The "Mr Crispin Jaw Dolly Clamping System" is an inspired work of genius !

The humor in these videos is dryer than a martini. Im here for it.

@twotone3070

2 ай бұрын

I don't drink either, but is it drier than port?

I have discussed this multiple times and I believe Robin has talked about it too. Scroll chucks are made with a master key. For best results you need to tighten the master with a torque wrench and then grind. The same torque needs to be applied every time to get the best repeatability because the torque deflects the chuck and jaws.

MR CRISPIN! Great to have you back. Hope the absence wasn't a forced one. Informative, educational , and entertaining as usual. Thank you. You were missed.

@MrCrispinEnterprises

10 ай бұрын

Pleased to be back

Glad to see you back and the project complete. I was beginning to think you had moved on to other interests. I found the jaw loading discussion particularly helpful.

@MrCrispinEnterprises

10 ай бұрын

No don't worry, if I was going to get bored of machining I would have done it by now!

The jaw clamping dowel invention is a brillant idea. Way back when I was being trained I remember our instructor used to always tell us to use all three pinions every time when tightening. To get the work piece more true.

Following the example/advice of other content creators, I have moved my angle grinding operations OUT of the shop to a portable work table to minimize the abrasive filth that gets spread around the shop. I also employ an N-95 mask to minimize the abrasive filth that gets into my respiratory system. Nice job on the tools.

Good to see you again, sir!

Nice video mate just a quick tip for your search for ultimate precision , when i worked as a machinist many years ago we used to mark each chuck so that we used the same chuck key pinion every time. we were machining to tolerances to the value of a few tenths of a thou ( old school ) so you are on the right track m8 . loved your solution of the jaw dolly clamps pure genius keep up the good work

@MrCrispinEnterprises

10 ай бұрын

Thanks

Robin renzetti always talks about two things about the chucks he uses. He uses the same tightening position as he ground with and also uses a torque wrench to tighten his chucks. Some food for thought. Enjoyed your work as always.

@MrCrispinEnterprises

10 ай бұрын

Thanks

@rok1475

10 ай бұрын

I recall he also mentioned the concentricity will change as the chuck clamps any diameter that is different from one during grinding. The cause of that is imperfections in the grooves in the scroll plate.

Very fortunate that you had the large ring available, from your brother's automobile. He always has the proper tools. 😊

Welcome back Mr Crispin. Fascinating stuff as usual. So, a round file in the tail stock…. No, I’ll not go there. LOL. Learned so much about a lathe chuck during this series. Thanks for sharing and stay well.

you are 100% correct. The scroll wear WILL contribute to runout as well as how much play are in-between the outer surfaces of the jaws. Meaning the non-grooved sides riding in the chuck body. At our company we used to spend a lot of time doing what you do did but soon realized wear plays too much of a factor. Hence we also went the dowel way where we removed the jaws from the chuck and then ground them in a jig. Our dowel jig system held the jaws flat, on their sides but in a circular jig, if you know what I mean.

When you are opening, and closing your chuck you are relying in the accuracy of the scroll to keep the jaws concentric. I believe the level of accuracy you attained is about the best you can expect from a scroll chuck.

@lezbriddon

10 ай бұрын

Was just about to say the same, the scroll isnt ever going to be perfect and how linear it is depends on its quality of manufacture and if that employee was in a rush to get himself home that day

@aj7utu

10 ай бұрын

There will be a different runout at every diameter due to compound inaccuracies in the scroll, worms, and jaw teeth.

Thanks for sharing. Your thought process is very insightful. It points out to me that a machinist is always dealing with less than perfect tools.

Mr. Crispin, brilliant work. Thanks for another superb job!

Great to see you back Mr C. Thanks for another informative video.

Awesome. Glad to see more content. It's been WAY to long! :) I've been curious about this situation in my shop. Thanks for sharing some great ideas.

Great video, enjoyed your technique and explanations, a great enlightenment on our humble 3 jaw chucks. Cheers Mr. C!

Always good to see a new video from you. Thanks.

From Australia - Great to see you back doing stuff. Even if you are a Brit 😉

@markrainford1219

10 ай бұрын

From Britain - Wanker. 😁

There's a certain amount of slop in the scroll in the chuck body, and of course the wear on the scroll working surfaces will not be even, so it would depend a lot on where the jaws were located in their travel when they were ground. If you can get a self centering chuck to centre within 2 to 3 thou you're doing well, even if the chuck is unworn. I notice on my old Burnerd 3 jaw one of the scroll gear stations has a punch mark... probably the most accurate spot last time the jaws were ground. Love your little dollies.... must make myself a set... brilliant...

@MrCrispinEnterprises

10 ай бұрын

Thanks

@KW-ir5mf

10 ай бұрын

I forgot where it says in the machinist manual that chucks can also be used as a vice. 😄

Robin had mentioned, possibly in the same regrinding video, to always using the same key slot to tighten and only using one rather than tightening all 3. Seems you’ve proven the theory. A good one to ponder. Great to see you again!

@JSmith19858

10 ай бұрын

That's the case with most chucks. Pretty much all good quality chucks I've seen have a pinion marked 0. On my Harrison, using a Pratt chuck made in this century, starting at the pinion marked zero and supporting the part correctly will see most items come in under 20 microns of runout. I swaped ends on a part 145mm diameter and 120mm long earlier and it was 10 microns out just by holding it in place and tightening it down correctly. Personally I round file 3 jaw chucks that are worn out or keep them for holding round parts on the mill. Pissing about grinding them is not worth it compared to spending £600 on a new chuck, more so when you're earning money with it.

welcome back to the videos and great video I actually learned something very interesting. Thank You

I'm pleased to see you appear roundly chuffed about being back. Cheers!

@MrCrispinEnterprises

10 ай бұрын

Yes it's good to be posting videos

So glad you're back!!! 👍👍👍

very helpful info and a very thorough investigation. thank you for taking the time to investigate these phenom. this clears up a lot of questions ive had but didnt know how to analyze.

Chuckception pt2 the grinding of the rings continues. Thanks for taking your time to produce these videos they are intresting and very useful

He's alive!!! Glad to see you back MrCrispin. Love your content.

So happy to see you again. I sure did miss you.

Absolutely Brilliant! You have been sorely missed.

Welcome back Mr Crispin, it’s been a while. Thank you for another entertaining and educational video. Have a good one 👍🇦🇺

The Mr Crispin Jaw Dolly is a fabulous piece of kit. Thanks for the demonstration. 👍👍😎👍👍

Great to see you back, very interesting to see your thought process when you tackle these things, something I will never do but interesting all the same, hope to see you back more regulary

@MrCrispinEnterprises

10 ай бұрын

Yes it's been quite an exercise in thinking!

You'v been mist Good to have you back , and its never dull, hope to see you more often.

Glad to see you back just wanted to thank you for all the great information 😊

@MrCrispinEnterprises

10 ай бұрын

Thanks

Excellent! I had always wondered how accurate one of these old chucks could be (re)made. Per results, 0.0015 appears to be the answer. I find it amazing that the thread in the scroll and the jaws is that repeatable!

Many years ago, i went through exactly the same processes with exactly the same disappointing results. My conclusion was that it is due to wear in the scroll plate. Making a new scroll plate sounds like an interesting project !!! . Glad to see you back

@MrCrispinEnterprises

10 ай бұрын

Yes it does but I think I'll try and get back to that Locomotive instead!

Astonishing. A wealth of information and an innovative and very well thought out solution.

@MrCrispinEnterprises

10 ай бұрын

Thanks

Nice to see you back Mr Crispin, interesting video.👍👍

@MrCrispinEnterprises

10 ай бұрын

Thanks

Very well thought out, thank you for this, it has now become part of my machining world view

WOW!!!!!! YOU ARE SO METHODICAL, IN YOUR ANALYSIS!! MUCH APPRECIATED!!! BRILLIANT WORK!!! THANKS FOR SHARING!!!

It's good to see you back sir

Yes I like it before viewing it, exactly what i was looking for for years THX

Really nice work and explanations.

Fascinating. Educational and entertaining from beginning to end. Thank you sir 👏👏👍😀

@MrCrispinEnterprises

10 ай бұрын

Thanks

Thank you my good sir for the brilliance...

Adam of Abom79 found with a new six jaw chuck that all three tightening lugs must be used for best concentric for near zero runout. Thanks for your explanations and your wonderful invention. 😊

The best solution to an old problem that I ever saw.

I'm pleased to see a new video on your channel!

What a superb idea! For years, I have been mulling over how to put pressure on the jaws so that I could accurately grind them. Voila, the elegant solution.

Great video Mr Crispin. Brilliant solutions in setting up the chuck for grinding. Glad you showed the final results, as I recently checked my Myford chucks run-outs. Pleased that they are well within the tolerances compared to yours. Glad you're back with your videos. Cheers Nobby

Well done Crispin, neat little aids, great design. Constant battle with larger chucks, a handful of different thickness shims now you have parallel clamping is advisable, helps you get to near zero quite quickly as usually only one jaw needs correction. I use this method quite often. Cheers, Jon

@MrCrispinEnterprises

10 ай бұрын

Cheers John

Thanks for your thorough investigation and demonstration of this ... thoroughly complex business! I like your Jaw Dolly Clamping System which deals effectively with the important issue of biasing the preload "parallelism" situation. Resulting in much stronger and truer grip on the workpiece. As to all the other variables, I tend to use a shim on one jaw, or two if required. Beyond that - its back back to the independent 4-jaw! In any case, good to have you back. See you soon again Mr Crispin!

You kept your promise...good man!! Lol Thanks for the new video!!

Fantastic work! Really clever solution with the Jaw Dolly.

I really like the jaw dollies. I have a six jaw that I wasn't looking forward to trying to drill for pins. Stefan Gotteswinter has done a few things about using a single pinion for best accuracy, and that it is mentioned in some chuck documentation and that some top made chucks still have only a single pinion to ensure things.

Nice grinding fixture for the internal preload Mr C. There is another style I have seen recently that worked on the same principle but was built on a large dia ring. Yours is much simpler to make. The outside ring from a brake drum is some good stuff as well. Well done sir

About time! THANKS and a great video

Thanks for posting this. I ground the jaws of my 3 jaw chuck a while ago and was most disappointed to find that things had apparently not improved. However armed with the knowledge from your post I checked all the tightening positions and one produced a run out a quarter of that of the others. Much grief saved!

Good evening Mr Crispin, And welcome back ! I have given the matter of work-holding concentricity in the three jaw chuck some thought previously, and I offer my thinks . . . . 1. Three jaw chucks from Pratt Burnerd are supplied with matched jaws, having a unique reference number, and I deduce that this is for a reason. 2. The quality standard of accuracy is given in different grades ; the higher accuracy of run-out is obtained with the precision series of chucks, which is reflected in their price . . . . 3. The scroll is a circle of continuously changing radius and more importantly, curvature, whereas the mating teeth on the back of the jaws can only be produced with one curvature. It follows that there can only be one radial position where each tooth curvature matches that of the scroll ; at all other positions, contact is at best at one or two points. When the points are small, loads will induce deflection, which appears as movement of the gripped component away from concentricity. I perceive that full contact may well occur at different radii for each of the jaws, which might further affect concentricity of components of differing diameter . . . . This implies that attempts to true up the jaws at one radius may not necessarily produce a similar improvement at all radii ; indeed, it could make some worse . . . . 4. As others have pointed out, age-related wear and tear will increase the “float” in the scroll on its locating spigot, and our concentricity is ultimately dependant on where the scroll positions the jaws, with respect to a fixed point, which is the axis of the spigot. It follows that increasing float will allow the jaws to take up different positions, depending upon which of the key pinions is tightened first, and by how much . . . . Grinding the jaws will offer no improvement in this instance . . . . 5. Jaws which are “bell-mouthed” are either showing signs of wear in the slides, or have been badly strained at some point in their lives . . . . It follows that, whilst not doomed to failure, grinding the jaws is not going to restore the chuck to its original manufactured accuracy, but as long as this is borne in mind, it will certainly yield some improvement. 6. Three jaw chucks should be treated as precision items, and kept away from anything other than truly circular or hexagonal bar stock ! My thoughts, but I humbly invite debate ! Kind regards, Steve A.

All is right with the world, the English Island still exists and Mr. Crispin is back in the shop. God save the King.

Your back, and about time, missed your videos fine, fine, pression work

Great idea on the 3 plates to grind the ID on the chuck jaws. I have found that i always use the same key to open and close it works well ,great presentation

What a Bobby-dazzler Mr Crispin, well done.

It is, in fact, your big head that makes your videos so compelling!

Good to see you back! Your results are pretty much what I achieved. The big benefit I got was the jaws before grinding appeared bell mouthed and did not grip short pieces at the tip of jaws. After grinding I had good support at the tips. My machine was essentially new so I suspect the OEM Chinese jaws had never been ground.

In addition to the factors that you have mentioned, realize that grinding only yields concentricity for that one exact jaw diameter. If you change rhe diameter, the jaws are held by an entirely different section of the scroll.

thanks i learnt a lot from an honest man .... 100%

The most thorough, yet enjoyable, course on getting a lathe & chuck find common… ground! Grind! oh bother… Anyway, thank you again for taking us along! P.S. I think Clough42 has met your brother…

Very, very ingenious. If I was wearing a hat I'd take it off to you

I took a different path after grinding with three bolts and nuts adjusted on opposing jaws on the 45 degree chamfer of the jaws. Similar results. Copied John Mills from double boost and machined 5 thou off the backplate spigot and improved it by drilling and tapping 8mm holes on the periphery of the chuck body. Fitted setscrews and it is a simple method to slightly loosening the backplate screws and adjust with setscrew and retighten the backplate. Essentially a set tru chuck for precise setup.

Quite informative, thank you. Love the music.

Impressive as usual.

Some exciting solutions to what seems to be the never-ending questions or problems in trying to make a 3 jaw more accurate, and yes ROBRENZ has a good video on this topic as well... CHEERS.

Wehey! He's back!

The legend, the hat, the man! in no particular order.

another great video - thank you!

I've been enjoying the videos and hello from a rolls-royce employee from the US.

Our patience has been rewarded! I hope you had some earplugs in for the angle grinding job, those things are loud!

When he said he took his series 2 Land Rover Brake Drum and cut it in two so he could get a ring big enough for preloading while maintaining the original radius, I had the thought: “Ah, He is one of my people 😂” -> Subscription Clicked!

Your jaw dollies are the best solution I've seen. I drilled my Pratt Burnerd jaws for dowels with a carbide drill no problem. But I'm so glad you got somewhat disappointing TIR just as I did! The lesson seems to be that whatever you do you can't make an old chuck as good as new.

@MrCrispinEnterprises

10 ай бұрын

Yes it's been quite an exercise in thinking!

In my time as a centre lathe turner in the UK we had two piece jaws that accepted a machinable bolt on top that could be indexed forward or backwards using serrated faces. You would position the jaws to the size of the component and then m/c the jaws very lightly to match. We would still use internal/external rings to eliminate backlash in the scroll. This would eliminate scroll wear and distortion of the scroll caused by previous over tightening. I would suggest that if you used a test piece that matched the clamping position that you used when grinding the result would be a lot better.

Brilliant information.

excellent idea. thank you for sharing. best regards.

Great to see you today

You hooked me with "Do you have bar sag?" 😂😂😂

Great idea mate 👍

About bloody time

That is actually VERY interesting discussion you've made. Thanks! New sub:)

@MrCrispinEnterprises

10 ай бұрын

Good to have you watching

I was taught to always use the same position on the chuck to cut the the jaws with a spider as you do when gripping the part . I have managed to get consistent concentricity of around 0.01mm with this method . Basically grip the spider using the key in the position where the chuck badge is then once done grip the part using the same chuck position with the badge . It'll work 👍 24:20

@martinconnelly1473

10 ай бұрын

I have at least one chuck with one of the pinions marked with a zero. This is the pinion that should always be used for final tightening of a workpiece and for truing the jaws. The theory I have read regarding this is that the scroll will always be pushed in the same direction against its internal bearing surfaces, there is always some clearance otherwise it would not rotate and this gives consistent closing of those clearances.

@borloc1

10 ай бұрын

@@martinconnelly1473 exactly mate .Over the years we have made lots of sets of bespoke welded up jaws for hundreds of jobs and using this method taught by my old mentor it always worked well 👍

As below, wear in the location diameters of the scroll is most likely the issue. Turning the pinions imparts a radial load on the scroll as well as a tangential one so any clearance in the scroll will allow the jaws to move. I was always taught to find the truest pinion on any chuck (where the jaws were ground) and just use that one (usually the one adjacent to the nameplate pad on burnerd chucks) Regrind the insides of the jaws intentionally using one pinion and see how you get on. Nice video though, glad you're back

@MrCrispinEnterprises

10 ай бұрын

Thanks

BRILLIANT!

Excellent video!! Been wondering when we'd heart from you again! 😎

Your back ! 🤗

@larrymac8538

10 ай бұрын

Dear Peter ... it is ' YOU ARE back ' or if you wish to be a lazy Millennial then you can just shorten it to ' You R back ' or if you want to be like a cool American then just say ' U BACK Bro ! '

Great solution!

Very informative, I bought a 4-jaw independent chuck. :)

And welcome home sir. 👍

Thanks for the video!

I must confess that I just zipped through this video because I already knew the problems you were going to need to address and I wanted to see your solutions. When I came to the part where you realize that concentricity can be lost depending on which pinion you turn to tighten the chuck I thought I should add a comment. I recently retired after a 45 years or so of being a machinist, being self employed for most of those years and I specialized in high precision lathe work, so maybe my comment will have some weight. Anyway, the main problem with using different pinions to tighten the jaws is because the scroll inside the chuck will shift some when the chuck is tightened and the direction it shifts changes depending on which pinion is used to tighten the jaws. The scroll shifts because it must have some clearance to rotate and then it wears over time which only adds to the running clearance. So, to get the best repeatability the same pinion must always be used to grind and then tighten the jaws. In my opinion decent lathe chucks should only have one pinion for tightening. Also, I should say, all of the lathe chucks in my shop are adjustable for concentricity. Except for one that came with an antique lathe that I am restoring. The lathe and chuck were made in 1899 and I'm not sure adjustable 3 jaw chucks were made in 1899. Cheers, Eric

@MrCrispinEnterprises

10 ай бұрын

Thanks for the info, I think we can agree that a master pinion is the solution for a non adjustable chuck