| The Craftmans Shop > New from Old |
| The Sequel - Oh Blimey I bought a CNC Lathe (Beaver TC 20) |
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| djc:
--- Quote from: RussellT on April 30, 2021, 05:11:04 AM ---...a close fitting plug in the holes... --- End quote --- And the very closest fitting plug possible might be to drill the long 6mm hole first, as a first operation on the raw stock, and the larger holes afterwards. In the same vein, it might be possible to machine the perimeter of the stock so that the 6mm drill enters perpendicular to the surface, and then later on make the curve. |
| awemawson:
Yes that would be best, but it very significantly adds to the indexing / locating issue which is bad enough already. The stock is circular so your second idea can't unfortunately be applied. Holding this thing so that it can accurately be inverted is still defeating me - certain features on both side MUST align, but machining both sides removes any location aids. The central through hole gives me an accurate bore that I can pick up with my Heidehain probe, but the rotational positioning is a hard nut to crack. I may have to machine a flat on the side but I am trying to avoid that. There are through holes for bolting to the spindle which are an obvious feature to use but they don't exist until the second side is machined. I've decided that I'm going to leave both the male and female tapers unmachined, then set it up in the four jaw on the manual lathe and machine the female A2-6 recess. It then can be mounted on the target spindle on the CNC lathe and the A2-5 male taper machined. |
| djc:
--- Quote from: awemawson on May 01, 2021, 01:43:08 PM ---Holding this thing so that it can accurately be inverted is still defeating me - certain features on both side MUST align, but machining both sides removes any location aids. --- End quote --- There must surely be space somewhere on it for two 3mm dia. through holes which can go into a sub-plate for locating dowels when you invert it. Even without a sub plate, you can indicate it back in off the dowel pins and a straight edge. Plug the holes when finished. No space or do not want holes? Weld/glue/soft/silver solder two lugs to the outside of the stock and put the location holes in them. Remove lugs when finished on mill and before transfer to lathe. |
| awemawson:
I'll try and post up some 3D images tomorrow if I get a chance (grand daughter in tow at the moment !) |
| awemawson:
OK Here we go - I've removed the A2-6 (female) and A2-5 (male) tapers and replaced them by a parallel sided bore and boss respectively as I intend to machine the A2-6 female taper on the manual lathe when the CNC bit has been finished, then fix it on the target spindle nose of the CNC lathe to machine the A2-5 male nose taper. I think that CNC milling the A2-6 side has to be the first operation, as it provides the widest support when inverted to machine the A2-5 side. So I think the operations are probably: A/ Machine the A2-6 side B/ Machine a spoil board flat and level with suitable holes for location pins C/ Invert the adaptor A2-5 side uppermost on the location pins, clamp down D/ Accurately locate centre of adaptor with Heidenhain probe E/ CNC machine the A2-5 side F/ Set up in 4-jaw in manual lathe and machine A2-6 female taper to (already ground) test gauge F/ Mount on CNC lathe nose and machine A2-5 male boss testing to fit on actual collet chuck that all this fuss has been about (!) NB the EN24T stock that I am using is 170 mm - adaptor max diameter is 165 mm so not much wiggle room. |
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