How To Adjust a Griptru Lathe Chuck

Рет қаралды 9,422

6 жыл бұрын

The Burnerd Griptru is a three jaw self centering chuck that can be easily adjusted to run with little or no runout.
In this video I show how to adjust one on the Myford ML7.

Пікірлер: 44

@petecooper3701 4 жыл бұрын

Hi John, theses chucks were manufactured in the late 50s and on. The factory was at the Winnal trading estate in Winchester and it moved from London just after the war. Most of the machinery was war issue, still had the Big Arrow. To turn the scroll, many Herbert lathes were modified to make the cross slide into a thread cutting device, a brilliant piece of engineering. The factory was almost completely self contained, the steel bar, billets and cast iron blanks came from up north. All stages of manufacturing including heat treatment were carried out there. Burnerds were bought out in the 70s by an American Co, Pratt Woodworth who extended the factory in order to make specialist diaphragm chucks which were sent to Italy to go on Italian auto machines that ended up going to Russia to turn Russian army lorry wheels! (The cold war was still going on) I worked there in the 60s and 70s on all sections ending up in Pratts welding the jaws to the diaphragm chucks, learning welding at Sparsholt Agriculture College, (still there). Thanks for your effort on this, Pete on the Isle of Wight .

@CreaseysWorkshop 4 жыл бұрын

Thanks Pete that’s very interesting. I love my Bernerd chucks. My Mum grew up in the Isle of Wight. I visited there a couple of times many years ago. Near Cowes I think.

@brianjohnson217 3 жыл бұрын

One thing that I would add to John's video is that you should always loosen the bolts on the back plate and turn back the 3 adjusting bolts on the chuck body otherwise the adjusting bolts will be fighting against each other. The griptru chuck is a fantastic piece of kit

@CreaseysWorkshop 2 жыл бұрын

Yes good point.

@johnhall8455 10 ай бұрын

Not a good point…you should not touch the tie bolts at all…that means every time you want to make an adjustment you would have to remove the chuck to access the bolts…that’s not the idea at all…The only adjustments are made using the micro screws…Read the instruction manual…

@toma5153 4 жыл бұрын

I got one of these on an Ebay auction for a whole assortment of Myford accessories. So it's been sitting around about 8 years or so. I better start using it! Still in original Pratt-Burnerd box.

@MarcelDiane 6 жыл бұрын

Great video and glad to see your full info is back.

@johnhall8455 10 ай бұрын

It’s a good idea to first strip your chuck down for a clean, that then gives you good idea of how it works….easy peasy once you get the hang of it…

@iangraham6730 6 жыл бұрын

Very nice chuck John, thanks for sharing!

@grahamsengineering.2532 4 жыл бұрын

Hey John I have my Grandfathers old N130 Griptru. It has the same key as yours and is at least 50 years old. Used it yesterday for the first time. Pop use to use it for doing the live steam injector cones.

@TheKnacklersWorkshop 3 жыл бұрын

Hello John, I have just got myself a GripTru chuck so this video was very useful to see one in action... Take care. Paul,,

@CreaseysWorkshop 3 жыл бұрын

I hope it helped!

@halstoolroom5985 6 жыл бұрын

After 50 years in the trade, that's the first one I've ever seen

@brianjohnson217 2 жыл бұрын

In addition to the comment that I made regarding setting a griptrue chuck, if you are in doubt about how this type of chuck works , dismantle it (very easy) That way you can see how the internals work , which greatly helps in being able to bring the chuck to zero . Also a good opportunity to clean and lubricate

@johnhall8455 10 ай бұрын

Excellent advice…they are really simple to use once you understand how they work..

@EmmaRitson 6 жыл бұрын

awesome. another thing I need. thanks

@CreaseysWorkshop 6 жыл бұрын

Hopefully my video won't inflate the price too much! :P

@grahamsengineering.2532 4 жыл бұрын

You'll have to rob a bank first Emma. hehe.

@captcarlos 4 жыл бұрын

Funny enough I just picked up a 6in 6 jaw adjust tru scroll chuck 2nd hand for $60 Au..

@TheJoyofPrecision 6 жыл бұрын

Tremendous!

@PracticalRenaissance 6 жыл бұрын

slick!

@MaturePatriot 6 жыл бұрын

Must be nice to have that adjustable three jaw. Once it's running true, faster setup than a 4-jaw but as accurate.

@CreaseysWorkshop 6 жыл бұрын

Yes! Best chuck ever!!

@FirstnameLastname-uh4rk 3 жыл бұрын

So, once you’ve initially set the griptru chuck up with a round ‘test bar’ and got everything to run true on the dial gauge, is the chuck now set up for concentricity on all following jobs, or do you have to repeat the ‘truing up’ every time you put another piece of stock in the chuck?

@CreaseysWorkshop 3 жыл бұрын

Yes ideally. Scroll chucks are never perfect though so it all depends on how precise you need to be.

@dahut3614 3 жыл бұрын

They are true for subsequent parts of a given diameter, but not so for all diameters!

@johnhall8455 10 ай бұрын

That’s the whole point of the chuck, it needs re-truing for individual pieces, but once you get used to it it only takes seconds

@rinklestiltskin 6 жыл бұрын

Do you not have to loosen/tighten the screws holding the chuck to the backplate, like a Buck Adjust-true?

@DecoyTango 4 жыл бұрын

Yes I believe you are advised to slightly slacken off the screws at the back of the chuck, and retighten when adjusted.

@johnhall8455 10 ай бұрын

Definitely NOT….the tie bolts should not be touched…that means you would have to remove the chuck every time you made an adjustment…they are not clamping bolts for the micro adjusting screws…It’s a common fallacy……Read the instructions

@john2478 10 ай бұрын

@@johnhall8455 John, I have had a Bernerd Griptru chuck and a Bison set tru chuck which are essentially the same mechanism using 3 screws. The better chuck by far is the Bison chuck which is just very robust, very accurate and expensive. It is assembled with screws through the front to the backplate so you can ease the securing screws slightly to aid the setting up of the chuck before tightening them fully up and checking the result. To my mind the Bernerd chuck with its hidden screws is not as user friendly because if you disassemble it then you will have lost whatever the torque settings were on the factory installed screws, with no instructions as to what they should be and no means of adjusting them from the outside. This can only be remedied by fitting the locking screws from the outside but adjustable from the rear. The 3 screw positioning griptru chucks in my view are not as easy to adjust as they would be if they had 4 screws. I have made several adjustable 3 jaw chucks using cheap Chinese chucks and machining the cover plate reducing it in height about 7mm and increasing the depth of the backplate recess so there is enough space to drill 4 equally spaced screw holes and tapping M5 for grub screws. These chucks have been very successful and are much easier to adjust using the same technique for a 4 jaw chuck with a pair of hex socket drivers in opposite positions turning one in and one out. I cannot understand why the Chinese do not make them like this and charge a little more for the advantage they offer. John

@ianbertenshaw4350 6 жыл бұрын

Never used one and would love to know how they work but surely a 4 jaw would be quicker ?

@CreaseysWorkshop 6 жыл бұрын

ian bertenshaw The advantage is that once trued it is repeatable.

@44Celt 5 жыл бұрын

The adjusting screws are tapered and locate against posts that are cast on the inside of back plate. As you screw down it pushes the chuck body away from the cast posts

@johnhall8455 10 ай бұрын

Easy peasy once you get the hang of it…. It’s a good idea to strip your chuck for a clean, then you get a good idea of how it works

@SupraSmart68 2 жыл бұрын

That sounds like quite a tongue twister John! So how many true chess pieces could a GRIPTRU chuck chuck if a GRIPTRU chuck could chuck true chess pieces?

@CreaseysWorkshop 2 жыл бұрын

32 :-)

@SupraSmart68 2 жыл бұрын

@@CreaseysWorkshop I see, so would they be delivered in a red lorry or a yellow lorry? Repeat after me out loud; Red lorry, yellow lorry, red lorry, yellow lorry, red lorry, yellow lorry, red lorry, yellow lorry....... Also, how many chucks could a chuck truck truck if a chuck truck could truck chucks? Would it be as many pleasant pheasants as a pleasant pheasant plucker could pluck?

@pierresgarage2687 6 жыл бұрын

That's a first... At least for that chuck...

@fasousa4798 6 жыл бұрын

John 0.016mm is actually 0.0006". You are missing a zero. Here is when a zero counts a lot... he he

@CreaseysWorkshop 6 жыл бұрын

Wild Weasel one zero too many actually. I noticed too after I had uploaded.

@johnspencer6270 2 жыл бұрын

Fella, you havn't a clue about what you are doing. I use one of these chucks all the time. Setting the work to run out with a TIR of 0.0001 - 0.0002" takes me less than a minute each time. You are trying to adjust the runout in the same way you would with a 4 jaw by alternately tightening an loosening the adjusting screws, it may work but it takes far longer than it needs to Put your dti against the front of the workpiece not on the top of it. Then loosen all three adjusting screws. Rotate the chuck to find the max TIR, now set the dti so the zero is halfway between max and min values of runout. Rotate the chuck so the adjusting screw with the lowest point of the workpiece runout is facing you. Tighten that screw until the dti reads zero. Repeat the operation. Next tighten the screw at the highest point of workpiece runout until just snug (gently nipped up. Repeat the zero setting of the dti and tighten the lowest runout screw etc. You may need to loosen the highest runout adjusting screw at some point in the exercise. Most workpieces take me less that 1 minute to set running true, often less than 30 secs.

@CreaseysWorkshop 2 жыл бұрын

Thanks I will try this.

@johnhall8455 10 ай бұрын

About time someone gave a decent explanation…no one seems to read (or actually have) the instructions… They are so easy to use once you get the hang of it… If you’ve bought a second hand one, it’s a good idea to strip it down for a clean, and to get a good idea of how it works before you start