Gallery, Projects and General > How to's
Thread cutting video part 2
NickG:
Possibly Andy, I've never thought about that or looked at the pitch of it. There are 30 graduations and it says each one is 0.002" - didn't realise until just now it says each is also 0.05mm so guess it's really a 1.5mm pitch.
So just as a sanity check, as you say, If I give it say 10 revolutions I'm expecting it to go 0.6 of an inch = 15.24mm but it actually goes 15mm and that's the 1.6%. Doesn't sound a great deal but if positioning holes say 4" apart - I wind the dial 66 times plus 40 thou and it actually moves 100mm - 1.6mm out, enough to cause a problem!
I will do some checks on that Andy - bit of a school boy error on my part if it is that! :lol:
Fergus, I think the gibs are tight, I've never noticed them move but then again haven't been looking for it. I'll have a look into that too. Am sure I clocked the table one and it got higher towards one end! Judging by the some of the errors on the 626s that John and Rob have shown, I wouldn't put it past em, obviously is no quality control. I was thinking buying a 626 would be a massive improvement for me but I won't be giving that any more thought.
lordedmond:
another great video there John
well done
pretty poor nut you have there they do not know the sequence of pops eg bore , screw cut & face off whist still mounted in the chuck , or maybe it was a stick and rusty nail they used :D
Stuart
andyf:
Nick,
Using metric screws and the fiction that 0.040" = 1mm seems common on budget Chinese machines. My lathe is "imperial", but the only imperial thing about it is the leadscrew. The feedscrews on the cross slide, topslide and tailstock ram are all threaded 1mm pitch, but with dials marked in inches. As your example shows, that creates problems on the miller, but it isn't so bad on the lathe. If I wanted to reduce a 0.500" diameter to 0.200" and relied only on the "inch" dial, the error would be on the safe side, and a bit more would need taking off. But I don't rely on the dials, and use a micrometer when getting close, which would show that another cut is needed. That's better than trying to put metal back on again.
Andy
NickG:
Good point Andy, at least it leaves stuff on the large side on the lathe. I guess for me a DRO would transform the milling machine - esp if I can get the table trued up etc. Don't fancy making new screws like John - there's not as much weight to support on mine with just the head and motor so guess it should last longer!
DaveH:
Super video John, :bow: :thumbup: :clap:
I think you should go into the film business
:beer:
DaveH
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