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13th Jul 2019, 05:42 PM #16Most Valued Member
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Ahh, I'd missed that. That explains the imperial machines. Although I believe Canada went metric around the same time as Australia did in 1975? I guess sharing a border with the US might explain why a high school in a metric country would want imperial machines.
Enjoy the weekend.Chris
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13th Jul 2019, 06:02 PM #17
Yes, exactly, on all counts, except metric was just mandated for things directly pertaining to the people, as dictated by the government. All temperatures, volumes etc. food stuffs all had to have metric labeling. All things mechanical, in industry etc. seemed to go on with imperial, even to this day machine shops work in inches ( for the most part) I still measure snow in inches, temp in Deg. C, weird how it was sort of partially implemented.
So, yes, imperial lathes.
Cheers
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13th Jul 2019, 06:58 PM #18australian metalworking hobbyist
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14th Jul 2019, 08:02 AM #19
Sucess! I figured out the gear train.
Well it only took 2 minutes but taking all the gears off of the end allowed me to see how everything works. The stud gear is actually a 30T that is driven by the tumblers, and then the 20T or 40T goes on the ed of that shaft. I put the 40T in the stud position and 45 stayed on the screw gear position, and with the gear box set for 8 TPI I now get 1 revolution of the lead screw per 1 rev of the chuck...yeah! It sure turns the lead screw in a hurry, it actually bogs down and almost stalls the motor when I engage the saddle, mind you it was set for 400 RPM or so, probably won't be turning threads at that speed.
Anyway, I now know how it all works, and know what gears I need to thread metric. I still don't know why there is a 56T on the other lathes' lead screw shaft instead of a 45T? Someone may have put a change gear from a 9 on it at some point to get a slower LS speed.
Thank you for all your help.
Back out to the shop to rebuild some live centers.
Cheers
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14th Jul 2019, 09:54 AM #20Mechanical Butcher
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Cars and motorcycles made in USA nowadays have metric fasteners.
UK still measures road speed and distance in imperial. No need to dig up historic milestones like they did here.
I heard a radio story about how soon after the war of independence the Americans prepared to adopt metric standards.
But on the way over from France, a ship carrying an important meter-long standard was attacked by pirates and lost.
So they stayed with the British system instead.
In its defence, for metalwork, a "thou" is a very nice unit to work to.
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14th Jul 2019, 10:45 AM #21australian metalworking hobbyist
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reverse gear
I see why you didn't understand now. The inner 30 tooth gear is called the "reverse gear" and has the same tooth count as the spline on the main spindle and as such means at that point the ratio is 1:1. This is a fixed value on all 260"s and plays no other part in the gear system.
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14th Jul 2019, 12:36 PM #22Most Valued Member
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15th Jul 2019, 07:28 PM #23
I went from metric to imperial as I mentioned earlier. But this is how I used the gears I needed to cut 12g thread.
Just thought it might help.
I bought the "kit" - from Mal - allowing imperial threading. This consisted of a set of gears - the 80 is not shown but that came with it too.
It also included this table
So I changed gear setup and found I didn't have another bush and bolt for the 80 tooth gear as shown in the table but I was advised that if I can get the compound 63T-64T to drive directly to the screw gear - 48T -it's fine as the 80T only transfers from one to the other.
BTW here's how I connected it
Then used the gear box as it shows LH on 1.2 and RH on A
So no need for the 80T
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15th Jul 2019, 08:53 PM #24Most Valued Member
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Without the 80T transfer gear doesn't the screw gear turn the wrong way?
Chris
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15th Jul 2019, 09:18 PM #25
That's what I thought too but it worked and I cut the threads no problem.
Well it ain't perfect but with practice it'll be better, but it was workable.
20171027_115747.jpg
Since then I made an idler bush and bolt so I can now add the 80T if I want but it's not needed.
20171105_150835.jpg
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15th Jul 2019, 10:48 PM #26Most Valued Member
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In your picture isn't the reverse tumbler in the reverse position, there fore giving the correct direction for the screw gear, if you had the reverse tumbler in n the normal position for threading/ feeding the carriage would be feeding towards the tail stock, also from your post people need to realise that this particular 80 tooth gear is just an idler without keyway and if used will allow you to have the reverse tumbler in the normal position.
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17th Jul 2019, 08:44 PM #27
Yes, you're correct. I just reversed the tumbler position and I had what I needed.
However, having no metal turning experience and learning as I go I figured out that the tumbler position will allow me to have the correct feed direction only after I changed the tumbler position and trying it out
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