hi guys, have had this idea floating around in my head for a while now but finally got it down on paper and thought id post it up here for criticism/improvements
like many hobby machinists I dream of having a mill to go with my lathe, but finding a good one locally one seems to be like unicorn hunting, so like many before me my thoughts have turned to milling attachments for my lathe.
after pondering over various milling attachments I came across an old articlee on converting the compound slide into the basis of averticall slide. http://www.vintageprojects.com/machine-shop/lathe-millingattachment-plans.pdf
this seemed to be fairly simple to fabricate so I started trying to scrounge up some parts.
some more thinking and procrastinating I realised that iv only got an old worn 4 jaw chuck, so would also have to sort out a collet chuck to hold the milling cutters with . . .another job to the list. .
some more thinking and wishing I had an actual mill I started looking at diy milling machines (definatly out of my current capabilities) that got me looking at diy spindles and I came across a nice looking DC brushless spindle on a cnc site http://www.mycncuk.com/threads/3793-Diy-brushless-spindle
this really got me thinking . . hmm would be nice to have an independent milling spindle on that lathe, maby a tool post grinder, or a bit of profiling of things held in the chuck?? . . a third job to the list.. .
so I started looking at diy tool post grinder/spindles and doodling up ideas to mount the spindle on the yet to be built vertical slide.
everything I saw and came up with had lots of overhang and to me looked prone to twisting at inopportune moments.
then I asked myself a few questions
1. why am I trying to bodge up my compound to make a vertical slide, that will have loads of overhang and not be particularly ridged
2. why am I trying to bodge a nice diy spindle onto the side of a not very ridged vertical slide, creating even more overhang.
3. what do I actually want to accomplish with having this milling slide/spindle contraption?
so back to basics I went, and came up with a list of what I needed/wanted to do
1. mill key ways on shafts
2. profile edges of items
3. drill holes off center
4. drill radial holes in items
5. mill flats onto items
6. anything else I come up with along the way
now ideally id do all those things + more with a nice mill and a rotary table but thatís not happening soon, so what can I do with the lathe??
well the lathe has a built in rotary table, it called the headstock ;) and with a bit of tinkering I could even have it indexed
a tool post mounted spindle could then be my milling head, though id only have a x and a z axis no y
but its a start
so lots more thinking ensued, how to solidly mount a spindle to the tool-post?? bolting onto the tool post looses rigidity, replacing the tool-post with a custom mount for the spindle would be better but how do I clamp it to the compounds t-slot and the compound isnít as solid as id like to begin with. do I actually need the compound to use as a z axis?? etc etc
finally I figured the most solid solution would be to remove the compound and to mount the spindle directly to the circular dovetail cast into the saddle, the z axis would be the saddle feed, but that should be good enough for me.
so a mounting block was designed, to bolt directly to the saddle and with a hole bored through at center height for the spindle, looking good now
but then the missing y axis kept giving me doubts about how useful this would actually be, and whether I could improve upon this design. . but how to create a solid vertical slide type affair for the round spindle?? and what to do about dovetails?
then it dawned on me . . . why does the spindle body have to be round?? why not square? thatís easier to bolt to things! and while im at it, why do I need dovetails? surely a square bodied spindle running in a channel would be just as solid for this contraption!
and so with a lot of hours sketching up things on the computer, creating cad drawings, modifying things to suit, re-checking sizes etc. I came up with this!
frame made from welded flat stock o a tuned base, brushless spindle to be fitted into the sqaure block and a bit of M16 studding for the screw. et voila! simple solid toolpost spindle with height adjustmet