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Old 01-04-2020, 04:14 PM
ezreub ezreub is offline
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Default Tube Bending for Mini Bike

Hi,

After completing a go-kart two summers ago, my sons have it in mind to build an old-style mini-bike. They want to modify these plans that call for 7/8 inch round tubing roughly .085 in thickness, and I'm trying to figure out how to bend it without spending a fortune on a tube bender or going to a fabrication shop (we used square tubing on our go cart and no bending was needed). Does anyone have a good suggestion? On Youtube I've seen people use sand and bend the tubes around various objects or use a Harbor Freight hydraulic pipe bender with some success. I've seen some okay looking tube benders on ebay for about 90 bucks, though the bending radiuses seem a bit big. Please let me know what you think.

Thanks.
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Old 01-04-2020, 06:49 PM
mckutzy mckutzy is offline
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Ironically sand packing is used in industrial bending.. It helps prevent wall collapse...
This will be the best helping measure for these benders, aswell as lots of grease on the dies...

If you handy with wood, one could be built with plywood and 2x4's. Add some reinforcements with metal here and there... itll work...
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Old 01-05-2020, 01:55 AM
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http://www.diygokarts.com/vb/showthread.php?t=34894

I have built two with the harbor freight pipe bender, in the way the plans depict.

Once you go over 90 degrees with the HF bender, kinking and deformation becomes a thing. Sand helps as noted above. The 1/2in die fits the tubing well enough, but to make it easier/cleaner you could use 1/2in water pipe, what the bender was designed for. I would not trust this material for the forks.

Tubing is stronger, pipe is more malleable/bendable.

With time/patience it can be done with 7/8 tubing, one more thing to note is if you want the frame loops to be one piece, they need to fit around the bender, so the dimensions in the plans might not work out so well.
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Old 01-05-2020, 10:02 AM
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Quote:
Originally Posted by ezreub View Post
Hi,

After completing a go-kart two summers ago, my sons have it in mind to build an old-style mini-bike. They want to modify these plans that call for 7/8 inch round tubing roughly .085 in thickness, and I'm trying to figure out how to bend it without spending a fortune on a tube bender or going to a fabrication shop (we used square tubing on our go cart and no bending was needed). Does anyone have a good suggestion? On Youtube I've seen people use sand and bend the tubes around various objects or use a Harbor Freight hydraulic pipe bender with some success. I've seen some okay looking tube benders on ebay for about 90 bucks, though the bending radiuses seem a bit big. Please let me know what you think.

Thanks.
Get ya a harbor Freight bender & some water pipe

I've made a couple of things with mine

!Arriba!
http://www.diygokarts.com/vb/showthread.php?t=37852

Damien
http://www.diygokarts.com/vb/showthread.php?t=40084

Atom
http://www.diygokarts.com/vb/showthread.php?t=40167
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Old 01-05-2020, 03:01 PM
ezreub ezreub is offline
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Thank you all for these responses--they're very helpful. It sounds like the HF pipe bender is the way to go--maybe I'll give it a try on the 7/8" like Karl suggests and then if I can't get it to work, I can go with the 1/2 water pipe. I hadn't thought of that as an option--I didn't think it was strong enough. But those are some great karts, Functional Artist, and it seems like except for maybe the front fork it should be fine and maybe even for the fork.

The only other bender I was thinking about was this one: it got decent reviews and handle the 7/8s and comes with a bunch of dies. Not a very tight turning radius but not bad. I don't know if anyone has tried it but let me know if you have.

Thanks again for the responses.
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Old 01-05-2020, 10:17 PM
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I don't have any experience with "that" bender
...but, it looks like it's built more for use with material like conduit

Even the specs say: Wall Thickness of Pipe: 0.8-2.0mm

Q: How many ton bender?
A: Manual

* IMO waterpipe should work fine for the forks too

The !Arriba! kart (made outta water pipe) even holds up to poppin' wheelies

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Old 01-06-2020, 06:00 PM
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Okay, thanks, Functional Artist.

And nice wheelies!
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Old 01-26-2020, 11:38 AM
shelby1 shelby1 is offline
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Default tube bending

sand will work needs to be packed very tight and capped...... I did this a different way ....did the sand then used a cutting torch to heat the pipe to cherry red then slowly formed the tubing around a 4 inch pipe that clamped in to a vice......I made headers for flat head Ford motors in the 50s this way ....packem with sand welded freeze plugs in the ends heated them and formed them around gas cylinders....paid for my first car building headers this way...... Good luck
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Old 02-07-2020, 04:24 PM
metalhead1982 metalhead1982 is offline
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If you are going to be making more, you could drop the $75 (after coupons) on this bad boy.

https://www.harborfreight.com/compact-bender-38470.html
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Old 02-07-2020, 06:09 PM
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Quote:
Originally Posted by metalhead1982 View Post
If you are going to be making more, you could drop the $75 (after coupons) on this bad boy.

https://www.harborfreight.com/compact-bender-38470.html
The title lacks the word tubing or pipe, because it bends solid rod, not hollow tubing. It will just flatten tubing.

The pipe bender harbor freight offers does not cost much more.
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Old 02-09-2020, 08:54 PM
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There's a tubing bender style that occasionally pops up on ebay that can sometimes be found by searching "Imperial Tube Bender, or Handy Tube Bender" The style is round and is geared. They come in many sizes as small as 3/8" and as large as 1". People around here have used these to make handlebars, besides frames.
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