terryd
Well-Known Member
Hi,
I'm building some live steam models and will need to bend quite a few tubes in the near future. One pressing need was to make a pressure tester for the boilers I build and this also involved some mini tube bending - 3 mm diameter in this case. So I decided to make a manual bending device to ensure consistent bends - well actually I could have used many methods such as filling the tube with an incompressible material and just bending around suitable diameter bar but I like to have a method of reliable reproduction of results so I decided to make a device. Besides I'm a masochist and have the time to indulge myself now I'm retired and shielding from Covid-19.
I looked up quite a few types of bender on the internet and eventually came up with a nice design by one C. Horace Clarke from Model Engineer published in March 1956. It was a bit complicated but I quite like the challenge using techniques I've not used before, or not recently at least. I had also seen another design on a forum, not sure which one now, could even have been here and that looked as if it was derived from the one by Horace Clarke.
This is the one that I found on the forum which if you examine carefully is very similar to H Clarkes but a bit simpler. Here is Mr Clarkes from Model Engineer
Design By C. Horace Clarke
The main difference besides a few minor details is that the upper Device shown by Mechman48 does not seem to have the clamping mechanism of the Clarke design.
Anyway here is my version of the Clarke bender, actually an exact copy except that I converted to metric from the original Imperial measurements as most of my equipment is metric apart from some Imperial stuff (BA taps, rules etc):
My version of Mr Clarkes Bender.
The clamp jaws at the bottom are operated by a cam which is in turn operated by the short flat lever, this clamp prevents the tube from being pulled through the device while bending. It uses split collets of suitable diameters for different size tubing up to 8 mm, I have made a 3mm and 2 mm ones at the moment for my immediate needs. The brass collet is seen running through the clamp jaws in the picture. The clamp overall is adjustable in relation to the fixed roller to enable different roller diameters to be accommodated (for different radius bends and diameter tubing) which explains the slots just visible in the base. The shiny screws shown at the top right are homemade taper screws which lock the arms to the fixed roller spindle. The long screws enable the lever arm to be adjusted to roll tube around larger diameter fixed rollers.
The bending roller is in an adjustable lever handle which locks in place while bending but releases when retracting the lever and swings out of the way so that the tube can be manipulated. You can just see the head of the loose pin which holds the bending roller in the lever arm this head locks into a cutout milled in the upper arm which causes it to lock when bending but allows the arm to swing clear at other times, a rather elegant solution, to me at least.
Another View of the Bender - the cross head screws are temporary while awaiting delivery of suitable rivets.
This view shows the split collet clearly, the device can make bends up to 180° hence the cutout in the RH clamp jaw (the one fixed with screws). You can also make out that the clamp is mounted on its own baseplate which is adjustable on the main base. You will note that the material is not highly finished, it's deliberate, it's not just laziness - I suffered a devastating garage fire in 2010 and much was lost but most of my materials survived but had to withstand not only very high temperatures for several hours but also drenching by the fire crews who attended and several days in the rain before they could be rescued and stored in a new shed erected specially for the purpose. I still use these materials and de-rust and clean as necessary. By not bringing then up to a high level of 'bling' I am reminded regularly of the fire and to take precautions to prevent a second happening.
Initial Test
To test the device I made up a connecting pipe for my boiler tester rather than just making random bends. I first made up a copper wire pattern,
Then I made the bends using the wire as a pattern:
Which was trimmed and fitted using o rings to seal:
Overall a rather satisfying project only spoiled by my making some stupid errors resulting in reworking or remaking some parts which others of course never do or so I suppose.
I have more pictures of the making as well as copies of the drawing which I could turn into an extension of this thread explaining the stages of manufacture if anyone is interested. - let me know.
TerryD
I'm building some live steam models and will need to bend quite a few tubes in the near future. One pressing need was to make a pressure tester for the boilers I build and this also involved some mini tube bending - 3 mm diameter in this case. So I decided to make a manual bending device to ensure consistent bends - well actually I could have used many methods such as filling the tube with an incompressible material and just bending around suitable diameter bar but I like to have a method of reliable reproduction of results so I decided to make a device. Besides I'm a masochist and have the time to indulge myself now I'm retired and shielding from Covid-19.
I looked up quite a few types of bender on the internet and eventually came up with a nice design by one C. Horace Clarke from Model Engineer published in March 1956. It was a bit complicated but I quite like the challenge using techniques I've not used before, or not recently at least. I had also seen another design on a forum, not sure which one now, could even have been here and that looked as if it was derived from the one by Horace Clarke.
This is the one that I found on the forum which if you examine carefully is very similar to H Clarkes but a bit simpler. Here is Mr Clarkes from Model Engineer
Design By C. Horace Clarke
The main difference besides a few minor details is that the upper Device shown by Mechman48 does not seem to have the clamping mechanism of the Clarke design.
Anyway here is my version of the Clarke bender, actually an exact copy except that I converted to metric from the original Imperial measurements as most of my equipment is metric apart from some Imperial stuff (BA taps, rules etc):
My version of Mr Clarkes Bender.
The clamp jaws at the bottom are operated by a cam which is in turn operated by the short flat lever, this clamp prevents the tube from being pulled through the device while bending. It uses split collets of suitable diameters for different size tubing up to 8 mm, I have made a 3mm and 2 mm ones at the moment for my immediate needs. The brass collet is seen running through the clamp jaws in the picture. The clamp overall is adjustable in relation to the fixed roller to enable different roller diameters to be accommodated (for different radius bends and diameter tubing) which explains the slots just visible in the base. The shiny screws shown at the top right are homemade taper screws which lock the arms to the fixed roller spindle. The long screws enable the lever arm to be adjusted to roll tube around larger diameter fixed rollers.
The bending roller is in an adjustable lever handle which locks in place while bending but releases when retracting the lever and swings out of the way so that the tube can be manipulated. You can just see the head of the loose pin which holds the bending roller in the lever arm this head locks into a cutout milled in the upper arm which causes it to lock when bending but allows the arm to swing clear at other times, a rather elegant solution, to me at least.
Another View of the Bender - the cross head screws are temporary while awaiting delivery of suitable rivets.
This view shows the split collet clearly, the device can make bends up to 180° hence the cutout in the RH clamp jaw (the one fixed with screws). You can also make out that the clamp is mounted on its own baseplate which is adjustable on the main base. You will note that the material is not highly finished, it's deliberate, it's not just laziness - I suffered a devastating garage fire in 2010 and much was lost but most of my materials survived but had to withstand not only very high temperatures for several hours but also drenching by the fire crews who attended and several days in the rain before they could be rescued and stored in a new shed erected specially for the purpose. I still use these materials and de-rust and clean as necessary. By not bringing then up to a high level of 'bling' I am reminded regularly of the fire and to take precautions to prevent a second happening.
Initial Test
To test the device I made up a connecting pipe for my boiler tester rather than just making random bends. I first made up a copper wire pattern,
Then I made the bends using the wire as a pattern:
Which was trimmed and fitted using o rings to seal:
Overall a rather satisfying project only spoiled by my making some stupid errors resulting in reworking or remaking some parts which others of course never do or so I suppose.
I have more pictures of the making as well as copies of the drawing which I could turn into an extension of this thread explaining the stages of manufacture if anyone is interested. - let me know.
TerryD
