roll cage fab

heywebonya · Posted: Mon Dec 19, 2011 3:20 pm Post subject:

It was a typo - 0.145"

Didget, Thanks for the reminder - all things are possible; many are not beneficial!

I remade my clamp to get it tighter and will clean my shoes; I was confused and thought "sticktion" was a resistance to movement. My first clamp was not sufficient (it was just a piece of 1" wide strapping)

I need the shoes to prevent small dents made from the rollers; it appears to spread the load nicely.

Thanks for the help,
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WilliamA · Posted: Mon Dec 19, 2011 3:57 pm Post subject:

Hey Jeff,

Something for you to check. Make sure the die you're using is the right size for the tubing. Don't go by the die number. Schedule 40 plumbing pipe is sized by I.D. Tubing is sized by O.D. (or is it the other way around. Anyway, the die must fit quite close to the tubing. My dies that came with the harbor freight had numbers on them that didn't reflect the actual diameter of the tube. I had to go one size down to make it fit. If the die fits well on the tube and you have the shoes tight on the tubing, it will do a good job of making dependable bends. I bent thousands of feet of tubing and never had a kink. Check your die fit first! PM me if you still have problems...

William
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heywebonya · Posted: Mon Dec 19, 2011 7:06 pm Post subject:

I tried and am going to express my frustration! ARRRGH (sorry, but it requires three R's of angst)

Here is my second attempt with due diligence

Image may have been reduced in size. Click image to view fullscreen.

I used schedule 40 pipe for the sleeve

I made the sleeve fit tightly

Welded together with a section of tubing to show the fit and minimal gaps

This is 1.25" diameter with 0.120 walled DOM tubing

Approximately 50 degrees bend

This is 80 degrees (goal of bend)

Finally, the crappy result of this project

It is hard to imagine that the difference between 1.25 and 1.33 (0.08") results in this much crappy bending. Can you buy 1.33 OD tubing? Am I missing something.

I am going to try and tighten the sleeve a little and see if this helps.

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If I knew what I was doing; I wouldn't be building a buggy!

Lo Cash John · Posted: Mon Dec 19, 2011 7:32 pm Post subject:

Looking at the next to last pic, I have a theory.

I think you have flex in your "strap" that's allowing the tubing to lift away from madrel. The shoe that rides directly against the tubing looks okay but the "straps" each have a bend. Since the forces at work are pretty darn high (high enough to bend tubing!!) they are certainly high enough to flex those straps allowing the tube to lift slightly and kink a little.

Redesign the straps to eliminate the curves they now have. This reduces the flex and should help.
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joescoolcustoms · Posted: Mon Dec 19, 2011 7:37 pm Post subject:

Your tubing is too small for the shoe. The tubing has to fit firmly in the shoe itself with no gaps or looseness.

I never had a bend look like the last photo. They all were perfect with no kinking or flattening. If the tubing does not fit the shoe, it allows room for the tubing to creep into the voids of the loose fit.
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heywebonya · Posted: Tue Dec 20, 2011 5:25 am Post subject:

Could someone measure the distance across their 1" die? Mine measures 1.33" and I have tried to use this for 1.25" tubing unsuccessfully.

I will try a third strap / fixture today removing the bends.

-Jeff
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If I knew what I was doing; I wouldn't be building a buggy!

joescoolcustoms · Posted: Tue Dec 20, 2011 5:35 am Post subject:

My 1 inch die measures 1.329. 1 1/4 tubing is too small for that die and the tubing will deform in the extra area of that die.

The only tubing I have matched up to the HF dies is 2 inch, 1 5/8 inch and 1 inch. If the tubing does not fit tight in the die, it will move and distort. That goes for any bender, not just the HF unit.
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Bad News Racing 2018 NORRA 1000 3rd in Class
Best Day Ever Racing 2022 NORRA 1000 2nd in Class and first All Female team to complete the race

Everyone is gifted. Some just do not open the package.

Looks like it was painted with a live chicken,polished with a brick and buffed with a pine cone

Lo Cash John · Posted: Tue Dec 20, 2011 6:49 am Post subject:

I don't think 8 thousandths of an inch is the cause of the kink. That kink looks like it was caused by the the tubing lifting away from the die in the dead center. The "shoe/strap retaining widget needs to be very tight with no allowable flex or give. At least that's my way of thinking.
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More brains than bucks...Believe it or not!!

If you actually drive your VW, you need www.AirMapp.com

My boss told me I need to work on my mutli-tasking. So now when I use the bathroom at work I surf The Samba on my iPhone.

JamisonWorkshop · Posted: Tue Dec 20, 2011 6:53 am Post subject:

Here is a little something to go by. Gives wall thicknees minimums as well which is nice.

Yes you need the piece of strap to be longer and thicker. There is a reason the followers for the JD2 type benders is made out of solid chunck of billet steel. That is what everything stretches against. The die is there for support but the follower does the pressing and stretching.

http://vansantent.com/model_3_bender_dies.htm

heywebonya · Posted: Tue Dec 20, 2011 2:45 pm Post subject:

Here are the measurements for the HF Dies and my guesses for tubing selections. Can anyone confirm?

Label___Width___Depth___Tubing
1/2_____0.899"__0.056"
3/4_____1.062"__0.60"____1.0" OD
1_______1.344"__0.788"___N/A (based on two trials)
1 1/4____1.658"__0.80"____1 5/8"
1 1/2____1.937"__1.057"___2"
2_______2.423"__1.457"

Sorry for the terrible table formatting.

Jeff
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If I knew what I was doing; I wouldn't be building a buggy!

Lo Cash John · Posted: Tue Dec 20, 2011 4:18 pm Post subject:

I had a thought about the design of the retaining "shoe/strap". Since the objective is to hold the tubing tightly down in the die, it needs a different design. Instead of a U shape with a through bolt, why not a U shape with a pair of studs & wing nuts to draw it down very tight? Not sure what size hardware though.
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More brains than bucks...Believe it or not!!

If you actually drive your VW, you need www.AirMapp.com

My boss told me I need to work on my mutli-tasking. So now when I use the bathroom at work I surf The Samba on my iPhone.

heywebonya · Posted: Tue Dec 20, 2011 5:04 pm Post subject:

Lo Cash, I agree there could be an "adjustable" system but again the high loadings may not work well

What are the weakness? (Other than the sleeve fit)
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If I knew what I was doing; I wouldn't be building a buggy!

Lo Cash John · Posted: Tue Dec 20, 2011 5:14 pm Post subject:

I'm on my iPhone so no graphics from me.

I was thinking something more like a connecting rod cap or main bearing cap (non VW). There'd be two studs pointing up off of the mandrel and the "cap" fits down on the studs and is tightened to secure the tubing.
_________________
www.LoCashRacing.org
More brains than bucks...Believe it or not!!

If you actually drive your VW, you need www.AirMapp.com

My boss told me I need to work on my mutli-tasking. So now when I use the bathroom at work I surf The Samba on my iPhone.

joescoolcustoms · Posted: Tue Dec 20, 2011 6:36 pm Post subject:

bdkw1 · Posted: Tue Dec 20, 2011 7:44 pm Post subject:

BuggyFaron · Posted: Wed Dec 21, 2011 7:56 pm Post subject:

I really like the bender that I found. It has been used to make Sprint Cars for the last 50 Years, does all sorts of Chassis Fabrication, and welds like a roll of nickels. I dropped it off Friday, and will pick it up Tuesday. All I have to do is hand it a little cash before I take it home! LOL

heywebonya · Posted: Thu Dec 22, 2011 4:41 am Post subject:

BuggyFaron, you are definitely correct about the simplicity and accuracy of your system. I contacted on fab shop already and they do not make cages. Based on the time I spent goofing around I would have been miles ahead contracting this out.

What did you need to do to get a cage hired out? Did you need to make a PVC mock up? Remove all the interior? What should I expect to pay?

Thanks, Jeff
_________________
If I knew what I was doing; I wouldn't be building a buggy!

didget69 · Posted: Thu Dec 22, 2011 7:40 am Post subject:

wythac · Samba Member Joined: August 02, 2004 Posts: 2791

Heywebonya,
While you might think that finding someone to do it is simpler and easier than doing it yourself, I would offer that to a certain extent, those values and choices are completely dependent on geography and blind chance. You should spend some time looking for a local (and willing) fabricator, but be open to the possibility that you may not find one, or, if you do, the work will be cost prohibitive.
I lost more than a few months on my project dicking around trying to find someone to do the work. At one point I even considered having someone make a "knockdown" cage for me that they could ship in pieces and I could weld up.
Ultimately I decided that the best way to get the cage I wanted was to buy a good bender and die (as you can see with previous posts I had an HF bender too) and get to it. I had the whole cage bent up and stuck together soon after, picked up a new skill, and even had some fun.
My point is: Look for a fabricator, but keep your own wheels turning on the topic of doing it yourself, because you might find that you end up being the fabricator you were looking for.

Lo Cash John · Posted: Thu Dec 22, 2011 9:17 am Post subject:

Well said!!!
_________________
www.LoCashRacing.org
More brains than bucks...Believe it or not!!

If you actually drive your VW, you need www.AirMapp.com

My boss told me I need to work on my mutli-tasking. So now when I use the bathroom at work I surf The Samba on my iPhone.


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