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Four Jaw Self Centring Chuck

by hexitex, published

Four Jaw Self Centring Chuck by hexitex Jan 25, 2011

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The design is based on the Longworth Chuck, it's a great movement and normally used for Woodturning. The chuck's original designer sadly died after showing the design at a club meeting. The late Mr. Longworth of the Hunter Valley Woodturning Club, New South Wales, Australia should be given full credit in this chucks movement.

I added my take on the design by giving it more mass, taken away the need for wingnuts (making it safer) and generally done as much as possible to make it useful - The nice thing about this design is that it could be made in any material with very little changes to the file. It's a good size chuck maxing out at the makerbot's 10cm build surface wide and 7cm tall.

You can design new Jaws to suit your requirement! It is a great tool to have either fitted to a lathe, drill, dremel or just being used to hold items on your bench.

Had an educational time modelling in Carrara and Hexagon which I used to create this thing. I've been using it for a longtime doing fun stuff and mixing it with photography but never tried anything precise.

You are going to need 8 M4-40 cap screws, 8 locking nuts, 1 M7-40(min) hex bolt and nut.

Video of the chuck in action http://youtu.be/94ZhwGUWB5I


The diagram should provide the best explanation for building it. Everything has been designed so that detail and structure is built face up with little overhang.

Use the capscrews on the jaws to lock and loosen the chuck, rotating the grips will move the jaws in and out. It is important to tighten all four jaws!

Safety with anything that can blind you should be taken seriously!

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Such a good idea! I have several Longworth chucks and tightening the wing nuts is always a hassle. This is a major improvement! Great work!

does anyone have scaling to use only m3 bolts?

How do I scale this to fit on a #2 morse taper 8 tpi wood lathe?

Made it, perfect for my mug plotter. Well done and thanks for the inspiration.


This is exactly what I was looking for.

I surely make one of this, in Nylon for durability. Ty

Yeah soapy.. I noticed that too. Great chuck though! I've printed two (good ones) so far along with a bunch of Emmet's gear bearings (4 good ones after messing up the first three where I had the tolerance to tight). New to this and these were great prints to really learn something on (Oh and generate a bunch of scrap in the process also!). Once I discovered Cura for slicing and ABS slurry it's been smooth sailing. ABS on Makerfarm I3 tucked away in a small heated (by the machine) cubby, Magma hot end at 210C and bed at 70C. The cubby probably stays around 100* F, with no drafts and a posterboard door I occasionally look in. Post print brushing with acetone. The guide required a little sanding where it mates with the base and trying all 4 positions yielded one direction that fit best. I marked both pieces with a line to line up. Works great!

Can you link to the gear bearings you used?

Brilliant design, but 23 comments and not one person has pointed out that a 40mm long bolt won't work through the jaws? It falls about 10mm short. The other 4 bolts work fine, to the mm.
Also, the 7mm hole for a bolt is a weird choice. Go with 6mm, which people might actually have, and also allows anyone using a 6.25mm (1/4") shaft to use it without a load of messing - it's harder to add the material after than just drill it out a bit.
I plan to do a 3 jaw version if I can get my CAD package to behave.

Does anyone else have issues slicing the jaws? The file looks sane in notepad, but slicer returns an empty print and meshlab gives me a "premature end of file" warning.

Maybe a download error, download to a new name. Also you could try the obj file everything is in there. thanks

This is great! Very impressive and inspiring!

I printed it at 50% of the original size and it fit together really well. I had to widen the slots with a dril to use no.4 machine screws. I didn't use the skids and have not printed the jaws as this was more a proof of concept print before printing it little larger. :)

Nice one, thanks for printing it :) - I did actually print it full size and got very nice quality at 50mm/sec but have not got round to uploading pictures and video of it in action, i'll do that in the next day or two -it's a massive bit of kit and everybody was amazed that i could print something like it. Redesigning it for rear jaw locking and have a new set of tapered jaws with reverse grips for for v2 (although v1 jaws work well). The cam slots needs reversing in direction as well as I get confused closing and opening and it isn't the right direction for a lathe in forwards running (it should if anything tighten with pressure)

oh and skids are not worth it anyway, works just fine without them.

And I thought I was the first. I was going to change it to have the locks on the back as well. And was wondering why you made it a four jaw chuck and not a three? Will you be uploading the new version soon? My lathe is flying a long nicely now.

4 jaws are better than 3, three is cost saving. four will hold a odd shaped thing better, 4 will hold flat/straight things better, 4 will hold a bowl better (although 8 is better still for inside holding);)

And reversing the slots is as easy as mirroring the entire OBJ file on its Y axis.

really like the progress on your lathe - would raising the lead screw make it stuffer ^ here is the vid of my print http://youtu.be/94ZhwGUWB5Iyoutu.be/94ZhwGUWB5I

POC== ?

I don't see any arrogant comment here? You deleted some or?

Awesome chuck design!

Would love to see a printable lathe at some point...

In terms of how items come out of the printer, there's two things that influence it strongly; first is shrinkage. ABS shrinks a few percent when it cools - so I generally design my pieces with a 3-5% tolerance. In addition, you can get "squis
hing" when printing - basically, every piece you print out is at least slightly liquid on the top layer as its printed - this forces the perimeters (inside and outside) out slightly. The effect is difficult to predict, as it depends on how big the object is - smaller objects take less time to print
per layer, so the layer is more "squidgy" while it's being printed. It also depends on ambient temperature, your bot's characteristics, and if you're using active cooling.

The best way to handle squish is to print and mount a small fan to blow on the top layer of the object. Bonus points for cre
ating a laminar flow that doesn't blow across the nozzle or the hbp...

Cheers. check down the replies and you'll see Sublime already has a lathe in progress. Great information on the printing process, thanks. 3 -5% is a bit worrying is PLA better?

Hello hecitex,

I am wondering if you have blue prints for the longworth version of the chuck you designed . I would love to machine it on my new table top 5 axis cnc machine. I will be happy to send you one if I can make it.

Best regards,

Jade Elisar. :)

Not sure what you mean about blueprints, the OBJ file has everything you need if you want to break it up. But please let me know if i can help out. Best to wait for my V2 revision as it has better locking and jaws

How cool would this be for eggbot like structures too? Wonder if it can handle the reverse rotations and stops without loosening?

Yeah it should be very firm for cnc provided the cap screws are tightened up when youve lock the item. But for light use you could just use a couple of grub screws in the rim.

This is great! I'm in the middle of designing a printable lathe, and was mulling over chuck designs. Perhaps I'll give this an attempt on my mendel and see how it turns out!

Thanks, would love to see it made and working and obviously any improvements ;)

I am still in the debugging stage of my printer so printing something of that scale is still aways in the future. Hopefully with your chuck it will be complete.

Before you spend to much time designing an entire lathe you may want to look at this. http://www.thingiverse.com/thing:4322http://www.thingiverse.com/thi...

Great work on the chuck, I was looking at a wooden version online a few weeks ago that someone had made.

Sublime, seen your lathe and its looking very good, have you tested any of it yet? The gearbox looks great.