LATHE CHUCK MAGIC TRT#5
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- Опубліковано 7 лют 2025
- How to get optimum performance of a lathe chuck by properly loading the jaws before boring or grinding the gripping surfaces.
#practitioner_of_the_mechanical_arts
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Return of the King
The man with mental FEA. He sees tenths in colors.
I was already rewatching all of your and Toms old videos. And then there it is, a new video 😀
Thanks for doing such a thorough description on boring jaws, picked up some new hints from it.
That reminds me I have some catching up to do with the last 3 videos on your channel.
Oh! And thanks for the pipe chuck key - Made one years ago after you showed them first. And its so nice compared to a regular one.
So when can we expect a similar video from you?
@@Watchyn_Yarwood To be fair to Stefan he has posted quite a lot of regular video content onto UA-cam recently. I had failed to catch up with his last few because of being distracted with other matters.
Exactly the same here, Stefan. LOL🙂
I sincerely appreciate your putting the effort into explaining the hows and whys of this process and all the other things you have contributed to making the rest of us that bit better a machinist than we every would have been without you. Thank you!
I appreciate that!
Enjoyed! Great to see you pop up again.
Do you sell that purple CBN? Willing to pay a little extra of course.
Great video Robin tons of info per usual, and sorry T.O.T. but if you have to ask... We'll you already know. Take care you two. Thanks!
We miss you too! Hope you had a great Thanksgiving
You have to be careful of that purple stuff, degrades terribly during time travel. I have some pink CBN which can withstand temporal displacement much better. Happy to hook up a fellow traveler for the right price.
ToT has joined the chat. Glad to see you’re scurrying about in the gutters of the interwebs. 😂😂
Thanks watching Tony!
ATB, robin
I used to work with an older gentleman at my first job who was 84 yrs old. Started at age 14 in Germany, came to the US to find better work. Between you and Tom Lipton, I feel like I still get that kind of education that those 70yrs of experience used to teach me. Thank you for what you guys do for the rest of us. Can't find much experience like this anymore... especially not for free!
Glad you appreciate the content.
Man Robin, You never ceases to bring the goods with USEFUL information. Thank You.
I loved the last tip about making the 5C mounted chuck adjustable. Thanks so much for your time and effort producing these videos.
I really wish I could give a thumbs-up every time I learn something in Robin’s videos. This one would easily get 5, and I’m not even done watching!
No cannot be true!!
HE IS BACK WOW!!!
THE BEST OF THE BEST IS BACK!
THANK YOU!
Our patience has been rewarded, welcome back to UA-cam Robin!
Nice to see you back at it Rob! Looking forward to more videos as you have the time! Thanks for posting and take care!
Enlightening as always, Robin. Thank you for always providing such concise and precise videos as are required in machining. Your content is second to none.
Many thanks!
Always pleased to see a new Robin video sharing his vast knowledge with those, "me", less fortunate mortals!
You sound like a magician!
“That’s why we have this other ring!”
😂😂😂😂
GREAT VIDEO ON YOUR TECHNIQUE THAT MAKE A LOT OF SENSE, as I’ve thought it should be but being an apprentice, I couldn’t figure it out how to load the internal faces for fixing them. Difference is that I’m dealing with a couple watchmaker lathe, one antique, and the other an used Sherline. I’m suspecting that the Chuck I have isn’t an used Sherline branded but an used import, hence the reason to repair the jaws, what your method came to shed some light on my endeavor. Now, off to find those damn ball bearings in the right size!!!! 😂😂😂 thank you very much for sharing your vast knowledge on an art that must be kept alive beyond pressing the buttons to run a program in a CNC machine but using real brain muscle instead!
Good to see you back Robin, and great content as usual. Very unique(and clever) way of trueing chuck jaws!
Another brilliant solution to a problem I’ll never have, as I’m not a machinist. These videos make you smarter no matter your vocation.
Welcome back Robin, we missed you.
Gee its great to see you in the shop again Rob. I always look forward to your work. There is another way to load the jaws on a chuck for grinding or hard turning.
Take 3 equally sized .5" (12mm) thick rectangular blocks of say 4140 although mild steel will work also, they all have to be the width you wish to space the jaws at. Then fit them between the outer ends of the chuck jaws a bit of a fiddle but not hard. Then tighten to the level you want. Lastly bore the blocks and the jaws together. No need to alter the jaws! I have done it and it works.
Not sure you can be guaranteed equal pressure on the jaws that way.
Assuming the chuck was made to high accuracy, and most are, and the blocks are also made accurately to the desired width, it works fine. What we are really doing is forcing the outer edge jaw key against the back face of the slot in the body of the chuck and the inner edge of the jaw key towards the front face of slot in the body of the chuck. Thus taking up the looseness allowance made by the chuck manufacturer necessary for it to slide. also any wear in the key and slot that holds the jaws. It will work with any number of jaws above 2 Forcing them this way gives preference to the front gripping part of the jaws. This stops any lateral movement of the part while turning caused by gripping errors. Particularly useful with older slightly worn but still serviceable chucks.
Excellent video Robin! It would be awesome if you would do a 101 video on cutting/soldering/grinding Carbide and CBN tooling. Materials, techniques, fluxes, solders, temps etc!
Great suggestion!
Yes. The legend is back. 🎉.
It's been a long time!
Good to see you back!
Definitely, this is the right way to true up chuck jaws! Absolutely!
Hopefully Ox Tool will make a reappearance as well......
Thanks for another wonderful tip to make our tools perform like they were meant to! :)
Tom's etching press vs Robin's surface plate, which will outlive the Sun?
I'm not a machinist of any sort, but I do have a background in Structural Engineering which means that I can understand your comment about everything being made of rubber.
However your videos always fascinate me , for the way you consider, then explain the processes so simply and clearly.
Thanks, and it's great to see new content
I now fully understand why Quinn coined the adjective "Renzettiness." Excellent work, Robin!
Who?
@@ShainAndrews Get a clue Shain.
@@carlhitchon1009 Why don't you step up and try...
@@ShainAndrews, Blondiehacks.
@@Ddabig40mac Gotcha. Not a fan of her work, and I was trying to think of a guy instead. Frankly I didn't know that was her name. LOL.
Your language clarity and descriptive ability are matched by the validity of the methods/tips you are so generous in sharing. Thanks very much.
Wow, thank you!
Excellent descriptive narrative throughout. Very easy to follow.
Hello Robin! I'm glad to see you. You were gone for a very long time. Constantly visited your channel in the hope of seeing new videos. I am writing a message with the help of a translator, I do not know English, but your videos are clear to me without translation. Thank you.
Another gem Sir. Thank you for continuing to support the community and share your endless amounts of brainpower! Happy holidays!
I haven’t even watched the vid yet. I just wanted to say that I missed your content. Glad to see you back sir
When ever I want to see the right way to do things, this is the channel I come to!
2:52 these few clips here were really well filmed. Thanks for the great close ups
Glad you enjoyed it
Another master class, thank you.
Glad you enjoyed it!
As always, thank you for an excellent presentation of the nuances to any subject that you are covering. Not just, do this then that 'cause I said so. Very well done.
Much appreciated!
Fantastic as usual. I love your attention to detail and clear explanations of the forces involved. Hope it is not as long to the next video!
I’ve struggled with this in the past. I couldn’t find/figure out a method to load the jaws. I made a ring but it wasn’t sufficient and my grinding rig was poor, especially the stone. I made everything worse. The ball bearing race is a great idea.
And mentioning the accuracy of the scroll is huge. Ive banged my head off the wall before with a cheap 6 jaw chuck I use. I modified it to be a bolt thru design in order to use it like a set through by relieving the outside of the locating hub on the back plate a few thou to allow adjustment.
All great info as always, Robin. I’m always learning something from you.
He'll yeah 👍🏻 So happy to see this in my Feed
Thanks Robin
This is a great topic most everyone can benefit from. Nice
Very nice master class on lathe prep for accuracy! Very valuable information indeed! Most machinists on UA-cam need to study this.
There are many things you show in your videos that I have no chance of using in my very modest, tiny workshop. I love watching them anyway, because I always learn interesting and useful things. THIS video is different. Everything shown is extremely useful. I have used very similar method (hard-drilling the jaws for pins) to grind in my lathe chuck. Thank you for taking time to take us to your workshop.
Wow what n surprise. Awesome to get another video from You.
It was long dark night Sir, but you bring us sun.
Like you, I too have SolidWorks and SolidWorks Simulation as well. It is fun and quite interesting to model things such as a chuck assembly and apply the loadings you describe to the assembly and then of course exaggerate the displacements grossly and visually see the distorted shapes of things. Things behave just as you indicate, you have a keen dye for how things distort. Will say there has been times I was surprised, they didn't take the shape I has anticipated. But then when you actually see the shape it will make sense. Excellent video indeed. Very well done, thank you.
Thank you!
I see robin video, I click video, no questions asked. Thanks for making us all that bit better!
Hey Robin, thank you for all your time and effort producing these video's. I do appreciate it and are very happy to see your back in the saddle making high quality content again. Much appreciated. 😁
Rob, GREAT to have you back ... REALLY ! Cheers.
Thank you for the highly detailed description of process and your reasoning. Always appreciate the density and tight editing you put into your videos. Every chuck we have for our Hardinges at work are badly worn to the point I don't consider using them for first ops, much less anything where I need repeatability. Very very frustrating, but I think now I know what I need to do.
Please never leave us out here that long in the dull,uninteresting UA-cam universe again Robin
Thanks Robin, As usual a gem that I will no doubt revisit.
Rob, another great episode full of useful and valid information! My C5 chuck is going to be modified just as you did! Thank you Rob!
I've seen an alarming number of videos that show clamping down normally onto a spacer to grind the chuck faces. I always thought this didn't make sense to me. Your explanation was very simple and DID make sense to me. Thanks
Great teaching from the Master Machinist! You class is my favorite. May the Lord bless you richly for the wealth of knowledge that you freely give!
Thanks, you too!
Good to see you back, thanks for sharing
I always enjoy seeing your videos. They inspire me to improve my accuracy. Loved the freebie at the end.
Nice to see you again. Great video.
Brilliantly explained and executed, I do like the appreciation that all the metal is rubbery under tension loads to some degree, and to degrees that matter for accuracy and precision.
Thank you for returning
Nice to see you back Rob!!
Another point to add is using different pinions around the chuck will give a different result also. I agree most parting and vibration issues are chuck related. I use a strip of paper around the front of the job in a pinch. Bell mouthing also affects tool posts and tool vibration.
Yes, only use one pinion if it has more than one.
Just thought about the paper trick only hours ago. Gauge foil is an alternative. Will try that one tomorrow!
The only problem with watching robrenz videos is they highlight what a complete hack I am...😁
Seeing that Shars indicator on this channel is fantastic! Go Shars!
Very interesting video. Welcome back!
This is strange, just today I was going over your D-Bit Grinder videos as I just got one for myself. Now a new video. Well, I should have done this sooner.... Thanks for this one. Good to see you back.
Thank you Robin😁
Beautiful work . I love the detailed explanation. I have that same 6" Buck 6 jaw and I really like it.
This is the clearest explanation i have ever heard about this problem. Well done! Thank you. I would love to see a follow up video on your surface plate resurfacing project- how it is holding up and anything you would do differently and so on.
I really appreciate your mental process and awareness of “systemic precision”.
Excellent video, thanks Robin. I reground the jaws on my 1980s Pratt Burnerd 8 inch 3-jaw because I was having chatter issues. I used pins and a ring to apply the preload at 45 mm opening with a 38 mm dressed stone on the toolpost spindle and it worked superbly. I mapped the runout across a wide range of diameters using a range of turned and ground bars clamped using the 'O' jaw to see how terrible the scroll was. It's near-perfect from 35 to 65 mm, and below 18 mm, but there's a section around 25 mm that's well off, I bet that was the size of most of the production jobs this old Colchester 1800 was used for. I wish I had an LVDT indicator so I could map the thing electronically. I just have a cheat-sheet listing the problematic diameters where I might need to re-true the chuck.
The only other channel where a new video is as exciting as new material from ROBRENZ, is Clickspring.
Thank you for an excellent and clear presentation, Robin! Whilst machining, we can tend to go into “auto pilot” mode and stop thinking about all the forces acting on the parts and the jaws. This really woke me up again! The part I found especially thought-provoking was the runout after the machining of the jaws being attributed to the accuracy of the scroll. Thank you once again! Keep up the great work!
Thanks Robin, glad to see you back.
Hi Robin! Nice to see you upload again. It's always fascinating to get a glimpse into a mind that thinks in precision.
Thank you Robin. Christmas Treat! Wonderfully thorough and clearly explained.
Kind regards from John Spargo in CapeTown
So much information in a short video,
Thank you for your generosity in teaching.
Cheers
Always an honor and a pleasure. Thank you.
So much knowledge & experience, thanks for sharing 🙏
Oh happy day! Welcome back Robin! Have missed your particular outlook on things very much. Another great video. Thank you!
Good Stuff!!! The "Freebie" with the 5c fixture plate with the chuck mounted on it, was a great tip. You saved the best until last.....!
So glad to see you back.
New ROBRENZ video, don't blink.
Nice one Robin! I had to have my faithful go to chuck face ground and OD ground and new jaws made because even though its a fairly high precision chuck, especially made it look like a washboard from many years of it being torqued to limit into workpieces.
Thanks Rob.
I spent hours grinding my jaws.
I had a ring just the way you said not to and so was wasting my time and with the way the chuck performs I can believe I have made it worse.
Hey Robin, great to see you back my friend. As always, this is a great video to watch. Let’s have plenty more.
Super interesting! I’ll never look at a Chuck the same again, thanks Robin!
Robin, I can’t wait until you retire and do UA-cam full time! I have to say that as a new machine hobbiest, I was worried you’d be going way over my head. This was perfect, you’re such an awesome guy.
Thank you so much!
Thank you for this fascinating video and welcome back to UA-cam videos, you were missed!
ah... so now i realize that you are the same infamous 'robin' that other machinists keeps referring to. however i found your videos from eevblog instead. those marvelous probes. and other such machining for electronics.
for this video i followed along it is amazing. really fantastic and a pleasure to watch. so many thanks
Thanks Robin. I've been wanting to do this for a long time but alas, I don't have the means or the courage to hard turn a face groove. I think I can manage drilling the dowel pin holes though.
Regards, Mark
That's no walk in the park either!
I think you would need to have them spark eroded.
I had no idea that the body of a chuck is that flexible. Awesome lesson as always.
Awesome content! I get what you are saying about scrutinizing your mounting processes through the filter of the origins of the loads on the work. I think I use a similar principle when engineering a structure or tool that needs to be welded. Noting the particular loads that metal structures or tools will be subjected to and the direction of their origins.
Glad to see you back. Always digging your content.
Oh so happy to see you again and your genious in perfection.
For some yt reason your annoucements where turned of😮, so i pushed the bell a second time ☆☆☆☆☆
Grtz from the netherlands Johny geerts
Man I'm glad to see you back!
Hey thanks Robin. Did mine today. All from this video. Came out great.
Welcome back, Robin. Thanks! There is the possibility that variations in the scroll grind could make the jaws parallel where you measured them and no longer parallel at a different diameter. There is a long pivot arm outside the jaw face so that a much smaller shift at the scroll end could give a surprising result at the jaw tip. I suspect that this problem is not such an important factor for a well ground scroll. If my explanation wasn't clear, picture a perfectly perpendicular scroll contact at one diameter and a 89 degree scroll contact at another.
Surely it's the tenons in the chuck body engaging with the grooves in the jaws which provide the predominant jaw guidance with respect to parallel or otherwise?
Correct.
Your attention to detail is phenomenal, simply awesome. Thankyou Robin
Nice to see you back hope everything is good love your videos from Ireland you and Tom the best
By far the best in detail video on chuck dressing that exists. One thing that always bothered me about lathe chucks is they always use square drive for tightening and on set true chucks, the screws are always hex. I really want to make torx screws for all of mine and use a torque wrench to tighten my chuck and set screws for adjustment always to the same torque to take even further variation out of things. On the main chuck tightening screw, I wonder what the best method for doing that would be, filling the cavity with weld and then hard milling a torx hole? Perhaps boring it out and putting an hardened torx insert in, and brazing it? But then that would lessen the hardness of the screw and you would have to heat treat it again... I wonder if you ever think about this. Squares and hex always eventually strip, I've lost count of how many lathes I've had to use on the job that had stripped tightening squares, drives me nuts 😂
Great to see you again RobRenz! And thanks for this particularly - loaded with insight and information. You know initially I was thinking "got to have some diagrams here" to clarify the deforming moments and so on. But actually I found a great value in really thinking hard about the details, re-watching some segments of the vid, and gradually getting (pretty) clear what you were getting at. Thank you very much, and please come back soon !!!
Best wishes for 2023 and onward.
This is the exact issue I needed to solve. Picked up a newer Buck Forkardt 6 jaw on ebay for a great price awhile back with the solid jaws, basically identical to these older bucks. As with anything, you get what you pay for and it was gummed up pretty bad upon arrival but it looked nearly brand new on the outside. Opened it up and it looked like it was crammed with carbon fiber dust and rust in the scroll. Jaws were alittle funky but I couldn't think of an obvious way to preload them to grind the inside.
Thanks for sharing this. As a hobby machinist, you've brought to attention some things that I didn't even think of. It's time to grind my jaws.
I am glad to see you return. I sincerely hope to see more.
For me it's only a hobby and yet very instructive to see how "it can be done". Glad to see your video pop up on my notifications!
So happy to see a new video from you. Always incredible content, thank you!