44" Landing Legs

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Recently completed for one of the members here. I deviated slightly in that the main legs are polished stainless steel tube rather aluminium and devised a more secure way internally of locking the hardened ankle pin in place but externally they look the same. There's a set of feet to follow.

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A slightly closer look:



I made up two right and two left because psychologically it seemed the right thing to do but in reality it doesn't make any difference unless you quibble over which side the bolt hex head or the nuts should be. I'm obviously pleased and happy that you're pleased H.

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Originally Posted by cricket

How long do they measure in real life?

They're about 5 1/2" long as shown there.

OK, granted you need a lathe but work slowly and carefully and they're easily within the capabilities of a lot of people here. Apart from the main leg outer body and main shaft, most of the rest could be made by hand with a junior hacksaw and a set of files.

[Howard]

Oh my - fantastic!

[Pete Schmitz]

What kind of ball park would legs like that cost?

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As pictured there, basically £100 each including materials. There's a shed load of work in each one. For each one, there are 21 separate operation on just the main sleeve and lower ring alone and 17 on the leg shaft. Most require the piece to be rechucked each time. Then there's the plates, torque links, ankle pins etc.

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Originally Posted by ostrein

I really would like to see your workbench and your tools.

The work for the legs is done on this. It's a Myford Super 7 long bed with induction hardened bedways. It's also specially calibrated in metric although most Myfords are imperial. Even though Eagle components are usually measured in inches, I still love this machine over my previous older (and more tired) imperial Super 7. Although I bought it second hand, it's hardly been used. I don't regret buying it for a minute.

However, if I was honest, 99% of the time, it doesn't look as clean as this.

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It's so much easier to do accurate work with a machine in good nick than on a knackered one. There are some very good lathes coming in from the far east now that are more than reasonably priced too.

For example, there's a vertical milling machine exactly the same as mine, made in the same factory but with a different badge, that you can now buy for less brand new than my second hand one with the expensive badge cost me ten years ago.

[w8cmp]

What gets me is how you manage to make several parts with complicated surfaces, all exactly the same...and all by hand.

Do you use any sort of template or something...for example with engine bells ?

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I made a radius cutting tool in the case of the engine bells. It allows the cutting tip of the tool to swivel around a predetermined point. It's basically a slotted plate with a bronze bush that you can bolt to the cross slide and then bolt the toolpost at the right distance from the pivot. I added a lever to mine so I'm swinging the tool by hand around the pivot rather than by screw thread as it allows you to feel the cut. If you draw the bell profile on graph paper, you can work out where the centre radius point of the final curve you want is. There are two on an Eagle main engine bell, one for the front section and one for the rear. People always think you can only generate straight lines with a lathe but there are many ways to make curves. The advantage with a radius cutting tool is that you get a smooth surface straight from the tool where CNC machines tend to cut a series of steps.

For very small parts, you can grind up a form tool that has a tip that matches the profile shape you want but if the cutting edge is too broad you risk chatter in the work. Attitude thrusters can often be done with a form tool but you need to be light with the cutting. I think this is what w8cmp is alluding to.

Grooves can be accurately spaced by noting the numbers on the graduation wheels that move the slides.

It's also worth investing in a genuine precision chuck rather than a standard. They're more expensive but they'll hold things far more accurately to within specified limits. One thou run out or under is excellent for a self centring chuck. For real precision, collets are unbeatable but they only come in smaller sizes as they usually fit inside the head stock.

You can even turn some metals with hand held tools like a wood turner but obviously you need to take a lot of care. These guys who do ornamental decorative turning in brass often use nothing but hand held tools.

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A quick sketch of the radius cutting tool to make it clearer:



The tool post and plate pivot around the bronze bush to the rear of the cross slide.

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I've got many books on the subject all saying basically the same things. Most are actually quite old books just updated (a bit) and re-published but the one I find the most interesting and useful is this one. It's not Myford specific (which is good) but many of the illustrations and photos are obviously set up on a Myford:

The Amateurs Lathe by Sparey Lawre

[Big Rab]

This is my first venturing in to a lathe,

http://public.fotki.com/44eagle/ive-got-a-lathe---/

Since that (a few weeks ago) i have used it to turn down, then tap axles for the same project, along with other things as well.

It is only a small lathe i have for now, but I love using it.