Hey everyone- since a lot of people seem to be losing sleep over it, no the pinion is not hardened or some fancy alloy that is going to be hurt by heating it. My Chinese lathe is honoured that you all think so highly of its components, but you can count on one hand the parts in these machines that are hardened or any alloy that would mind a little heat. So let’s not bother typing that any more. Now you can get some rest, finally! Also a lot of people saying the shear pin on the leadscrew didn’t do its job. Well, that isn’t that shear pin’s job. That shear pin is to save the leadscrew if you crash with the half nut engaged. It has a 4:1 (plus the rack) mechanical advantage over the pinion and there’s six gears and shafts between the two. That pin ain’t gonna shear from the power feed. This lathe SHOULD have a shear pin on that pinion. That would be nice. But it isn’t that existing shear pin’s fault. If it would was weak enough to shear from that pinion at the other end of a 4:1 gearbox, you couldn’t cut threads with it. It would shear from the force of the half nut pushing hard through a 13 tpi thread. So feel free to complain that there should be a SECOND shear pin here, but don’t blame that one. It’s doing its job by not shearing here. 😉
I also bought a Chinese 6125 lathe, the DC motor will becoming weaker some years later and you have to replace a better AC motor. Maybe I will buy a big second industry lathe.
Hey heads up, the shoulder of the pinion took a slight deformation where you applied the percussive maintenance with your precision impact device. Looks like it may create a wear spot on the cast iron case and pull the pinion out ever so slightly which could affect alignment. It may end up wearing itself some clearance, but just in case you didn't notice it. It can be seen clearly at 13:02 in the video. My 14 year old pointed it out to me. I love to sit down with my 10 and 14 (soon to be 15) year old girls and watch your videos, it inspires the hell out of them. I mean, I tell them all the time they can do this kind of stuff, but Dad is just Dad, I am supposed to say that, and they help me often in the garage/shop. But seeing you doing this work, your openness and honesty in your approach really speaks to them, thanks for putting out this content, it is much appreciated.
I pulled my first commercial lathe out of a green bin, my kids in grade school. That's been almost forty years, and five or six lathes later. I just sold my "extra bridgeport" a couple months ago, my daughter put it on facebook, you meet the nicest people, selling old machine tools, and buying them. It's always nice when one can tear it apart, and make it better than it was before.
Great repair. An alternate method of straightening is to heat the part and then put a wet rag on the high spot which will pull it back toward straight. Keep on keeping on.
bent a axle on my 4 wheeler 15 years ago .. priced a new one said I would try and fix this 1st ,, they told me and other people said do NOT heat it ,, it was hardened ,, I have a cheap pipe bender with the dies and a jack in it .. rolled the axle on a flat surface marked the bend .. put it in the bender and rolled it again checking and marking the spot repeated 3 or 4 times ..reinstalled tested ok .. just have to know what your heating is not hardened or you have to get it re hardened
I have succesfully straightened round items in the following way: first I machined aluminum half-rings, with the ring outer diameter double (or so) the outer diameter of the axle. (The rings were made with internal diameter to match the outer diameter of the axle that needed straightening, and then I sawed the rings in half.) The half-rings allowed me to exert a lot of force, without risking damage to the surface of the axle. I used a setup with three half-rings. I clamped the assembly in a vise with wide enough jaws, with the middle half ring set to push at the spot along the axle where it had been bent. So one jaw of the vise was pushing only the outer ends of the (short) axle, and the other jaw was pushing only the one half-ring at the spot where the bend had occurred. I supported the axle, so I could back off the jaws without the axle sliding down. With the jaws hardly pushing I slowly rotated the axle to feel where it was binding a little. At the orientation where the axle was binding the most I turned up the force of the vise, and then I backed off again. If I could feel no reduction of the bend then I would try again, turning up to a little more force, each time backing off again, and then rotating the axle to feel if there was still an orientation where it was binding a little. That way I was able to straighten that axle back to a point where I could roll it over a surface plate and I could no longer see any wobble.
Supporting the leadscrew with a machinist jack for tapping out the tapered shear pin is a great idea and convinces me it's time to make some machinist jacks.
Quinn, in my opinion, this is one of your very best videos, especially for a newbie like myself. I'm bound to make more mistakes than you and this video encourages me to dig into the nitty gritty to solve and fix the problem. Just brilliant!
@@dans_Learning_Curve Nothing wrong with this method. I just wanted to suggest a nice easy lathe project. Not sure how well known they are as far as tools go, with a few different attachments (various thread sizes for example) they can be really useful. Sometimes its really helpful to be able to tappy-tap-tap instead of gradually build up the force. If you use them to remove dowel pins you do that first, before undoing the bolts. Probably not worth buying for most people, but simple to make out of some random bits of steel.
I bought a little Atlas lathe years ago at an estate sale that had a similar problem with it I paid $10 for it because the carriage wouldn't move but somebody had crashed it while it was in feed and did quite the number on it thank goodness there were still parts at that time available mid-90s ALL HAIL QUINN!!! Not only Machinist,, but up-and-coming machine maintenance mechanic..😸😼👑
It's good to see manufactures are still protecting consumers interest by making sure a pricy precision ground and hobbed part fails before the inexpensive bog standard shear pin needs replaced!
I don't think there is a world where the shear pin on the lead screw would break before anything in the apron would fail. It's there to protect the lead screw itself. Also some guy called Don Not told me that this ain't the most pricey machine in the world. I ain't judging Quinn, I'm sure this is a very useful and durable piece of machinery when used properly.
@@Shit_I_Missed. I take it you never had a Clausing, LaBlonde or Elliot Cardiff Major. We have broken shear pins on the lead and/or power feed shafts on all of them. (Pushing too heavy a cut) The pins are made of brass and/or aluminum at very specific diameters for a reason, you know. Just ALWAYS either use a factory pin or an exact shop made duplicate,,,including the alloy and they will do their job.
@@mathewmolk2089 Perhaps I misunderstood how the power was being transferred on this machine. I assumed it was going through the worm gear on the apron into the gears inside the apron which then bent the drive pinion. As Blonde said, the shear pin on the worm gear would be intended to save the half-nut if that is what was driving into the stalk. I guess the half-nut is also in the apron, but that's not what I intended to include.
Quinn, I love seeing you do this stuff, it gives me more confidence in my journey with Machining. Remembering that we have the tools to fix the tools is a hard lesson to learn.
Awesome video and a good result. One way I have used to straighten things is to put it in a hydraulic press, and use a dial indicator to measure the deflection.
Love your vids! I was a machinist in a refinery for years, now retired and missing machining! I don’t want this to sound bad, certainly not my intentions but I love to see a woman doing this kind of work in a previously male dominated trade, good for you! Keep up the great work! Plus, you’ve got me thinking about getting a hobby lathe and possibly a mill after I finish my Charger project.
I'm working hard to not retire, I worked twenty years at a small machine shop with a woman who did very fine work, and "worked straight up, with the guys" a real peer, in every way. I spent two decades in the marines, and it was good to find "peers" there as well. It's also a challenge for a man to work in a woman's venue, I worked many years on assembly lines, on the side, in female dominated work. We each have our own ways, and learn across the gap, I think.
We have been there. Keep the faith, you are not alone. I took the pinion out, cut the shaft off, drilled a hole through the pinion and replaced the shaft with a straight bit of ms. Just used the compound for turning. It worked fine as well.
Hi Quinn I just found you channel, and you are completely awesome!!!!! I am a hobby machinist, I have learned so much in just the short time I’ve been watching your channel. Years ago I got a 13/40 lathe for 50 bucks. I had to go through it and clean it up ways where lightly cover in powdery rust(no pitting). I used electrolysis to clean a lot of the parts, polished the ways with ultra fine diamond hone. Got it dialed in, started it up and found that the carriage had been crashed like yours. The same part was bent. I drilled it and used drill rod turned to correct diameter and pinned just like you said. Been working for 15 years now. I love being able to make or build what I need. Thank you so much for sharing your knowledge it’s nice to learn new things. Take care and God bless you and yours.
Oh, flashbacks! A few years ago, I bought an older lathe. The bronze nut for the cross slide/feed had worn out almost completely. All the shavings had ended up in the gearbox...
Reminded me of pulling the main cam/bull gear assembly out of a much abused & misassembled 1875 platen press. Beautiful old machine, over 100 years old. Did get it fixed but it was quite a puzzle getting the beast to run smooth again. (Nothing’s more fun than running a treadle powered cast iron beast. And yes, I had the same pin problems.)
Hi Quin, thanks for these videos, always good to see people figuring out solutions and fixes instead of just going and buying replacements. I think now you have the lathe back and operational, it would certainly be a good idea to fabricate a replacement with, as you said a shear pin. As has already been suggested a ground out chisel gives you more control for placement of 'tickling' blows, further to that, should you be faced with similar is to calculate blocks to fit beneath the 'tickled' area to prevent you from blowing beyond straight into a negative bend and then have to try and straighten from the other side, too many of them will eventually result in fracture. Re the oil in these lathes, being as they are literally just dipping the teeth as it rotates, I personally would look at filling as high as possible, at least to half the height of the shafts. Overfilling won't damage as it's not a pressurised system, and this way should keep bearings bathed in lube. Anyway, keep up the good work 👌👍🏼
I had a table saw come in to the shop this week. Very similar damage as you are seeing, but my lathe was (is) still intact. Evidently, someone was moving this heavy saw, and it fell over, and bent the height adjustment shaft. 30 (or so) degrees. I managed to get the shaft out, bent it straight. Within 4 or 5 degrees, but the shaft was no longer really circular any more. (Did I mention my lathe?) Chucked it up, and filed/sanded it, until it ran true. We had another table saw come in, that is the same model, and I used the one I had apart, to figure out how to service the newer one. When I got the first one fixed, it ran better than the newer one. Yes,I DO get inspiration from your videos, even though when I went to machine shop, men were walking on the moon. steve
Hey Quinn, I have a Craftex CX-708 10" X 18" Lathe new, it's got about a year or two on it now with low use (I know, my bad).. When I first unpacked it, I drained the factory oil out of the gear box because I 1) didn't trust it 2) it was almost empty (shipped with minimal oil). I put in fresh recommended oil in and noticed it was "noisy", I noticed the gears weren't "picking up" what I would consider enough oil to properly lubricate the gear head. I added about 4 oz. of Lucas heavy duty oil stabilizer to the oil. Wow, what a difference, the noise was completely dampened and the gears were all picking up a great coating of oil which reduced the gear lash and noise big time. The lathe was completely different in performance as well, it doesn't labour like it did before when taking an aggressive cut. We use to use the Lucas Oil Stabilizer in Semi Trailer tractor transmissions, it increased the service duration of the transmissions by offering that "coating effect" to the square cut gears that you don't get with standard gear oil. I also added it to my collectors 1983 Kawasaki 440 LTD motorcycle oil and it's the difference between day and night for performance and smooth shifting on long rides. You like to share tips and tricks so, I thought I would pass this along in return. Thank You for sharing and have a great day.. Cheers from Canada!
Nice job. Although in a similar job, I recommend using your mill bed, hold down clamps and V-blocks. By using the V-block to hold down the thick shaft, you can locate the bend and actually use a dial indicator to see how much you are moving the bend back into position. Just a suggestion as we used to straighten bent shafts this way in my time in the Navy.
I just had a thought of a helpful tip: Hot glue the roll pin perpendicular to a screwdriver or scrap of metal. Use it as a skinny helper to position the pin in those tight quarters. Once you get it started just break off the hot glue.
I've seen other people straighten Shasta by heating only the high side of the bend, then letting it cool. The metal shrinks and bends it back the right direction. Then just repeat until straight. Might be difficult on something as small as yours, but might work with a small enough torch tip. The nice part is, you can keep it between centers on the lathe and check the run out each time.
Good job on the repair. On that pinion shaft bending, I see a major flaw in the design being that the pinion hangs out way past the last support bearing on a rather thin shaft. The apron casting should have had an extended boss where the bearing goes through and have the bearing directly behind the pinion, for proper support.
I really like your videos, I’m looking at getting the same lathe to learn on. You’re a good machinist/mechanic. I’m a pipe fitter/welder, HVAC mechanic so I’m pretty excited about learning something new over 40 years experience in my trade. Thanks for sharing your project videos and tips. Thanks,Tommy
Having taking apart a 1940/50's (1943 design date, unsure of actual production date) lathe's carriage powerfeed and leadscrew assembly, I am VERY envious of that coupler to remove your lathe's leadscrew from it's gearbox, aswell as the pillowblock's alignment pins that are front-removable! In my case I had to take the gearbox, apron, and pillowblock off and back onto the lathe as one large, unwieldly assembly!
Good fix! Was surprised to see a sump system on your carriage for a half size lathe that you have. Mine is slightly larger but just uses gun oiling at some points plus greased gears. Oil bath sounds far better!
Happened on my CQ6239. Best part was that the quadrant gear, (The piece that holds the gears that enable different ratios for thread cutting) disengaged. I had buggered up, and not tightened the quadrant properly, hence allowing it to move. ( under the increased load) Now, I never "tighten" the bolt. Nip it up, sure, but not "Tight".
I have come across a few tapered brass pins on various cheaper machines over the years but I wouldn’t say their that common, great vid, methodical working out of how to do things 👍
Very well done with the careful figuring it out steps. Having done a similar job on 100 + year old Drummond lathes the point to take home here is gently finding out exactly what holds the damn thing together. It's often plain (ish) to see but never 100% certain that it's a taper not a thread. LH thread ? and my favourite ,stacked grub screws.
I just bent the same pinion due to inattention on my part. I'm now have to do the same repair and maybe buy a replacement to have as a spare. Funny thing is there was the left overs of a plastic bag/wrapper in the bottom of the apron.
I don't have machine tools myself, and what I do in my father's shop isn't within tolerances to qualify for the term "machining." Nevertheless I learn so much from these videos - like tapping in the alignment pins before tightening the bolts. These kind of attention to detail things can make a huge difference even for my not-precision projects.
I am impressed! Nice repair, and no the pinion is not hardened in any way. It may have had the pinion gear teeth put through a ring to induction harden them a bit but it is transfering stuff all horsepower so why would anyone bother. If it is like most of the Chinese rack pinions I have worked on you likely could have held the gear end supported in a vice then cold bent the the other end by slipping a suitable thick walled tube over the exposed shaft. Then true it up with gentle persuasion, hammer or physical pull, or both. Hope the teeth on the rack were not damaged! This quite often happens in such incidents. I fix machine tools at schools as part of my job so have faced similar situations.
I think if you removed the lead screw first before apron it's easier to get apart but when reassembling, the key on the worm-wheel falls out and is just about impossible to re-fit. I seem to remember it being done but don't remember the machine. It was about a 1-1/4" dia screw but the parts were too heavy to manhandle so it had to be done through an access hole
I haven't visited your channel for months. Those alignment pins with threaded holes are pretty common on big machine tools, they also make a type that is designed to be removed by forcing hydraulic oil in there, at a high pressure.
About the brass shear pin…………..I use bamboo kitchen skewers instead of brass or steel shear pins, I kid you not…………….if they fail I just hammer in a bit of new skewer and get on with the show!!! I always try simple, convenient and inexpensive remedies before I panic and spend good money!! Stavros, friend of Pete Agora’s.
Roll pin pro tip: Grind down the tipmost tip of your pin punch to fit *inside* the roll pin, this makes it nigh-impossible to drop on installation because you can pinch the pin between the punch and your finger instead of having to aim two separate bits AND hit it with a hammer
“with a little deduction and not forcing anything…” Well that’s just not the way I work - picture Homer Simpson... Excellent tips, of course. Excellent content, as usual. Cheers & thanks!
Glad you were able to effect a repair fairly easily. Thought for a minute there you were going to have to order parts that would take 3 months to arrive. Now on to the next adventure 😊
A handful of fittings and a valve would make that gear box drain easier to manage. My 1920ish lathe has an oil bath in the apron and it’s still kicking so it might not be the best oiler but it’ll last 100 years if you take care of it. Great video!
The beautiful thing about buying a lathe from the 1940's that has been sitting in a shop neglected and abandoned is, the first thing you get to do is learn how to completely DCOA the machine before you can use it.
I like putting magnets in oiling systems. Nice if you can drill and JB Weld in a drain plug. If that does not work, you could drill and tap a bigger hole with an appropriate plug. Don't put the magnet close enough to gears and other rotating parts where the magnet or its load of debris will be rubbed into the works.
Been there, done that with using a long screw and a stack of washers to pull pins. In my case, dowel pins in blind holes on an ATI robot tool chuck when replacing a retainer race plate. Too lazy to fetch a slide hammer.
What impresses me is that you've had this lathe for how many years before you managed to do this? I was replacing this very same part within like, a month of owning the machine lol. So, ya know, well done on that. Side note, my "shear pin" was literally just a rough ground piece of steel. So quality is apparently a moving target with chinese machines... 😂 Edit, slide hammer works great on taper pins. They're cheap, in case you ever see one at a yard sale for a buck or something, pick it up just in case maybe. Edit Edit, I must have fished that roll pin out 7 or 8 times. It was a gas watching you go through this and reliving my own drama. What a pleasure, thanks for sharing this!
I did break the lead screw nut on my cross slide in the first two months (crashed it into the inner stop), but I didn’t have a YT channel at the time. 😁
I think the big issue alot of people have, myself included is being intimidated by their own machines. In the past I've just left things well alone because of the fear of making things worse than when I started. And believe me this has happened a few times. I just think to myself, why did you get involved?! Now its completely f*****! However, you'll never learn anything if you dont take these leaps of faith. Sometimes it'll work great like Quinn here and sometimes you'll make it worse. But its a learning curve, The saying; "The comfort zone is a beautiful place, but nothing ever grows there." definitely applies to us machine hobbists. Get out there and embrace the learning curve!
I'm curious if the small runout would be visible as a pattern in a light finish cut. Basically, the carriage accelerates (by minuscule amount) every two turns of the handwheel and decelerates (averages out) th next two turns.
