Page 4 of 6 FirstFirst ... 23456 LastLast
Results 76 to 100 of 137

Thread: Lathe chatter

  1. #76
    Join Date
    Jan 2006
    Location
    In A Nice Comfy Chair
    Posts
    18,780
    Post Thanks / Like

    Re: Lathe chatter

    Quote Originally Posted by Willie B View Post
    Moving on!
    Today I wanted to mount a faceplate, instead of a chuck. I downloaded a manual for my lathe years ago. I found the file, It contained a 1 page description of the gearbox made for converting line shaft machines to electric motors.

    I have a South Bend book says place a wooden block on the bed, wedge it under a notch in the chuck, engage back gears at lowest ratio. Turn the belt by hand. The faceplate is right hand thread.

    I've smashed oak blocks half the day. I'd usually resort to a torch in this case. I think a torch is not the best choice here.

    Any ideas?
    Thread it on BY HAND!!!
    As you use it it will tighten up on its own.


    ...zap!


    I am not completely insane..
    Some parts are missing

    Professional Driver on a closed course....
    Do not attempt.

    Just because I'm a dumbass don't mean that you can be too.
    So DON'T try any of this **** l do at home.

  2. #77
    Join Date
    Apr 2020
    Location
    Vancouver Island Canada
    Posts
    29
    Post Thanks / Like

    Re: Lathe chatter

    Quote Originally Posted by Willie B View Post
    Moving on!
    Today I wanted to mount a faceplate, instead of a chuck. I downloaded a manual for my lathe years ago. I found the file, It contained a 1 page description of the gearbox made for converting line shaft machines to electric motors.

    I have a South Bend book says place a wooden block on the bed, wedge it under a notch in the chuck, engage back gears at lowest ratio. Turn the belt by hand. The faceplate is right hand thread.

    I've smashed oak blocks half the day. I'd usually resort to a torch in this case. I think a torch is not the best choice here.

    Any ideas?
    Iím guessing that youíre trying to remove the chuck but itís stuck.

    Iíve removed stuck chucks by chucking a length of steel, maybe 18Ē long across the face of the chuck, like a long handle.

    Put a few blocks of wood behind the bed positioned so the end of the steel will strike them.

    Pull the pin that holds the bull gear to the cone pulley so the chuck spins freely. Or just disengage the belt.

    Swing the bar smartly so the hits the wood blocks. A couple of good whacks against the blocks should free it up.

    Whatever you do, DO NOT ENGAGE THE BACK GEARS AND USE THEM TO STOP SPINDLE ROTATION. The gear teeth are easily broken off.


    Sent from my iPhone using Tapatalk
    David
    Millermatic 130
    Coming soon - Primeweld 225ACDCp

  3. #78
    Join Date
    Dec 2013
    Location
    Mount Tabor VT
    Posts
    6,739
    Post Thanks / Like

    Re: Lathe chatter

    South Bend describes using the back gears, pull the belt by hand. It is very stuck. I'll try the method you suggest.
    An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.

  4. #79
    Join Date
    Dec 2013
    Location
    Mount Tabor VT
    Posts
    6,739
    Post Thanks / Like

    Re: Lathe chatter

    Quote Originally Posted by zapster View Post
    Thread it on BY HAND!!!
    As you use it it will tighten up on its own.


    ...zap!
    It hasn't been removed this century, maybe not in the last. I imagine bearing lube finds its way to this thread, and maybe a bit of cutting oil. I hadn't expected it to be stuck this hard.
    An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.

  5. #80
    Join Date
    Dec 2013
    Posts
    1,480
    Post Thanks / Like

    Re: Lathe chatter

    I assume you are splitting your wood on the back side of the bed. That is you are turning in the correct direction,opposite of normal turning? Maybe not the best idea but if you take a piece of square stock, solid or tube, and weld a piece of flat bar, or whatever, to it you can hold the tube in the chuck and strike the flat bar with a hammer carefully. It is possible to break teeth in the back gear or on the spindle. You are correct do not heat the chuck, you can damage the bearing in the head. Like DavidRS above we usually just spun the chuck by hand though.
    Last edited by Meltedmetal; 04-23-2020 at 07:29 AM.
    ---Meltedmetal

  6. #81
    Join Date
    Dec 2013
    Location
    Mount Tabor VT
    Posts
    6,739
    Post Thanks / Like

    Re: Lathe chatter

    Struggled with it more today, I have a 1" diameter punch with replaceable plastic ends. I beat on it all the way around with a 3 LB hammer. It ain't budging.


    Name:  Chuck.jpg
Views: 225
Size:  66.2 KB


    It looks to be a two piece chuck. A flange threaded to the spindle, then most of the chuck bolted to it. How does it center? is it a taper it presses onto? Might I unbolt to access the thread. I don't want to use a pipe wrench, but possibly a plate with 4 holes I could weld to. Still, there is no way to hold the spindle in place except the extensive gear train. I don't want to break something.
    An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.

  7. #82
    Join Date
    Sep 2013
    Location
    central Wis.
    Posts
    4,691
    Post Thanks / Like

    Re: Lathe chatter

    I would use a large strap wrench to hold the pulley. Put a big adjustable wrench on one of the chuck jaws and lay down something to protect the ways. Give it a good solid hit on the wrench with a heavy sledge. If that doesn't do it your probably not getting it off

  8. #83
    Join Date
    Apr 2020
    Location
    Vancouver Island Canada
    Posts
    29
    Post Thanks / Like

    Re: Lathe chatter

    If you have some Kroil I would try and get it into the spindle threads.
    Let it sit.
    Another option is a piece of hex stock chucked up and rattled with an impact gun.


    Sent from my iPhone using Tapatalk
    David
    Millermatic 130
    Coming soon - Primeweld 225ACDCp

  9. #84
    Join Date
    Nov 2009
    Location
    Pensacola , Fla
    Posts
    1,085
    Post Thanks / Like

    Re: Lathe chatter

    Sometimes a different action is needed to loosen things, try using a large punch and use it on the side (parallel to the flange) of the flange in the threaded area. A few good bangs in a side area (rotate the flange for each strike maybe one in each quarter turn) will shock a connection and help loosen them. I have used this with lug nuts on a wheel just a straight on hit with a hammer helps to break any kind of rusted connect and the nuts will then come off easily.
    DIY CNC Plasma table USB BOB Price THC
    Hypertherm 65
    Everlast PowerTig 255 EXT
    Miler 180 Mig
    13" metal lathe
    Mill/ Drill
    ECT, ECT,

  10. #85
    Join Date
    Dec 2013
    Location
    Mount Tabor VT
    Posts
    6,739
    Post Thanks / Like

    Re: Lathe chatter

    I got it!!! I unbolted the 80 LB chuck business end from the adapter flange. This exposed the end of the threaded spindle. I soaked it with Kroil. I was able to put bolts in the four holes, beat on the nuts with a brass bar & rotate the shaft as I went. After pounding on it 5 minutes, I used an electric heat gun just enough to make it feel warm to the touch. 2 blows after heating it began to move.

    Thanks guys for the advice.
    Willie
    An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.

  11. Likes DavidR8 liked this post
  12. #86
    Join Date
    Apr 2020
    Location
    Vancouver Island Canada
    Posts
    29
    Post Thanks / Like

    Re: Lathe chatter

    Well done!
    David
    Millermatic 130
    Coming soon - Primeweld 225ACDCp

  13. #87
    Join Date
    Dec 2013
    Location
    Mount Tabor VT
    Posts
    6,739
    Post Thanks / Like

    Re: Lathe chatter

    This ain't good!!
    Curiosity got the best of me. I took the bearing cap off. Looks to me the shaft has been reduced in diameter. A 1/16" thick brass collar has been placed over the shaft by splitting it one slice. A thin piece of shim stock fine tunes the fit. No telling how many years ago all this happened. Nor do I know if this can be corrected.Name:  bearing.jpg
Views: 211
Size:  80.4 KBName:  bearing2.jpg
Views: 214
Size:  74.3 KB
    An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.

  14. #88
    Join Date
    Oct 2016
    Posts
    77
    Post Thanks / Like

    Re: Lathe chatter

    I have a Sebastian conehead with similar bearings. It aint that bad, but here's how you can deal with it short of machining a new bearing set out of a very expensive chunk of bronze.
    Pull the whole shaft off, and take the bearings out. Using something the same diameter of the shaft (turn a wood dowel to size, or build up a piece of pipe with tape) allowing enough for sandpaper. Wrap sandpaper around that and set to sanding it straight, not the sides tho, just into the bottoms of the bearings. Think of two half circles, the radius of the circle reduces as the two halves come together.
    WHen they fit on the shaft well enough, sand down the flats where the shells come together till they fit, and shim under and over the bearings to center them.
    When I got my sebastion (free) many years ago the rear top bearing was gone, so I made a full bearing out of bronze, and just slid it over the shaft, and have since used this method to repair the front.
    This spring I noticed it was pointed down a couple thou, so I shimmed up the lower bearing a bit more. The chuck is tight now, smooth to spin, no more chatter

  15. #89
    Join Date
    Mar 2018
    Location
    San Jose, CA Kelseyville, CA
    Posts
    1,365
    Post Thanks / Like

    Re: Lathe chatter

    Sorry if I missed Willie, but why are you opening up the bearing caps, was there movement with a dial indicator while applying pressure on the chuck with a dowel?

    You can close the gap by taking material away where the bearing caps fit together, but you should be very careful in ANYTHING you do to that lathe. It's one thing to even learn how to use a lathe, and it's another to start taking it apart and trying to fix it...just sayin'...

    Unless you have a lot of slop in the spindle I would leave it alone, shims or not.

    Even if it does have a little slop, you're only making a backhoe pin...

  16. #90
    Join Date
    Dec 2013
    Location
    Mount Tabor VT
    Posts
    6,739
    Post Thanks / Like

    Re: Lathe chatter

    A while back, one of my extra sons needed a big lathe. He knew I had one sitting on a back burner, asked if I would help. I kind of lean too far toward helping one of the boys. The lathe had been here a long time, I bought a phase converter, then lost it, (very long story).

    I hadn't bought a single phase because speed comparable aren't available in single phase. As an electrician wanting to keep my life as simple as I can, I resisted a very big three phase & the variable frequency drive needed to make it work. I waited for the gearbox built for conversion.

    When Andy needed it, we pi$$$$$ed away a couple days, bought some stuff, built a new frame for gearbox, jackshaft, and motor, raided the warehouse for motor control, and push button station. Not factoring UPS, we set up the lathe in 2 days.

    Andy spent about twenty days & nights in the garage doing the lathe work to revive the Ford 4500 backhoe. Mrs B is pretty tolerant, but grinding at 2:00 AM she was close to shooting him.

    Andy had a problem with chatter, we found about .020" of movement then. I don't remember what was done then, we trued it up a bit , tightened it up to .004". I've done a few things with it since, nothing I cared much about chatter.

    My backhoe thumb bent a cylinder rod for the 3rd time, I decided it was time. I can't find a thumb I feel will fit this machine. Case now offers a factory installed thumb, but this machine won't accept it. I'm on my own.

    I knew the lathe was wandering, suspected an issue. Four more bolts, I can look at it. I often turn away before looking. Knowing is often worse than wondering.

    It's back together, functional, with .002" play using a 2x4 pry bar with a dial indicator.

    The fix I found seemed destined for failure. I can't say when this repair was done, I've had it 12 years, The friend who sold it to me, I'm sure didn't know. He owned several lathes in several buildings. I believe he kept this one, wanted to build a large brass cannon. Inquired the price of the brass billet, reconsidered! I'd be surprised if this lathe has run more than 50 hours in 50 years.
    An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.

  17. #91
    Join Date
    Mar 2018
    Location
    San Jose, CA Kelseyville, CA
    Posts
    1,365
    Post Thanks / Like

    Re: Lathe chatter

    Quote Originally Posted by Willie B View Post
    Andy had a problem with chatter, we found about .020" of movement then. I don't remember what was done then, we trued it up a bit , tightened it up to .004". I've done a few things with it since, nothing I cared much about chatter.
    .004" is not bad on an old lathe like that. I wouldn't even worry about it. Sure, it's not within .001, but it's not a toolroom lathe by any means and neither is the work you're doing.

    The chatter has more to do with the setup on the lathe, as well as the tool bits and/or how they are ground. Taking a small amount of time to get a properly ground bit and get it setup properly on the lathe would most likely help the situation greatly. Honestly, there could be more involved than appears from my cheap seat on the Internet, but you don't need any greater precision, IMO.

    Quote Originally Posted by Willie B View Post
    My backhoe thumb bent a cylinder rod for the 3rd time, I decided it was time. I can't find a thumb I feel will fit this machine. Case now offers a factory installed thumb, but this machine won't accept it. I'm on my own.

    I knew the lathe was wandering, suspected an issue. Four more bolts, I can look at it. I often turn away before looking. Knowing is often worse than wondering.

    It's back together, functional, with .002" play using a 2x4 pry bar with a dial indicator.
    I don't know your thoughts, but I would be doing the snoopy dance. The thumb is not a precision part of the machine, it's not as if it's one of the pistons or that the rings are blowing 2 quarts of oil every 10 minutes, the thumb is only for for positioning the bucket, isn't it? Does the thumb fit on the boom as you received it? Or do you need to make some of the pins or something?

    Quote Originally Posted by Willie B View Post
    The fix I found seemed destined for failure. I can't say when this repair was done, I've had it 12 years, The friend who sold it to me, I'm sure didn't know. He owned several lathes in several buildings. I believe he kept this one, wanted to build a large brass cannon. Inquired the price of the brass billet, reconsidered! I'd be surprised if this lathe has run more than 50 hours in 50 years.
    It wouldn't be my first choice for a lathe to learn on, but at this point it is what you have, try to make the best of it so you can fabricate the parts you need.

    When you put the bearing caps back on the lathe, how much run out do you get? I'm talking about run out on the threaded spindle which you took the chuck off from? If you put a dial indicator on the either the outside or inside of the spindle, how much run out do you get when you spin it in neutral ?

    The next question is what is the actual part you need to fabricate for the thumb? Is it one of the pins that secure the thumb to a specific angle? Usually there are like 5 positions the thumb will secure the bucket in while it is attached to the boom. Or is it a bolt that needs to be made?

    BTW, that threading tool is yours if you want it, I didn't mean to imply you could turn a pin with it, the threading tool is intended to cut external threads on a round object held in the lathe. The cutter is 60 degrees, the needed angle needed for most all common threads. Anyway, not to digress...not sure how large the opening is in your lantern post, but this probably won't fit in your quick change. How wide is the slot in your quick change holder? Opening in lantern post? Don't get distracted with this threading tool, let's try to resolve your thumb problem. The threading tool isn't going anywhere, and as I said it's yours if you want it. However, if you need to make a specific bolt and add threads to it, this threading tool could help you do that if you don't have a ground HSS tool bit for that purpose.

    EDIT: always make sure you oil those bearings whenever you use the lathe. There should be either oil cups or zirks on the bearing caps, but I believe you will need to manually oils those bearings and if you don't it could cause a lot of damage to the spindle.
    Last edited by TraditionalToolworks; 04-23-2020 at 08:15 PM.

  18. #92
    Join Date
    Mar 2018
    Location
    San Jose, CA Kelseyville, CA
    Posts
    1,365
    Post Thanks / Like

    Re: Lathe chatter

    Quote Originally Posted by Willie B View Post
    I hadn't bought a single phase because speed comparable aren't available in single phase. As an electrician wanting to keep my life as simple as I can, I resisted a very big three phase & the variable frequency drive needed to make it work. I waited for the gearbox built for conversion.
    Willie,

    I know you work for the electrical company in your area, and yeah, 3 phase is a problem for most people. I use a Rotary Phase Converter at my current house where I only have 125 amps for the entire home which includes my shop that I run on a 30 amp 240v single phase circuit to power my 7-1/2HP RPC. This handles my machines up to 5HP, but I have some I'm not able to use in storage for my new shop.

    I just had a meter installed to my telephone pole to be used for my electrical drop, and I'll be getting a 320 amp service, to be used for 2 x 200 amp panels, one for the home, one for the shop.

    I bought a Phase Perfect 20HP digital phase converter a while back to use for the new shop, it requires 100 amps of single phase 240v and will supply 55 amps of continuous 3 phase 240v. I paid $2500 for this converter, which is about 1/2 of what the MSRP was on it when it was new. This was only used for about 1 month, so it's like new. When I contacted Phase Technologies, they encouraged me to buy it used and said the PT-355 I got has very little that can go wrong, and the parts are very cheap if they do. Very nice people.

    I could have gotten 3 phase at my pole, the transformer across the street has 3 phase. However, PG&E wanted me to pay $15k for the transformer, where the 320 amp transformer is free. They also wanted quite a bit, although not as much for a 400 amp continuous service, so I went 320 amp continuous which they told me is a 400 amp non-continuous, hence I'll be running 2 x 200 amp panels. Does this sound right? I'm not an electrician.

    Power is an issue, that goes for commercial and home shops. But home shops are typically more difficult. The largest motor I have to power is a 7-1/2HP, I have 2 or three machines with that size motor. I have a 36" vertical band saw that I can't power on the RPC. I'm hoping to convert my sawmill over to a 15HP 3 phase motor now that I'll have the needed power at the new shop. It currently has a 23HP Briggs & Stratton V-Twin, but it's loud and requires gas to power it.

    How big of a motor did you replace the one on your lathe with? Sounds like it's single phase?

  19. #93
    Join Date
    Dec 2013
    Location
    Mount Tabor VT
    Posts
    6,739
    Post Thanks / Like

    Re: Lathe chatter

    I do not work for the power company. I'm an electrician in a very rural area. Dairy farms were once a big part of our work. Next town had 70 dairy farms in my youth, now 3. Home wiring continues to be a big component of our work, and in the ladst decade we've had a couple manufacturing facilities we handle. My relationship with the power company is sometimes adversarial. They used to have "THE CAN DO COMPANY" written on each truck. I kid they have now added 't Now they are "THE CAN't DO COMPANY"

    The lathe has zero run out with the dial indicator simply turning by hand. Just a shiver from rough surface. After reassembling, I found .002" I was able to lift it. I'm hoping that is close enough. I'm a little wigged out that someone cut the diameter of a hollow shaft this much. The unconventional substitute bearing is a major concern. Yes it seems to function, but for how long? It won't see a lot of use in my ownership. If it fails, I got 1.5 tons of scrap iron.

    I would certainly like to have the threading tool if it is sized to fit my lathe. I'm not sure how they are sized.

    Three phase is the stuff we pay the price when it is about industry. Home shops, not usually. I'm seeing industry where they used to use a diesel generator having three phase power lines built. An employee at a local sawmill tells me Green Mountain Power came up with a negotiated price of $.09 per KWH. A homeowner pays about $.18

    If you have a few machines you need to power consider Variable Frequency Devices. They convert power of whatever the source to single phase DC. This is converted to three phase AC. They are needed dedicated to each machine. They must be in a very dry, dust free, climate controlled environment. I believe understanding genetic code is easier than programming one of the more complex VFDs.

    The motor I installed was a three HP 1725 RPM. I have a 4 speed gearbox built in 1939 for the purpose of converting line shaft machines to electric motor. The gearbox powers a jack shaft with three cone pulleys. Top speed is around 400 RPM, Lowest is 12 RPM.

    I loaned a little Atlas lathe to a friend. He totally restored it. It is museum quality. I would feel like a criminal asking him to use it, he is SO anal about cleanliness. It takes him half a day to get it clean enough to meet his standards.
    Last edited by Willie B; 04-24-2020 at 07:46 AM.
    An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.

  20. #94
    Join Date
    Mar 2018
    Location
    San Jose, CA Kelseyville, CA
    Posts
    1,365
    Post Thanks / Like

    Re: Lathe chatter

    Quote Originally Posted by Willie B View Post
    I do not work for the power company. I'm an electrician in a very rural area.
    For some reason I thought you worked for the power company, my bad.

    Quote Originally Posted by Willie B View Post
    The lathe has zero run out with the dial indicator simply turning by hand. Just a shiver from rough surface. After reassembling, I found .002" I was able to lift it.
    This is not enough to worry about, the .002" could be due to those shims around the bearing, not sure, OTOH those shims may bring it down to .002". Either way, let's move on, the problem is either in the setup or the tool bit.

    Quote Originally Posted by Willie B View Post
    I would certainly like to have the threading tool if it is sized to fit my lathe. I'm not sure how they are sized.
    Your lathe merely needs to be able to hold it securely and that the threading bit itself is at the correct height. Before we talk about that, let's figure out what is wrong with your lathe.

    Are you putting the piece in a 4 jaw or 3 jaw chuck?

    There is a very slight reason being the chuck is not mounted on the backplate properly, but I don't suspect that. I suspect it's in the setup or in the tool bit.

    If you are using a 4 jaw chuck, can you describe how you centered the pin in the chuck?

    Quote Originally Posted by Willie B View Post
    If you have a few machines you need to power consider Variable Frequency Devices.
    I currently have a couple VFDs but they are only cost effective for 1HP-3HP machines. I have a LOT of 3 phase machines, and therein lies *MY* problem. That's why I went with the Phase Perfect, it is one of the best solutions for single phase shops, IMO, and many people use them for CNCs.

    Quote Originally Posted by Willie B View Post
    The motor I installed was a three HP 1725 RPM. I have a 4 speed gearbox built in 1939 for the purpose of converting line shaft machines to electric motor. The gearbox powers a jack shaft with three cone pulleys. Top speed is around 400 RPM, Lowest is 12 RPM.
    Actually that motor would be a good candidate for a VFD had it been 3 phase, as it's only 3HP. Was the original motor 1725 RPM? You may need to do the math with the pulleys to figure out what actual speed you're turning.

    Quote Originally Posted by Willie B View Post
    I loaned a little Atlas lathe to a friend. He totally restored it. It is museum quality. I would feel like a criminal asking him to use it, he is SO anal about cleanliness. It takes him half a day to get it clean enough to meet his standards.
    But it is an Atlas and always will be. There are some things that can't be changed. I have a few South Bend lathes, they will always be South Bend lathes. That is not to say they are bad, but they will never be industrial quality lathes like my Rivett toolroom lathe is. That's just the facts. They don't weigh 4000 lbs. either.

  21. #95
    Join Date
    Mar 2018
    Location
    San Jose, CA Kelseyville, CA
    Posts
    1,365
    Post Thanks / Like

    Re: Lathe chatter

    Willie,

    Still determined to help you sort your lathe out, because the spindle is not the problem. Maybe it is that you need a tailstock support in order to turn a 14" long 2" diameter pin, but I think we can help you get it done without if you don't have one.

    It sure looks like you're using a 4-jaw chuck, and even if the work is not centered 100%, it should still be able to turn without .002" after you turn it round. IOW, if it's offset you can still turn it down so that it is round.

    That's not a flimsy Atlas, that's a decent lathe by the looks of it. Don't give up, let's sort it out!

    Let's sort centering the work, centering the tool bit on diameter and turning to get a nice finish.

  22. #96
    Join Date
    Dec 2013
    Location
    Mount Tabor VT
    Posts
    6,739
    Post Thanks / Like

    Re: Lathe chatter

    South Bend says use a hand held piece of chalk to center it in the four jaw. I used a dial indicator on the carriage to center it. It seems I was doing it wrong in that I should be correcting one axis at a time. I was rotating the chuck tightening the jaw with most run out, this often required loosening the opposite jaw. It takes a while to center. I was giving up at about .004" run out, then centering the far end. The symmetry of grease fittings is not critical, It could be done in the drill press. I believe I'll have to use the tailstock for everything else. I haven't risked any more stock yet. I'm confident it'll be a different experience next time. Though I'm unclear, Samm's bit looks utterly different from what South Bend shows. I have the sense South bend is cutting 3/8 at a time from a shaft, where Samm is reducing the whole diameter by only thousandths. I'm not clear if that needs a different shaped tool.

    I received a box of bushings. I guess I have a hybrid backhoe, lots of them the parts book says won't fit, they are for a newer model, but some fit. Others I'll have to dismantle further to check.

    I'm told the 4140 steel pin stock is unsuitable to weld. Plan A was to use a 1/4" thick washer on one end to retain it, and a 1/4" groove to accept a fork to retain the other. If I can't weld, both ends get a groove.
    An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.

  23. #97
    Join Date
    Mar 2018
    Location
    San Jose, CA Kelseyville, CA
    Posts
    1,365
    Post Thanks / Like

    Re: Lathe chatter

    Quote Originally Posted by Willie B View Post
    South Bend says use a hand held piece of chalk to center it in the four jaw. I used a dial indicator on the carriage to center it. It seems I was doing it wrong in that I should be correcting one axis at a time. I was rotating the chuck tightening the jaw with most run out, this often required loosening the opposite jaw. It takes a while to center. I was giving up at about .004" run out, then centering the far end. The symmetry of grease fittings is not critical, It could be done in the drill press. I believe I'll have to use the tailstock for everything else. I haven't risked any more stock yet. I'm confident it'll be a different experience next time. Though I'm unclear, Samm's bit looks utterly different from what South Bend shows. I have the sense South bend is cutting 3/8 at a time from a shaft, where Samm is reducing the whole diameter by only thousandths. I'm not clear if that needs a different shaped tool.
    [DISCLAIMER: I am not a professional machinist, so if you don't like my advice please get some from a pro]

    Don't focus as much on the shape of the toolbit, it's mostly the contact point at the material that matters. They need specific clearances that all make sense once you start to understand the geometries and the needed clearance so the bit doesn't drag on the material below or to the side of the cut.

    In regard to centering on the 4 jaw, you mention axis. I like to think about this as 2 axis, where 2 opposing jaws move the work back and forth to center it. There is a handy trick, that is to use 2 chuck keys that are short so you can hold them in one hand, and be able to turn/tighten the opposing jaws at the same time. This makes it easier for people with less experience in centering on the 4-jaw, but this is certainly not a requirement.

    Not advocating this channel, just found it quickly on YT:



    You don't need to use 2 keys, once you learn how to do it properly one large key works better as it will give more torque, but you need to measure, flip the jaws around 180 degrees and loosen the low side, then flip it back to what was the high side and tighten it. This procedure gets easier the more you do it and you can get pretty quick doing so with having the need for 2 chuck keys.

    I used to use 2 keys as it was easier for me to center when I first started using a 4-jaw, but nowadays I only use one large key.

    See this video: (again, no affiliation, not advocating the channel)



    You should do this centering on 2 positions of the work, close to the chuck and the farthest point away. If you get both of them centered, then the work will be as close as you can probably get it on the lathe in a 4-jaw. In your case close to the jaws and the far end of the pin, farthest away from the chuck.

    You didn't talk about tool height. This is another area of concern as you should be on center, meaning the top of the cutting edge should be at the center of the diameter. This relies on the correct geometry with proper clearance so that there is a proper cutting edge to press on the steel rule.

    Earlier it was mentioned to use a steel rule. I like this method, it can usually get you in the ball park, but you will quickly find out that there is some variance in using this method for what appears to be centered and what really is. With a properly sharpened toolbit you have the point where it hits the work piece. By placing a thin steel rule between the toolbit and the work when you apply pressure with the carriage, since the part is round as you press on the steel rule the top will either flip towards the work if you are over center or towards the toolbit if you are below center. Adjust and rinse/repeat. I find that even when I do this, it gets me pretty close but ultimately when you turn the end you will end up with a nub/tit on the end of the workpiece, or in some cases no nib/tit, but if you look at the end you can see where the nib/tit got knocked of in most cases, but more importantly where the center of the worAdjust the toolbit accordingly.

    With all of the above stated, if we can get you to a point where we are confident you have the work centered, have a properly sharpened toolbit, and that the toolbit is centered on the diameter, we can then move on to taken even a small cut to see if we can get a clean finish on a test piece of round, only sticking a few inches out of the chuck. If we can achieve that , then we can talk about turning the 2-1/2" x 14" long pin you need, with or without a center in the work piece. First, let's try to make sure you're all centered and can turn a nice finish on a test piece.

    Quote Originally Posted by Willie B View Post
    I received a box of bushings. I guess I have a hybrid backhoe, lots of them the parts book says won't fit, they are for a newer model, but some fit. Others I'll have to dismantle further to check.

    I'm told the 4140 steel pin stock is unsuitable to weld. Plan A was to use a 1/4" thick washer on one end to retain it, and a 1/4" groove to accept a fork to retain the other. If I can't weld, both ends get a groove.
    My choice would be to use 4140HT or 4130HT, those are heat treated (tempered). However, I've also heard you should not weld in the tempered state and that it should be annealed as the welding can anneal the metal anyway. I would personally use HT and not weld on it. If you need to weld it would probably get more complicated if you needed it tempered. You can probably weld HT and not anneal it if you're careful, but I will defer to other more knowledgeable welders to answer that question. Mostly I don't want to give you the impression I know all the answers, as that can happen on the Internet too easily.. This is why I disclaim much of the information I share with you. I am not a professional machinist or am I a professional welder, so take what I say with a large grain of salt if you like.

  24. #98
    Join Date
    Dec 2013
    Location
    Mount Tabor VT
    Posts
    6,739
    Post Thanks / Like

    Re: Lathe chatter

    To boldly go where no man ever felt the need to go.

    The thumb will pivot on a longer pin where the bucket links now connect to the dipper. Plan A was to put home made bushings in the thumb holes, they could be replaced easily. It got complicated, so I opted for a machined hole the right size in the 1" plate. The old thumb failed repeatedly, but not at this point. It lasted 12 years with a 1-1/4" pin. The holes were sloppy, but functional.

    I did something wrong, opened it up .027 too big.

    Gotta try bore welding sometime, why not now.

    I'm now .007 shy of 2" just like the factory bushings I've bought. I can't find a pin to work, so I'll make one. Center bits are on their way. Must be fifty broken ones here.

    I'll do the other half, then the pin. Welds will be 8" away from the pin to minimize alignment problems.
    An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.

  25. #99
    Join Date
    Mar 2018
    Location
    San Jose, CA Kelseyville, CA
    Posts
    1,365
    Post Thanks / Like

    Re: Lathe chatter

    Quote Originally Posted by Willie B View Post
    The thumb will pivot on a longer pin where the bucket links now connect to the dipper. Plan A was to put home made bushings in the thumb holes, they could be replaced easily. It got complicated, so I opted for a machined hole the right size in the 1" plate. The old thumb failed repeatedly, but not at this point. It lasted 12 years with a 1-1/4" pin. The holes were sloppy, but functional.
    My $0.02, if it lasted for 12 years with no issues on the pin, I would have left it be.

    Quote Originally Posted by Willie B View Post
    I did something wrong, opened it up .027 too big.
    No worries, we all make mistakes. .027" is too much slop, IMO, and it's too small for a bushing that will only leave you .014" on the wall. Best to bore it out larger to get at least .125", and even so that will only give you 1/16" on the wall, for something as heavy as a bucket you will need more, IMO.

    However, even if you need to get another piece of material to make a larger pin, that's the easier path in this case. Just get another piece for a pin and make it fit the larger size. That's what I would do, I think it's the easiest path.

    Quote Originally Posted by Willie B View Post
    I'm now .007 shy of 2" just like the factory bushings I've bought. I can't find a pin to work, so I'll make one.
    I would definitely make one, you gotta be able to hit a pin closer than .007", IMO. Sneak up on it and only take .001" at a time if you have to. Time is on your side.

  26. #100
    Join Date
    Dec 2013
    Location
    Mount Tabor VT
    Posts
    6,739
    Post Thanks / Like

    Re: Lathe chatter

    I'm less stupid than last week. Gonna hang out a shingle; "Bore Welder" (I'm kidding).

    Chatter is gone, the perfect finish I see on the computer still eludes me. Once I figure out whether the cross slide is calibrated in actual measurements or diametrical inches I'll improve. I felt I was miles away from size, working in .010" increments I was .030 from size. Next cut .010, I was .027 too big. I'll figure it out somehow.

    Final cut, I snuck up on it changing the cross slide only .001 each pass. Brought it in exactly
    where I hoped.

    welding the bore I was tempted to TIG, that meant faceplate & all would go to the cellar. MIG worked fine. I have too much build up on the back side of the plate (it's now 1-1/8" thick I'll take care of that with a grinder, I'll take a face cut on the exposed face & chamfer a bit.
    An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Page generated in 1,594,620,778.64124 seconds with 13 queries