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View Full Version : Ideas on Converting HFT Rod Bender to Tubing Bender



bill70j
09-28-2012, 01:37 PM
Thanks ahead of time for any and all ideas on my project! I would like to know how to machine grooves into flat sided cylindrical metal bender dies to accept tubing. Here are the particulars:

I am doing an engine swap on a '87 Jaguar and am in the midst of building the air conditioning system. I need to custom bend AC tubing to fit the new engine compartment.

I have had a lot of success with this metal bender (http://www.harborfreight.com/bench-top-bar-and-rod-bender-38471.html) on flat stock and rod, and would like to convert the dies so they can also be used to bend tubing. I am working with 3/8, 1/2, and 5/8"D aluminum 6061-T6, 0.065" wall thickness. I annealed the 3/8 and bended it is a conventional Eastwood hand-bender, which worked great, but now I need to do the 1/2 and 5/8 stuff.

In my first attempt to machine a 5/8" groove into the 3" bender die on the lathe, I grinded a pair of 1/2" HSS tool blanks to a 5/8" round profile, with a 10 deg end clearance angle, but without side clearance or back rake. I got the groove done, but the chatter was such that it took forever, and the final product shows the chatter marks, which I don't like.

Is there a better grind for the lathe tools, or a better way to machine these grooves? Or maybe even a better way to accompliush what I'm trying to do? Thanks!! I have a 3-in-1 machine, a horizontal rotary table, but not much more. Thanks!!

Oh, I forgot to mention, that I thought of chucking a 5/8" ball-end mill and using the horizontal table, but am scared of doing something like that without prior experience or knowledge.

531blackbanshee
10-03-2012, 04:19 PM
if you could tilt your mill head over,then you could use an endmill and your rotary table to cut the groove.

or build your self a radii cutter and use your lathe and cut them that way.

http://www.ebay.com/sch/i.html?_nkw=radii+cutter&_sacat=0&_odkw=radi+cutter&_osacat=0&_from=R40

to expensive to buy(for me anyways)but i built my own.

https://lh4.googleusercontent.com/-VSdvWQasSZU/S-1GRfYZHpI/AAAAAAAAAwk/-CAGxJ023lU/s800/tdubswingarmaeroshiftlinkage.JPG

which went along with my home built tubing bender.

https://lh3.googleusercontent.com/-gDBuB0IbV2A/S-1GS3V-o_I/AAAAAAAAAw0/29g1IA1EQRQ/s800/tdubswingarmaeroshiftlinkage%2520%252812%2529.JPG

that i use to build things like this

https://lh6.googleusercontent.com/-p3k77S5-glA/UGyfoBJRp1I/AAAAAAAACB4/q7krpisNjVs/s800/krazyridersunderbracedkz650%2520%25285%2529.JPG

and this

https://lh5.googleusercontent.com/-mxB0LQAg-_g/TBZJTUEBSaI/AAAAAAAAA5A/Pa1r1b2C9Y4/s800/z1rluggagerack%2520%25281%2529.JPG


i hope some of this helped,

leon

531blackbanshee
10-03-2012, 04:36 PM
i used a hand ground hss form cutter to machine this one for 1/2" tubing.

https://lh4.googleusercontent.com/-n173YwVXDvU/S1IU1ZrELyI/AAAAAAAAAfQ/CevT5gwb2Z8/s800/PICT0058.JPG

if you think you can do it,you can.

if you think you can't,your right.

leon

Bob Ford
10-03-2012, 10:46 PM
You could use a vertical mill, 1/2, and 5/8 endmills, and a rotary table. Using the side of the endmills to cut your grooves.

Bob

bill70j
10-04-2012, 09:29 AM
You could use a vertical mill, 1/2, and 5/8 endmills, and a rotary table. Using the side of the endmills to cut your grooves.

Bob

Thanks for everyone’s ideas. Very helpful.

To groove the bender dies, I ended up using standard bits to rough out the grooves on the lathe, then for cleanup used a hand ground HSS pattern bit and a rat-tail file.

Here is a pic of the set-up for 5/8” tubing. The dies can be flipped end-over-end to return the bender to use with rod and bar stock. I am building an extension for the bender’s stop block to serve as a fence to make it easier to secure the tubing while bending.

My attempt at annealing the aluminum tubing was a dismal failure. I covered the bend area with acetylene soot, then burned it off using a neutral flame. But after it cooled, I saw that the tubing had cracked, making it completely useless. I would appreciate any better ideas or methods for annealing aluminum tubing. Thanks!!

http://i1113.photobucket.com/albums/k515/bill70j/Bender1.jpg
http://i1113.photobucket.com/albums/k515/bill70j/Bender2.jpg
http://i1113.photobucket.com/albums/k515/bill70j/Bender3.jpg