I have an application that I will need to put a 30deg. and 75deg. bends on the same plane on a 30" length of 1/2" EMT. This will be a production part. Is there a machine to do this? Has anybody seen internal or external plastic caps for conduit? This will be a handle for a cleaning tool.
I could do it on a punch press but that sounds just plain frightening. Or, are there off-shelf dies I could use on my 50-ton hydraulic press? (seems like overkill and it's slow)
I've been researching all night and have had a series of epiphanies. I figure about 4k pieces/mo and with a bit of futzing in the shop I think I can do the whole thing in-house...cheap! Made in the USA baby, by American union people! The friggin' Chinks can kiss my hairy ass!
First, did you know the premier mfr of emt benders is Gardner? LOL!!!
Since your application is non-critical, you *could* do these by hand, kluging together some stop clamped to your workbench and a some simple floor jig. Very easy, BUT you need some length of tube to make these bends, proly a min of 2-3 ft for 1/2".
You should be able to rig sumpn in a vise to bend this emt in a horz'l plane, along the lines of an hvac hand bender or a Diacro, to do these, as well, poss. using a Gardner hand bender.
Industrial electricians use a hydraulic version of this for repeat bends, or for large tube. I'm sure these are expensive, tho, but there are many diy designs for this, as well, and your press could be set for max speed -- using the Gardner hand bender as your die..
Also, you can buy premade 90 deg bends in emt, mebbe you can just cut at the right angle, if you don't need straight tube at both ends.
Caps: mebbe some standard tube size cap can be force fit. emt is an odd size, but they make these caps for all size tubings/gauges, so mebbe one comes close. I think msc has these.
Attaboy! I knew you couldn't resist the chance to build a machine to do it. I know I couldn't.
Lessee ... the cut-to-length piece is placed/dropped* on the bender. A hydraulic clamp grabs it between the 2 bend points. Hydraulic cylinders push rollers or shoes to bend the pipe against dies. The piece is unclamped and lifted/popped* out. Maybe 5 second cycle.
The rollers/shoes are on arms the same radii as the bends/dies so the hydraulic pusher doesn't have to worry about the motion path.
'Course there's a gazillion details to work out, but that's the fun of it. Hey, can I come work for you building this?
- it seems like straight, 30" pieces of 1/2" conduit could be automatically fed from a hopper. And the bent piece popped out into a basket. Totally automated.
Any standard hydraulic tubing bender could be tooled up for it, Tom. You'd probably want a mandrel-crimped style of bend for strength. Those look like they've been collapsed in on themselves on the inside of the bend.
I was gonna say "Dayum, that's a large brush to use such bristles as EMT, Tawm!"
Roll your own dies and/or bender, Tom. Or go new, but the Greenlees put simple bends in, keeping the inside of the tubing completely clear.
-- You are today where your thoughts have brought you; you will be tomorrow where your thoughts take you. -- James Lane Allen
How precise does it have to be? An experienced electrician can use a hand bender to make pretty consistent bends repeatedly. There are hydraulic conduit benders, but I never needed one for stuff 1" and smaller.
Gardner Bender manual conduit benders come with an instruction book. Follow the book and your pieces fit pretty well. I can make bends pretty darn fast, and if I had to do say 10 pieces the same, I would just mark them all then bend them all.
1/2 EMT is pretty soft though. I use it for hanging hooks in the shop for cords and rolls of conduit and smurf, but that is about the heaviest use I would put to it.
IMC might be a better choice for a tool handle (do they even make IMC in
1/2"?) unless you are 100% certain nobody will ever put much force on it.
If I had to do a lot of IMC I would either get a benchtop compact bender or get a hydraulic bender.
I guess the first question should have been, "How tight do you need the radius of bend? A compact bender might be the only choice if a conduit bender radius is to large.
The hand benders (hickeys?) that electicians use have handles about 3 feet long and it takes little effort to bend 1/2" EMT to 90° with them. So, if money and development time ARE an issue, I think the Harbor Freight $49.99 bender that is a mini-Hossfeld knock-off would work, (bench model) if you make your own dies. In fact, you might simply go to any electrical supply house and buy the 1/2" hickey and use it (slightly modified) for the inner die. Then, all you'd need is a simple concave roller to complete the set.
Good point, but not a killer; you can start with a 5' length and bend in four places, then cut into two identical parts. The common 'hickey' tubing bender, and a concrete floor with some tape markings, is all the jig you need for this; if you want to get fancy, the hickey can grow a couple of level vials to tell you when your angles are right.
Bending by hand is easy and quick; a hydraulic bender for 1/2" EMT is overkill.
I've designed servo hydraulic presses that position to 0.001", something like that would give you programmable end stops for the bends. Another idea would be to use servo motors with gearboxes to bend a specified number of degrees. Two servos and gearboxes could give you 2 bends simultaneously. I guess it makes a difference how many you plan to make, I like controls options because the components can be reprogrammed for future projects, plus the ebay prices are usually reasonable.
You could make your bending dies out of fixture metal. Just get a preformed part and boil up some fixture metal and pour yourself a forming die. Then you just need a hydraulic ram with a two stage pump.
One possibility. If both bends could be made at once... you could use 2 gear reduction servo motor indexers, configure to run to a setpoint and back, adjust setpoint for correct bend. Insert EMT, hit 2 hand trip control, both motors bend to setpoint and go back to load/unload position in a couple seconds (depends on power of motors), ready to remove bent part and place another blank.
One shift, 1000 a week, 25 an hour, 2 bends in 1/2 emt - automation may make it easier to find someone to do it, or allow them to do that and something else, but it's certainly within the very possible realm to crank them out with a hand bender at that rate. Likely not cost effective, but certainly possible, at more than minute per bend.
Probably even double that rate is quite achievable (or only half a day spent doing that job, which makes it more reasonable to pay a body and all it's overhead and still hit 50 cents cost to make), especially with a few simple jigs to make the bending "non-fiddly." Would also require a body that wants to work, not just push a button and get paid for it. More of those out there than you might think, but finding one when you want one can be tricky.