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lynnl
02-25-2004, 10:23 PM
Was browsing thru some old MW mags and came across a John Forster article on making some candle holders. They were truly beautiful! I've tried that a few times but with pretty disappointing results. John advises to turn from large dia to smaller, which makes sense. And in fact I can sometimes get pretty good results on the convex surfaces. But concave, and especially at the inflection points, things start to get nasty. Does anyone have any good tips to offer? Or is this another of those 'practice, practice, and then practice some more' issues.

John Foster
02-25-2004, 11:12 PM
lynnl, thanks for the kind remarks. I know the problem you are having and practice is a whole lot of it but a 1/2 round file of various sizes help too! Get as close as you can and then finish with the file. Hope to have some more projects, one of these days. John

spope14
02-25-2004, 11:56 PM
Quick Quick!!!!!! What mag, and what dates!!!!!

I have just got to try this!

x39
02-26-2004, 12:28 AM
I've made quite a few items on the lathe that were ornately curved. I generally cut out a cardboard template to check my work with. I find it helpful.

lynnl
02-26-2004, 11:44 AM
Spope, I don't have it available right now, but I think it was a Dec-Jan issue of MW... 2002-03 I think. But may have been 2001-02.
I'm sure it was MW.

Correction: That was the 2000 Dec-jan issue of MW.

[This message has been edited by lynnl (edited 02-26-2004).]

mklotz
02-26-2004, 02:31 PM
One way to do complex, non-dimensionally-critical shapes on the lathe is to use
a square ground tool to cut a 'stairstep' profile that mimics the required
shape and then file or hand-turn the resulting piece to the final finished
shape.

Lautard suggests this technique for cutting spherical shapes but it's equally
useful for other shapes. I've used it for both spheres and ogives (rocket nose
cone shape). See the BALLCUT and OGIVE programs on my page.

For more complex shapes, I wrote PROFILE. It allows the user to specify, via a
data file, the part outline and then produces a cutting schedule that you can
use to rough out the stairstep form.

The overall technique is somewhat tedious but, if you're sculpturally
challenged as I am, allows one to reliably generate a usable part on the first
try. Not recommended for production but this is a recreational group, eh?

All the programs on my page are free so it won't cost you anything to give it a
try.

Regards, Marv

Home Shop Freeware - Tools for People Who Build Things
http://www.geocities.com/mklotz.geo

DR
02-26-2004, 03:32 PM
When I was in college back in the sixties I worked in a shop that made boat air horns from brass castings. An old retired gentleman would come in about once every two weeks and run a bunch. The shop owner depended on this man, but worried because of his age that they wouldn't be able to depend on his ability in future years.

The man did the outer/inner profile turning strictly by hand/eye coordination. I watched a couple of times and it seemed nearly impossible to achieve the smooth contours he was able to do. These ranged from about 4" diameter up through about 10" at the big end. I'm pretty sure he used power feed longitudinally with the cross feed done by hand.

One of my jobs was to set up some sort of tracer attachment in case the man wasn't able to do the work any longer. He didn't show up for a couple of weeks once and I got a chance to adapt the old tracer the shop had laying around. I still vividly remember the look of disappointment that flashed across his face when he saw what I'd done. No one realized the pride he took in his hand turning. He quietly removed the tracer and continued doing the horns by hand. I heard that soon after I went back to classes that fall the company switched over to a modern electronic horn design so his services were no longer needed for turning.

michaelm
02-26-2004, 03:49 PM
lynnl,

We do quite a bit of hand turning in our shop and even made up a special set of chisels:
http://www.hammerinhand.com/uploads/scrapers3.jpg

One of the things I have found to be indispensible on the 1820's treadle lathe is the "jack" on the back side of the saddle. This is basically a screw that allows you to tip the saddle up or down in order to raise or lower the height of the rest. When things get sticky, I have found that it is usually the angle that the tool is being held at.

I am currently hand turning 180 small carving chisels at the new shop, and am working on a design for such a jack that will mount on the cross slide.
I would love to hear from others who have done a bit hand turning!

michaelm
02-26-2004, 03:58 PM
should clarify:

By tool angle, I mean specifically the tool itself, not the edge. If your rest is stationary in the z axis, Then to raise or lower the tool edge necessitates changing the over all angle. By raising or lowering the rest this problem is eliminated.

does this make sense??

jeastwood
02-26-2004, 07:49 PM
I use mklotz's method all the time to turn balls. I wrote a small program that takes the diameter of the stock, desired radius, and size of steps as inputs, and prints out a schedule of feeds to use to get a nice "piecewise linear" approximation of the shape. Apply layout dye, then use a file until the dye disappears. It's quite quick and gives good results.

Toolmaker Extrodinair
02-26-2004, 11:59 PM
a tip for the candle end, use a taper pipe reamer for the actual candle holder. Made two sets out of naval brass, one for the wife and one for the mother-in-law. Use your imagination as they will be unique and unlike any store bought pieces. Good luck.