Making A steady Rest For The Lathe

  Рет қаралды 216,021

Artisan Makes

Artisan Makes

Күн бұрын

Пікірлер: 330
@OtherWorldExplorers
@OtherWorldExplorers Жыл бұрын
Two axioms I noticed that you work with. 'Why buy what I can build" " Do the best with what you have" A true Machinist.
@chauvinemmons
@chauvinemmons Жыл бұрын
It often is the case making things yourself could be much more expensive either immediately or in the long run. Every time you need a bolt do you get a piece of barstock or do you go and buy one.
@untamedhacker
@untamedhacker 10 ай бұрын
@@chauvinemmonsyes but a lot of the time the "cheap" (as in actually affordable) stuff is usually pretty shoddily made and it's really easy to get pissed off at something you bought, but if you made it yourself you kinda accept it as is/fix it. Plus not everything in life is about money, if you enjoy machining stuff you might as well do it for the enjoyment of doing it.
@allanpowell7208
@allanpowell7208 Жыл бұрын
I've yet to see you do anything that you should be embarrassed about. I started at metalwork when I was 12 ( yes we were trusted with a lathe and forgework at that age) I'm now 68 and it pleases me no end to see a young chap like yourself having both the interest and ability in the field. Cheers matey and long may you run.
@lancer2204
@lancer2204 Жыл бұрын
Nice job! I almost spat my coffee across the desk when you showed the manufacturer's steady rest.
@Pushyhog
@Pushyhog Жыл бұрын
lights, action, camera, edit, timing, focus, audio, filmography & more. Thanks again A.M.
@irishwristwatch2487
@irishwristwatch2487 Жыл бұрын
This is definitely up there as one of your better builds. It looks head and shoulders over the OEM part
@artisanmakes
@artisanmakes Жыл бұрын
Cheers
@LittleAussieRockets
@LittleAussieRockets Жыл бұрын
I am so happy I watched this video as I need to do something similar for my lathes. There's a few things you did really helped piece it all together for me. Your welds were more than adequate.
@cokhichetao72
@cokhichetao72 Жыл бұрын
Nhìn máy móc mà phát mê
@Trainwreck1123
@Trainwreck1123 Жыл бұрын
If you hack sawed that 25mm steel bar and didn't show it you did yourself a great disservice!
@ErikBongers
@ErikBongers Жыл бұрын
Agreed. Unsubscribing.
@minigpracing3068
@minigpracing3068 Жыл бұрын
Like a lot of us, he doesn't have a powered saw to do that kind of work. I normally do a bunch until my arms are tired, tame a break, come for more. Really slows the progress down!
@ErikBongers
@ErikBongers Жыл бұрын
I have one of those portable bandsaws converted to a little table saw. But for most cuts, I still like the manual workout.
@psykosis101
@psykosis101 Жыл бұрын
He used a grinder. You can tell from the the end in shot just before he cleans it up with the mill
@GJT-nc4zk
@GJT-nc4zk Жыл бұрын
Push mig drag stick
@wizrom3046
@wizrom3046 Жыл бұрын
Great result! 👍 I have a small suggestion for the lower T-nut. If you mill or grind the 2 sides of the top of the oval piece, it will make a small raised square area maybe 1.5mm or 2mm high on top of the oval piece. Then, you can still insert the nut into the lathe bed just as easily, but when you tighten the thread the raised square will lift up and will "lock" into the space between the lathe bed. Then you wont have to worry about the oval piece rotating when you tighten the thread.
@artisanmakes
@artisanmakes Жыл бұрын
A good suggestion
@D3nn1s
@D3nn1s Жыл бұрын
​@@artisanmakesi can add to this, if you make it a rhomboid shape with a radius on the dull corners itll lock into place without needing to be pulled up. Thats whats being sold for extruded aluminuim too
@fredflintstone8048
@fredflintstone8048 Жыл бұрын
Nice. I built a very similar steady rest for my chinese mini lathe. I started with a 6" disk 1" thick. I bored it 4". I didn't weld mine to the base but milled a shallow slot in the base and milled flat the bottom of the disk to give it a solid mount that's bolted. I did this so if I decided to use it with a different lathe in the future I could do it without too much trouble. Mine will take up to 2-1/2" diameter material and I'm using small roller bearing races to meet the surface instead of brass or bronze.
@MegaLostOne
@MegaLostOne Жыл бұрын
Nice build, I did one very similar a few years for a Atlas 6" lathe that I have. One thing that I recommend is to place tape or cardboard on the side you are machining on to keep the chips out, if they get in there they will damage the surface and cause early wear to form as well as causing it to want to bind the piece or chew away the brass surfaces so the piece becomes loose.
@jakeevans8819
@jakeevans8819 10 ай бұрын
I have an atlas 618 and I need a steady rest do you have any photos of it you can provide so I can replicate it?
@jakeevans8819
@jakeevans8819 10 ай бұрын
@@MegaLostOne awesome thank you!
@mrvector257
@mrvector257 Жыл бұрын
The cut from the parting tool to the hacksaw audio made me chuckle.
@clayz1
@clayz1 Жыл бұрын
Well that ought to do it. Your steady is about three times as heavy as needed, but it is rather hard to hollow out cross sections like big production machines have, ha ha. Nice work.
@chrisford9045
@chrisford9045 Жыл бұрын
The weight is good for damping noise /harshness /vibration
@Kami8705
@Kami8705 Жыл бұрын
For the leadscrew holders, why not thread or make them a press fit into those holes in the ring, have them go most or all of the way through. No welding needed and easier to modify in the future if needed
@artisanmakes
@artisanmakes Жыл бұрын
You can, I’m sure that would work, just a different way doing doing the same thing I guess
@johncolvin2561
@johncolvin2561 Жыл бұрын
Steady rests need to be hinged to open or at least have slot cut in the ring to allow easy removal and insertion of the workpiece.
@t0mn8r35
@t0mn8r35 Жыл бұрын
Nice project. It's your narration that makes your videos enjoyable.
@matthewhendrickson1575
@matthewhendrickson1575 Жыл бұрын
Grinder and paint make me the welder I ain’t!!
@jrkorman
@jrkorman Жыл бұрын
All and all I would put this build at the top of the list of projects you've shown. Very good work!
@michaelwooda9444
@michaelwooda9444 Жыл бұрын
I would add some big bevels for your welds in the future.makes a stronger joint and also alot easier to clean up the welds.
@kabal911
@kabal911 Жыл бұрын
Love this channel. A treat when a new video appears
@robdogz01
@robdogz01 Жыл бұрын
bloody good shit mate!! keep up the great work!! no excuses needed when your working with what you got
@n9viw
@n9viw 10 ай бұрын
Brilliant! Love watching your work. Congrats on a great build.
@KarKamp
@KarKamp Жыл бұрын
I’m so glad I subscribed to this channel
@billshiff2060
@billshiff2060 Жыл бұрын
Kudos for that. I rarely have the time to build pretty stuff. It's always "the part has to be out by tomorrow" stuff so it has to be as fast as possible , as cheap as possible with what's on hand, so long as it works.
@UncleKennysPlace
@UncleKennysPlace Жыл бұрын
I would consider cutting the ends of the tee nut flanges down just enough so that they catch the bed and won't rotate unless dropped further down.
@JohnK8
@JohnK8 Жыл бұрын
I've been wanting to build one of those for some time now. Thanks for the inspiration. Very nice work.
@dirtybarry7002
@dirtybarry7002 Жыл бұрын
I've found the same on my projects - never assume stock is round or flat or to nominal size. It bites us every time.
@AmateurRedneckWorkshop
@AmateurRedneckWorkshop Жыл бұрын
That was really well done. Thanks for the video keep on keeping on.
@matthewf1979
@matthewf1979 Жыл бұрын
Don’t be so hard on yourself. It turned out perfectly serviceable and you can get some bearing bronze later. Great job!
@Horus9339
@Horus9339 Жыл бұрын
You really are doing special work, outstanding design and workmanship. Thank you for sharing your time with us.
@mg30ebay
@mg30ebay Жыл бұрын
18:16 It is hard to tell for certain where your welding ground clamp is, but when a part is mounted in a machine like that it should be on the part itself. Otherwise current will be flowing through the spindle bearings and possibly arcing across any tiny gaps there.
@Flying0Dismount
@Flying0Dismount Жыл бұрын
He has the ground clamp on the bed rails just ahead of the tail stock, but I agree that this is bad practice as there is a possibility that electricity, trying to find the lowest resistance circuit, could go through hidden bearing surfaces and cause damage. In this case the risk to the spindle is low as he welded to the base block first, but there could have been some arcing at the ground clamp end or under the base block, causing some scarring to the lathe bed ways, but at least those are easily dealt with using a stone.. Same thing applies when welding on a vise as he does in earlier on: best to clamp directly on the part or at least on the jaw/body of the vise. Many people clamp on the handle or the lead screw ball and then they wonder why their vise screw is starting to get so crunchy, because in this case, the current most certainly does flow through the lead screw and nut before hitting the body and finally the part being welded...
@OhHeyTrevorFlowers
@OhHeyTrevorFlowers Жыл бұрын
For future builds, for the arms you might consider “bearing bronze” which has a bit of iron and aluminum
@philsmeanderings7991
@philsmeanderings7991 Жыл бұрын
Another thing of beauty. Have used the oem steady. Does work but me thinks yours is bound to be a step up. Good stuff bloke .
@KW-ei3pi
@KW-ei3pi Жыл бұрын
Looks like a nice completed project. Consider adding labels for sped up video. Some are obvious, but when it appears to be at normal speed, your speeds and feeds seem to be too fast. I would think that some of the problems you encountered here could have been eliminated by slowing down the feeds and speeds. Looks like RPM is way too fast on both machines. Thanks
@wrenbrighton2358
@wrenbrighton2358 Жыл бұрын
I have an idea for if you ever decide to put ball bearings in it maybe you could Machine a sleeve to fir snuggly over the bearings out of bronze or something soft!. Great video though!
@clonoid
@clonoid Жыл бұрын
Nice one - I've been thinking about making one for my lathe, and this video has reassured me I can do it
@RB-yq7qv
@RB-yq7qv Жыл бұрын
I must say a great job. The small machines performed way above their intend working compacity. You where right to build your own, the off the shelf model is a heap of crap that are only good as a paper weight. The steady rest will give years of service and looks good.
@bscoffeeandwelding7236
@bscoffeeandwelding7236 Жыл бұрын
You must have guns like the humongous after all that hacksaw work mate, nice build!
@MattysWorkshop
@MattysWorkshop Жыл бұрын
Gday, the steady turned out good, certainly a ton better then the factory steady, great job, cheers
@artisanmakes
@artisanmakes Жыл бұрын
Cheers matty
@mftmachining
@mftmachining Жыл бұрын
Excellent job. TOP.
@jdscott20101
@jdscott20101 2 ай бұрын
gorgeous and amazing build. nice video and thanks for sharing
@huntz3215
@huntz3215 Жыл бұрын
Great work, I can't justify buying a mill and have nowhere to put it but your videos still tempt me to find an excuse.
@GeneralChangFromDanang
@GeneralChangFromDanang Жыл бұрын
Find a spot, whatever it takes lol. The two machines compliment each other and I wouldn't want to go back to one without the other.
@andreasbrunnhofer
@andreasbrunnhofer Жыл бұрын
Nice work! 😎👍 When working with a steady rest its always a good thing to have some sort of protection to prevent metal shavings getting caught in between the bearing surface and the workpiece. Cardboard with a cutout for the workpiece sticked in front of the steady rest is doing a great job for it.
@sicstar
@sicstar Жыл бұрын
Sleek build, came out really nice! And good choice not going with ball bearings on that tiny steady rest. For copper and aluminium you need quite a bit of widht on those (the ones on big lathes usually come with a radius on em too which can cause all sorts of funky problems on soft parts that are heavy as frig...) which you can't get from too small of a diameter, which you'd had to use here since the thing is rather tiny. But those Brass Bushings should be up to most stuff with a drop of oil or two as long as the material riding on em isn't too scuffed up.
@RossMarsden
@RossMarsden Жыл бұрын
I tell you what! I am impressed with the amount of use you are making of that milling tool you made a few videos ago.
@heathmurphy3735
@heathmurphy3735 Жыл бұрын
Great job there digger
@mbak7801
@mbak7801 Жыл бұрын
Very interesting but a huge amount of work. Personally I would use the blondihacks approach of making bearing based support fingers and keep everything else.
@harmlesscreationsofthegree1248
@harmlesscreationsofthegree1248 Жыл бұрын
Awesome vid! Good to see the face mill making light work of its task. The steady rest *turned* out really well 😉
@lawrenceclifton1765
@lawrenceclifton1765 Жыл бұрын
Good solid steady, for mig welding push the torch, currently you are dragging as for arc/stick welding.
@artisanmakes
@artisanmakes Жыл бұрын
Great point!
@adamandrews2528
@adamandrews2528 Жыл бұрын
Nice build, mate. You are getting better and better.
@TheDistur
@TheDistur Жыл бұрын
Oh boy that's fancy.
@seansysig
@seansysig Жыл бұрын
Great build! I wish I had one for my Sieg
@antonio39776
@antonio39776 10 ай бұрын
this is a beautiful professional work, well done!
@homemadetools
@homemadetools Жыл бұрын
Great work as always. We shared this video on our homemade tools forum this week 😎
@SouseMouse
@SouseMouse Жыл бұрын
20:08 😬 The part was tipping up out of the vise! Should use a vee block, and I recommend putting the vee block against the fixed jaw rather than the moving jaw. With the block on the moving jaw you still have two pivot points- the round part against the fixed jaw, and the moving jaw against the leadscrew. The jaw doesn't have a lot of clearance to pivot, but it has some. With the vee block against the fixed jaw it provides two stable contact patches on the part. Nice steady rest!
@jackphilp7057
@jackphilp7057 Жыл бұрын
Awesome video! I've always wondered though if you could make a steady rest with each of the fingers being able to "ratchet forward", that way the movement from chatter would tighten it by itself.
@buddyhoover57
@buddyhoover57 Жыл бұрын
Beautiful work!
@transmitterguy478
@transmitterguy478 Жыл бұрын
Excellent work. I will cobble one together for my small lathe.
@artisanmakes
@artisanmakes Жыл бұрын
Best of luck
@gofastwclass
@gofastwclass Жыл бұрын
Fantastic job! Lot of work but that turned out very well. As I watched I was slightly concerned that the hacksaw wouldn't make an appearance but alas, I wasn't disappointed. Time to head to my shop and create something.
@OhHeyTrevorFlowers
@OhHeyTrevorFlowers Жыл бұрын
That’s solid work.
@AndyFromBeaverton
@AndyFromBeaverton Жыл бұрын
22:17 I thought you would be using roller bearings instead of bearing pads.
@patrickbeaumier8616
@patrickbeaumier8616 Жыл бұрын
Nicely done 👍
@kalusovsky
@kalusovsky Жыл бұрын
Hi I think that maybe you should try dcgt inserts for boring because they have a geometry with sharp cutting edge. This might decrease the cutting force and improve a surface finish.
@artisanmakes
@artisanmakes Жыл бұрын
I’ve used them a lot in the past. Great inserts although I seem to have broken them all. I need to buy some more
@williamsantiago7303
@williamsantiago7303 10 ай бұрын
That looks awesome sir👍!
@KF-qj2rn
@KF-qj2rn Жыл бұрын
way better than the 9x20 version which looks like a skeleton in comparison next channel acquisition: TIG welder, the primary benefit part cosmetics rather than structural
@thedolphin5428
@thedolphin5428 Жыл бұрын
Nice job. A couple of tiny improvement suggestions: Place locking T-nut on RHS/OUTSIDE of rest, rather than LHS/INSIDE. Could still be done with a new base-V milled, then flipped around. Toolless knurled or T-bar locking plugs for the 3 rest finger tighteners instead of needing an Allen Key tool.
@jamesriordan3494
@jamesriordan3494 Жыл бұрын
Well done 👍🏻
@leeharveygriswold6160
@leeharveygriswold6160 Жыл бұрын
Nice work mate, well done. If I could offer you some advice it would be to change your welding from a drag to a push with a bit more heat or less feed and no wiggle. Try it out on some scrap and see how you go. Also a light dust of anti spatter spray makes the world of difference.
@paulthomas3782
@paulthomas3782 Жыл бұрын
Fantastic effort well done.
@artisanmakes
@artisanmakes Жыл бұрын
Thankyou
@michaelallen1432
@michaelallen1432 Жыл бұрын
It occurs to me that a good way to make sure that it's aligned would be to change the order of the machine operations a bit. It probably doesn't matter if the actual ring is perfectly concentric with the chuck. It could be off a few thousandths so long as the holes and leads screw are concentric. I'm thinking,, if you had to do it again, make the ring, and attach it to the base before drilling the three holes. Then bore the three holes indicating off the base. The OCD part of me wants to machine little flats so the three housings seat better. Then put those on and bore them in place. Now it all has to line up right. Don't get me wrong though, it looks awesome. I'm going to make one myself.
@artisanmakes
@artisanmakes Жыл бұрын
Maybe. I don’t know how perfect it needs to be, I’m sure there is a tolerance and this seems to work just fine. There is probably a better order to do this but as I said I was making it up as I was going along and half this stuff isn’t presented in the order that it is filmed. Cheers
@shiro-r4m
@shiro-r4m Жыл бұрын
I'm sure you've heard this a lot by now but a 3 phase motor with a vfd for the lathe would help a lot with parts like this large ring to run it at a slower speed. It would likely stop you burning through inserts on these kinds of parts by running at a more reasonable speed
@artisanmakes
@artisanmakes Жыл бұрын
Yea I have heard that a lot. Maybe one day :)
@jameshisself9324
@jameshisself9324 Жыл бұрын
Nice, I've been thinking about making one of these. Can not for the life of me figure out why you didn't create U slots in the ends and mount sealed bearings with a through bolt to work as rollers. I agree about the scraping effect being undesirable and mine will have to have these rollers.
@rescobar8572
@rescobar8572 Жыл бұрын
BRAVO AMIGO 🎉👏🏼
@vivigarr
@vivigarr Жыл бұрын
The rouging process seems like it could be done in the rotary table / dividing head. Chuck it up and then spin it under the face mill and a roughing endmill for the ID
@artisanmakes
@artisanmakes Жыл бұрын
Not on my rotary table but if you had a bigger more substantial one it could
@lesmaybury793
@lesmaybury793 Жыл бұрын
Nice neat job.
@tomsmith3045
@tomsmith3045 Жыл бұрын
Great project! If you can get Argon as well as the gas mix, you might want to try TIG. Way easier to do detail work with TIG than MIG, and it's really pretty simple with mild steel. A DC TIG will do it, and you don't really need HF start. It's also easy for stainless as well. I think you'd like it because you're detail/precision oriented, and it would save you quite a bit of cleanup. With an AC TIG and HF you can also do aluminum, but I won't kid you that that's an easy process to master.
@peter360adventures9
@peter360adventures9 5 ай бұрын
Awesome build
@scroungasworkshop4663
@scroungasworkshop4663 Жыл бұрын
Brilliant 👍👍
@jasonhull5712
@jasonhull5712 Жыл бұрын
Wow. I nerf one of them for my 13" clausing metosa c1330s. I was planning on making myself. Yours turned out extremely well.
@Lone-Wolf87
@Lone-Wolf87 Жыл бұрын
Well done. 👍👍👍👍👍
@tomeyssen9674
@tomeyssen9674 Жыл бұрын
Nice rest. Beefy too.
@jackdawg4579
@jackdawg4579 Жыл бұрын
Nice job - the annoyance I find with that style I use on mine is not being able to put it in place without removing the end support, also when realising I need my cross slide on the other side of it! Definately the first mod for mine will be to change it so a large section of it can unbolt and allow it to be put in place when something is already dialed in between the chuck and live centre.
@raymondhorvatin1050
@raymondhorvatin1050 Жыл бұрын
looks great🙂
@delalima
@delalima Жыл бұрын
that was amazing
@angelramos-2005
@angelramos-2005 Жыл бұрын
I subscribed to your chanel.Excellent project.Thank you.
@nardaoeletronica
@nardaoeletronica Жыл бұрын
Always excellent job.
@HM-Projects
@HM-Projects Жыл бұрын
Looks very cute and solid. Nice upgrade. I guess you can make a roller bearing style 3 point contact with Al or Phosphor Bronze, that'll avoid marking the stock.
@grahameblankley3813
@grahameblankley3813 Жыл бұрын
Very impressed 👍🇬🇧.
@glennwright9747
@glennwright9747 Жыл бұрын
Interesting build. The retaining caps you spot welded were superfluous, the knurled knobs will retain the screws.
@artisanmakes
@artisanmakes Жыл бұрын
No you do need them. Or the lead screw will simply unscrew when you try and unscrew the fingers. It is a common complaint on the stock sieg C3 steady
@glennwright9747
@glennwright9747 Жыл бұрын
I must of missed something.. on mine the shaft of the screw is reduced diameter where it goes through the cap. When I take my adjusting knobs off the screws can then be removed from the frame towards the centre. Like the arrangement of an auto scissor jack. Just a different configuration.
@Kineth1
@Kineth1 Жыл бұрын
​@@glennwright9747 His lead screws are inserted into the mechanism from outside the ring, so something is needed to keep them in. If he had designed it so that the lead screws were inserted from inside the ring, then just the knob would be sufficient to retain them.
@glennwright9747
@glennwright9747 Жыл бұрын
@@Kineth1 yes!
@garyshirinian
@garyshirinian Жыл бұрын
Great video, how about making your self a bandsaw. Breacks my heart seeing you cut things with hand held saw.
@asterope1604
@asterope1604 Жыл бұрын
You just keep getting better and better. Keep it up man, I can't wait for the patreon to kick off and get you some bigger machines
@doylerabjohn3435
@doylerabjohn3435 Жыл бұрын
That functions great & looks good. Definitely a better welder then me. I cant weld at all. Great job
@thomasfkeefe
@thomasfkeefe 6 ай бұрын
I really like this design and would like to make a similar version. From watching the video, I could not determine the size of things very well. Can you indicate the diameter of the fingers and also the width and diameter of the ring that supports the fingers. Thanks.
@andreassiegler2238
@andreassiegler2238 Жыл бұрын
I'd recomend a scissors type knurling tool and WAY less rpm! These knurls haven't seen enough pressure and therefor are almost non present. You can do them in more than one step, as the wheels will fin their groove again, once they are formed propperly. But with this small lathe and these poor press-on knurling tools, you won't be able to achieve any good result, especially with small diametres and coarse knurls. I also feel high rpms are often a problem here, causing chatter, brocken, or cooked out tools.
@davidrule1335
@davidrule1335 Жыл бұрын
Good Job!
@binomair9326
@binomair9326 Жыл бұрын
Nice work, It looks great for small and home lathe and personal used good job man.
@vinceearl4240
@vinceearl4240 Жыл бұрын
Question: Would it have helped to mill flats on the OD of the main body so you weren't welding a flat part onto a round part?
@minigpracing3068
@minigpracing3068 Жыл бұрын
Nice. You can get a lot of work done on big things if you get creative with these small machine tools. It would be nice to have a full machine shop with big monster tools, but not everyone has room for that.
@howder1951
@howder1951 Жыл бұрын
Nice work, and a great Bir of designing. Amazing work for your smallish equipment, it looks like your mill is really well tuned. Enjoyed very much, cheers!
@kirkswater
@kirkswater Жыл бұрын
Very very cool my friend! Hope you will consider a website or other online delivery tool to offer plans for your well thought out and excellent projects!
The New Lathe Has Some Issues, But I Can Fix Them
17:01
Artisan Makes
Рет қаралды 156 М.
Making A Surface Gauge - DIY
28:17
Artisan Makes
Рет қаралды 127 М.
Миллионер | 3 - серия
36:09
Million Show
Рет қаралды 2 МЛН
Amazing remote control#devil  #lilith #funny #shorts
00:30
Devil Lilith
Рет қаралды 16 МЛН
Из какого города смотришь? 😃
00:34
МЯТНАЯ ФАНТА
Рет қаралды 2,4 МЛН
Making A Power Feed For The Milling Machine | Cheaper And Better
25:41
Making A Wedge Lock Quick Change Tool Post For The New Lathe
19:09
Artisan Makes
Рет қаралды 117 М.
Rotary Broaching Eccentric Cams || INHERITANCE MACHINING
20:46
Inheritance Machining
Рет қаралды 528 М.
Lathe Ball Turning Attachment Build
24:54
Artisan Makes
Рет қаралды 341 М.
What Is Wrong With The Lathe Now?
27:05
Artisan Makes
Рет қаралды 137 М.
Making a 2 Piece Vise For The Milling Machine
23:42
Artisan Makes
Рет қаралды 126 М.
Setting Up a Steady Rest
17:02
Practical Machinist
Рет қаралды 25 М.
Миллионер | 3 - серия
36:09
Million Show
Рет қаралды 2 МЛН