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Benders and Bending Which bender is best? How do you use a bender? How do you calculate bends? Everything Bender related...


Benders and Bending Which bender is best? How do you use a bender? How do you calculate bends? Everything Bender related...

View Poll Results: How do you drive your tube bender?
Manual or ratchet / cheater bar 59 28.92%
Harbor Freight air-hydraulic jack 63 30.88%
SPX or Enerpac type air-hydraulic 29 14.22%
Electric hydraulic 44 21.57%
Other 9 4.41%
Voters: 204. You may not vote on this poll

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  #101  
Old 06-23-2016, 06:31 PM
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ducas99 ducas99 is offline
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Anyone use a swag off road bracket to mount a double acting cylinder for a elec hydro set up?
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  #102  
Old 11-26-2016, 11:30 AM
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bullnerd bullnerd is offline
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Well that sucks, typed out a long explanation and hit reply, got the "page does not exist" notice!

Heres the condensed version.

Harbor freight pipe threader (like used on the Swag tube roller setup) driving a pinion made from or similar to, an auto starter pinion gear, driving an auto ring gear/flex plate/ fly wheel, driving an over the counter JD tube die?

What do you think MR Bandit? Is that enough reduction? Would be cheap, and electric would be easy to make an electric stop. If it would do 1-1/2" tube, id be happy.
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  #103  
Old 11-28-2016, 12:49 PM
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TheBandit TheBandit is offline
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Yes I'm sure that could work. You can make just about any power source bend tube with the right amount of gearing.

Let's try the numbers. The HF 62203 specifications indicate it puts out 2.15hp. That is 1,183ft-lb/second. Based on https://www.youtube.com/watch?v=R2qX4v-eIEw, it looks like it can turn half a revolution in about 2 seconds, or 0.25rev/sec. Converting this to radians per second, the output runs at 1.57rad/sec. Now divide the power by the speed to get torque: 1,183ft-lb/sec divided by 1.57rad/sec = 753ft-lb. So that tool, if you believe the HF specifications, can deliver roughly 750ft-lb of torque at the output shaft. Now if you want to bend tubing, I've said in the past you need around 5,000ft-lb for 2" capacity. Therefore you would need a gearing system that would deliver a ratio of 5,000/750 = ~7:1. A SBC flywheel is either 153 or 168tooth and the mating starter is 10tooth, so you can get either 15:1 or 17:1 reduction with that combination. That would give you a 2x safety margin and bend tube at about 90degress per 15seconds. I say go for it! I would be interested in whether or not the gearset could handle the torque.
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Last edited by TheBandit; 11-28-2016 at 01:10 PM.
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  #104  
Old 11-28-2016, 04:32 PM
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Wow, that sounds cool! Thanks Mr. C, I knew I was asking the right guy.

So the plan would be to mount the HF motor and gearing down in the base with some form of insulation to deaden the sound of the whiney motor, and add weight down low. And feed up to the die with a cheap, stock auto axle, splines on top. Possibly using unit bearings at both ends? Haven't thought that one through yet.
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  #105  
Old 11-28-2016, 04:47 PM
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TheBandit TheBandit is offline
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The calculations should really be checked. 750ft-lb seems like an awful lot of torque, but it does use a worm drive to achieve gear reduction and that can result in very high torque. There is really no guarantee it would actually hold up to that kind of torque since I'm guessing normal use doesn't come close to using that much torque (imagine trying to hang onto that thing!). Also I don't know about an axle shaft holding up as a direct drive for the die. Take a look at these results: http://www.pirate4x4.com/forum/toyot...e-results.html

In theory, practice and theory agree. In practice, they don't!
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  #106  
Old 11-28-2016, 05:11 PM
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That is interesting. I had no idea the torque was that high.
I'm starting to rethink some of this.
Anyone have a HF threader that wants to do some experiments for the greater good? LOL.
Thanks again for the input. Nice to have someone other than my 18 yr old daughter to bounce my stupid ideas off of.
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