Treasures from the shed pt II

[Michael G]

In a previous thread I mentioned a Volstro head and was asked by one or two members for photos. The first photo is of a boxed up one in very good condition. The second and third photos are the one I have, one step away from scrap I suspect as the castings are broken away in one place. Needless to say I got mine for a lot less than they normally go for. It is also an earlier version as it hasn't got some of the features mentioned in the mk 3 manual. In the fully loaded version there are a couple of toothed pulleys. These heads could even be set up to be driven from the machine so that if you had a large hole that you were chewing away at it could be power driven, saving hand cranking.

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What do they do and how do they work? The head attaches to the mill head and spindle and through the two cranks can rotate around the spindle as well as offset the spindle. Below are 2 PDF's that show a cut away of the head, and a page from a brochure demonstrating the sort of things that it does. Like a lot of the treasures I have in my shed that are gotten on a whim the capabilities are way cool even if I haven't found a must have use yet. The photos below show the splined shaft that transmits power regardless of offset and there is just a hint of worm for the rotational aspect.
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This last PDF is the killer though. I whipped this up on AutoCAD this morning. As I said in a previous post, these things only seemed to have been made in an R8 version. I have to convert my volstro to a 40 taper. As can be seen in the sketch, a 40 taper (red) will fit but I will need to make an adaptor from the R8 (magenta). It also needs to be mounted on something solid, so I need to machine the mill head casting (blue line) so that I have a reference surface to clamp to (existing volstro casting = black line). The mill has a machined surface I could clamp to but it is 1.6mm in diameter smaller than the volstro collar, so it is sadly just that little bit small. I'm not sure how I'm going to do that yet - the head is around 50kg+ (the mill even has a small jib on it to assist removing it). I keep thinking of a boring head mounted in the horizontal spindle while clamping the removed head to the table but as always, the logistics could be "interesting".
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Michael

NB. There was a question as to whether the collets could be replaced with ER ones. Sort of. The spindle thread for the nut is 1 1/4" by 12tpi, so I'd have to make up a nut as ER is metric.

[Stustoys]

Hi Michael,
Well I didn't know I needed one of those until this morning :)
And now I know what that funny little step on the Bridgeport head is for. I don't recall having seen anything else use it.

I'm not sure I fully understand what's going no but here goes anyway.
The parts of the casting that are broken are the ears that hold the bolts that clamp the head to the mill quill?
The way I see your CAD drawing, the quill should be lowered about 40mm before the head is clamped to it. Then you wont have room for your adaptor. From a quick look at the parts PDF making a new input shaft with a 40 taper doesn't look undoable. Failing that the R8 will go all the way into the 40 taper. You could then make a sleeve around 30mm high with the 40 taper outside and the R8 taper inside. You'd just need a way to remove it from the taper end.

Or am I up the wrong tree? either way nice score.


Stuart

*though I can't find a picture of your mill so maybe this doesnt apply.

[Anorak Bob]

Volstro Rotary Milling Head - Home Model Engine Machinist (http://www.homemodelenginemachinist.com/f13/volstro-rotary-milling-head-16436/)

I'm starting to get an understanding of how the Volstro works but I can't see the thing being able to run on auto pilot. Some dexterity at the controls would be required.

The collet nut might be tricky if you planned to use ER collets Michael. The trickiness would be the incorporation of the eccentric retention/ejection ring. I have a Schaublin nut for their ESX collets ( ER equivalent). It has a separate clip in ejector. I'll get out the camera.

BT

[Michael G]

The manuals have full details of how to attach the head to the mill. Without re-reading it, from memory the quill is lowered onto the R8 fitting, secured and then the circular part of the body is clamped onto the mill (it is the clamping ears that look to have been broken off by the way). The detritus that came with mine included a large two piece split ring that looks as if it were made up to provide some clamping force.
The one thing that I would change on my mill is the quill, as it doesn't have one. As a result any adaptor that I make up will probably need to have some telescopic or sliding feature to it so that I can securely locate the drive spindle before attaching to the machine. John Stevenson showed a way of making up splined shaft sockets using a broach (Quick way for cutting splines (http://bbs.homeshopmachinist.net/threads/48878-Quick-way-for-cutting-splines?)) so that might be the next plan to be considered. The previous mill had a loose fitting end face key and slot that drove the vertical head (another horizontal machine) so I am anxious to avoid that sort of wear/ noise/ slop.
I had to go looking, but my mill is here - #93 (http://www.woodworkforums.com/f65/show-us-your-mill-121568/index7.html#post1425224) Solid, but lacking quill. The second photo shows the vertical head well enough.


Michael