machining curves

[plunger]

How would one machine something like this repetitivly on a manual lathe. This is my first shot at a photo so hope it works

[Evan]

You would use a tracer lathe that follow a 2 dimensional pattern and moves the tool in and out correspondingly.

[jugs]

Use a copy attachment or form tools.

john

[plunger]

Nice to have you back evan .Tracer sounds hydraulic . Would this be difficult on a standerd lathe or just plain impossible. There are 14 to be made which would be done on cnc as I am an agent for a company that makes obsolete parts. Problem is they are 600km away and often a client wants a sample and its just too time consuming to get it made and sent back and forth.Truth is I think its a pain in the arse for him to make it as a sample hoping to get the job with no guarantees of getting the work. This is for the local casino.
They want it to look the same except it needs to be chromed as they find it too much maintainence to keep it polished.I often get asked for these funny requests and if I could make a sample then it would speed up the process and take the load off head office. I was hoping to try to make a niche market for myself so that I am the go to guy for these funny requests.

[djc]

...Tracer sounds hydraulic. Would this be difficult on a standard lathe or just plain impossible?...

You don't necessarily have to use a hydraulic tracer. Think about how a pantograph engraver works - purely mechanical.

Make a template that fits the original. Set it up parallel to your lathe's axis. Rig up a pointed stylus attached to the top slide that follows the template. Disconnect the topslide feedscrew and install a strong spring that keeps the follower in contact with the template.

The difficulty is adjusting the depth of cut. You could use a boring head set up in a Morse holder in your QCTP and put on the cut by adjusting this.

A better way would be to make a template that uses a rounded or ball bearing follower, but this is more difficult. If you can draw out the profile, it is easy to get a template CNC water-jet, laser or plasma cut from sheet.

[jugs]

Tracer sounds hydraulic

Yes it's a copy attachment that bolts on back of lathe + a hydraulic tool-post,

If you have a sample - to make a few off is quicker than CNC as there is no programing time, just mount the original on tracer table, put blank in chuck, zero tool & tracer finger, start cutting - simples

john


edit - http://www.copy-turning.com/hydrauli...ing_attachment

this is turning wood but is same for metal - http://www.youtube.com/watch?v=tn6ZbnwWeJ4 see @ 3 mins
john

[plunger]

I remember seeing a photo of this setup somewhere. One without hydraulics. I sort of understand a template follower but struggle with the set up . i tried looking under copy attachment on google but no luck. Any better terminology for this when I do a google search

[Black_Moons]

I have seen lathe copy attachments that are just mechanical followers, But mainly for wood lathes. A metal one might work with light cuts.

As for doing it 'manualy', I would likey cut to size/diamiter all the ledges with a parting like tool after laying out lines on the part, Then just rough it in either using the compound (Most accurate) or by having power carriage feed enabled and moving the cross slide axis by hand. You don't have to be 100% for decorational parts, And a heavy sanding will smooth out all the transissions beween diffrent angles.

Assuming you mean just the 'handle' part, and not the elbow and bent part. Those would be much harder to make.

Have you asked them if they could just get thier existing ones chrome plated?
Maybe not directly plated, but usally theres a metal you can plate something with, that can be plated by another metal, that then can be chrome plated.

[JCHannum]

Here is a photo of a very simple manual tracing attachment in use. The concept can be adapted to any lathe, a fixed stylus on the cross slide that contacts a profiled template.

In the photo, the template is being held in the drill chuck of the tailstock. It can be located in a number of places depending on the set up and complexity, but for a long piece such as being contemplated, the rear of the machine is best. The template holder should be relatively stout, but the follower need not be pushed in with a great deal of force.

The cutting tool should be radiused for the best results. The follower and cutting tool are approximately the same radius.

http://img.photobucket.com/albums/v3...9-0966_IMG.jpg

I was fortunate enough to pick up a hydraulic tracer for a ridiculous price, and have had a lot of fun with it.

[neonman]

Plunger, try investment casting. You can expect accuracy to .005 to .010, and you can offer them the part in many different metals. SST would be a good choice since they are wanting low mantanence. If there is an art foundry near you, discuss the project with them

Neonman