Bought myself a mini lathe..

Pcmaker

Obsessed Member
#21
Looks like I bought an oversized QCTP. I bought an AXA instead of 0XA. I have some 1/4 HSS blanks that I haven't messed with yet.
 

NYECOGunsmith

Obsessed Member
Staff member
Moderator
#22
Yup, it does look a bit big for your lathe, wasn't sure from the pictures. But if the QCTP will let you get a tool bit on the center line of the lathe, it is still useable. And a lathe that size doesn't really need 3/8 bits, 1/8, 1/4, and 5/16 all would work fine, it's not like you will be taking 1/2 inch deep hogging cuts in some 4140 pre hardened steel with it!

We can teach you to grind the HSS you have, and there are some great videos out there on how to do it you might want to watch as well, check out Tubal Cain's tool bit grinding videos, and those by Sherline, the maker of the desk top line of really small hobby lathes and mills, they are some of the best videos on how to do this, after that, it's just practice, practice, practice. Check out how to sharpen drill bits while you are at it, another worthwhile skill.
 

Pcmaker

Obsessed Member
#23
Thanks, I ordered a book about metal lathes and it just came in half an hour ago. I've been watching a lot of videos on Youtube. They make it look easy. I dont' have any aluminum to start with, so I'm using hot rolled round bars from Curtis steel. I have 30 feet of that stuff. They all say to start with softer metals, though, to get a feel for the machine. My turns are coming out rough, probably because my took isn't centered. I can't center them without using shims. I'll just wait til I get my 0XA QCTP tomorrow and try again.

Also learned that you pretty much have to use the automatic leadscrew to turn something. Is there a way to make it stop a a certain point or do I just pull the leadscrew lever to off?
 

NYECOGunsmith

Obsessed Member
Staff member
Moderator
#24
That lathe is too small to have a lead screw clutch on it, so you just have to flip off the lever that closes the half nuts around the lead screw to stop it, and you better do so before the carriage or the tool hits the chuck, crashing the chuck is a BAAAAAAD thing to do!
The top cutting edge of the tool bit must be on the lathe's center line, there are a number of ways to do that. You can put a dead or live center , either one, in the tailstock, bring it up close to the tool, then eyeball the top edge of the tool to be even with the tip of the center.

Or you can take a thin, flexible machinist's 6 inch steel pocket ruler and put it between the cutting tip of the tool and the work piece. Adjust tool height until the ruler stands straight up and down, which indicates that the tool tip is on the lathe center line.
You can also buy all kinds of fancy tools to help you get the tool bit on center, or make them yourself. I'll show you some if you manage to get over here.

You can turn something down in diameter and get a smooth finish, that requires the right tool bit geometry, the right speed on the workpiece, the right depth of cut, and the right feed speed.

To finger out how fast you should turn a piece of metal, you need to look up the alloy, and find the recommended number of Surface Feet Per Minute for turning (there are different rates for turning, milling, drilling, etc. if you want to get picky about it) , then multiply the recommended SFPM by 4, and then divide the answer by the diameter of the work piece.

For example, lets say you are going to turn down the diameter on a piece of steel with a diameter of 3/4", and a recommended SFPM for turning of 65 Feet Per Minute , 65 X 4 = 260, divided by .75 equals an RPM of 346.66666 , Just get as close to that as possible, a little over, or a little under won't hurt. The SFPM is the number of FEET of the work surface that will go by the tool bit's cutting edge in a minute, and of course as you turn down the diameter, the required speed in RPM will go up, but don't worry about that, set the speed for the initial diameter and go for it.

Remember, whenever you move the cross slide or compound in to reduce the diameter of something, the diameter will be reduced by TWICE the amount that you move the cutting tool into the work piece.

So if you had a piece of stock that was 3/8" in diameter (.375 " in decimal form) and you need to reduce a portion of it to .3125" (5/16ths ") you would subtract .3125 from .375, to get .0625, then divide that by 2, and get .03125" which is how far into the work piece you would advance the cutting edge AFTER it just barely makes contact with the surface of the work piece.

And you wouldn't advance it all at once, sneak up on it, taking careful measurements after every few half a thousandths (.005" ) until you measure the exact diameter you want.
You can't just dial in the calculated amount and expect it to be right on the money at the end of the cut, because of spring back in the work piece, heating of the work piece and tool bit, and slop in the drive gears and screw of the cross feed or compound.

Oh, and I should mention, no matter what type of metal you are working on, there should be no more that 1.5x to a maximum of 3x the diameter of the work pieces unsupported beyond the chuck (towards the tailstock I mean). The 3X only applies to larger diameter stock by the way.

So, for example, for a 3/8 inch (.375") diameter rod, you would want no more than .5625 (9/16ths) unsupported beyond the chuck. Any more than that and you will get so much spring back that it will whip on you, bend, crack, or do other bad things. So if you need more than 1.5XØ to 3XØ hanging out there, you need to use a steady rest or a follower rest to support the work so that the end you are working on is close to the supported point in the rest, or you need to turn it between centers, so that both ends are firmly supported, and if it's a long piece, even then I would use the follower rest so that it is continuously supported directly opposite the tool bit.

A steady rest bolts to the lathe ways somewhere along their length, and stays there. A follower rest bolts to the back side of the cross feed, and moves with the carriage as it travels the length of the ways, and its 3 support points parallel to the tool bit, and to the left (chuck) side of the tool bit to reduce that spring back and whip action.

Next question?
 

Pcmaker

Obsessed Member
#25
Thanks. That's a lot of into to take in. I bought a mini-lathe book to help also.

The 3 jaw chuck feels "gritty" when I turn it. I thought maybe there's some shavings in the gears. I took it apart. Everything looks clean, but dry. I had to carefully use a punch to get the bevel gear out. Pretty sure they're supposed to just "drop" if you mack it with your hand? I cleaned the existing oil off and added new oil and it's still a bit snug in there. Is this normal? After putting it back together, it still feels "gritty," even though it's just been cleaned and oiled.
 

NYECOGunsmith

Obsessed Member
Staff member
Moderator
#26
No, the chuck should scroll smoothly from fully closed to fully open or vice versa. Gritty usually comes after lots of use, and there is swarf (chips) in the scroll or in the teeth on the jaws, or in the scroll worm gear, or all the above.

Did you put the jaws back in the same slots they cam out of?

If not, it's not a disaster, it's just that most often when a chuck is assembled, if there is any quality control going on, they stamp a number on each jaw, and a temporary number on each slot, then the jaws go in a slot, get all three in, and then check the chuck for runout and write it down. Then they move the jaws to another slot, and repeat, until each jaw has been in all three slots.

They look at the combination that gave the lowest runout, put the jaws back in that configuration and stamp a number on the side of the chuck under each slot that matches the number stamped on the jaw currently in that slot. This yields the least run out. 3 Jaw chucks always have some run out, not much you can do about it unless you want to true the chuck then grind the jaws true while on the lathe.

For precise work, like threading barrels for the receiver or for a muzzle brake, where the threads have to be perfectly concentric with the BORE, not the outside diameter, get a 4 jaw independent chuck, where you adjust each of the 4 jaws one at a time, instead of scrolling like a 3 jaw self centering chuck does.

I can teach you how to adjust a 4 jaw on a round or square object so that it only takes you 30-60 seconds to get it in there and dialed into .001" of perfect runout, maybe 2 minutes if you want to get it to within .0005" run out. Just requires you to have a dial indicator that you can mount with a fixture, clamp, or mag mount, on the lathe so that the tip of it bears against the workpiece.

Dial indicator like this one is fine:
https://www.kbctools.com/products/M...S @@26 ACCESSORIES/DIAL INDICATORS/10586.aspx

Range of 1 inch is plenty, reads to .001" which is close enough for most things, even on guns, unless you are really finicky (I am) then I use one like this:
https://www.kbctools.com/default.aspx?page=item+detail&itemcode=52-520-129&catlist=9750&parent=9447

Only has a quarter inch of travel, but I get it to .001 with one like the one above, then switch out the Dial Indicator for one that reads to .0005, and try to nail it down to .0000 runout.
 

Pcmaker

Obsessed Member
#27
Yeah, I put them back exactly the way they came in. It's centered.

I've been using AR and BR carbide cutting tools to face a 3/8" mild steel rod. Can't seem to cut it square. The end always comes out semi round. I have the tip centered with the dead center. Not sure what's going on. I've been cutting off .005 at a time, then tried .010 and kept going up, but the end I'm trying to face is still rounded or tapered. Tried a different angle on the compound from 0 to 30 and still the same. Something's giving, not sure what. I've tightened the work piece as much as I can already, I was thinking it was going into the chuck as I'm facing.
 

NYECOGunsmith

Obsessed Member
Staff member
Moderator
#30
Yeah, I put them back exactly the way they came in. It's centered.

I've been using AR and BR carbide cutting tools to face a 3/8" mild steel rod. Can't seem to cut it square. The end always comes out semi round. I have the tip centered with the dead center. Not sure what's going on. I've been cutting off .005 at a time, then tried .010 and kept going up, but the end I'm trying to face is still rounded or tapered. Tried a different angle on the compound from 0 to 30 and still the same. Something's giving, not sure what. I've tightened the work piece as much as I can already, I was thinking it was going into the chuck as I'm facing.
Nope, the cutting edge of the tool is not perpendicular to the axis of the lathe spindle, so you are cutting a taper as you face. It doesn't matter what angle you have the compound set at, to face to a square shoulder the cutting edge has to be 90° perpendicular to the lathe bore axis.

With the lathe STOPPED, put the AR tool bit in the tool holder, loosen the compound so you can swing it easily, bring the carriage up close to the chuck, and then gently bring the carriage, and cross feed up really close to the chuck, now move the compound until the tool bit's cutting edge is flat against a face of the chuck, and tighten the compound so that the angle is whatever, doesn't matter. Now when you feed in with the cross feet, the cutting edge will be traveling perpendicular to the lathe bore axis and you get a square shoulder.

IF you get a small teat in the center when the tool tip gets there then you don't have the top of the cutting edge truly on center.

I have family here tying up my time until Sunday July 1, but after that we need to schedule some time at your convenience for you to come over for some lathin and millin lessons...……..maybe we can get Geo to video them and start a NVS subsection on machining how to's for beginners.

Facing and turning are pretty easy to figure out on your own, or from videos, but for boring and threading you would be a whole lot better off with some hands on instruction on a big lathe where it's easy to see what 's going on because of the size of the work, tool bits, etc. My 14x40 lathe is big enough to let you see it easily.

Wish I still had the 24x160 Clausing, it was really easy to see what was going on with that one, with a 24 inch diameter by 160 inch long piece of metal chucked up you could stand back 30 feet and still see it clearly!
 

Idaho Shooter

Very Active Member
#31
If it hasn’t been covered, take off any jewelry, do not wear gloves when turning and don’t wear long sleeves or loose clothing. Always wear safety glasses.

McFadden Dale sells some machining tooling. I know they have a good assortment of milking cutters and taps so they should have some lathe tooling.
 

NYECOGunsmith

Obsessed Member
Staff member
Moderator
#32
^^^^^^W covered that in an earlier conversation, but it is one of those things, like firearms safety, that can not be repeated too often, good timing since PC Maker is just starting to make chips on his new addiction.

In addition, no long , free hanging hair, I've seen guys scalped by a lathe when they leaned over and let long hair get caught in the chuck.
And just like with firearms, never use a lathe, mill or other power tool when you are tired, hung over, high, low, etc. Even an electric drill can kill ya, a neighbor of mine did just that 20 years ago, working on an addition to his home, too tired after long day at work, put a piece of wood on his leg for a brace and intending to drill a 1/2" hole through the board.
He slipped, and drilled through the board and into his femoral artery. Despite paramedics efforts, he didn't make it.


Just checked McFadden Dale's web site, they carry drill bits and drill bushings, but as far as I can see, with a variety of search arguments on their web site, no other machinist tools in the way of end mills, lathe tool bits, etc. They do have taps and dies, but that seems to be it. Too bad, if they carried more lathe and mill tooling, they'd get to know me by sight!
 

Pcmaker

Obsessed Member
#33
I took video footage of the two issues I currently have

1st is the graduated collar on the compound slide doesn't turn with the handle. The allen screw is already super tight. I took the compound slide out and cleaned it, didn't see anything out of the ordinary, but this is my first time messing with this

2nd part of the video shows that I'm having problems facing off the work piece. The cutting tool ends up tapering the work piece and doesn't stay square. I've tried different cutting tools, different angles, different work pieces. I've been cutting off .005 to .030. It all ends up the same. with a rounded end of the workpiece.



 

NYECOGunsmith

Obsessed Member
Staff member
Moderator
#35
Nice looking bench top mill, has some good features and enough horsepower for things you would want to do that complement the size of the lathe.

Not having a carriage lock is not an issue, if the carriage is moving left or right while facing, you just have to hold your left hand on the carriage hand wheel and keep it steady is all, I occasionally have to do that with my big lathe if it's a tough cut.
Need to show you how to move hand wheels smoothly, there is a trick to it, and it would be tough to describe with words. Will make a big difference in your surface finish though, and may also end your cone shaped facing. .

Try turning that tool bit 90° to the left so the tip points towards the chuck and the butt of the shank towards the tail stock, and face with it that way, I think you will have better results from that too. It will reduce the total contact area to just the tip, so the left edge of the tool can't bear against the surface just faced by the tip and push the carriage away from the face.

Like I said, a few hours in my shop, with Geo videoing, so you can have the videos of yourself doing each operation the lathe is capable of to go back and reference later, will make a ton of difference.

Did you read up on, or watch videos of Speeds and Feeds, to get the right surface speed in RPM for the mild steel you are working on? That will help eliminate chatter which can also cause that cone shaped facing to occur.
 

Pcmaker

Obsessed Member
#36
Nice looking bench top mill, has some good features and enough horsepower for things you would want to do that complement the size of the lathe.

Not having a carriage lock is not an issue, if the carriage is moving left or right while facing, you just have to hold your left hand on the carriage hand wheel and keep it steady is all, I occasionally have to do that with my big lathe if it's a tough cut.
Need to show you how to move hand wheels smoothly, there is a trick to it, and it would be tough to describe with words. Will make a big difference in your surface finish though, and may also end your cone shaped facing. .

Try turning that tool bit 90° to the left so the tip points towards the chuck and the butt of the shank towards the tail stock, and face with it that way, I think you will have better results from that too. It will reduce the total contact area to just the tip, so the left edge of the tool can't bear against the surface just faced by the tip and push the carriage away from the face.

Like I said, a few hours in my shop, with Geo videoing, so you can have the videos of yourself doing each operation the lathe is capable of to go back and reference later, will make a ton of difference.

Did you read up on, or watch videos of Speeds and Feeds, to get the right surface speed in RPM for the mild steel you are working on? That will help eliminate chatter which can also cause that cone shaped facing to occur.
I haven't seen any videos of speeds and feeds yet, but I'm coming along on reading the book I ordered. i 'll get there eventually. I just ordered a carriage lock from LMS for $35. I'll try doing it again later and hold the hand wheel like you said.
 

Idaho Shooter

Very Active Member
#37
^^^^^^W covered that in an earlier conversation, but it is one of those things, like firearms safety, that can not be repeated too often, good timing since PC Maker is just starting to make chips on his new addiction.

In addition, no long , free hanging hair, I've seen guys scalped by a lathe when they leaned over and let long hair get caught in the chuck.
And just like with firearms, never use a lathe, mill or other power tool when you are tired, hung over, high, low, etc. Even an electric drill can kill ya, a neighbor of mine did just that 20 years ago, working on an addition to his home, too tired after long day at work, put a piece of wood on his leg for a brace and intending to drill a 1/2" hole through the board.
He slipped, and drilled through the board and into his femoral artery. Despite paramedics efforts, he didn't make it.


Just checked McFadden Dale's web site, they carry drill bits and drill bushings, but as far as I can see, with a variety of search arguments on their web site, no other machinist tools in the way of end mills, lathe tool bits, etc. They do have taps and dies, but that seems to be it. Too bad, if they carried more lathe and mill tooling, they'd get to know me by sight!
Next time your in LV stop in there. I know at one point they did carry end mills.
 

NYECOGunsmith

Obsessed Member
Staff member
Moderator
#38
GRRR stupid internet! When I tried to use their search engine, and it came up no end mills or lathe tool bits, it was because it took me to the McFadden Dale Do IT Best Hardware Stores site, and they don't carry that sort of thing. But if I force it to go to the McFadden Dale company site, no reference to "Do It Best", while they don't have a search engine they do have a product list and it does list end mills and lathe tool bits. Wonder why they don't have a search feature to let you actually see what they really carry.
 

NYECOGunsmith

Obsessed Member
Staff member
Moderator
#40
That's a start! Hey Geo, you willing to produce, direct and film a video so PC Maker can have a reference on how to run his lathe?