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| Set-Over Centre |
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| DaveH:
Wong, Well it is looking good :clap: :clap: :clap: And no blood makes it doubly good :thumbup: :thumbup: :thumbup: Well done, by the way that hole, that is what I would have called precision drilling :) :) :) :beer: DaveH |
| wongster:
Hi Dave, The precision part was definitely not my doing... It was the drill held in the collet (ER16) :) I was surprised as how easy the silver steel can be drilled through; no chatter, just felt as if it slided in and out... The steel used for the Base and Slide weren't the case. Regards Wong |
| wongster:
The machining of the "softer" end of the 2MT Arbor was completed. The job was to turn down a 5/16" section and put on the 5/16" BSF thread to thread the Base on. The softer end of the supplied arbor seemed rather tough to work on with my little experience. The 2MT arbor was fitted on a 2MT to 3MT adapter sleeve for the spindle bore. The "soft" end measured 1" in diameter. The first job is to turn this down to 3/4". First is to reduce the 1" diameter to 3/4". Surface finish was rather bad. Next is to reduce a section down to 5/16" leaving 3/16" length of the stock at 3/4". In order to know which I should stop turning, I tried cutting a groove but parting this material turned out to be rather unpleasant. The AR Warner's part-off tool just jammed mid way through the cut. But what was done provided sufficent visual of the stop point. The section was turned down as planned but short by about 3mm in diameter. Can't proceed as the live centre body was blocking the tool from furhter advancement. I don't really have a good feeling of what I'm doing on the arbor. There was slight wobbling when the lathe was powered on. And so the Centre Turning Accessory was brought out and put in service. Too much pressure on the tailstock causing excessive heat. The grease was boiling, darkening the end of the section I was working on. The workpiece was taken out to clean off the burnt grease and reapply fresh dose. This time, I went easy on the tailstock when applying pressure. After turning down to the required diameter, I tried parting off the excess with the sleeve back in the spindle bore. It didn't work. I can feel the job flexing away from the parting blade. The spindle guard was removed and the hacksaw drafted into service. Thank God I've only about 7.9mm diameter to saw through. Facing done and sharp edges deburred with a file. The shoulder was also faced making it nice and flat. Sherline's grooving tool in use. I find it rather expensive but it has proven itself to be a very useful tool. The groove created is the undercut for the threads. The live centre was only pressing against the stock lightly to keep the job in place. Threading the 5/16" BSF was next. The 3 M6 cap screws were used as grip while turning the die holder's handle. Hope they wouldn't damage the threaded holes for mounting chucks and other accessories. Threading completed. I had to cut away the half formed thread near the shoulder to allow the Base to go all the way in. The whole works on the arbor. Next is to find a way to get the 2MT arbor out of the 3MT sleeve. The threaded end of the 2MT arbor is just a tad lower than the slot for easy knocking out with a wedge tool (I don't have one anyway...). The 5mm Allen key and a small hammer did the job of breaking it free. Though still short of the 2 adjustments screws, a group photo of its members so far won't hurt. The Set-Over Centre on its rightful place. The 2 x 5/16" have yet to be trimmed flushed. I'm getting excited as I'm coming to an end of this project. Wanted to buy the 2 x 2BA screws but the shop I always frequent only have them in brass. Maybe that will work. Should have buy them to test than merely walking away disappointed. I've yet to test if the centre lies up with the centre line of the lathe. Feeling exhausted from the long boring showflat duty I was scheduled this afternoon, I decided to stop work, wash up, and do some reading before bed. Got to get up early for Resurrection Day service tomorrow morning. |
| andyf:
Nearly there, Wong! In my experience, the soft end of some of those blank ended arbors gets a bit hard at the back end, where it joins the tapered section. You could probably avoid the 2BA screw hunt. I think you have already drilled the holes 4mm and tapped them 2BA, with a thread pitch is 0.81mm. An M5 screw has a pitch of 0.80mm, and the tap drill is 4.2mm. You could run a 4.2mm drill down the holes and follow it up with an M5 tap. The tiny difference in thread pitch would disappear in the process. M5 screws will be easier to find. Andy. |
| wongster:
Andy, I will make the 2BA screws to complete the project. If I screwed up making the screws, I'll use the M5 cap screws. Thanks for sharing. Regards, Wong |
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