PDA

View Full Version : Another Freehand Lathe Tool



john hobdeclipe
04-20-2019, 09:23 PM
When I read this thread, http://bbs.homeshopmachinist.net/threads/77769-Turnado-freehand-turning-system I decided that I needed something of this nature, but I wanted something a bit heavier and more robust. And I didn’t really like nor see the need for the pantograph tracer. So after a bit of pondering and conjuring, I built this:

http://www.auldooly.com/imagehost/P3100231-19.jpg

This plate bolts to the cross slide of my lathe and has an array of 1/4-20 holes to accept a pivot pin and various motion limiting stops that I made. Note the pivot pin in the corner near the motor.

http://www.auldooly.com/imagehost/P3100237-19.jpg

A “radius bar” fits into a groove at the bottom of the tool and controls the curvature of the cut.

http://www.auldooly.com/imagehost/P3100240-19.jpg

I can do concave and convex radius cuts.

http://www.auldooly.com/imagehost/P3100245-19.jpg

More to come…

john hobdeclipe
04-20-2019, 09:24 PM
First real creation was this lamp finial:

http://www.auldooly.com/imagehost/P3100251-19.jpg

It works well using it freehand:

http://www.auldooly.com/imagehost/P4200325-19.jpg

And I can use it as a ball turner, also:

http://www.auldooly.com/imagehost/P4200326-19.jpg

Just playing:

http://www.auldooly.com/imagehost/P4200327-19.jpg

More to come….

john hobdeclipe
04-20-2019, 09:26 PM
I made a setting device to set the cutting radius reasonably precisely. Here I’m setting it to 4” concave:

http://www.auldooly.com/imagehost/P3100241-19.jpg

And here it is at 2” convex radius. The surface that the cutting bit is against is equal to 0” on the rule. The cap screw keeps the cutting edge back behind the end of the “foot” and that make the tool stable. Below the cap screw is a template follower. For template work, I align the cutting tool and follower against the setting surface.

http://www.auldooly.com/imagehost/P3100235-19.jpg

For template work, the cutting tool and the follower must be ground to the same radius and aligned vertically.

I’m not using the pantograph system of the “Turnado” tool. I made a holder to align the template directly below the workpiece. I think this will work better by eliminating any inevitable looseness in the panto pivots. The drawback to this method is that it somewhat limits the max diameter of my workpiece. Here is the template holder mounted on the table

http://www.auldooly.com/imagehost/P4200330-19.jpg


I decided to jump in head first and turn a largish piece to a pattern. So I made a template of 1/8” thick acrylic, put a piece of 2-1/4” dia. X 9-1/2” long aluminum in the lathe, and started learning.

This will be a candle holder, so first I turned a tenon on what will be the bottom. This will fit into a base, yet to be made.

http://www.auldooly.com/imagehost/P4100283-19.jpg

More to come…..

john hobdeclipe
04-20-2019, 09:30 PM
Rough out the shape manually using the carriage and cross slide feeds.

http://www.auldooly.com/imagehost/P4120296-19.jpg

Set up the template and start cutting to final shape:

http://www.auldooly.com/imagehost/P4130297.JPG

Flip the template and do the other end. A 5/16” stud is threaded into the bottom of the tenon, gripped in the 4 jaw chuck, then the tenon is centered. Note the stop screwed to the table, lower left, to keep me out of trouble:

http://www.auldooly.com/imagehost/P4130305-19.jpg

And here is the finished piece, after polishing:

http://www.auldooly.com/imagehost/P4180322-19.jpg

This is fun! I think I could play with this for the next ten years and not get bored.

Next I need to make a way to accurately set the height of the cutter, and incorporate it into the setting device. And work out a more accurate method of grinding the cutter and the template follower to match.

kev74
04-20-2019, 09:37 PM
I like it!

lakeside53
04-20-2019, 10:39 PM
very nice!

mickeyf
04-20-2019, 10:51 PM
yes, Very!

Tim Clarke
04-20-2019, 11:10 PM
Yes! John, you need to submit this to George as an article for the magazine!!!!

Sun God
04-21-2019, 04:02 AM
This pleases me. Glad I could share something that was inspirational.

I was thinking about the Turnado again yesterday, so it's fortuitous that this should be posted. Great execution.

john hobdeclipe
04-21-2019, 10:32 PM
Thanks, guys.


This pleases me. Glad I could share something that was inspirational.

I was thinking about the Turnado again yesterday, so it's fortuitous that this should be posted. Great execution.

And thanks especially to you for the original post!

I had done a bit of freehand turning of brass and aluminum using a makeshift tool rest and woodworking lathe tools, but I was never fully comfortable with it. This rig is much safer, I think. It was the use of wood lathe tools that led me to a design with a long handle.

plunger
04-22-2019, 04:21 AM
I have often puzzled how to do curvy shapes and have a need to do so right now. I cant see how the template is followed by the cutter. What part of the cutter body follows the template.?

john hobdeclipe
04-22-2019, 07:51 AM
I have often puzzled how to do curvy shapes and have a need to do so right now. I cant see how the template is followed by the cutter. What part of the cutter body follows the template.?

I'll get a better picture of that aspect and post it later today.

George Bulliss
04-22-2019, 09:08 AM
Yes! John, you need to submit this to George as an article for the magazine!!!!

Yes, would love to have this in one of the magazines. PM me if interested.

john hobdeclipe
04-22-2019, 05:24 PM
I have often puzzled how to do curvy shapes and have a need to do so right now. I cant see how the template is followed by the cutter. What part of the cutter body follows the template.?

Here's a better pic of the cutter/follower arrangement. Note that the template is about 5/8" above the table. On the tool itself, the follower protrudes from the front of the body, directly below the cutter. The follower is held in place by a brass machine screw.

And note that both the cutter and the follower are about 3/16" behind the front of the foot, so that the downforce from cutting keeps the whole rig stable.

http://www.auldooly.com/imagehost/P4220338-19.jpg

Dan Dubeau
04-22-2019, 05:57 PM
Nice job John. Well thought out and executed. I like the template idea. I can see that being very handy for ornamental stuff.

J Tiers
04-23-2019, 12:10 AM
I assume you do not even have to keep the tool perpendicular to the work, since the tool tip and the follower are exactly above one another.

john hobdeclipe
04-23-2019, 07:59 AM
I assume you do not even have to keep the tool perpendicular to the work, since the tool tip and the follower are exactly above one another.

Correct.

Mcgyver
04-23-2019, 10:53 AM
fun stuff.....gazing into my crystal ball, I see a brass and AL chess set in your future :D

john hobdeclipe
04-23-2019, 12:06 PM
fun stuff.....gazing into my crystal ball, I see a brass and AL chess set in your future :D

Well...don't know about that. Never been much of a chessist....haven't played since high school.