First time cutting threads in the lathe! 1of2

[OuBallieParticipant @ouballie]

12tpi x 1.1/2″

[OuBallieParticipant @ouballie]

It's been a while since I last posted, BUT I've achieved a landmark in using the lathe.

Chuck back plates
I've had chucks gathering dust waiting for me to machine backplates for the lathe and dividing head, so decided it was high time to start machining the 4 ready screwed backplates I got from Warco and making two for the Bertex Dividing Head.
Machining the OD of the last Warco one, using power feed, I selected Saddle feed in error rather than Cross-slide and a big dig-in was the result, BUT the brass tube I used to replace the spring pin didn't shear as I had hoped it would. (Need to think again, and maybe time to fit that clutch to the Gearbox input shaft now.)

Ideas on a replacement waisted spring pin design please. To

I panicked a little, as expected following on from my first episode, and instead of pulling the clutch lever to disengage motor, I made a grab for the Feed Shaft lever to disengage the Feed Rod.
After recovering from the 'shock' I found that it was now impossible to engage the Feed Rod no matter what I tried or how much effort I exerted, so I finished off in manual mode and walked away, working on the Austin Seven to take my mind off what further damage I'd done inside the Apron.

With the Carport at 27°C & 80% humidity during September, it just wasn't conducive to working on the Austin Seven, so Workshop time.

I wasn't in the mood to remove the Apron once again, to look inside, so settled on finish machining the backplates in 'manual' mode.
Imagine my delight and surprise to find that the Feed Rod Lever was completely free and back to normal with no hint of it having locked up.
I can only surmise that when I made that lunge to disengage the Feed Rod lever I must have inadvertently made contact with the Half-nut lever, thus partly engaging the interlock.
Those two levers are next to each other, albeit the Half-nut one on is on the side of the Apron.
Soon had the backplates for the lathe chucks mounted and registers done, then time for the Vertex dividing head ones and they had to have a 12tpi thread to fit spindle.
No way was I forking out for Myford chucks/backplates, so procured a 4" 3-jaw Pratt plus a 6" 4-jaw Bernerd.

This meant doing some screwcutting in the lathe for the first time believe it or not, as I've been able to get away with using taps and dies till now, and quite frankly funking the very thought to boot.

Geoff – Continued, with photos, due to word limit.

[OuBallieParticipant @ouballie]

continue/

Fun and games ensued checking the diagrams printed on the side cover of the lathe as to what change wheels where needed and where, then finding that NONE where marked with number of teeth, so had to count and stamp each one.
Chucked a piece of aluminium to test, and then problems as I just could not get 12tpi, the closest being 11.5tpi!
The usual wtf but after an hour of checking the positions of the feed and gearbox levers and finding them in their correct slots, plus change gears, went to have a bite to eat and coffee to calm down
Back to the lathe and I just could not believe what I saw!
As plain as possible the diagram on the gearbox showed two 40 tooth gears where needed and for some inexplicable reason I had fitted one 32tooth.
What relief when that was rectified and the thread gge confirmed 12tpi!
Measured the Vertex spindle nose and cut the thread in the aluminium rod to size to use as a gge for the backplates, and very pleased and somewhat surprised at how easy it was.
I remember thinking to myself "Is it this easygoing!"
Aluminium, so MS no doubt not the same.
First go at screwthreading

Replaced the 3-jaw with the large 8" 4-jaw and used thick aluminium plate for the two backplates, machining the centre holes then cutting the internal threads using the Jog facility, and leaving the Half-nuts engaged, just reversing the lathe using the 'Jog' facility again that the VFD control has.
Took a little fine fiddling with Top-slide feed to get the threaded plug gge to screw into the plates all the way, but again pretty pleased, after being not a little apprehensive in the past about screwcutting in the lathe.
Blind holes a totally different matter.

Next problem was how to trepan the centres out.
Easy said I, mount the aluminium on the dividing head, onto the Marlow and use a small dia end mill.
After three passes I cried enough and time to use the lathe to trepanne the centres out.

Found the toolbit I used to trepan the thick plastic from 'Oompa Lumpa' to make holders for Angle Eye lamps I made to fit round the spindles of the the Mitco and Marlow, and soon had both done.
https://youtu.be/eXFRk-fUI_8

Chuck mounting holes drilled and tapped.

Chucks mounted on the Vertex.

The Marlow spindle speed has subsequently been increased

Geoff – Hopefully back working on the Austin tomorrow.

[Neil WyattModerator @neilwyatt]

Blimey Geoff, back with a bumper crop!

[Harry WilkesParticipant @harrywilkes58467]

All good stuff well done !

H

[Nick_GParticipant @nick_g]

.

Good man.

Nick

[mechman48Participant @mechman48]

Good job Geoff, nice pics.

George.

[OuBallieParticipant @ouballie]

Thanks for the kind comments.

Remembered how to do YouTube links, surprising myself to boot.

Trepanning using the Dividing head:

Geoff – Carport here I come.

Edited By OuBallie on 21/10/2016 10:55:20

[Michael Cox 1Participant @michaelcox1]

Hi Geoff,

Brilliant stuff.

Mike

[Author]

Posts