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| Motorbike question... |
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| AdeV:
Thanks Eric - I think you're right; he did mention something about 1/4mm clearance or thereabouts... Excellent. I'll price up the lumps of metal tomorrow... he'll get stainless if it's not too dear. |
| AdeV:
Done! A bit later than anticipated, mostly due to work - there was I hoping for a quiet week, but oh no. Complete chaos... This is, of course, the second one... the first one suffered a massive tool crash (biggest one for me yet) which destroyed a tip, damaged the tip holder, damaged the QCTP holder (fortunately, the main QCTP survived), and bent a foot of 30mm steel bar such that the runout was approximately an inch. The cause? Easy; when going from a surfacing to a facing operation, I forgot to change the apron gears, so when I engaged the drive, the carriage pushed into the work instead of across it... Seeing my error immediately, I went to disengage but accidentally pushed the lever too far, into screwcutting mode... well, at 400rpm, it didn't take more than a second for all the damage to be done. By the time I hit the e-stop, the lathe had already stalled. Fortunately, all the damage was easily remedied, except to the work piece. I did try to carry on (after straightening the bar as best I could), but the central hole ended up off-line, hence having to make the second one. Anyway, the 2nd one looks better IMHO, and is definitely holding a tighter tolerance to dimensions, and it only took around 1/4 of the time to make... Next time, I'll make a practice piece in ali first... I'd also like to hat-tip Bogs at this point - your suggestion of using a home-made drill extension to turn a 4" blacksmiths drill into a 8"+ deep-diving beastie was an excellent one. It worked a treat, once I'd ground the back end of the drill down a bit. |
| Brass_Machine:
Very good Ade! That's a nice looking piece. The owner owes you a drink! Pictures of what it is used for would be nice from him as well... Cause I am curious :smart: Eric |
| Jonny:
Must have a larger lathe decent finish as well. Bet that took some drilling. Since he didnt specify a material that must weigh a lot :lol: Still want to know what its for. |
| AdeV:
Thanks chaps :) As I understand it, it works like this: There are 3 bearings on this piece; one (a roller bearing) sits in the cut-down section, it has a spacer next to it, and is trapped in place by the frame. The OD of the bearing & spacer bring the whole piece to a 28mm bar. On this bar, 2 caged bearings ride, the swing arm then rides on these bearings, and the whole lot is bolted in between the frame with one mahoosive 17mm bolt. I think the idea is the swing arm rotates around the bar (which stays stationary) as the suspension does its thing. I'm not quite sure what the small bearing does, or why its there. Once assembled, it is apparently right down in the black depths between engine & wheel & gears and brake lines & such like, so it not that easy to see. However, I'll ask him to take some pics of it as it's assembled, so we can all figure out how it works! Jonny, thanks - yes, my lathe is quite chunky, 6.5" centre height & approx 40" bed. It's also old & slow, so the only way I can get a finish like that is to sneak up on the final cuts at around 0.001", which is fairly tedious. I used an Aluminium-cutting insert (available from Chronos) instead of a regular carbide cutter to make the final cuts, I plan to buy a few more of them as they're really good on a range of materials, much better at finishing than Carbide alone. The cutting was followed with about 10 mins of work with some coarse valve grinding paste, then some 600 grit wet & dry paper (wetted with cutting oil rather than water), and finally some Meguiars "NXT generation All Metal Polysh" metal polish, to give it a bit of a shine. Material is regular EN1 mild steel. |
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