Would someone please explain to me how to set up to turn between centers using a faceplate and dog. I am a beginning machining expert taking my first baby steps. I have only so far used regular chucks for turning. Have never yet turned between centers only between chuck and tail stock center.
I'm also clueless but put a dog on the chuck end the other is simple. Not sure how to "center" the chuck end on the bore.
I'd probably chuck up the barrel put the end on a center,, turn the end so bore was in "center", flip it around chuck the turned portion and turn it to dia.
Last edited by bearcove; 11-19-2012 at 09:29 PM.
first you have to centerdrill both ends with a center drill. then use a lathe dog thsat hooks into the face plate. then install the tailstock center. then you are ready to go.
First you have to center the part. You can start with one end in a chuck and set the other end in a steady rest. The center can be cut with a small boring bar or a center drill. Reverse the part and do the other end. Now the end running in the chuck might be running out a thou or so but subtend that out the length of the barrel and you come up with a error factor running out to five or six places. Close enough !! Most people cannot accurately measure that close.
Clean your tapers ( and the centers) pop in the centers and use the dog of your choice. Put a copper pad on the contact area of the dog. Do not over tighten the tailstock center and be sure to use a good sticky lube. As you cut remember that the barrel will elongate due to heat. Re-adjust your tail stock center frequently to allow for this.
Try to find a copy of the Atlas or Clausing Lathe Manual ( ebay ), they show you how to tie the special knot ( using a leather thong ) that will hold the barrel at the headstock end tightly in the center without causing distortion. You will need this to hold the barrel tightly to the headstock while you run the tailstock end in a steady rest for chambering.
This is the most accurate way of doing things.
The part I am not getting is when I remove the chuck from the head stock and install a faceplate how do I hold a center (live or dead) without a chuck?
As I am trying to understand the faceplate/dog are only to transfer power to turn the centered piece so how then to hold the center? Its probably simple but I am not getting it yet.
I'm with you on that. It would seem that you would need to turn the one end at the tailstock concentric to the bore then put that in the chuck. I can't see how you coud indicate off the bore and get it centered in a dog after you turn it around.
On those lathe manuals on ebay all I am finding are model specific manuals of parts and operation.
What exactly am I looking for?
Sorry for being a pain in the behind!
The workpiece is clamped to the faceplate, typically using t-nuts in slots in the faceplate, or less commonly threaded holes in the faceplate itself.The faceplate was the ancestor of lathe chucks, an arrangement of three or more adjustable 'dogs' bolted to the faceplate providing a primitive chuck arrangement. Basically it would only be used for odd shaped pieces that wont go in a 3 or 4 jaw chuck or a flat plate like a flywheel shape /flat plate to face , etc.
Maybe this will help...http://www.cnccookbook.com/MTLatheHolding.htm
Rich
You Know You Might Be Facing your DOOM , if all you get is a click, Instead of a BOOM !
If God had wanted us to have Plastic gun stocks he would have planted plastic Trees !
If I am reading this right, you are asking "what holds the center" ?Originally Posted by Bullshop
In almost all lathers ( there are a few exceptions ) there is a taper cut in the spindle of the headstock. Might be anywhere from a number 2 Morse to a number 5 Morse depending on machine size and even here there are a few exceptions that do not use a Morse taper.
After removing the chuck that taper is carefully cleaned along with the correct center and the center is snaped into the taper in the spindle. Don't try to make a home run with it , just pop it in and it will, if all being correct, lock into place. Tapers tend to lock.
This reinforces the need to keep tapers on both ends very clean and basicly keep the whole machine clean and properly lubed.
The tapers of the machine and the centers must be the same. Chips, dirt, grit etc, will cause a improper fit and will damage the tapers throwing off the accuracy. Cleanliness is next to Godliness in the machine world but then again you would never know it looking at some of the machines being used.
You are correct in assuming that the dog will only transfer rotation to the part ( the barrel ). Actually when setting the dog you want to make sure it dosn't bind. There will actually be a bit of "rattle" to it but when the cutting pressure is applied, the pressure will stop any rattle present. Any binding will cause the barrel to bend to a degree, throwing everything off.
I keep a box of cheap paper towels by the lathe, use them to clean centers. My lathe has a cylinder into which a #5 MT center goes in for the headstock. The tailstock gets a #3 MT center. Dead centers go in the headstock, live centers go in the tailstock. Frank
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.
Last edited by leftiye; 11-20-2012 at 06:04 AM.
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Every "freedom" (latitude) given to government is a loophole in the rule of law. Every loophole in the rule of law is another hole in our freedom. When they even obey the law that is. Too often government seems to feel itself above the law.
We forgot to take out the trash in 2012, but 2016 was a charm! YESSS!
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.
the headstock is made to take a moreis taper. on small lathes it is usly the next size larger then the tailstock. example. my 9 southbend lathe has a number 2 taper in the tail stock. the head stock has a number3 taper.
the larger lathes have even larger headstock tapers some even have tapered sleeves. this done so they can have a larger hole through the headstock.
this is all covered in the reprint of the southbend book how to run a lathe. i know people don't want to be bothered to read a book. but i have been doing machine work for over 40 years and i still go back to the book to get ideas for a set up or help with a problem. the books by guy lautard the machinest bedside readers are good reads with alot of ideas. maching is a contuing learning experince.
Go to you tube and look up South Bend video's they have a factory video from the 40's that shows it all. Turning between centers was a lot more common with the older lathes with small holes through the head stock. In the old ones you needed to center the part in the center rest to drill the centering holes as nothing over 3/4" would fit in the chuck. Watching the video is worth about 200% more than any written explanation.
You can also make your own dead center for the chuck end by setting the tool holder at 60 degrees, and then use a live center on the tailstock.
I do this so I can use a 3 jaw self centering chuck and avoiding having to install a 4 jaw chuck and indicating in the work piece.
You cannot discover new oceans unless you have the courage to lose sight of the shore
Dont bother with the faceplate. Use your chuck as God intended it to be used. If you are profiling a barrel, then you already have the bore for the centers, but you will want to make sure that you have a square end, and a 60 degree chamfer on the bore on both ends.
If this is a bar of metal that has no centers, mount one end in the chuck, and the other in the steady rest. Use a common 60 degree center drill to make the centers in both ends in this way.
Once you have 60 degree centers in both ends, find a piece of stock less than 1" in diameter, and about 4" long. Install this piece in the chuck and cinch the living bleep out of it, with all three (if you have more than one) key holes.
Set the compound crank to 30 degrees, 60 included (ie, set it up to cut the piece of stock in the chuck to a 60 degree point) and turn down the end to almost a perfect point (a little flat will not matter).
Now you have a center in the chuck that is perfectly aligned with the rotation of your headstock.
Install the center in the tailstock, and grease it with center point grease.
install the lathe dog on the end of the stock (with copper shim to prevent marking) so that the leg catches on one of the chuck jaws.
Take a skim pass over the piece of stock, or barrel blank to establish a measurable surface.
Adjust the tailstock to produce the desired taper, or parallelism.
Viola.
Precision in the wrong place is only a placebo.
The straight tail lathe dog is supposed to be more accurate than the bent tail lathe dog. When the straight dog is used, it is driven by a stud in the face plate. I have not used a straight dog, only the bent ones.
I have only recently been taught to turn between centers at school. We've turned various cold rolled steel rounds with a dog, face plate and live centers. I'll keep this simple because we are both beginners and I don't know much.
In preparing my round stock, I would initially cut it to approximate size with a cut off saw, leaving it about 1/8 inch too long, more or less, for facing (that's a lot but I get tired of re-cutting stock because I faced off too much).
Facing is simply making the end square to the axis (axis- I believe that's the right term). I placed the round stock in a 3-jaw chuck and faced off one end so it was square and then drilled it with a center drill (I've been using a No. 3). I then loosened the chuck, flipped the round stock around and repeated on the other end, but facing to the correct over all length.
After drilling and facing I removed the 3-jaw and attached the face plate. I installed a rotating 'live center' in the tail stock and mounted a 'dead' center in the spindle nose through the face plate (This center will turn with the spindle and actually becomes 'live' because it turns. A dead center in the tail stock would need to be lubricated, so we use a rotating live center in the tail stock.)
I then placed a lathe dog on the round stock and installed the tail of the dog into the slot on cut into the face plate (to provide drive). The dead center tip is aligned in the center drilled hole. I then moved the tail stock quill outwards until the 'live' center's tip moved into the other center drilled hole. With the stock secured between centers, the dog in the slot and every thing tight, you should be ready to turn.
There are many experienced machinists on here and I am not one of them. When I read some of their posts, sometimes it's a little overwhelming.
I have made some scrap, so if you goof up, don't let it get you down.
I have links to a lot of on-line lathe info. If you want me to post them, I will.
I read quite a bit and watched various videos about lathe operations before starting school and it helped quite a bit.
I strongly recommend Mrpete222's videos on Youtube. I also have links to an MIT lathe and mill series and various other things.
Still, nothing beats hands on experience.
We started with very simple straight mandrels and have progressed to shoulders, threading, etc. Each new operation is an opportunity to pull your hair out. Fortunately for me, mine's all gone.
Take care,
John T.
Last edited by John 242; 12-02-2012 at 10:48 PM.
Good point about the shim and adjusting for tapper.
We use bent pennies in the dog to keep from garfing up a finished surface.
We were taught to use a test bar and indicator to get the tail stock aligned, but I've found that unless it is way out of wack, dialing in adjustment following light cuts seems to work pretty good and is much faster. Not sure if that's the right answer or not, though.
John 242
Thanks for the help. I am certanly overwhelmed just trying to learn terminoligy. I would very much like to get some schooling but for me that is out because there is nothing available anywhere near me.
The only way for me is to ask questions and just do it. Sure would be nice to have someone local to watch sometimes.
Hey Bullshop,
Sorry about the slow reply, but last week was kind of crazy. Within the next couple of days I'll post a few links here that might be helpful.
If nothing else, you can get a grip the terminology and have a feel for the process.
Take care, John T.
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