Team Bitza

[Niels - Team K.a.L.M.]

Alternative link positions on a FBS?

Other than out of the central stationary column? Ideally want it somewhere else to save weakening the shaft.

Ideas?

Some use a tail sticking out from onder the machine.
But that would be a weak spot with all those drums chewing up the floor.

[Flag Captured]

I had some problems with some 3/8th UNF brass nuts a while back, not sure if they're quite the same, but a change of drill gearboxes sorted that. Not sure what the problem was though. The new ones have been fine ever since, so I'd assume it's either a bit of damage somewhere, or the shafts themselves have twisted slightly out of shape?

[PJ-27]

All brand new stuff, both connectors do it on both gearboxes. I'll try a different motor/gearbox and see if that changes then I'll know who the culprit is.

[Ellis]

Sounds like they might be the wrong pitch. Imperial threads are written in the diameter of the screw in inches followed by the number of threads per inch. I believe drill shafts are 3/8-24. If you got something other than 24 (if someone can confirm that they are indeed 24tpi) then it won't thread on.

[PJ-27]

It threads on very nicely to start with, then just stops. Bought a 3/8UNF tap for £3.50 on eBay, figured it would be good enough just to sort this (although the tap cost more than the connectors.....)

[Ellis]

Exactly, it will go on on for a few threads, which is just the slop you have between a fitting nut and bolt being taken up, then it will seize. Tapping it will either permanently wreck the threads as it attempts to tap it to a different TPI or do nothing as it'll be the same TPI as the nuts and just pass through. No reason for a brand new nut to not thread onto a clean drill shaft unless the threads don't match.

If you have a spare nut, cut it in half and hold up the exposed thread to the drill shaft. If it matches exactly but the nuts still don't go on you need to report a glitch to the man in the sky! :P

Disclaimer: if I am missing something stupid pls don't hurt me

[PJ-27]

I dunno, I just assumed 3/8UNF was 3/8UNF, no thread pitch listed on the connector stats. Replacing the nut will be a bugger.

[Ellis]

If the seller specified that it is a 3/8UNF (that's 24tpi) then I'm at a loss! I don't understand how it can be too tight, especially if it winds on a little way, and still be the right thread. Hopefully they just have a bur from manufacture inside that tapping will clear. I suppose it's possible that they're somehow manufactured too tight but I don't see how really. Perhaps the seller incorrectly listed them as UNF, but even then if they were the other imperial standard pitches you'd have 8 threads too few or too many, which you'd think would be noticeable.

Anyway, hope you can fix it! Am fully prepared to eat my hat, seeing as I don't have one.

[PJ-27]

Forcing in a 3/8UNF bolt makes some progress, I think it's just crappy manufacturing. Will sort it with the tap.

Anyone know a source for extra long left-handed thread bolts for the end of the drill shaft?

[PJ-27]

Made a little more progress, put the arms on to see what it looked like.

IMG_0431.jpg
IMG_0430.jpg

Going to be a pain fitting the actuator in!