Making an Articulating Spider Chuck

[Big Al]

I know some of you guys like to read about the engineering aspects of my work so I thought this might be of interest.

 

The method I use for dialing in my barrels before chambering or muzzle crowning requires the ability to move the barrel at both ends of the headstock, this allows me to control both radial and axial alignment.

 

A simple rear spider mounted on the back of the lathe spindle is all you need to control that end of the barrel. At the front where the action happens its important to have a good grip on the workpiece but also be able to control radial alignment while also allowing the barrel to pivot so you can use the back spider to adjust axial alignment. If you just put the job in a 4 jaw and adjusted for radial concentricity the large contact area of the jaws wouldn't allow any movement needed to achieve axial alignment, as you crank on the rear spider it would only flex the barrel and would not move the front end at all beyond the jaws. In the past Ive used small cylindrical copper contact pads between the chuck jaws and the barrel to overcome this but it was never ideal with the biggest risk being slippage, it never happened but with very small contact areas it was always a risk and it could be improved upon.

 

Last week I had a bit of spare time so made myself a good front spider that I had been thinking about for a while but never had time to make. One with easy articulation but also a good contact pad area to stop the risk of the work slipping. I guess the pictures tell the story quite well.

 

M14x1.25 metric fine cap head socket screws give me the rigidity and control I needed. I tipped them with 8mm ball bearings and machined 8mm seats into my copper contact pads. I adjusted the length of the set screws so that while holding 34mm diameter barrel banks they were just under the surface of the chuck and they have enough adjustment to then hold 16mm diameter muzzles. At all times the set screws are within the diameter of the chuck so as to avoid any contact with my knuckles or anything else that gets too near!

 

An added benefit of articulated contact pads is that it allows me to hold tapers without having to machine a specific collet, very useful for muzzle threading as you can see. Its satisfying when you get around to making useful tooling and infinitely cheaper than buying stuff made by others.

 

Holding a barrel blank.

 

How I got the articulation.

 

Keeping the set screws below the surface at all times is a sensible safety precaution.

 

A more basic spider controls the rear.

 

A tapered muzzle held securely for threading.

 

The end result, I will use it for chambering later in the week.

[Davy]

I like the idea of the ball bearings in the end of the screws to align the pads however do you find the 1,25mm pitch to be fine enough?

[alpha1]

Nice job.I like the idea of recessing the screws.

[johnnyb0_1]

Very interesting, thanks for posting. JP.

[Big Al]

I like the idea of the ball bearings in the end of the screws to align the pads however do you find the 1,25mm pitch to be fine enough?

 

 

Yes, its plenty fine enough. Finer would do no harm but finding 14x1 socket head cap screws wasn't easy. My local supplier had 14x1.25 which is metric fine and since I already had a tap I felt it would do. In practise with a large handled chuck key you still have to move it a fair bit to adjust a few tenths. I had no trouble dialing in that muzzle today to nothing.

 

When you think that the pitch on your 4 jaw scrolls is coarser than this and we manage well enough with them most of the time.

[swagger]

Very smart Al!

 

Always pleasing when you come up with a solution and put it into practice.

 

ATB,

Joe

[onehole]

Love all this stuff,,,,nowhere near all this and in awe,,,,spending a lot of time on U Tube lately as I,m hopefully getting a decent Myford ML7 to be able to at least machine accurately,,,,,albeit in a smaller way!!! ....You guys make it all look so easy,,,,,,thanks for posting,,,,,,O

[Murph]

Looks like Colchester lathe you are using. I've an imperial bantam myself with a few modifications done to it. Nice tidy job you made of ir. it's hard to beat making your own tools to make life easier for yourself.

[bradders]

You've done it now Al, you're giving secrets away and everyone will copy you and steal your work and ideas!!!!!

[Big Al]

You've done it now Al, you're giving secrets away and everyone will copy you and steal your work and ideas!!!!!

 

 

Most of what I know was taught to me by many others Mark, Im secure enough to not worry about it and happy to share.

 

This spider is just a variation on a theme that suits my work and the materials I had available or that were easy to source.

[Big Al]

Looks like Colchester lathe you are using. I've an imperial bantam myself with a few modifications done to it. Nice tidy job you made of ir. it's hard to beat making your own tools to make life easier for yourself.

 

 

Im using a Warco GH1330 now Murph.

 

I started with a Harrison M300 that had seen better days but was available locally at a fair price. I then came across this Warco last summer in Manchester, it had been owned from new by a guy who had turned a bit of aluminium for his motorbike and other than that it had sat redundant for almost 20yrs. It was made in 1997 which means its a Taiwanese built machine, they were supposed to be built better than the current Chinese ones.

 

Either way I bought it as my second machine just for jobbing as it was reasonably priced, when I got it into the workshop and had a good look at it it was much better than the M300 with no wear at all. Once it was levelled and adjusted properly its as accurate a machine as Ive ever worked, that includes numerous Colchester/Harrisons so the tatty M300 was sold on.

 

To be honest I served my time on British built machines and anything foreign was poo poo'd as rubbish, now Colchester/Harrison get their machines made in Taiwan. I wish I could find another one like this but with 1000mm between enters, sadly they dont make them. It has its quirks but its an honest accurate machine, if my business continues to grow at the current rate I will most likely buy a new long bed M300 later this year but I would still keep the Warco for jobbing, its just too good to sell on.

[gunner]

Nice tooling indeed , roughly how long does it take to get a blank / bore dialled in ? Nothing like having all the right kit . Thanks for sharing .

[Big Al]

Nice tooling indeed , roughly how long does it take to get a blank / bore dialled in ? Nothing like having all the right kit . Thanks for sharing .

 

 

From picking a blank off the shelf I would say around 20 mins, I clock the throat and the muzzle. Its one of those things Ive never really timed and not something you ought to be doing in a hurry

[Murph]

Im using a Warco GH1330 now Murph.

 

I started with a Harrison M300 that had seen better days but was available locally at a fair price. I then came across this Warco last summer in Manchester, it had been owned from new by a guy who had turned a bit of aluminium for his motorbike and other than that it had sat redundant for almost 20yrs. It was made in 1997 which means its a Taiwanese built machine, they were supposed to be built better than the current Chinese ones.

 

Either way I bought it as my second machine just for jobbing as it was reasonably priced, when I got it into the workshop and had a good look at it it was much better than the M300 with no wear at all. Once it was levelled and adjusted properly its as accurate a machine as Ive ever worked, that includes numerous Colchester/Harrisons so the tatty M300 was sold on.

 

To be honest I served my time on British built machines and anything foreign was poo poo'd as rubbish, now Colchester/Harrison get their machines made in Taiwan. I wish I could find another one like this but with 1000mm between enters, sadly they dont make them. It has its quirks but its an honest accurate machine, if my business continues to grow at the current rate I will most likely buy a new long bed M300 later this year but I would still keep the Warco for jobbing, its just too good to sell on.

Funnily enough I'm going to look about an m300 long bed later on today. From all accounts it is a very clean machine with very light use - fingers crossed!

[Big Al]

Funnily enough I'm going to look about an m300 long bed later on today. From all accounts it is a very clean machine with very light use - fingers crossed!

 

 

Good luck with that, if you get a nice one they are the perfect rifle building machine.