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Old 03-27-2017, 02:31 AM   #1
[JP]
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Default How to bend handlebars? tips on how to be accurate?

Hi gents,
wonder if anyone can help here.

So I have a JMR tube bender with a 1" die with a 3,5" CLR (couldn't find anything with a tighter radius).

I've been bending some bars to try out but I'm finding sometimes they come out different on each side.

So let me give you what I'm doing. I first bend a 150deg bend, previously marked every inch and half.
and then as I was bending, I was marking out every 10deg.
this allowed me to find out how much material is used for a certain bend.

this is all good and matches perfectly my marks.
My problem is on the bending on the same plane.

So what I have done is I have a level gauge clamped to the end of the tube.
So say I put the tube in place and reset the gauge to 0deg.
bend the grip.
then I turn the tube until I get the desired pull back - say till the gauge shows 150 deg.
then I bend the first bottom bend, slide the tube over, make sure the gauge shows 150 deg as before and then bend the second bottom bend.
then i turn the tube all the way till the gauge shows 0deg and bend the second grip (this makes the first grip be on the same place as the second)

So this is all nice and dandy on theory, but I'm finding is I think the tube is turning slightly as I bend it.
meaning that both tubes that rise up dont sit flat when laied on a bench.. one is higher by 1/4 inch or so.

damn I dont even know if I'm explaining this right.
anyway... any tips for keeping things more accurate?
And also does anyone know if there's anything available that makes a tighter bend? some handlebars seem to have a really tight radius.

I've bent these on saturday morning before taking the bike out to break the engine in.


here's some photos of my setup



on this one you can see the gauge bolted at the end of the tube. this was right at the start when I was still playing with lengths, now I use a shorter lenght, about 5ft


and how it all comes out
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Old 03-27-2017, 06:58 AM   #2
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Default Re: How to bend handlebars? tips on how to be accurate?

Don't know for sure,but I think you need to support the "free" end of the bars while bending. You are probably getting some twist from simple gravity pulling down on that end. They do look nice though. Good job
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Old 03-27-2017, 07:36 AM   #3
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Default Re: How to bend handlebars? tips on how to be accurate?

yes, it's exactly that what I'm getting!
I think when it starts bending, its slightly turning, as when it ends is like 2degs out from the previous bend.

there's 2 "pinch" adjustments done with a bolt. there's one bolt on the backing die and one on the radius die - this one holds the tube, but I havent done it up too much as it marks the tube.

Might I should try and put a bit of ally between this bolt and the tube, and then tighten it up hard, see how it goes.
but would love to hear from people that do this how they manage to get accuracy.
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Old 03-27-2017, 08:33 AM   #4
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Default Re: How to bend handlebars? tips on how to be accurate?

It's good to use a level to try to keep everything in the same plane, but you gotta make sure your bender is 100% level in all directions or your perfect bubble read will be "off" compared to the world.
What you are doing isn't easy and it looks like you are doing pretty good for a start.
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Old 03-27-2017, 09:05 AM   #5
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Default Re: How to bend handlebars? tips on how to be accurate?

I use a digital gauge on the end of the tube, the gauge doesnt move at all.

So what I do is slide the tube in
Attach the gauge in the end and reset to 0
bend the right hand grip
then I slide the tube and rotate it to achieve the desired pull back - say till gauge reads 150deg.
bend the first bottom bend
slide tube and make sure gauge still reads 150deg to bend the second bottom bend - this would mean the 2 bends are on the same plane.
then slide the tube and rotate it so gauge reads back at zero, so the second grip is bent at the same plane and pull back as first grip.

Do you think the bender being leveled makes a difference, seeing as I'm using a digital gauge and can reset at zero when I start? I can't see/think how it would affect it the bender being leveled.

I think, as KCGran says, the tube is rotating slightly when I'm bending it, meaning the second bottom bend ends out about 2 deg out from the first one. this is where I'd like to know tips on how to stop the tube rotating.

everything else is spot on now, where I mark it to bend and where i mark it to finish is perfect. I do all the marking on the straight tube, as I now know how much material is used for x amount of bend.
something like this -

grip 7" - 95deg bend 5" 1/4 - 6" rise - 85deg bend 4" 4/8 - 6" wide straight - 85deg bend 4" 4/8 - 6" rise - 95deg bend 5" 1/4 - grip 7"

I'm really enjoying making the bars, soon I'll start making them like rabbit ears etc and other designs. I'm no professional but I'm enjoying it.
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Old 03-27-2017, 10:26 AM   #6
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Default Re: How to bend handlebars? tips on how to be accurate?

I used to work with professional tube fabricators who made the very complex multi-bend hydraulic tubing used in aircraft. They were running CNC benders that were programmed to make all the bends and rotations in sequence exactly the same every time. The fabricators were very highly paid individuals even with all the high tech machinery, since every single tube had to be checked and tweaked to get it to fit properly. It's just the nature of metal tubing to not be perfect. The grain structure causes it to react a little differently to bending at different places. Using ERW (electrically welded tubing) with a seam will make it worse, DOM (drawn over mandrel) will be better, and extruded tubing would be best, but most expensive, to work with. You'll probably still end up needing to tweak it a little though. It looks like you've got a good process worked out though, better than I've ever been able to manage.
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Old 03-27-2017, 02:24 PM   #7
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Default Re: How to bend handlebars? tips on how to be accurate?

You need a few things.
!] a heavy table (steel is nice, being able to level the table is best,this can be done simply by shimming under the legs)
2] A good angle level
3] HD bending bar 96806-40. http://www.ebay.ca/itm/Harley-Frame-...xXYBao&vxp=mtr
Pricey, like impossible to find so look it over and fabricate your own.

To start place your bars on the table with the front of the bars face down.
Do they lay flat on the table? if yes skip next step.

If no they need to be twisted so they do lay flat. Do this by putting one side off the table, lay a board or piece of steel 2x2 angle will do, across the 2 legs of bend you left on the table (this is best done at a corner on the table) and clamp it to the table. Use your HD 96806-40 and level to correct the twist.

Now with the face flat to the table check your kick back angles at your next bends (do this in 2 directions) Likely they will not match.

Usually I will clamp the bars down at the corner of the table with the top bend close to the tables edge. Then with 96806-40 correct the angles to match or to your wanted specifications. If these are 6 bends you get to repeat this step on the next bends.

Last draw out a T on your table set your bar lined up with the top of the T and bottom bar tube centered on the leg of the T and check you 2 bottom bends. Correct as needed.

When you do a few you will usually do this in 20 minutes.
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Old 03-27-2017, 03:47 PM   #8
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Default Re: How to bend handlebars? tips on how to be accurate?

Thanks Joe.

so basically there's no way of them coming out perfect? Must have been lucky on my second attempt as they were spot on, but were also the only ones lol.

Thanks for the tips, I'll make one of those bending bars, seems pretty easy.
guess basically cut 1" tube in half and use that welded to a bar with a gusset behind. that should work...
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Old 03-27-2017, 04:49 PM   #9
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Default Re: How to bend handlebars? tips on how to be accurate?

This is a good video:
https://youtu.be/lyKStnmu5I4
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Old 03-27-2017, 05:01 PM   #10
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Default Re: How to bend handlebars? tips on how to be accurate?

yep.. that's from that video that I got the idea of using the digital gauge.

however, that video doesnt help me because he does it in 2 halves. so it will always be flat on a table.
I'm doing it all from one single piece. but I think what joe suggests will work to make little tweaks.
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Old 03-27-2017, 08:28 PM   #11
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Default Re: How to bend handlebars? tips on how to be accurate?

Not impossible to get it right bending, but no big deal if your a little off or have bent your bars to straighten them.
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Old 03-27-2017, 09:20 PM   #12
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Default Re: How to bend handlebars? tips on how to be accurate?

Just a crazy idea, if your up bends are consistently the 2 degrees off as you say, couldn't you rotate the tube the two degrees with your gauge before the second bend? But if I guess the rise of your bars at 18" and given the .250" gap you're saying your giving when laid flat on the table , you are only off .79 of a degree. I'm curious what the degree of accuracy your gauge is? If it's plus or minus one degree it would miss this. For a back up to the gauge I would clamp the tube pre bend to a flat surface and draw line along its length with a fine sharpie,laying the sharpie flat on the table,( if you have to tape a pice of some thing to the marker to make the point .5" off the table) then affix a pointer to your bender, bolt your gauge to the tube and set to zero, rotate the tube to your 150 degrees and make your first top bend. Then slide it to your next bend rotating the tube back to zero. Your pointer should be back on the line, make that end and move to the next checking your gauge against the line/ pointer.
I'm a welder/machinest/ fabricator by trade and I'm always amazed at how accurate you can be using the lines on the dials of machines. Of course we won WWII using those dials so why shouldn't they be accurate? The line and pointer is the same thing.
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Old 03-28-2017, 02:33 AM   #13
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Default Re: How to bend handlebars? tips on how to be accurate?

ohhhh I like that idea with the line.
the 2 degrees off is not consistent, to be honest I have only bent 3 sets so far, with pretty good results for a newbie I may say so.

I will try what you suggest KCgran, I like that!
Next set of bars I'll do that.
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Old 03-28-2017, 05:32 AM   #14
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Default Re: How to bend handlebars? tips on how to be accurate?

Would one of these be useful?

http://www.homedepot.com/p/Klein-Too...-203195010-_-N

Electricians use them for conduit bending.
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Old 03-28-2017, 05:43 AM   #15
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Default Re: How to bend handlebars? tips on how to be accurate?

mehhh.. not really. the digital gauge I have shows the exact angle. that's how I know I was 2 degs out.
bubbles are not accurate enough.

the main thing here is the tube is turning as I'm bending it, so was looking for tips on how to stop it from turning, but seems like I have a few ideas to practice over the weekend.
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Old 03-28-2017, 05:14 PM   #16
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Default Re: How to bend handlebars? tips on how to be accurate?

DOM doesn't fight as much as CREW.
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Old 03-28-2017, 10:21 PM   #17
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Default Re: How to bend handlebars? tips on how to be accurate?

So I have a point for you to think about. As stated in my earlier post, if you apply trig to your quarter inch difference in the planes of the tubes going up, and assuming there is an eighteen inch rise on them, you are truly only out .79 degrees. So if your gauge only measures in whole degrees you could easily be out that on your gauge by being at 359.6 degrees on the first bend and 0.4 degrees on the second bend. I of course am assuming your gauge rounds up or down from .5 to the nearest whole number. The line and pointer technique will help you be closer than that I think. Now I'm wondering if you shouldn't make a second line at 150degrees from the first to make your grip bends with the line and pointer technique.?
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Old 03-29-2017, 02:45 AM   #18
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Default Re: How to bend handlebars? tips on how to be accurate?

the gauge actually shows .1, .2, .3... so it's pretty accurate.
now thinking about it, it's probably not 2deg out, is less than that. the rise is only 6" (marked on the straight, not counting the bends)

I'll have to have another play at the weekend.
I need to work on my idea of mounting a panhead type handlebar clamp on springer forks, because I like narrow handlebars at the bottom, and after I'll play on bending some more bars

DOM and CREW.... will have to look for that. find it really difficult to find the right tube in 1" around here. not many places sell it. the more common one is 25mm, 1" is 25.4mm
wall thickness is also a pain to get the right one, I managed to find 2mm thick, about 0.083

cant even find stainless steel tube! that should be on about 3mm thick? 0.120?
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Old 03-29-2017, 06:05 PM   #19
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Default Re: How to bend handlebars? tips on how to be accurate?

.


Steeltubedirect.co.uk Sell tubing online. You need to use a seamless tube to get consistent bends. Ask them which tube is best for bending

Last edited by Mick Ridley; 03-29-2017 at 06:19 PM.
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Old 03-31-2017, 02:42 AM   #20
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Default Re: How to bend handlebars? tips on how to be accurate?

damn!! the seamless stuff is well expensive!
I paid £20 for 6 meters of the stuff I'm using which is 2mm thick

on that website, the seamless, 2mm thick is £56 for 3 meters...
I guess you have to pay for quality!

oh and thanks for that website link, didn't know about that.
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Old 03-31-2017, 03:47 PM   #21
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Default Re: How to bend handlebars? tips on how to be accurate?

Hi JP,

£56 For 3 meters is a lot even if it includes carriage.

I found that site by doing a search on "Steel tube stock holders uk"

I did a search on " Steel stockholders Southampton", and found this site, It looks like they will supply and deliver small quantities https://www.metalsupermarkets.co.uk/metals/round-tube/
These 3 tube types from that site are seamless and should be ok for what you need, but call them to be sure...

Cold Drawn Seamless (CDS)
Drawn-Over-Mandrel (DOM)
Hydraulic

I live 20 miles south of you in Stockbridge, if you need some more help, PM me, and Ill ring you and try to help

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Old 03-31-2017, 03:52 PM   #22
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Default Re: How to bend handlebars? tips on how to be accurate?

Hi JP,

£56 For 3 meters is a lot even if it includes carriage.

I found that site by doing a search on "Steel tube stock holders uk"

I did a search on " Steel stockholders Southampton", and found this site, It looks like they will supply and deliver small quantities https://www.metalsupermarkets.co.uk/metals/round-tube/
These 3 tube types from that site are seamless and should be ok for what you need, but call them to be sure...

Cold Drawn Seamless (CDS)
Drawn-Over-Mandrel (DOM)
Hydraulic

I live 20 miles south of you in Stockbridge, if you need some more help, PM me, and Ill ring you and try to help

Mick
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Old 04-02-2017, 02:15 PM   #23
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Default Re: How to bend handlebars? tips on how to be accurate?

On another note.

I have been talking to some of the dudes on instagram and they are using dies with a 2" CLR in order to get the right radius at the bottom of handlebars, now.. these dies are not available to buy, they have to be custom made.

anyone have any idea where to start to ask someone for a price to get one made? even if in the US as I can get a friend to bring it over.

I have a 3" CLR die for 7/8 bars, but I dont think they can be modified as its hardened steel.

thanks
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Old 04-14-2017, 11:10 PM   #24
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Default Re: How to bend handlebars? tips on how to be accurate?

I was a muffler guy for about 4 years. later I bought a JD2 bender for my personal projects. It looks similar to what your using.
In the exhaust world we would make our first bend then slide a degree wheel over the tubing and set it at zero degrees. The degree wheel would be clamped to the tubing and usually the tubing was fed through the bender in one direction. We would roll the tubing 180 degrees if we wanted opposite bends, we would keep it at 0 if we wanted bends on the same plane. Since we knew that our first bend was at 0 degrees it made it somewhat easy to establish how to properly rotate our tubing.
I've built quite a few handlebars and I typically use a magnetic degree wheel from the hardware store and with some patience and a level bender I have had good luck just setting the degree wheel on the tubing after a bend has been established. I think the biggest thing you can do to make consistent bends is to
#1 remove all free play from the bender before setting your degree wheel. For instance just use a little tension on your leverage bar to hold the tubing in the saddles.
#2 The next big thing I have found to make consistent degrees in your bends is to completely lock out your bender till the two leverage arms clank against each other. It may be a few degrees off from a perfect 90 degrees or whatever your desired number may be, but by completely locking out your bender in your final bend It ensures consistency.
I hope this helps
I frequent my IG more than the JJ just out of convenience. If you have any more questions I'd be glad to help. @mandrew401
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Old 04-18-2017, 09:25 AM   #25
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Default Re: How to bend handlebars? tips on how to be accurate?

Thanks mandrew, that's pretty much the same i'm doing, with locking the arms and setting the gauge.
I haven't had a play with handlebars recently as been busy riding, but soon will give it a few more tests.
would really like to get a 2" CLR though.
i'll find you on IG. mine is @jpintheuk
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