Lathe copy attachments

Hi Everyone,

Is it still possible to buy hydraulic copy attachments for lathes? I guess cnc has taken place of this kind of device but wonder if it's a simple alternative?

Thanks,

Chris

Used ones come up occasionally, often at prices that make CNC look like a better and cheaper option.

Yeah I'm starting to agree with that the only attachments available currently are on lathes that are priced the same as an industrial cnc machine. I'm just not sure how quickly I can get cnc setup and making parts.

Hopefully our member with a hydralic attachment on his M300 will be along later.

Simple alternatives are to remove the screw from the cross slide, make a template and follower and have a simple spring to hold the follower to the template. Really depends on how big the parts are, how many and how much you want to take off in one go.

Jason, that's definitely an interesting idea I'm just trying to work out how you would control the cuts for each pass?

Turn the topslide so it advances the tool across the lathe and use that to put on the cut. Use auto traverse to move the follower along the template.

A lot of the older lathe books make reference to copy turning type attachment lashups in bygone years, usually involving a strong spring across the cross slide

This is from "metal turning made easy" from 1923

Edited By Ady1 on 23/09/2015 09:28:59

Often wondered how practical it would be to make an electronic copying attachment with a displacement sensor on the template probe and stepper or servo motor drive to the feed screw. Looks easy enough in principle but I know from bitter experiences how simple control loops can turn round and slap you in the face by usually but not always working. For a sample system you merely need the sensor to hold things as close to its central zero position so pretty much no processing is needed. Basically a potentiometer and op amp could work.

If a little more complexity is acceptable for a more comprehensive system feed settings for multiple cuts could easily be arranged by switch "programming" of the sensor offset output. Whilst you are at it auto tool withdrawal and auto return via direct drive of the feed is worth having for near complete automation. Any one of the cheap micro systems should be up for this. Old farts like me could do it in hardware without too much trouble.

Yup. Just re-invented the EMI-Mec.

Clive.

.

Not a name that I knew, Clive

But found this for reference.

Thanks for the lead

MichaelG.

Like now! As far as I am aware new hydraulic copy units are available, at least in theory, from India and possibly China. Hydraulic copy lathes seem to be more widely available, although primarily for the woodworking industry. The OP is correct that CNC has largely replaced hydraulic copy units for medium volume production.

The units appear regularly on Fleabay, which is where I bought mine. Of course what lathe it is will run on is important. The units were designed for industrial lathes, so there's not much point in trying to run one on a mini lathe. Here is my unit in operation:

The (rusty) pattern and follower can just be seen bottom right.

My personal view is that small CNC lathes are not particularly useful; certainly compared to the smaller CNC mills. Once you get up to a sensible size, with the potential for live tooling, the cost has gone up a lot to.

Andrew

Micheal,

More info for you, origin of EMI-Mec? Easy EMI = Electric and Musical Industries, EMI mechanisation.....EMITron = EMI electronic camera for TV (1936),  EMI Scanner, yes we invented CT scanning as well!

Edited By KWIL on 23/09/2015 10:35:30

Edited By Nobby on 23/09/2015 11:19:39

Edited By Nobby on 23/09/2015 11:20:51

Thanks everyone I'm taking the plunge for a hydraulic copy attachment. I got into engineering to get away from computers so the longer I can hold off cnc the better

I have an old lathe that I could try the spring method on as the screw is already missing maybe set it up for some little repetitive jobs.

Nobby is that a myford setup for making handles?

Andrew I'm sure I'll have questions on setup. I'm just thinking about turning on centres how do you set it to stop before hitting the dog leg?

I have one on a Harrison 155.

I mainly use it for tapers, a ground bar mounted on the rear T-bar (where templates are fitted) and can be adjusted for the angle required, almost as quick to use as turning the top slide, gives a smoother finish than me winding the handle on the top slide as well!

I've also bolted washers to the T-bar to make a radius for sperical washers, works well.

Also I used a paint brush handle between centers on the T-bar to make a handle for something.

Here is a blast from the past ! I once worked for a company that had to make batches of cams every few months. This was in the olden days. A cam was made by hand, and clamped with a central bolt on top of the cam blank. This was centralised on a rotary table. A cutter was fitted with a ball race bearing which followed the cam form. The clever bit was that the table cross feed was disabled by unbolting the screw thread bush, thus allowing the table to 'float' freely. The ball race was then pulled onto the cam using a lash up arrangement of strong springs, so that when the table was rotated,the cross slide moved, governed by the cam profile. I can't see any reason why this arrangement could not be adapted for turning profiles. It could be a challenge!

Roy M

Chris Heapy designed a copying attachment as an add-on to his taper turning attachment for Myford lathes. Perhaps it could be adapted for other similar sized lathes.

http://easyweb.easynet.co.uk/~chrish/cancelled%20account/taper-t.htm   for the TTA
http://easyweb.easynet.co.uk/~chrish/cancelled%20account/profile.htm   for the copy attachment

Dave
The Emerald Isle

Edited By steamdave on 23/09/2015 23:31:08

I worked on a very early NC machine built by EMI , the control system was valves, toroids and relays, it was still limping along in the mid to late '70s but the axis travel was getting shorter as we could not source replacement glass inductosyns and so moved the end ones to the damaged area.

Keller copy mills used a tracer to follow a model and each axis had 2 elctromagnetic clutches controlled from the tracer. The machinist would set the machine up and sit back to read his book. It could take a few days to mill a large body panel die.

Mike

I can remember in the late 1950s at EMI we had Kearney & Trecker/Cincinnati mills being fitted with NC controls at the same time we were building the first UK all transistorised main frame computers EMIdec 1100 and 2200, all in the Hayes Dawley works.

Ultimately you need to knock off the power feed, exactly as per normal turning. However, design of the pattern can help. Naturally the stock needs to be longer than the part to be machined to allow for the drive dog. In my picture you will note that the hydraulic copy unit is set at about 30º to the cross slide. This is so that the unit can move perpendicular to the work without needing an infinite feed rate. At the left hand end of my pattern the line parallel to the cross slide is long enough to ensure that the tool clears the work, and is not getting any closer to the headstock end of the lathe until the power feed is knocked off.

Andrew

Hi Chris
Yes it is On my super 7 Mk one