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| Edgwick spindle taper adapter |
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| AdeV:
Wow, this is proving to be a nightmare... Dunno about "fun" Ralph, guess I need a lot more practice on the lathe yet... ...having cut, filed, re-cut, re-filed the taper umpteen times, and still getting absolutely nowhere near even close to a fit, I've decided to try plan "B"... The major hassle is taking the chuck off each time to check the fit. It takes lots of time, and is ultimately disappointing... so plan "B" is to make a copy of the Edgwick spindle taper in aluminium (and I can use the original sleeve to check the fit, fettling it until it's just right. Once I'm happy with the inner taper, I can re-chuck the steel, and use the aluminium piece to check whether i'm on target with the taper or not. When THAT's done, I can finally remove the chuck & stand a fair chance of having the new taper actually fit... What a palaver. |
| sbwhart:
Hi Ade There may be something not quite lined up or lose in the set up, Bearing nackered compound not following a true line etc, this could be why your having problems hitting the mark, have you thought aqbout trying another method are usualy turn morse tapers between centeres by off setting the tail stop. The set up is similar to this, it takes some of the oportunity for error out of the set up. Hope this helps Stew |
| Dean W:
How are you coming along, Ade? Dean |
| AdeV:
I've not had much time in the shed of late, the taper in the aluminium is partially cut, but other than that I'm no further forward... Hope to progress on the sump this weekend, but I'm going to put the spindle off until after I'm finished with that one. |
| AdeV:
Right. As the glue is still curing on the sump, I figured I'd work on something else tonight. And what better than this damn spindle sleeve, which is what drove me nuts a couple of months ago... It was all still sitting there in the lathe, so I figured what the heck, let's crack on. As per my last couple of posts, I've been making a "female" version of the spindle taper; the idea is, I can trial-fit the original spindle sleeve until it fits; then when I cut the steel piece, I can use the aluminium version to check the fit of that. However, having had a few months off, and having had no luck getting the taper to fit right, I decided to go back to step 1. That's where today's little adventure starts... The first job was to re-measure that taper. I had a bit of a brainwave :smart: (at least, -I- think it's a brainwave). Wheras before I'd used calipers & measured in 2 places, this time I used the mill. Should be much more accurate. Here's the setup: The original taper is clamped lightly to the mill bed. The dial indicator is setup to deflect as it bumps into the side of the taper. I used the "Y" axis to get it bang on the centre line (i.e. the point where deflection was at its maximum - see 2nd pic above). Having established this, I then backed away, and came back in, zeroing the dial. Once the dial read zero, reset the X-axis DRO to zero, and back away in the X axis. Now raise the table by 1" (effectively lowering the DTI by 1"); and finally move the X axis back in to the taper. When zero is indicated, the taper-per-inch can be read directly off the DRO. It was 0.025": Just for good measure, I repeated at 2" and 2.4" (that being almost the entire taper length), getting readings of 0.0495" and 0.0585" respectively. Next, a bit of triggery-pokery (you know, I've not used this much maths since I was in school....), gave me an angle of approximately 1.4o Just before I go any further, I'd like to point out something that you, dear reader, as well as I both missed: Back in my very first post, I measured the taper-per-foot at 0.605". In fact, as you've probably guessed by the description above, I actually measured the taper-per-inch (reading 50.4thou - not bad for hand-held calipers). What I failed to do was divide the result by two! :doh: The actual Taper is 0.300"/ft - my machinery's handbook is not handy right now, so I don't know if that's a standard taper or not. Anyway, back at t'lathe, I reset the cross-slide to 1.4o as near as I could eyeball it, and re-cut the taper at the new angle. Then, the moment of truth: I blued up the original spindle adapter, and gently whacked it into the aluminium piece: And there it is! It fits! It doesn't wobble about like a wobbly thing! It was actually quite an effort to get it back out again, it stuck that well, and here's where the blue has gone: Now..... I realise the surface finish in there is a little sub-optimal (let's face it, it's sh*t) - that's because the boring bar chattered like mad. I'm not desperately worried, because the 3 lines of blue show it's basically the correct angle. All I'm interested in is that it grips top & bottom of the taper; I don't care about the middle (well, not much anyway). I've not taken it off the lathe yet, though; can anyone give me any hints on how to reduce chatter in the boring bar? If so, I will have a couple more goes at getting a better finish. I was cutting at 430rpm, using an HSS tool, which seems quite chunky; but it vibrated like mad. It sang even more at 630rpm (the maximum my lathe will do), and about the same at 290. I didn't fancy going lower because I'm sure slower != better in this case. DOC varied, that last cut is about 0.005". But it chattered like mad at any DOC from 0.030" (the deepest I dared take) down to 0.001". I'll probably be back on the sump tomorrow, but I'm MUCH happier now I know what I did wrong before. And especially now that the taper fits properly. :headbang: |
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