Adjustable coiled tube straightening tool

**thehomeengineer** · Jan 9, 2018, 02:33 AM

Adjustable coiled tube straightening tool

Hi All

I am making a copper boiler for a 3" scale Foden steam engine and need to straighten approximately 44-foot of 3/8 coiled copper tube to make 63, 9" long fire tubes. I have purchased 2 x 25-foot coils of 20-gauge tube.
So, after a little research and viewing both commercially and homemade designs I came up with this which seems to work very well and is adjustable for other diameter tubes. I purchased the bobbins from eBay for a pound a piece which included the bearing and made the shafts and main body of the tool.

It works very simply, to set the bobbins you get a straight bar the same diameter as the tube to be un-coiled and straightened, adjust the bobbins to contact this bar so it can move smoothly between all six bobbins. Then roll the coiled tube between the bobbins. I went backwards and forwards a few times on the piece shown in the photo, as it was very bent before I started. Therefore, after this quick test it seems to work OK

Many thanks again for taking the time to view this post.

Adjustable coiled tube straightening tool-img_0438.jpg

Adjustable coiled tube straightening tool-img_0439.jpg

Adjustable coiled tube straightening tool-img_0440.jpg

Adjustable coiled tube straightening tool-img_0441.jpg

Adjustable coiled tube straightening tool-img_0443.jpg

**toma** · Jan 10, 2018, 01:54 AM

A very good idea to make pipe straightener from the combination of two pipe benders...!

**thehomeengineer** · Jan 10, 2018, 03:04 AM

Thank you
I would like to say it was my idea/design (but I can't) after searching the internet I found lots of ideas and someone had made one very similar to mine out of old pulleys but this could only strighten one diameter of pipe. So I decided to try and improve this style of design so I could strighten any size pipe within reason a model engieer would use. So I just adapted their design I am affraid.
But thank you for viewing the post
The home engineer

**toma** · Jan 10, 2018, 04:12 AM

Do not be afraid,any tool improvement is welcome..
Best regards..

**Toolmaker51** · Jan 10, 2018, 07:07 AM

Originally Posted by thehomeengineer

Adjustable coiled tube straightening tool

Click image for larger version.

Name: IMG_0439.jpg
Views: 1004
Size: 302.7 KB
ID: 21382

Click image for larger version.

Name: IMG_0440.jpg
Views: 952
Size: 473.7 KB
ID: 21383

I've been associated wire straighteners, they work the same way. The spool hub is under just enough tension to not allow slack and wire initially fed through the rollers by hand. Rollers are set to diameter of equivalent music wire, on 7 'stations', all mounted on a single plate, arranged otherwise like that made by thehomehengineer. Of two different adjustment types; one had rollers mounted on eccentrics, other machine had rollers on slides adjusted by a screw/ jam nut. Either plate was adjusted on the bench, then mounted on the particular machine.
Entirely analog, machine cut wires to length and partially stripped each end, in gauges between 18-28. The insulation was separated, not removed until placement and affixing terminal or soldering.
With the additional number of stations, material straightens in a single pass.

Same process works in die presses, straighteners preparing sheet metal for the feeder mechanism as pulled from the uncoiler. Thickest I've ever seen run was 8 gauge, but that is nowhere close to the limit.

**DIYer** · Jan 10, 2018, 07:19 AM

Thanks thehomeengineer! We've added your Coiled Tube Straightening Tool to our Metalworking category,
as well as to your builder page: thehomeengineer's Homemade Tools. Your receipt:

Coiled Tube Straightening Tool by thehomeengineer

tags: straight

**olderdan** · Jan 10, 2018, 11:30 AM

Nicely done, thats a lot of tube to straighten, does the bobbin profile have to match the tube dia?.

**Jon** · Jan 10, 2018, 11:56 AM

Originally Posted by thehomeengineer

Thank you
I would like to say it was my idea/design (but I can't) after searching the internet I found lots of ideas and someone had made one very similar to mine

Both are probably true

. See Multiple discovery.

**thehomeengineer** · Jan 10, 2018, 04:21 PM

Hi olderdan
Thank you for taking the time to get in touch
The tube in one of the photos was used as a test piece and it was well and truely deformed to such a state I thought I might have to scarp it. The tool has made it reuseable and to answer your question the bobbins are not the same profile as the tube. The strightening process also doesn't seem to require much pressure from the bobbins, all I did when setting the tool, I simply used a stright solid bar of the same size as the tube to be strightened with the six bobbins in contact with the bar and when moved backwards and forward all bobbins rotated freely. Luckily this seems to work fine and I am pleased with the results so far.
The home engineer

**thehomeengineer** · Feb 19, 2024, 06:57 AM

Hi All

I have finally got around to using the coil straightening jig I made, it must be a few years back now.

The coil was initially uncoiled by hand for roughly 3' and then cut off at 27,1/4". Which would be enough material to make three 9" fire tubes per length. The 3/8" diameter copper was then fed back and forth through the jig and and rotated at the same time until straight. The tube came out really nice so really pleased with the homemade jig.