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Tubing Straightener

Horseplay

I Don't Care. Do you?
By request, here is a quick straightener I made today to assist when fabbing up all the hard lines for my car. I was going to buy something but it seemed I could put that money to better use. In order to do both the 3/16" and 3/8" SS lines would have required I buy two sized units or an adjustable one...both paths would have cost over $200 to my door. Forget that! I don't mind buying tools, hell, it's my favorite past time but I just didn't see me needing this often enough to warrant it. Anyway.....

I had some 1" square tubing laying around along with some 1/4" plate so I made my unit out of what was on hand. I did have to get some metal rollers and some hardware but I think my total spend was under $35.

Not too much detail as I hadn't planned on sharing here, sorry. The rollers are 1 1/4" diameter with a 1/4" hole in the center. I spaced them at 1.75" on center. Both upper and lower. The bottom "rail" has the roller axles (1/4-20 bolts) thread into the rear plate for a fixed mount. The upper rail "floats" above the lower rail guided by the two vertical posts on either end which are 3/8 -16 size. The bolts are long enough that the threads don't start until AFTER passing through the lower rail. This makes a tight fit through the two rails which keeps everything in line. This is why I have so many washers on the bottom to fill the void until the threads begin.

The spring between the two rails is not very heavy. Just enough to hold the upper rail up. By tightening the two vertical posts (bolts) the gap between the rollers is adjusted so I can do anything from 3/16" to 3/8".

I used 5 rollers on the bottom and 4 on the top simply because SS tubing is very hard to bend compared to typical brake line. The extra long pass helps to smooth things out very nicely. If you were using softer line you could get by with one less roller top and bottom.

The backing plate extends lower so it can be clamped in a vise or, as I did here, bolted to my welding table which makes it easier to position to run through longer lengths.

The pic shows me testing it out on some 3/8" SS fuel line I just received. Works great! Be plumbing the ride this week.tubing straightener.JPG
 

Ponyman66

Yak, yak, yak
Sweet! I was considering having four sets of rollers in a cross pattern (like the store bought stuff), using four pieces of angle. Since your design is much simpler, guess which way I'll go?! Thanks Terry!!
 

Horseplay

I Don't Care. Do you?
Off a new coil by just holding the coil vertical and in line with the rollers this design straightens it out great. My picture shows 3/8" stainless which is VERY stiff and it worked great. If you had some really wonky stuff you can simply rotate it as you work it back and forth to take out bends that are not all in the same plane. I also ended up using a small "c" clamp to secure the top rail against the back plate when I went to actually use it to make a section long enough to go from front to rear of my car. Relying on the two posts to align the two rails works great but there is still a few thousandths of play which get eliminated by the clamping. If I felt like it I could simply drill holes through the top rail on either end to allow me to run a bolt into the backing plate. Catch is since I want to do multiple different sizes the corresponding hole in the back plate would ideally be a slot to allow up and down adjustment of the top rail. Given the small travel distance between my max tube size of 3/8" and smallest at 3/16" I could get a way with just drilling an oversize hole and just using a nut and large washer on the back side. All that is needed is a clamping force so play in the hole size would not matter.

Word of caution though. When drilling holes for your roller mounting the individual holes MUST be perfectly in line. If one rides too high or too low it will mess up the effectiveness of the tool. Best done with a guide fixture on a drill press with a tight tolerance mast. Even then, scribe a line and then use a starter punch to mark the holes to help keep the bit from walking. Other than that it is a pretty darn simply thing to build.
 

Ponyman66

Yak, yak, yak
It's ironic that you mentioned rotating the tubing for bends not in the same plane. I almost asked if you did that but quickly figured out that'd be the easy way to address it......well duhh! LOL

Thanks for the additional tips!
 
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