@Steve_Cornford
Hi Steve,
Many thanks for the feedback. You have set my mind at rest -- other folks can successfully print the loose jaws, see them, and use them without going mad or changing to Gauge 1.
Having detached a pile of loose jaws, In practice in takes me about 15 seconds per jaw to pick up a jaw in a pair of cermic nosed tweezers (the type sold for vape users, not that I do) and insert into the slot and then press home. This with the aid of a cheap illuminated magnifying glass on a stand.
I think you might get a bit faster with practice. The thing to bear in mind is that you save the time spent thr
eading the chairs on the rail. Then noticing that you have got one in the middle the wrong way round, and removing them again. Then the next time you notice that you have got them in the wrong order and do them a third time. Finally they have to be carefully spaced out along the rail on the paper template so that they will drop into the sockets. The loose jaws option avoids all that. I have a hunch that with a bit of practice it might actually be a bit faster.
As far as the S1 chairs go (which are a test bed for check chairs say) it might be useful, as you have already suggested, to have the option of some thicker keys as you can "rock" the rail slightly compared with the fixed jaw S1 chairs
I hear you. We already have this adjustment:
Which modifies the effective key thickness without needing to add a custom rail setting -- originally included to allow for slight variations in batches of rail. But it's a good idea to have some additional separate rail-fit settings for loose-jaws. I have now modified the slot clearance setting for the loose pins, which should push the loose jaws more firmly against the rail. In addition to that I have now added this:
Setting that positive will tighten the keys against the rail. Negative to loosen them. Only small amounts of the order of say 0.03mm (1 thou) should be entered at a time. The loose-jawed chairs do not have to be thr
eaded onto or slide along the rail, so can reasonably be made a tighter fit on the rail. But not too tight -- they might stress-fracture over time.
This setting can be used to create batches of tighter keys, for example for use on the check rails if needed. But don't overdo it, it won't work:
The tweezers arrived. They are these:
https://www.amazon.co.uk/gp/product/B08MLB869C
4 for £8 was about 2 more than I needed, but I thought they might come in handy for other jobs.
Also available with stronger solder-proof ceramic tips:
https://www.amazon.co.uk/gp/product/B08LG6B82W
I didn't go for those because the tips looked less fine, and being ceramic they wouldn't be so easy to reshape. That may have been the wrong decision -- how fine are tips on your ceramic tweezers?
The reviews of the plastic-tipped tweezers were distinctly iffy, and I can see why -- the finish isn't going to win any awards, and the plastic tips are so weak that they simply bend under load. And no good anywhere near a soldering iron -- my guess is they are ordinary polypropylene.
I went for them for two reasons -- the cross-over reverse locking action makes them so much easier to use, and the screw fixing means I can make all sorts of other clamps and holders to fit them.
The first thing I did was to insert a packing washer under the forward screws to improve the clamping force on the plastic tip. Which was a bit better but not much. But for this application the loose jaw pins are so tiny that we wouldn't want to clamp them with excessive force. I also used the flush-cutters to trim off just the radiused very end of the tips, leaving a square end which is more convenient to use.
With the result that they are working fine for this task, but it would still be worth looking at 3D printing some tips specifically for holding the loose pins.
If you haven't used reverse locking tweezers they take a bit of getting used to, but are a great work aid. Squeeze them to open them, and release them to grab the part. You can then put them down with the part held, leaving both hands free and much less tiring on the fingers:
For magnification I use a pair of cheap close-up reading glasses for modelling, 3.5 dioptre, which are enough for my eyes, and more convenient than having to get the work under a fixed magnifying glass or lamp. Available up to 4.0 dioptres from supermarkets and pharmacies (where you can try them), and also from Amazon (where you can't):
https://www.amazon.co.uk/Suertree-Reading-Computer-Presbyopic-Eyelasses/dp/B08R57DZ6D (not sure why they think you need 3 pairs
*). Everyone's eyes are different of course.
*You could put 2 on at once, giving you 8 dioptres, or even all 3...
Back to making the separate chair screws strong enough to self-tap into the timbers...
cheers,
Martin.