullshop]

theperfessor
That is very kind of you but right now I dont have a way to run those.
David2011
Thank you every bit helps.
I did get a reprint on one of the old how to books but it seems incomplete. I will try to get the one from Borwnells. I say try because today is my wifes b-day so not appropriate to ask today.

[John 242]

This is the MIT website I spoke of. If found it to be more helpful in understanding milling than the lathe, but there is some lathe info.
http://techtv.mit.edu/collections/ehs-videos/videos

Another site that I really enjoy is Mr Lyle Peterson's Youtube page. Mr. Peterson used to be a shop teacher and he makes some very informative videos.
http://www.youtube.com/feed/UCKLIIdKEpjAnn8E76KP7sQg/u

I downloaded a 'free' copy of Southbend's How to Run a Lathe manual. It's a 1950's version, but that really doesn't matter much. It's a PDF file.
http://campkahler.com/files/How_to_R...he_SB_1of2.pdf

I have a bunch saved to my favorites. More to follow...

[John 242]

Here is the South Bend How to Run a Lathe book for sale at Brownells.
It A 1942 edition, which means the free one I linked above is actually newer. Regardless, the Brownells version is by Lndsay Publications and is of good quality. The price is $7.96 and the stock number is 100-001-043WB.
http://classic.brownells.com/.aspx/p...To-Run-A-Lathe

This is the US Army correspondence course for lathe operations. This contains basic lathe operator information and includes chapter tests and a finals exam.
http://www.hnsa.org/doc/pdf/lathe.pdf

I forget where this came from, but I think it’s translated from Japanese or Chinese. Regardless, it covers a few basics and is somewhat educational. Not my best link, but okay.
http://www.nmri.go.jp/eng/khirata/me...k/index_e.html

Here’s a link to Hong Kong University. Again, some basic information and the Chinese/English translation is pretty good.
http://mmu.ic.polyu.edu.hk/handout/0102/0102.htm

This is the Virtual Machine Shop. A very good site with lots of information.
http://www.kanabco.com/vms/library.html

A good amount of lathe info here, along with other shop info.
http://www.astronomiainumbria.org/ad...h/techindx.htm

Not really much here for beginners, but an interesting site none the less. This site focuses more on the mini-lathe and some of the information is a little dated, but Varmint Al is a shooter so I figured I’d include his lathe page here.
http://www.varmintal.com/alath.htm

You Tube-
South Bend's How to Run a Lathe Video
http://www.youtube.com/watch?v=9O-9_...885847&index=8

South Bend Instructional Videos
http://www.youtube.com/watch?v=7S-za...e=results_main

Smithy put out a surprisingly good video series that describes basic operations
http://www.youtube.com/watch?v=H0AyVUfl8-k

Lathe video series by Duke University
http://www.youtube.com/playlist?list=PLBFAB15BAA84879F4

An okay basic lathe video, but can be challenging unless you if speak Canadian.
http://www.youtube.com/watch?v=fmFQEnDZy6E

These videos include rifle barreling and chambering, which is not exactly beginner level, but interesting all the same.
http://www.youtube.com/user/suar0816...ow=grid&view=0

I hope this will work for now. If you need more, let me know and I'll see what else I can dig up.

[John 242]

If this helps, here are a few picture of a bolt mandrel being turned between centers. Note the lathe dog, face plate, dead center in the head stock and the live center in the tail stock.

[leftiye]

Leftiye,

There are several sets of correct but confusing information presented here.
1. You would only need to center drill if turning barstock on centers.
2. The method that discusses dogs in T-slots on the faceplate is for irregularly shaped objects, like a rectangular block that needed a round shape machined internally or externally.
3. If you're machining a barrel blank or other tubular item that already has a hole down the center you would turn it in the live and dead centers as described, using a lathe dog to drive it. The cool thing about turning on centers with a lathe dog is if you're threading, you can remove the workpiece from the lathe and return it without losing your indexing as long as you return the dog to the same slot or stop. Goodsteel described a great way to make a dead center on the fly. If the lathe bed is too short to accommodate the barrel between centers with the center in the chuck, then you will need a dead center that fits the spindle's tapered bore. That will give you several more inches between centers.

"How to Run a Lathe" is still in print and available at Brownell's. It's a bargain at $7.95: http://www.brownells.com/books-video...prod18158.aspx

David

Thanks, but I've had a copy of that since 1974.

[Willbird]

Also Bullshop a trick I picked up from my gunsmith. Just face the end of the barrel off nice and square with a sharp tool (with the barrel of running in the steady rest) then run the tailstock live center right on the sharp corner of the bore. Works nifty...then if it is a taper barrel I set the compound to match the angle of the barrel but just a bit more taper. Then turn the OD true(usually there is some runout) then put the steady back on the OD and face the end AGAIN, then again turn the OD true. Each time you do it the end gets more square to the bore, and that makes the OD run more true. Doing it twice usually means the bore will be within .0001 with the OD on the steady.

You can make an aluminum ring to clamp on the barrel OD if you to want to turn or otherwise mar it. Then just take a light cut from the ring to true it.

Some folks chamber barrels with the left end on a dead center in the headstock, and they hold the barrel back against that center with surgical tubing pulling it back. The right end runs in the steady rest.

[JIMinPHX]

Another trick that I've used many times is to tap a threaded hole in the face of a piece of stock, insert an Allen bolt, then run the Allen bolt in the slot on the faceplate, rather than use a dog.

There is more than one way to skin a cat & as you gain time on the machine, you will probably come up with a bunch of new methods that work well for you.

Being a machinist is a thinking man's game. The more you can think ahead, the less extra work you will need to do.

Good chess players usually make good machinists.

[MBTcustom]

I have used the bolt trick. Just be sure to use a stout enough bolt! I had a low grade 3/8-16 bolt driving a big work piece once. I was threading the end of this shaft, and the bolt bent. Almost jacked up my threads, but I was able to save it. Good quality bolts can take more side load than the cheapies. Whoda thunk it?

[fast ronnie]

Another good way to drive between centers is to use a one piece shaft collar. Take out the set screw and replace with a grade 8 bolt of enough length to drive against a bolt through the face plate. This is the method we use on a cylindrical grinder that I sometimes run. The collar doesn't have to be a perfect fit on the shaft. It just has to be large enough to fit over the shaft. If marring the shaft is an issue, a piece of aluminum or brass shim can be used under the bolt.

[DCM]

Another good way to drive between centers is to use a one piece shaft collar. Take out the set screw and replace with a grade 8 bolt of enough length to drive against a bolt through the face plate. This is the method we use on a cylindrical grinder that I sometimes run. The collar doesn't have to be a perfect fit on the shaft. It just has to be large enough to fit over the shaft. If marring the shaft is an issue, a piece of aluminum or brass shim can be used under the bolt.

Excellent tip! A collar like this would usually be easy enough to make too, especially as the collar itself doesn't need to be precise.
I love KISS solutions.

[ProfGAB101]

A few points:

If using a faceplate with a MT reducing sleeve and dead center in the spindle be sure to indicate the center to be sure its running true. Now days with so much cheap imported tooling there are 4 surfaces that have to be near perfect for that dead center to run true, each surface that has dirt, grit, dings or just sloppy manufacturing etc. multiplies the run out.

A small piece of 4140 or 4340 pre-hardened mounted in the chuck can be turned with the compound to make a disposable center, doing this guarantees that there will be NO run out until you loosen the chuck. Likewise on your workpiece, if it has a hole in each end you can indicate the part in a 4 jaw and use a small boring or other tool to cut the center angle. I use this method often for OD turning pipe.

Lastly - if using a dead center in your tail stock you need to keep your speeds down and re-lube the bearing surface of the tail stock center before each pass. This needs to be a very EP grease, and you can get grease labeled as center grease.

Tip - if you start getting harmonics during the cut, slow the rpm down a bit and place a shot bag or bag of small bullets on the tail stock body (not on the quill portion). This also works good to drape a shot bag on your compound, just be sure doing so does not alter your depth of cut. Don't have any shot bags - make some from the lower pant legs of worn out blue jeans.