Kia Ora from the bottom of the world. Tool hoarder & enthusiast.

[JohnFParticipant @johnf59703]

Well I thought I had posted a welcome reply a few days ago but its not on here !!! No idea why but welcome Simon,  you have got yourself a nice machine and looking at the dials it is Im sure Imperial, better IMO because the “metric” Myford’s are not truly metric.  Both the lead screw and gearbox remain imperial but they do fit a lead screw handwheel that has the nearest metric divisions.

My choice is to convert any metric drawing dimension to imperial and use the machine as is, the rust will be a metric component.

As for screw cutting metric threads here are some links to previous threads on this subject but be aware you cannot use the thread chasing dial for metric threads as you would for imperial — there is a workaround that can be used for cutting up to a shoulder.  I have a write up done many years ago but now there is a video explaining the process as well.

https://www.model-engineer.co.uk/forums/topic/myford-33t-and-34t-gears-for-metric-threads/

https://www.model-engineer.co.uk/forums/topic/myford-metric-lathe-leadscrew/page/2/

https://www.model-engineer.co.uk/forums/topic/availability-of-a-t33-t34-myford-change-gears/page/2/

https://www.model-engineer.co.uk/forums/topic/thread-cutting-2/#post-204892

John

 

[Neil LickfoldParticipant @neillickfold44316]

Hi Simon, I’m in Hamilton. My lathe came from the Oxley ? pram factory in Christchurch and I got it in February of 1987. Mine is made in 1972, has the Green gearbox, and was a Metric lathe with the Metric gear set and frame to hold the gears. The handwheel for the leadscrew has 3.18mm on it’s divisions. The lead screw is actually Imperial of 0.125 inches. So 1 turn in Metric is actually 3.175mm and I was caught out early on from that. Luckily the part was short and so was still saved and a lesson leaned.

You lathe is imperial , as mine came with an imperial cross slide nut and screw assembly, which is the same as on your cross slide. Each division on your cross slide is 1 thou cut, it’s a 0.100 inch pitch leadscrew.

I used the 0-100 dial from the imperial set up, and made an M8x0.5mm pitch cross slide screw for making accurate metric sized parts. It meant that every division matches the divisions on the micrometer spindle for diameter.

The early machines, had the dial in radius, as when used in milling, no conversion from diameter was required. I used to have the vertical slide and gave it away after I got a small mill.

I have added a 1hp 3phase motor to mine with a VFD. The real advantage with the VFD, is adding micro switches for the end stopping of the lathe, towards the chuck, and towards the tailstock. The switch will stop the motor, and in my case with some breaking assist, stops very consistently when used slower than 300 pm. makes it very easy for doing internal threads, or threads close to the centre with a minimal start clearance. It will transform thread cutting. Can’t remember the fellows name, but he made a Hardinge style modification to his Myford lathe, so that you can easily thread cut and pick and disengage the feed, without loosing the spindle orientation. I have not got around to this mod,and now with the VFD and micro switch set, may never do so.

I also added oil lines to the saddle where the oil nipples are. I got some low profile 4mm hose fitting and ran a die over them to suite the Myford holes. #2Ba I think is the die I used.  Also added a tailstock caliper too. It mounts from the oilers, and the adapters are different heights to have the digital gauge running parallel with the quill.

My lathe came with a rack and pinion quill as well as the Metric hand wheel Quill. I mostly use the rack and Pinion one.

I have also updated on mine , a 1um cross slide magnetic tape and a 1um, micro series Sino glass scale for the carriage. Mine is front mounted under the leadscrew. It allows me to still use the taper turning attachment. But did need to make an adapter , ad the rear tape reader on the cross slide was in the way of the arm for the connection to the cross slide. Making parts for the lathe is a lot fun and satisfying when it works.

I did make a new front tapered bronze bush, and recut the spindle on my one to get the taper back to round again. Scrapped in the spindle to the bush, as the distortion from the press fit, makes it very slightly out of round.

The latest change has been a 1 mm pitch micro M8x1 ball screw. I made an adapter for the nut and it was not that good. So added another nut , so it is 2 ball nuts back to back. They have about 0.05mm of backlash in them. But is very repeatable. I should have got an made to order ballscrew assembly grade 3. Actually would have been cheaper in the long run, both timewise and dollar wise, and would not have needed the extra nut to take away some of the backlash. In say that, the very low backlash has been really noticeable when parting off steel parts, like the head of 12mm high tensile capscrews for example. No noise and just went really well. I still have not set up the back parting off tool yet.

The lube oil I am currently using on the slide ways is the 80 weight synthetic gear oil. Also does not have a really bad smell.

On the top slide, cross slide, nut and screws, I am using the grease made for linear bearing for Deckel Milling machines. It is the best grease I have every come across for the slides and screws and bearings, including the rear angular contact bearings, the gear bushes etc. I don’t use it on the carriage to bedway though, not in the spindle taper. The spindle taper just gets regular 30 weight oil used for the lawn mower and works really well.

I am very happy with my S7.

It is always fun using it to make what ever it is you want to.

 

Welcome to the site.

Neil Lickfold

[Author]

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