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Boxford back from the dead

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seadog:
Don't believe the prices. I needed a nut for my taper turning attachment. It was shown as £14.44although I see they have updated it to £32. Well, it cost me £41, plus VAT, plus £10 admin, plus P&P. (2018 prices)

AdeV:
Thanks Allen - I wasn't specifically after a restoration project, but I seem to have got one anyway  :doh:  Maybe next time I'll spend a few extra pennies and get a working one!

Anyhow... moving on! As expected, on Saturday I was visited by a plague of locusts visitors, which is not to say they weren't welcome, just distracting... but despite this, I managed to get a bit further with the disassembly. The countershaft is proving to be a bear: I can't shift the pulleys on the shaft, despite the lack of a locking screw, or possibly the locking screw is broken, I'm not sure. And I can't get the bearing out because I can't make the setup work on my press. I'll need to make a jig to hold it such that I can push the shaft off the bearing (and thus out of the countershaft bracket); then I can look to pushing the shaft off the pulleys. That'll have to wait until next week, as I absolutely can't do that without the press.

Today (Sunday) I prepared a 200 litre barrel of citric acid (!), I used about 2/3rds of one bag of acid granules, but I've no idea how strong it really is. It tasted kind of lemony fresh  :lol: and very sharp, so I think I've got it right. Various parts are in there soaking now. I'm pretty sure I can leave them in there all week without doing the metal any harm. Citric acid really isn't that strong after all... is it? Anyone with experience, please speak now if I need to head down there tomorrow night to rescue them. The reason I needed so much? No suitable container for the leadscrew... On the bright side, I should be able to de-rust absolutely anything for the rest of time, without making any more. Shame I didn't have the foresight to put the barrel on a pallet, moving it around will be a nightmare!

I also managed to shift (pardon the pun) the gear shift lever off the front of the headstock. Turns out it just needed a spot of brutalising, and it popped right off. Unscrewing the cover this revealed allowed the eccentric and it's shifter block to slide out very easily.

Next up, tackling that pulley adjustment rod/broken casting. Attacking the rod with a file allowed me to finally withdraw it from the back part of the foot, which I put to one side. Removing the grub screw allowed the strange (more on that in a moment) knurled thing on the front with pin spanner holes in it to move, but it was really REALLY stiff. Eventually I just closed my eyes and used the arbour press to push it out. Which it did... it took a flake of the casting with it, and now I can see how it's gone wrong. I'll take some more photos of that tomorrow, if anyone's interested, with a bit of an explanation. Hats off to the Boxford engineers, though, it's a surprisingly elegant solution to the belt-changing problem, and deserved to last longer on the machine's production run than it did. The good news is, other than the thoroughly bent shaft, all the other bits can be saved and re-used.

So finally today, after an unexpectedly early finish was called due to an offer of a pub dinner, I glued the foot casting back together with some superglue. Obviously, that's not so I can use it like this(!), the idea is, by getting it 99% correct, I can now grind away a few areas with a burr, and TIG-weld the casting back together. I'll start by tacking it in a few places, then over a few days, I'll grind out more and more of the tacks and re-build with the TIG. Eventually, I should end up with a piece that looks original, IS mostly original, and should be more or less as strong as the original. A bit of work with the mill should bring it all back to square and flat. Hopefully, by tackling it bit by bit like this, with small welds and plenty of cool-down time, I'll minimise any distortion. Worst case, I'll have to ream through the existing holes to re-square them with respect to each other, to replace the tensioning shaft.

So... as  :worthless:, please find attached a few photos of the jigsaw I put together earlier.

Tomorrow, I'll do some details on the shaft, and some of the other bits and pieces.

AdeV:
Tonight's episode: Shafted!

So... cast (sorry  :hammer:) your mind back a few days, and I showed you this upside-down picture of the headstock foot (before I completely broke it):



Observe, if you will... the central shaft, which (you can almost make out) has a 3/4" hex head at the front (right-hand side), goes through a boss, there's a threaded section, then the shaft continues through the back of the foot and into an elongated boss on the pulley/motor plate. The other two shafts, one of which looks bent (but I don't think it is) carry the weight of the motor/pulley. I'm pretty sure that the "Y" piece at the far end (left) bolts to the bed so the foot isn't actually expected to take the entire leverage exerted by a heavy motor; although that's actually the first time I've noticed the hole in it's foot!

So... here's the shaft after a painful extraction from the casting:



You'd expect, looking at the above, that this would be a 2-piece shaft... except the OD of the threads is the same as the OD of the shaft... so how on earth did they do it?!

Simples, when you see it:



Yep - THREE pieces! The main 1/2" x 10 1/4" shaft, with a threaded section, and a relief on the end. The part that fits in the boss, and then a separate sleeved section carrying the hex head. Please excuse the condition of the threads by the way... the only way I could get the boss section far enough up the shaft to remove the hex end was to put it in the Edgwick and effectively destroy the threads.

Note the two "divots" in the shaft: The far (left) end has broken off, but one assumes it was a large screwed-in affair, with a protruding head. This engages in the "boss" under the motor shaft, and provides the "quick screw" action to tension/un-tension the belts. The entire effort of that thread/unthread - which one imagines could be quite considerable, was carried by the small grub screw passing through the outer sleeve and into a hole in the shaft. No wonder it looks more like a volcano crater than a nicely drilled hole! TO my mind, this is probably the weakest part of the design, and I may try something a little more robust when I rebuild this part.

Finally - the adjuster nut. This is the clever bit (in my opinion!) - it's designed to rotate in the headstock foot (hence the C-spanner pin holes), by "tightening" it (clockwise) one loosens the belts a bit, and "loosening" it conversely tightens the belts. So a nice easy way to take up any variation in belt length if you had to change it, or as it stretched over time. The 2 1/2" thread length also allows access to the hex sleeve grub screw, without having to drill any unsightly access holes. It's all about the aesthetics! I assume that, as it's knurled, it's supposed to be easy to turn.... mine was wedged most thoroughly in the hole though, and required the arbour press to remove it. The reason:



The grub screw, which also acts as a retainer to keep the adjuster nut in place, has bashed its way into the backside of the slot it's supposed to run in, so hard that it's gouged half it's own diameter out. Further evidence that this lathe fell over backwards. Possibly over a cliff. The burr raised is what made it impossible to turn, or withdraw; and obviously using the press will have damaged the casting (it pulled a flake off the front, I imagine it's also left a huge gouge in the bore. Nothing a bit of emery won't fix). I did file it down a spot, to see if it would slip back in, but it was still resisting, so I've not forced it.

So - my plan:

First - make a new shaft, which is as easy as pie. I'll put a phosphor bronze insert in at the end to engage with the quick screw tensioner.

Now... here's where I'm undecided. I quite fancy making a new sleeve, and using the die sinker, erode a hexagonal hole into it. THEN drill/tap for a grub screw. That way, the forces on the shaft, when tightening, will be taken by the hex that I'll cut on the end of the shaft, instead of by the poor grub screw alone. Also, it gives me an excellent excuse to finally use the spark eroder for an actual job - justifying the few hundred quid I spent buying it!

Last but not least, I'll weld up the damage to the adjuster nut, and clean it up on t'other lathe. I can either turn the end off a grubscrew to give a smooth running surface, or even cut a small fozzy-bronze block to ride in the slot. It won't stop it getting mangled if the lathe falls off another cliff.... but it might make it easier to take apart afterwards!

I also need to make a new tailstock nut. No pictures of that, 'cos it's literally very ordinary. The only thing that took me slightly by surprise its it runs on a normal 1/2" Whitworth thread, and not an Acme screw. Still, that should make it a tad easier to cut the threads.

Right, I'm off to haunt eBay  :wave:, I need some fozzy bronze  :palm:

AdeV:
A little bit of CADdery later, this is what I reckon the shaft & head will look like. Maybe not quite that colour...

JD:
Ade have a look at G&M tools in West Sussex for boxford spares a phone call may be you best bet, speak to Tim or Digger.
 In my folder John W stuff on Boxford forum is a wiring diag for a model c (later model) may be of use.

John

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