The Craftmans Shop > New from Old
Boxford back from the dead
awemawson:
Ade, I bought a job lot of 100 mm glass magnifying lenses a few years back and have one 'to hand' by most machines and also at my desk. One of those and putting the part on a sheet of white paper makes such comparisons much easier.
PekkaNF:
--- Quote from: AdeV on June 28, 2019, 06:35:46 PM ---... I think it's 55 degree, but it's hard to be certain. There's not a lot in it, and my eyes aren't what they used to be. If anyone has an easy way to determine a 55 degree vs. 60 degree cutting tool, speak now...
--- End quote ---
For threading tool, I would compare with aforementioned thread gauge. Maybe a little blue (sturat's or felt tip pen) would help. The tips of threading tools are getting smaller, I noticed that even my old bits have shrunk and I need to resort to loupe more often than before.
For readymade thread I go to local bolt-store and bug the senior sales guy. He really has a knak of knowing wht to look for and waht is most likely to go where.
Pekka
AdeV:
Today I finished machining up the front end of the belt tensioning shaft, and drilled the holes in the adjuster nut to take the handle, and the grub screw to secure the nut to the shaft.
First I cut the hex. To my surprise, I got within 2 thou of a tolerable fit first time out of the blocks... so after a little skim, it slipped on perfectly, with only a tiny bit of wiggle.
Next job was to cut the thread. To aid me, I'd purchased a new split die (I have a 1/2" BSW die, but it's not a split one, and it doesn't have a lead-in taper), but then I hit a snag.... by making the centre post that goes in the nut a little larger than Boxford's original... meant it interfered with the thread slightly! And being hexagonal, I couldn't get the die centred properly. :doh: So, plan "B" was invoked, and I single-point cut it all the way. The serrations on the hex are where the toolbit just touched the corners of the hex. I'd say it looks neat, but TBH it just shouts "amateur!!!". A few thou smaller would have made the problem simply go away... Anyway, we are where we are.
Once the threads were done and the adjuster collar was able to be screwed on/off, it's back over to the mill for some drilling. Ironically, you have to screw it on over the hex! It's a bit wobbly to start, but works surprisingly well considering how shallow those cuts are! I hemmed and hawed about the grub screw, but eventually went with an M6 thread, as I have about a bazillion cap-head screws, one of which I could cut down. Fitting the shaft and nut together, with the nut clamped precariously in the vice, I carefully drilled a 5mm hole into both nut and shaft (to assure perfect alignment. Purely by luck, the depth of the hole in the shaft was exactly 1/4"). Then I withdrew the shaft and tapped the M6 thread into the nut. Whilst I was there, I also drilled the 8mm (! yes, really, it's pin on 8mm) hole for the handle.
The cap-head screw has 1/4" length of thread turned off, to fit snugly in the 5mm hole in the shaft; then the cap was milled away to leave a grub screw. The original Boxford grub screw used an Allen key, but feeling lazy and in need of a coffee, I cut a slot (freehand with a 6" grinder, I'll have you know!) for a screwdriver. Unlike the original, this is just to hold the two parts together, there will be very little force exerted on the screw itself.
So... the pics show the component parts; then the collar screwed all the way in (out?) to allow access to the grub screw; an finally an overview of what it should look like in service.
The last remaining jobs on the shaft are to trim it to length (optional, quite frankly) and deburr the far end, drill and tap a hole for the "cam" which rides in the thingybob underneath the motor plate, and does the actual pushing in/out. I'll turn the "cam" bit out of phosphor bronze I think, since I accidentally ordered 2 pieces, so I've got more fozzy bronze than I'll ever need now!
There's one more thing to do to the adjustment collar; the big chunk that's missing from the relieved section (see 2nd pic) needs filling with weld, then turning back to diameter. The original Boxford setup had a grub screw protruding into that relief, which the collar then bore against when being adjusted. In theory, it shouldn't see a massive load (because you'd not turn the adjuster with the belts tensioned), but as we can see, it's vulnerable to being hit. Think I'll turn up a piece which is a nice sliding fit in there, drilled and tapped for a grub screw (or maybe just pinned, like my shaft). It wont be as strong as just using the grub screw, but it won't offend my OCD either. Somehow, just having the end of a grub screw sticking into that recess doesn't feel right.
More tomorrow, hopefully.
Sea.dog:
That's a nice job.
Now you only need find a diamond knurl with the right pitch to clean up the collar :D
AdeV:
I do have some knurling tools... not sure if I have a diamond one though.... but actually I was thinking of leaving it more or less as it was... or I may have a crack at using some needle files on it to try to restore it the hard way... Let's see how much enthusiasm I have left after a few more bits are done :lol:
I didn't do a huge amount today, being a lazy Sunday afternoon and whatnot... but I wanted to repair the ding in that collar. So.. set myself up for a bit of mild steel TIGging (Pic 92), ruined the belt sander (93) - remember children, don't get your tungsten stuck under the fence when you're using an inappropriate tool to grind a point on it, because nasty things happen... Actually, once I'd cleared the shredded bits out, half the belt is still fine, which allowed me to finish off the tungsten and not have to locate the spare belts I bought. They're in there somewhere....
Moving on, I'm really struggling with this welder at the moment. Dunno if it's me, or if it's not working properly.... but I just can't get it to behave. I managed to get some metal melted into the ding, though, and whilst it should have been a nice flow, I had to flatten the worst of it off with a flap disc before mounting it in the lathe to be skimmed flat. I used a brass shim which IIRC John Bogstandard gave me years ago to protect the polished end from the chuck, and managed to tap it around until I had about 2 thou runout - near enough for this task. Step 1 (94). After skimming, I used one of my superb Mircona parting off tools to fettle the groove (95 - please excuse the enormous bolt sticking up out of the top of the tool holder. I really ought to fix that...). The result (96) - not my finest welding hour, but it's way better than it was; and in use, you'll never see it. Out of sight, out of mind....
Next up, I turned a bit of bronze to match the ID and OD of the adjuster shaft (97), parted it off slightly too short, cut it in half and tidied the ends a little (98), and now it fits nicely(if sloppier than I'd like) in the groove (99). My plan with this part is to drill a hole, probably 3/16ths ish, in the centre, for a pin to drop into. Then I'll turn a special grub screw with a 3/16ths ish nipple on the end of it, so when the grub screw is tightened down, it engages with the hole in the bronze half washer thing, thus doing the same job as originally achieved by the bottom of the grub screw :thumbup:
There's even room underneath to store the other half of the ring, should I ever need a spare :lol:
So, that's it for this weekend. I forgot to bring the motor plate to the workshop, otherwise I'd have made the engagement pawl/cam thingy. I'll do that another day, once I've measured it. Meanwhile, I'm in the market for a new TIG welder I think... any recommendations? Needs to be reasonably priced, as my budget is a trifle limited right now...
Thanks for following along, hope you're enjoying the ride as much as I am so far.
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