Thread: What have you invented?

Nice Bob L.

A neat simple idea for that addresses the ever present problem of limited space.

How would you lock it in the required position? Maybe a locking mechanism could be conceived that avoids the requirement of a bearing and the associated machining of it's housing.

Bob T

Originally Posted by Anorak Bob

Nice Bob L.

A neat simple idea for that addresses the ever present problem of limited space.

How would you lock it in the required position? Maybe a locking mechanism could be conceived that avoids the requirement of a bearing and the associated machining of it's housing.

Bob T

Yeah I don't really need a ball bearing. It's not like it needs to spin or it will just tangle the power cords. maybe just a bronze washer and a grease nipple is all I need? It just needs to be able to rotate 120º one way and then the other.

What about turning up a steel collar that sits into the top of the pipe post and a short shaft that passes though a bronze washer and the collar and has a steel disc welded on top of that . A 1/2" bolt passing through the pipe and collar and into appropriate recesses on the shaft should hold it in place.



A pair of stops on the disc and the collar should stop it spinning more than 360º and tangling the cords?

I imagine that after a while your locking bolt will mutilate the shaft even if you mill flats into the shaft. Something along the lines of a cotter type clamp might work. What ever you use to lock the arms has to resist the forces of heavy grinding. You don't look like Willo the Wisp, Bob.

BT

Originally Posted by Anorak Bob

I imagine that after a while your locking bolt will mutilate the shaft even if you mill flats into the shaft. Something along the lines of a cotter type clamp might work. What ever you use to lock the arms has to resist the forces of heavy grinding. You don't look like Willo the Wisp, Bob.

BT

Most of the grinding I do is for wood work blade shaping so it's usually ziiittt, Zittttt, ZiiTTTTT, Zit (dip). But knowing how much vibration grinders put out I agree with you about mutilating the shaft.

By cotter type clamp do you mean the following. Start by making the shaft bigger and adding a slit in the top part of the collar and adding some tabs etc like this?

Bob,

I will take a photo of the bronze cotters in my dividing head, tomorrow morning for you.

Bob.

Originally Posted by BobL

Gents,


I reckon I can just squeeze in a ;
- Small Welding bay
- Drill press
- Metal cutting table saw
- MW Lathe

your gunna need a mill...even if you now think you wont......so make room

Bob.

A few photos of the cotters used to clamp the Hercus dividing head spindle. Your suggested method would be easier to build. Both methods achieve the same result.

Bob

Originally Posted by eskimo

your gunna need a mill...even if you now think you wont......so make room

Oh please don't say that!!!!

I do have reasonable access to a Bridgeport at work so I'm putting this off as long as I can.

Originally Posted by Anorak Bob

Bob.

A few photos of the cotters used to clamp the Hercus dividing head spindle. Your suggested method would be easier to build. Both methods achieve the same result.

Bob

Wow - I like it - that is a very elegant solution to clamping - and that is definitely going on my next chainsaw mill whether it needs it or not.

Hi Bob, (Anorak Bob that is... )

Thanks for posting those pictures, I think I can use that as the clamping mechanism for clamping the collar for the z-axis drive on the mill cnc conversion.

Regards
Ray

Bob and Ray,

If you do utilize the cotter type clamp and are in a position to do so, machine the cotters and bore simultaneously. I had to make the cotters independant of the dividing head casting using a boring head in the mill, a bit of awkward mucking around.

BT

Originally Posted by RayG

Hi Bob, (Anorak Bob that is... )

Thanks for posting those pictures, I think I can use that as the clamping mechanism for clamping the collar for the z-axis drive on the mill cnc conversion.

Regards
Ray

Ray,
You have the same set up in your quill.

Dave

Apologies for the long post, but it is difficult to describe the function of the machine without going into some detail about the end result. This is not really an invention, but a slightly more modern redesign of Thomas Blanchard's early 1820s gunstock lathe.


About ten years ago I realised I was going to need between eight and twelve rebuilt wood spoked wheels for my 1920s cars if I ever get around to finishing restoring all three of them, because the original spokes were too far gone for safe re-use. After pricing having the wheels rebuilt professionally, I thought no way - they can't be worth over $300 each. (I now know I was wrong)! I thought it would just be a matter of turning up a set of spokes on the wood lathe and assembling the wheels - wrong again.


Closer inspection showed the spokes were tapered and more or less oval in section, with the shape varying along the length of the shank. The shanks are curved or offset away from the vehicle, but the dowel on the outer spoke end must be parallel to the face of the spoke butt which is sandwiched between the two halves of the hub, though it is not on the centre line of the spoke blank. The butt ends of the spokes in a 12 spoke wheel have a taper of 30 degrees so they will fit together in the hub, and have an additional cross compound taper of 10 degrees so they can be assembled with the wide and narrow sides of the tapers alternating, then put in a press to lock them into place. Since the spoke are curved away from the vehicle this means that there are two types of spokes in each wheel, those curved away from the wide face of the butt, and those curved away from the narrow face.


To produce these some form of copy lathe was obviously needed. About this time Model Engineer ran a historical article on the early Blanchard lathes in the Science Museum in Britain, where the author deduced the feeds and speeds used by counting the teeth on the various gears. Using this information I built this spoke lathe, using mainly what was available from the scrap box. The two headstock spindles and the leadscrew turn at 17 RPM and the feed is about 45 mm/min, fairly close to the M E figures. The cutter is a modified laminate trimmer with round nosed router bit, and the pattern is a modified original spoke if a good enough one is available - otherwise a new pattern must be made. The same pattern can be used for both spoke types by varying the relation between the pattern and the workpiece. A second operation and a second pattern with a round section offset from the centreline by the amount of offset of the spoke from the hub is needed to get the dowel on the spoke end located in the centre of the outer end of the spoke.


The hardest part about re-creating this piece of mid 1800s technology having never seen one in the flesh was probably working out in advance what controls were needed to make it work. Now, thirty something wheels later, I don't think I ever want to see another wooden spoke again!


The photos show :
1. Front view of the lathe with the saddle positioned about the middle of the ways, which are down towards the bottom of the lathe. The two copy frames are pivoted on the saddle and connected by an adjustable pivoted link on top.
2. Assembled wheel mounted on metalworking lathe faceplate. The spokes have been faced and are about to be bored for the hub.
3. A complete wheel.


Frank.

Frank, beautiful work.
I would love to see some close up photo's of the machine, if it's not to much trouble.

Dave