taiwanese lathe spindle

[gina]

Hi

I have a Taiwanese lathe that I want to fit a modern chuck to.

The lathe is branded pacific Lathes but I think its a Shun shin ( or words to that effect) model SSB 5MK and was manufactured in march 1983.

The spindle shows every sign of being 8tpi with a whitworth thread form if my thread gauge is correct. problem is that its about 49mm dia showing six threads 21mm threaded length .

I cant find any spindles like it in the info on The net. anyone have any ideas on what it is and how I might get a new chuck mounting plate to fit it.

Gina

[spro]

Hello Gina and welcome to the board. Many of us have a lathe like this or have owned one before. You will find the answers. I think you need to measure the diameter of that spindle to help. Is it tapered?

[spro]

Well I haven't helped a bit since you already said the diameter. That 49mm is odd. Someone will know.

[Harold_V]

If the spindle thread is truncated, I wonder if, maybe, it's a 2"-8 thread. A ruler on the threads should line up every 1/8" if so. Certainly worth taking a look.

Welcome to the forum.

Harold

[stevec]

gina, Welcome to the forum.
Please indicate your general earthly whereabouts in your profile, as all of your respondents (so far) have.

I wonder what measuring device you have used to determine the "about 49mm dia." also I'm curious as to why you have a Whitworth
thread gauge, that is a particularly British, older thread type.

I agree with Harold suspicion that your spindle is probably 2" x 8 threads per inch.

[ctwo]

(6 threads x 21 mm) / 24.5 mm/in = 4.96 TPI

An M48 would have a 5 mm thread pitch

Just tossing that out there.

[Harold_V]

I arrived at my eight threads per inch by dividing the 21 mm (.826) by six. Yields .1378", which is close enough for an eight pitch thread to make it worthy of being measured with a ruler. There's a whole series of threads with eight, twelve and sixteen pitch on various diameters. It would quickly dispel the notion it's eight pitch if it isn't, and readily conclude that it is, if it is. Right now, it's my opinion that one should not conclude it's any particular thread, in particular by introducing the notion that it's Whitworth. It may or may not be, and it most likely is not.

Harold

[gina]

many thanks for your kind welcome to the forum.

I am a beginner when it comes to lathes. I have high hopes of being able to make some good things with mine. I have had it for around ten years but only just now decided to clean it up and get it going.

I have a job that requires the lathe to throw 7 aluminium stock. My chuck is five inch max dia capacity . I purchased the lathe from a friend who was a fitter and turner and used it mainly to make bits for his golf cart and golf clubs.

To answer some of your questions I have attached some pictures that i hope will help.

I used a whitworth thread gauge because I had one. I dont have a metric gauge and only a small thread form SAE one. ( I will get some more today) but the whitworth is a perfect fit . I worked out the TPI by counting the threads and measuring the distance from first to last then calculating that as parts of an inch.

below are the photos

[gina]

the thread gauge

[spro]

Okay Gina! I think if you measure around the unthreaded part of the spindle, you will get just under 2". The way it can be measured with calipers around the thread causes error and anyway the major diameter is slightly less. If this is correct then it's 2X8tpi .

[ctwo]

Well, that's what I get for trying to make it fit. Of course I had the wrong operators in there...

[spro]

Wait a minute, not done yet. Valuable contributions. We didn't know it was Australia. While I've seen that lathe sold in the US, a metric variation is possible. When G gets back to us, she can check her chuck and see what It is and if IT was wrong. The threads don't exhibit galling by incorrect fit.