Spiral Milling

A while back I converted a Drumond lathe head stock to work as a spiral milling attachment for my mill, photo's in my album.

Recently I was asked to do an interesting job milling a spiral into a shaft for a throttle assembly for an old motorbike. I used the Drumond head stock and it worked out really well.

The head stock is driven from the lead screw using a timing belt and pulleys, though in this case the belt had to be twisted to reverse the direction of rotation of the head stock, I've posted some pictures below.

I hope this is of interest and helpful

Nigel

Edited By tractionengine42 on 16/06/2021 18:11:33

You were lucky to get away with that crossed belt!

Nice ‘re-purposing’ … and an impressive result

MichaelG.

I did a similar thing using a a rotary table and a right angle drill adapter.

Les.

Done the same for one of my bikes a few years ago and got the gear tables from machinery handbook. An interesting job and very satisfying.

Watched your video last night Nigel and was suitably impressed, it's one heck of a helix!

Just need a couple more videos now, one of the throttle operating the carb, and another one on making the toothed belt pulley, looks like drilled holes and round bar did the job?

IanJ

Les, that looks a great set-up, I like the idea of using the right angle drill adapter. Getting a nice spiral groove is very satisfying.

Ian, thanks for watching my video, I actually used a form tool to cut the teeth on the timing pulley.

Nigel

Nice work that gets the brain going. It has been years since I did any and would have to read the gearing charts.

I did a similar job a couple of years ago, a 2 start square thread, I used gears rather than belts, but I did need to get a big gear ratio, I had to make the "banjo" and I 3d printed the gears as it was a one-off to make the part & 2 taps.

Not sure why this image is on it's side, it is not on my PC.

The cutter is 1/16", I used the handle on the dividing head to driver the table, the return was made & faster easier by making an adapter to use a socket on the nut driven from a drill.

Baldric

Impressive set up Baldric, that gear train must of taken some serious maths.

Nigel

Baldric, is that a Bridgeport with a 36" table ? If so a prized addition where workshop space is at a premium.

I made a provision on my Warco milling machine to drive from
the lead screw to some form of spiraling head ,it never was used.
The cnc route turns out to be a much more useful method ,easier
to set up and to get the result that you need ,here are some that
i have done in the past.

John

John, some interesting spiral milling, allot of versatility in the cnc route.

Nigel

Very interesting, I've been setting up my vintage c.1895 Pittler B2 to try spiral turning, it has an overhead drive to the tailstock, this is my first attempt but it's not milling on the video, just slowly cutting a coarse spiral as a test run.

The Pittler B2 uses a worm and one of 17 worm wheels for spirals and screw cutting

spiral cutting on a vintage Pittler B2

I next need to fit the milling attachment to the top-slide which will also run off the overhead drive if I can sort out the pulley belt from slipping.

Some spiral milling photos here 10 Tpi 1/2 inch diameter leadscrew finished length
about 20 inches , can be cut to full depth in a single pass , although i usually do a single
roughing pass and a second cut of about .010 " , rotation of work about 1 1/2 rpm.
Climb milling leaves a no burr finish, en8 is a good choice as it cuts clean and a
little stonger than free cutting steel.

Cutters seen here form relieved from silver steel on the Eureka device.

Useful for cutting worms , i use the cnc part of the machine for these odd pitches
as the pitch can easily be corrected to suit the chosen diameter, this one is 1 mod
for Vertex rotary table

John

Vic, Amazing set up and a beautiful lathe.

I also did a video spiral milling

John, very interesting set up, it must be very satisfying to complete a long slender lead screw like the one you show. It's good to see your making your own cutters, the Eureka device in on my project list.

Nigel

Another attempt on my vintage Pittler lathe, this time I have both the leadscrew drive and a milling cutter running off the overhead. It's running with the original milling head supplied with the lathe c1895. It takes 8mm collets but I don't have a suitable small end mill so it's fitted in a small chuck as a means to get it up & running

Milling a spiral on vintage lathe