Mini Tube bender.

Help Support HMEM:

terryd

Well-Known Member
Joined
Jun 15, 2010
Messages
95
Reaction score
45
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.

Mini tube bender (1).JPG


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

HClarke bender.png

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):


Tube bender.JPG

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.

Tube bender1.JPG

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,

WIRE TEST .JPG


Then I made the bends using the wire as a pattern:

Tube Wire comparison.JPG


Which was trimmed and fitted using o rings to seal:

Pump with tube fitted..JPG


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
 

minh-thanh

Well-Known Member
Joined
Dec 29, 2016
Messages
650
Reaction score
318
Location
Viet Nam
terryd !

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
Please extend of this thread ..
Thanks!
 

Ken I

Project of the Month Winner!!!
Project of the Month Winner
Joined
Oct 31, 2010
Messages
1,436
Reaction score
171
Location
Cape Town, South Africa
Excellent bender Terry.

Not to steal your thunder, I posted my own bender some time back
1592929219674.png

You mount it in a vice and the stops permit "production runs" of bends.
For whatever reason, it appears to have disappeared off the Downloads section so I have added the files here for anyone who's interested.
bendparts.jpg

I have bent 7mm diameter mild steel with this rig - but I have to admit that comes close to breaking it.
Regards, Ken
 

Attachments

Last edited:

terryd

Well-Known Member
Joined
Jun 15, 2010
Messages
95
Reaction score
45
Excellent bender Terry.

Not to steal your thunder, I posted my own bender some time back
View attachment 117359
You mount it in a vice and the stops permit "production runs" of bends.
For whatever reason, it appears to have disappeared off the Downloads section so I have added the files here for anyone who's interested.
View attachment 117363
I have bent 7mm diameter mild steel with this rig - but I have to admit that comes close to breaking it.
Regards, Ken
Hi,

that's a lovely piece of work, not quite as adjustable as the one from Mr Clarke but would have been sufficient for my purposes but as I said, I'm a bit of a masochist and enjoyed some of the challenges and at the moment I have no need to bend solid rods. I also like the ability of Mr Clarke's design to firmly clamp the free end of the tube as I found on an earlier type I tried without such clamping that the tube tended to creep while bending and this affected the accuracy where multiple bends were involved and I don't have the skill needed to make allowances for such movement.

But again, a lovely piece of work demonstrating good skill levels

TerryD
 

ICEpeter

Well-Known Member
Joined
Feb 27, 2010
Messages
140
Reaction score
60
Hello,
If anyone is interested to take a look at another pipe bender please search for a post titled "Bending brass tube" that I contributed to in 2015.
 

Ken I

Project of the Month Winner!!!
Project of the Month Winner
Joined
Oct 31, 2010
Messages
1,436
Reaction score
171
Location
Cape Town, South Africa
Terry, thanks for the comments - once again sorry for butting into your post but since Minn-Thahn was asking I thought I would just add in the link to my plans - but could no longer locate or find it - I did find the PDF file but not the rest - curiously missing - probably during the platform change a couple of years back ?
You are correct about "creep" - I never provided for clamping to stop it - I was aware it would happen but didn't concern me at the time as I intended to dress to size after bending. As you say you can allow for it but in retrospect the omission of clamping was an oversight.

I just dropped the plans I had to hand in here for Minn-Thahn's perusal more than anything else.
Look forward to any further elaboration you might provide on yours.
Regards, Ken
 
Last edited:

stanstocker

Active Member
Joined
Nov 20, 2015
Messages
25
Reaction score
18
Location
Gwynn's Island, VA
A nicely done tool indeed. Thanks for posting your pics and descriptions, look forward to additional pics you choose to share.

For those interested, the ME issue with these plans is 2861, 22 march 1956. Pages 470 to 473. Looks like a nice little bender to be sure, and here I was thinking the project list was getting down to only three lifetimes of things to enjoy making!

Best to all,
Stan
 

minh-thanh

Well-Known Member
Joined
Dec 29, 2016
Messages
650
Reaction score
318
Location
Viet Nam
Ken I !
Excellent bender Terry.

Not to steal your thunder, I posted my own bender some time back
View attachment 117359
You mount it in a vice and the stops permit "production runs" of bends.
For whatever reason, it appears to have disappeared off the Downloads section so I have added the files here for anyone who's interested.
View attachment 117363
I have bent 7mm diameter mild steel with this rig - but I have to admit that comes close to breaking it.
Regards, Ken
Great tool !
Thank you for sharing the plan .

ICEpeter !
I will find
Thank you.
 

HennieL

Well-Known Member
Joined
Apr 17, 2020
Messages
46
Reaction score
24
Location
South Africa
I will do that if there is more demand...
Terry, consider this as more demand ;):)

Actually, I would never dream to demand - but please, do post your plans and/or construction details if you can - I too would like to try my hand at making a mini tube bender, and your model looks really nice.

Thanks in anticipation
 

terryd

Well-Known Member
Joined
Jun 15, 2010
Messages
95
Reaction score
45
Terry, consider this as more demand ;):)

Actually, I would never dream to demand - but please, do post your plans and/or construction details if you can - I too would like to try my hand at making a mini tube bender, and your model looks really nice.

Thanks in anticipation
HI Henniel,

How can I resist? I know that in French at least to demand or command is not as strong as in English so I'll forgive you. Please be patient I have other projects on the go but will post within a few days and take it step by step.

I hope that is ok. Here's another view just to help in the meantime

Tube bender2.JPG


Best regards

TerryD
 

terryd

Well-Known Member
Joined
Jun 15, 2010
Messages
95
Reaction score
45
Baseplate and vice:

Hi'
the baseplate and vice are made from standard flat stock. They are relatively simple to make mostly using hand tools, bench drill and milling machine. I missed some pictures but the processes are quite straight forward to understand and parts made.

Vice basepate sub assemblies.JPG


Vice and baseplate sub-assemblies

The marking out from the drawings was done with standard tools, I use a cheap digital vernier to draw lines parallel to.edges, an engineers square and scriber to layout hole centres, a spring divider for stepping out multiple hole centres and arcs, and a centre punch for spotting hole centres.
I marked out the four major components: the main baseplate, the vice plate and the two jaws. and spot drilled using a small spot drill, not a Slocomb pattern, and drilled the main holes on the drill press, the two baseplates were then assembled using superglue (cyanoacrylate adhesive)

Baseplate viceplate drilled.JPG


Vice and main baseplates secured with superglue and drilled

The holes in the upper vice baseplate were spotted through to the main baseplate on the drilling machine, This was to ensure accurate alignment of the slots in the baseplate (see picture above) which will eventually enable the whole vice to adjust to larger diameter rollers and different diameter tubes in the range 2 to 8 mm diameter.

The baseplate was completed by sawing out the top right-hand section leaving a filing allowance which was quickly filed to size and draw filed to a reasonable finish. It was not worth setting up the milling machine as accuracy is not crucial, the cut out is merely for clearance of the moveable arm. The round bar with holes to the left is my small tapping guide. it is drilled for taps from 2mm to 8 mm plus there are holes drilled to accommodate other sizes (e.g. BA, small Whitworth) which I drill as needed. I used the guide to tap the holes in the vice baseplate. These holes are used for studs which pass through the slots in the baseplate. The studs can be seen in the picture of the underside of the vice. I prefer that solid plain rod slides in the slots rather than a threaded part.


Vicwe underside studs.JPG


Underside view of the vice showing the studs secured with Loctite

The studs were made by threading a 6mm length of a 5mm rod in the lathe using my home made tailstick dieholder. The correct length was cut off, the end of the rod faced off and process repeated. The studs were threaded by reversing in the lathe collet and threaded by the same process as before. Using the collets meant that the already threaded end is not damaged.

The manufacture of the vice jaws themselves and the clamping pivot was a little more complicated and will be described in the next posting.

I am preparing a new set of drawings translated to metric dimensions and I will publish these as well as the original imperial drawings.

TerryD

 

Roskrow

Member
Joined
Sep 2, 2017
Messages
11
Reaction score
5
I have been following the item on Mini Pipe Bending, and have a simple solution to offer.

I have a Mini bender made by Record Tools ... This is now known as Irwin Record the model is No. 210 Mini Bender

It is available on line at Amazon (UK) and covers Capacity 3, 4, and 6mm. O.D. 1/8, 3/16, and 1/4in O.D.

Cost about £29.00. I find it excellent.
Hope that is a help
Malcolm Farrant
 

terryd

Well-Known Member
Joined
Jun 15, 2010
Messages
95
Reaction score
45
Hi Malcolm,

I know about those benders. They are good, I have a couple of similar ones which cover 3mm to 12mm tubing, after that, I tend to use bending springs but they do not have the wide range of applications, bend radii and tube diameters than many of the workshop designs available, the design I have chosen works from 1 mm to 8 mm tubing simply by making the correct size guides and rollers and the bend radius can be from 3 to over 25mm according to tube diameter and forming roller size.

Furthermore, personally I really enjoy making working high-quality tools as part of my workshop activities and by making from available stock in my workshop they cost zero. Of course, I can't speak for everyone but I'm just publishing this for like minded folk. My latest tools include this versatile bender, an equally versatile ball turning device, and a tailstock die holder which accommodates thread diameter from 2mm to 8mm threads up to 300mm long. I regularly use the latter to make 5/32" BSW threaded rod, 11 1/2" long for my Meccano builder friends. Such versatility is often not available on commercially produced products for the home workshop.

Best regards

TerryD
 

Roskrow

Member
Joined
Sep 2, 2017
Messages
11
Reaction score
5
Terry, You are Correct....But I am just Old and LAZY !!
Best wishes
Lazy Malcolm
 

terryd

Well-Known Member
Joined
Jun 15, 2010
Messages
95
Reaction score
45
Mini Bender Jaws

Hi,
I have attached a pdf of the original document by Mr Clarke from the 1956 Model Engineer. I was reluctant to publish earlier due to copyright considerations but discovered that the present owners of the magazine only have the copyright on articles published since they have owned it, the copyright on an article from before reverted to the original author and if he wishes I will remove it. I believe that this is the reason that John Tom can publish ME designs from an era before the present owners of the magazine.

Anyways up, on to the making of the jaws for the bender. These are made from two 3/4" (20mm)x 3/8" (10mm) stock x 1 3/4" (44mm) long flat stock. In order to make the semicircular longitudinal cutouts for the clamp, he suggests mounting them on the lathe cross slide side by side on suitable packing to raise the height and with 1/16" (I used 0.7mm) packing between the jaws longitudinally, and then and drilling using a chuck mounted 5/16" (8mm) drill.


I did it rather differently. I glued the jaw blanks side by side with a strip of thin stainless steel between them, I then mounted them vertically in the Vice jaws of my milling machine such that they were pressed together and ensured that they were vertical I also used a toolmakers clam to prevent them coming apart while drilling. I then set the centre of the jaws to be drilled on the centre of the mill using a 'wiggler', I spot drilled and then finally used an 8mm jobbers drill to drill through to size. I didn't drill a pilot drill due to teh set up, it had to be all or nothing, and it was 'all' luckily. I had of course taken extra safety precautions because despite doing such stuff since 1963 I still have two good eyes, eight working fingers and two thumbs.

DSCN3466.JPG


Jaws drilled Note the other holes.

While in the milling machine chuck I also drilled the hole which is the basis for the cut out in the fixed jaw to allow 180° bends to be produced. I drilled 3 rivet holes in that yaw and 1 x 10 mm hole for the clamping cam in the moving jaw You can make these out in the pictures above and below

DSCN3469.JPG


Another view of the jaws

This shown more clearly the arrangement of holes in the jaws. The waste was removed from the fixed jaw where the long hole can be seen to produce a step for clearance of the tube when making a 180° as mentioned above. as can be seen below. Being a masochist I used a hacksaw and files to remove the waste. I love doing things manually for several reasons. First I like the quiet, gentle rhythms involved in hacksawing, filing etc and they are both quite easy to do if you used the correct blades and grades of file for the job in hand. I am quite happy to hand cut a length from a 50 mm (2") round bar when making loco wheels and through make that cut accurate so that the length can be faced off in one pass usually, occasionally I may veer off a little but that is usually because I can't be bothered to change a slightly worn blade.
Such exercise also helps to prevent muscle wastage which is a part of growing old and sedentary. The process of hacksawing uses many of the upper body muscles not just the arms and of course I do it standing so my leg muscles are getting a bit of a workout to add to my walking. SAves a fortune in Gym fees alongside my gardening activities.

DSCN3532.JPG

View showing the fixed jaw shaped to allow 180° bends

My Clarke also suggests not using a reamer as the texture left from a dill will help the gripping action of the jaws. I have made a couple of sleeves to allow in my case 2 and 3 mm tubing to be accommodated and will make more as needed. These can be seen in the picture above and ae simply turned brass leaving a collar, then drilling the appropriate size then slitting along both sides. The slit goes completely along one side but stops about 5 mm short of the end on the other. This section is then thinned to leave about 2 mm of material. I used a junior hacksaw to cut the slits as I couldn't be bothered to set up a slitting saw on my milling machine for such a small job.

DSCN3535.JPG

Image showing pivot pin and eccentric (centre left) and clamping jaw (top left)

To fasten the fixed jaw to the vice baseplate, I glued the jaw on to the baseplate using superglue (cyanoacrylate) spotted the holes through with a suitable size spotting drill then drilled tapping size for M3 screws (for temporary fixing) using my tapping block to ensure vertical tapped holes and then fixed with M3 countersunk screws. The clamping jaw was a little more difficult as the hole centre is based on the eccentric one in the cam and not the hole in the jaw itself. I did this by light clamping the loose jaw in position with the cam set in the hole in the jaw set just before full clamping pressure would be applied. I had to find the centre of this eccentric hole in the baseplate and I wasn't sure how to go about it, which I'm sure most of you all would know a method. What I did is that while everything was clamped in position I made a length of brass to fit the eccentric hole and drilled a 1.6mm hole on centre to accommodate an old gramophone needle (of which I have a few to make replaceable tip scribers and they work remarkably well). The brass was put in the eccentric hole, the gramophone needle inserted and hit with a hammer indicating the centre of the hole. I'm glad to report that no gramophone needles were injured or otherwise harmed in the making of this bending machine.

That's about all there is to say on the making of the jaws. I'm still awaiting countersunk head soft iron rives, you wouldn1t believe how difficult they are to find. I may have to make do with homemade brass ones which will be strong enough for such light clamping. If anything needs clarifying please let me know and I will do my best to please!
 

Attachments

terryd

Well-Known Member
Joined
Jun 15, 2010
Messages
95
Reaction score
45
Terry, You are Correct....But I am just Old and LAZY !!
Best wishes
Lazy Malcolm

Hi Malcolm,

I too am old with not too may left and have always thought of myself as lazy, but as I have been retired for many years than I care to remember I take my time.

Best regards

TerryD
 

HennieL

Well-Known Member
Joined
Apr 17, 2020
Messages
46
Reaction score
24
Location
South Africa
Furthermore, personally I really enjoy making working high-quality tools as part of my workshop activities and by making from available stock in my workshop they cost zero. Of course, I can't speak for everyone but I'm just publishing this for like minded folk.
Terry, I'm one of many such like-minded people 👍

Thank you so much for the detailed description and photos - this will make building this pipe bender much easier than trying to figure it out from scratch - MUCH APPRECIATED :)
 

terryd

Well-Known Member
Joined
Jun 15, 2010
Messages
95
Reaction score
45
Mini Bender Jaws

Hi,
I have attached a pdf of the original document by Mr Clarke from the 1956 Model Engineer. I was reluctant to publish earlier due to copyright considerations but discovered that the present owners of the magazine only have the copyright on articles published since they have owned it, the copyright on an article from before reverted to the original author and if he wishes I will remove it. I believe that this is the reason that John Tom can publish ME designs from an era before the present owners of the magazine.

Anyways up, on to the making of the jaws for the bender. These are made from two 3/4" (20mm)x 3/8" (10mm) stock x 1 3/4" (44mm) long flat stock. In order to make the semicircular longitudinal cutouts for the clamp, he suggests mounting them on the lathe cross slide side by side on suitable packing to raise the height and with 1/16" (I used 0.7mm) packing between the jaws longitudinally, and then and drilling using a chuck mounted 5/16" (8mm) drill.


I did it rather differently. I glued the jaw blanks side by side with a strip of thin stainless steel between them, I then mounted them vertically in the Vice jaws of my milling machine such that they were pressed together and ensured that they were vertical I also used a toolmakers clam to prevent them coming apart while drilling. I then set the centre of the jaws to be drilled on the centre of the mill using a 'wiggler', I spot drilled and then finally used an 8mm jobbers drill to drill through to size. I didn't drill a pilot drill due to teh set up, it had to be all or nothing, and it was 'all' luckily. I had of course taken extra safety precautions because despite doing such stuff since 1963 I still have two good eyes, eight working fingers and two thumbs.

View attachment 117526

Jaws drilled Note the other holes.

While in the milling machine chuck I also drilled the hole which is the basis for the cut out in the fixed jaw to allow 180° bends to be produced. I drilled 3 rivet holes in that yaw and 1 x 10 mm hole for the clamping cam in the moving jaw You can make these out in the pictures above and below

View attachment 117527

Another view of the jaws

This shown more clearly the arrangement of holes in the jaws. The waste was removed from the fixed jaw where the long hole can be seen to produce a step for clearance of the tube when making a 180° as mentioned above. as can be seen below. Being a masochist I used a hacksaw and files to remove the waste. I love doing things manually for several reasons. First I like the quiet, gentle rhythms involved in hacksawing, filing etc and they are both quite easy to do if you used the correct blades and grades of file for the job in hand. I am quite happy to hand cut a length from a 50 mm (2") round bar when making loco wheels and through make that cut accurate so that the length can be faced off in one pass usually, occasionally I may veer off a little but that is usually because I can't be bothered to change a slightly worn blade.
Such exercise also helps to prevent muscle wastage which is a part of growing old and sedentary. The process of hacksawing uses many of the upper body muscles not just the arms and of course I do it standing so my leg muscles are getting a bit of a workout to add to my walking. SAves a fortune in Gym fees alongside my gardening activities.

View attachment 117528

View showing the fixed jaw shaped to allow 180° bends

My Clarke also suggests not using a reamer as the texture left from a dill will help the gripping action of the jaws. I have made a couple of sleeves to allow in my case 2 and 3 mm tubing to be accommodated and will make more as needed. These can be seen in the picture above and ae simply turned brass leaving a collar, then drilling the appropriate size then slitting along both sides. The slit goes completely along one side but stops about 5 mm short of the end on the other. This section is then thinned to leave about 2 mm of material. I used a junior hacksaw to cut the slits as I couldn't be bothered to set up a slitting saw on my milling machine for such a small job.

View attachment 117529
Image showing pivot pin and eccentric (centre left) and clamping jaw (top left)

To fasten the fixed jaw to the vice baseplate, I glued the jaw on to the baseplate using superglue (cyanoacrylate) spotted the holes through with a suitable size spotting drill then drilled tapping size for M3 screws (for temporary fixing) using my tapping block to ensure vertical tapped holes and then fixed with M3 countersunk screws. The clamping jaw was a little more difficult as the hole centre is based on the eccentric one in the cam and not the hole in the jaw itself. I did this by light clamping the loose jaw in position with the cam set in the hole in the jaw set just before full clamping pressure would be applied. I had to find the centre of this eccentric hole in the baseplate and I wasn't sure how to go about it, which I'm sure most of you all would know a method. What I did is that while everything was clamped in position I made a length of brass to fit the eccentric hole and drilled a 1.6mm hole on centre to accommodate an old gramophone needle (of which I have a few to make replaceable tip scribers and they work remarkably well). The brass was put in the eccentric hole, the gramophone needle inserted and hit with a hammer indicating the centre of the hole. I'm glad to report that no gramophone needles were injured or otherwise harmed in the making of this bending machine.

That's about all there is to say on the making of the jaws. I'm still awaiting countersunk head soft iron rives, you wouldn1t believe how difficult they are to find. I may have to make do with homemade brass ones which will be strong enough for such light clamping. If anything needs clarifying please let me know and I will do my best to please!

Terry, I'm one of many such like-minded people 👍

Thank you so much for the detailed description and photos - this will make building this pipe bender much easier than trying to figure it out from scratch - MUCH APPRECIATED :)
Hi,

I mentioned using a brass insert and old gramophone needle and I forgot to photograph the process so I just made a reconstruction and pictured it as an aid to understanding. Note that the cam is positioned so that it is in maximum clamping mode whereas you really need to adjust it so that it clamps fully just before that maximum think 10° before TDC (for internal combustion aficionados) then the work can be clamped in the direction such that the clamp tightens if there is any movement of the work being clamped.

DSCN3557.JPG


This is a reconstruction of the pivot centre finding

The brass insert fits the hole in the cam quite closely and the centre hole in it was drilled to a sliding fit for the needle, Note that I had to move the clamping jaw to the left as the needle dropped through the existing hole in the clamp plate. When I did it originally I included the brass adapter and lightly clamped the jaws together with toolmakers clamps take care ot to clamp the jaws too tightly..
 
Last edited:
2

Latest posts

Top