Recently acquired a Harrison Milling Machine which was otherwise destined for the scrapheap, but is in fact in almost as new condition but for surface rust and a missing Lo-Vo light.

I got a great deal, but (unsuprisingly enough) no vertical head, and my understanding is that the Harrison vertical heads are now rare as hens teeth and command a price which is an order of magnitude more than what I paid for the machine.

So I'm going to have to make one, however before sitting down with the CIMT Machine Tool Design Handbook and reinventing the wheel vertical head attachment, I figured it would be worth looking for any published designs i could intellectually cannibalise adapt.

I have built machine spindles (last one was a 30,000 rpm ER11 spindle for a Taylor-Hobson pantograph) and gearboxes in the past, so not scared of taking on a complex and technically demanding project, but the less mechanical design and prototyping I have to do the better.

I have a detailed sectional drawing of a Huron/Elgamill style all-angle head (see below for the uninitiated), which I aesthetically and functionally think is awesome, but probably won't replicate because the complexity (and specifically cost/time involved in obtaining/producing the non-standard bevel gears) would be wasted on a non-ram type machine.

My ideal design would have a body consisting of 1 or 2 weldments made from plate and standard dimensions of tube or bored bar, ideally with a wall thickness of no more than 15mm, (I can access welding equipment which will cope with sections upto about 40mm, but it would mean getting an appropriate bottle of gas, spool of wire, liners and tips to set the machine up for really heavy welding).

Horizontal, though with the higher speed range (63-1500RPM)

I agree that the Harrison's 1:1 ratio and 22-1000 or 63-1500 speed range isn't particularly well suited to vertical milling with modern cutters, when a 10mm carbide endmill will happily run at 4000 rpm in EN1/EN3 and 2000rpm in 709M40T, which is a big part of why building rather than buying makes sense…

"Why pay over the odds for an attachment which would ultimately be unsuitable for a good proportion of my existing tooling anyway?"

The assembly you're showing for the spindle of your vertical head mirrors the way I planned to assemble the spindle if I make one myself.

However as with my comments to Clive there's a consideration as to how hard translating horizontal to vertical rotation would be and how that compares to the inconvenience of storing/lifting a much heavier assembly with a motor mounted on it; the approach you've taken is definitely simpler to execute from a manufacturing perspective than having mitre gears and a power-take off from the main spindle.

It's a shame that's a 40 taper, as it would otherwise be a good starting point.

Why do you suggest the carving from CI approach?

From an efficiency standpoint it would mean buying nearly £300 of material to then spend a lot of time and electricity machining the bulk of it away again.

I can conceptually see the benefit of CI over steel for damping (and to a lesser extent rigidity) but given its not easily (sanely even) welded, it results in a lot of waste for making a complex and hollow shape.

I would definitely be stress relieving any weldments:

The initial post-welding cycle could be done by heating to an even light yellow oxide colouration (or using a few marks with a 200C Tempilstik Crayon) with the oxy-propane rosebud then wrapping the whole thing in a welding blanket till it's cool; I could probably do this by baking the parts at Gas Mark 8 for a few hours also

After rough machining I'd want a full stress reliving cycle of something like 6hrs ramp to 600C, min 1 hr soak, 4 hours ramp to 200C, still air cool; the "how" element depends on the size of the final assemblies really:

• If the parts end up less than 200 x 250 x 450 mm I can do this "in house" (actually at a friend's workshop, with the PLC controlled heat treatment oven I built for his knife making workshop).
• If the parts end up bigger than that, or I have very slim machining allowances on any of the parts due to initial stock sizes, then I can send them out for controlled atmosphere normalising, (one of the benefits of living in Sheffield is the ready supply of every conceivable type of subcontract manufacturing service still).

That's another option, although at that point the price (at least from a search today) is such that it would probably be as well buying a second hand Bridgeport Head, and fabricating a mount for it which fits onto the overarm dovetails.

Both approaches also result in using a lot more storage space (something which is at a bit of a premium for me), and being even heavier/more ungainly to lift into position (I have been rather more cautious about lifting after I gave myself Sciatica in my mid 20's by thinking I was some kind of superman, thankfully it was fully cured by a course of muscle relaxants and physiotherapy on that occasion, but if I was to allow a "next time" I may not be so lucky).

I was struggling to picture how the riser block would allow me to use it in horizontal mode, but a quick search revealed this:

(Future readers with the same problem I have, click the image to link to the original build thread for that design).

Which makes everything make sense, seen as it's clearly intended to function as the overarm as well as raising the vertical head up… Very nifty indeed!