Smallest radius for 1/4" OD copper tubing.?

[deere_x475guy]

Well gang I decided I needed to build a tubing bender before I start on my next engine. The first tubing I need to bend is 1/4" OD copper tubing so my focus will be on that size to start with. I have a 1/4" ball end mill to mill a grove in the round die and the flat follower I have seen in several benders. I will start on it today but I am not sure of the smallest radius I can reasonably expect to make. What do you guys think the smallest radius I should shoot for?

TIA

 

[Cedge]

Deere
I spotted a neat source for bender wheels a while back. Ace hardware carries an assortment of small "block and tackle" style pulleys.... the type of thing you'd find on sail boats. The wheels are brass and already have the groove cut in them to accept a small rope line. They come in several diameters and groove widths and aren't expensive.

I picked up a couple and tossed them in my future projects box, just to see if they would work.

Steve

 

[deere_x475guy]

Cedge thanks, our local small town Ace looks forward to me coming in. The Siamese Twin has been there several times and I always got a lot of questions and great service when I am there. I am leaving for Meijers in a few minutes with the wife. I am going to pick up an aquarium pump while I am there and will look for the pulleys you are talking about.

 

[Powder keg]

A different way to cut the radius in the shoe would be to drill and ream the hole in some square stock. Then just mill the top half off.

 

[Mcgyver]

I could get down to a centre line radius almost equal to the dia, but no quite. plans like the Stuart triple call for centre line bends to a radius equal to the tube dia, so far that alludes me. Well, that's not true, i could do the bend, but what alludes is a bend that tight that still looks good and maintains the circular profile all along the bend. Like powder says on the shoe, drill ream and mill off half. the die is easier cut in the lathe rather than with a ball end mill imo.

 

[deere_x475guy]

Everyone thanks for your thoughts on this.

Mcgyer I did a seach and came up with your post on the other board and I really like the solution. I knew I had seen something similar to what you have and just found the plans here:
http://metalworking.com/Dropbox/_2002_retired_files/
Look for Precision Tube Bender.

I think I am going to give this a try. Moderators is it ok for me to post a build on this? If so where should I put it?

TIA
Bob

 

[deere_x475guy]

ARG!!!...one of those days. I just broke both ends of that 1/4" ball end mill. Two stupid mistakes in a row.....If this was 2008 I at least would have my quota of stupid mistakes out of the way ;D ;D. As it is now I am dozens of stupid mistakes over for 2007..... : :

Anyway looks like I will be taking kegs and Mcgyver's advise for the shoe. For the radius on the roll I remember seeing a post that talked about holding a tool just shy of vertical on the lathe. I am going to start making that tool as soon as this post is up...wish me luck...lol

 

[Tin Falcon]

Sure post the build in the tool section. Marv Klotz has already shared photos and descriptions of his custom tooling there. His posts and work are very much appreciated.
Tin Falcon

 

[deere_x475guy]

Tin thanks I should have thought of that....guess I am not on my game today. Your right about Marv, he is a great contributor to this board and I have used his programs for years now.

 

[Mcgyver]

I knew I had seen something similar to what you have and just found the plans here:
http://metalworking.com/Dropbox/_2002_retired_files/
Look for Precision Tube Bender.
TIA
Bob

lol, i put them there but had long forget about them - if you are going to build, check them carefully. I did them as an idea; they're not as builts or carefully checked. Also, the slot on the base should come a lot closing to the centre pivot axis, for some brain cramp reason i had an offset there.....closing would give more flexibility.

 

[deere_x475guy]

lol, i put them there but had long forget about them - if you are going to build, check them carefully. I did them as an idea; they're not as builts or carefully checked. Also, the slot on the base should come a lot closing to the centre pivot axis, for some brain cramp reason i had an offset there.....closing would give more flexibility.

HAHA...funny how that happens isn't it? Thanks for the heads up!!!