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  1. #1
    5thwheel is offline Stainless
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    Default OT: design of pinch rolls

    I have a need for miniature pinch bending rolls for a miniature project. This is to be of the two pinch roll design with a third roll that comes in at an angle to cause the metal to bend. There is nothing commercial small enough for my need so I plan to build a set. The diameter of the rolls will be 1/2". My question is at what angle does the third (forming) roll travel. Does it align with the center line of the top roll or does it align between the two rolls?
    Bill

  2. #2
    Limy Sami is online now Diamond
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    If I can find the drawings for mine / measure the angle today, I will, and get back to you after 21.00 GMT.

  3. #3
    5thwheel is offline Stainless
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    Thank you. I measured up an antique set many years ago but did not get that angle. I'm guessing it to be near 30 degrees. I would like to make a miniature of the antique rolls but I need to roll some tight cylinders so need a removable top roll which the antique ones did not have.

    Bill

  4. #4
    Ries's Avatar
    Ries is online now Diamond
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    they do make little ones-
    http://www.profiform.com/en/products/rondo.cfm
    I just bet they are pricey, though...

  5. #5
    Limy Sami is online now Diamond
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    Hi there, found my drawings,....... more luck than judgement

    I originally made the G H Thomas rolls as featured in Model Engineer - these
    http://www.hemingwaykits.com/acatalo...ing_Rolls.html

    They work very well, - as do all of his designs, I can't post drawings but you may well find them on the web.

    I have subsequently ''doubled'' and then ''halved'' the design and both work nicely.

    The deflecting roll is at 15 deg to the pinch roll stack, and the slot it slides in is set at a radius from the lower pinch roll so the deflecting roll misses by 1/32" and goes up high enough to touch the top pinch roll at max metal thickness.

  6. #6
    5thwheel is offline Stainless
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    Thanks. Nice set but too large for my needs.
    Quote Originally Posted by Ries View Post
    they do make little ones-
    http://www.profiform.com/en/products/rondo.cfm
    I just bet they are pricey, though...

  7. #7
    5thwheel is offline Stainless
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    Quote Originally Posted by Limy Sami View Post
    Hi there, found my drawings,....... more luck than judgement

    I originally made the G H Thomas rolls as featured in Model Engineer - these
    http://www.hemingwaykits.com/acatalo...ing_Rolls.html

    They work very well, - as do all of his designs, I can't post drawings but you may well find them on the web.

    I have subsequently ''doubled'' and then ''halved'' the design and both work nicely.

    The deflecting roll is at 15 deg to the pinch roll stack, and the slot it slides in is set at a radius from the lower pinch roll so the deflecting roll misses by 1/32" and goes up high enough to touch the top pinch roll at max metal thickness.

    Thanks. Again this set is also too large for my project but from looking at both sets it appears that the angle of the deflecting roll is not all that critical. The first one looks to be about 10-15 degrees and this last set it is parallel to the face of the pinch rolls.All the deflecting roll has to do is be in a position to cause the metal to bend as it comes in contact with the roll. The last one with parallel travel may not get the tight cylinder I need. A minimum angle makes the deflecting roll get progressively closet to the top roll as the cylinder diameter becomes smaler.
    Thank you all for your help.
    Bill

  8. #8
    Peter Miles is offline Cast Iron
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    What diameter cylinders are you wanting to roll?

  9. #9
    5thwheel is offline Stainless
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    Quote Originally Posted by Peter Miles View Post
    What diameter cylinders are you wanting to roll?
    Presently I plan on using 1/2" diameter drill rod for the rolls. I expect the rolls to be about three or four inches long. I would like to use 3/8 rod so I could roll 1/2" tubes but the gears I have on hand are too large.

    With this set I plan to roll from 5/8 to 1" diameter tubes but I also plan to roll miniature tubing and nickel silver rods into multiple bends (for miniature hand rails). I also hope to be able to roll .010 flat tin stock into S shapes by turning half rolled stock over to roll the reverse curves. I have done this on fullsize rolls.

    Bill

  10. #10
    wrenchhead531's Avatar
    wrenchhead531 is offline Aluminum
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    I am sorry but you will have to excuse any ignorance I may show here, but why would you want a fixed 3rd roller? It justs seems with your mixed lot of material and artistic bends you should be looking at an adjustable angle set up.

  11. #11
    5thwheel is offline Stainless
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    Quote Originally Posted by wrenchhead531 View Post
    I am sorry but you will have to excuse any ignorance I may show here, but why would you want a fixed 3rd roller? It justs seems with your mixed lot of material and artistic bends you should be looking at an adjustable angle set up.
    Your ignorance is excused just this one time. I did not say anything about a fixed third roll. What I want to know is which is the best angle that the deflecting roll must travel to make the best and tightest bends.

    Bill

  12. #12
    gary350 is offline Hot Rolled
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    This is what you need. Build it your self PLANS.

    http://cgi.ebay.com/BRAKE-Sheet-Meta...item4cecf02dc8

  13. #13
    5thwheel is offline Stainless
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    Quote Originally Posted by gary350 View Post
    This is what you need. Build it your self PLANS.

    http://cgi.ebay.com/BRAKE-Sheet-Meta...item4cecf02dc8
    I made a similar brake. It works great for small stuff. Those rolls, however, have a top roll that pushes down to make a bend rather than a deflecting roll. Below is a miniature set I presently am using. Several problems with this type. First there is no pinch so the metal slips as it is passed through (hard to keep feed of the plate straight. secondly it is impossible to make a tight cylinder. Also I can not bend in s forms with this type.
    ....

  14. #14
    5thwheel is offline Stainless
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    Below is some of the metal work I do. these are all inch to the foot.
    ............

  15. #15
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    Cool stuff!

    Here is a website that has plans for a larger sliproll, but the plans have a detail on how the third forming roll is installed to be adjustable along an angle. May be useful.

    http://www.metalwebnews.com/howto/rolls/rolls.html

    Here's another link from someone who made a similar unit.

    http://www.*******.com/forums/showthread.php?t=33819

    Good luck!

    Jim

  16. #16
    5thwheel is offline Stainless
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    Quote Originally Posted by bosleyjr View Post
    Cool stuff!

    Here is a website that has plans for a larger sliproll, but the plans have a detail on how the third forming roll is installed to be adjustable along an angle. May be useful.

    http://www.metalwebnews.com/howto/rolls/rolls.html

    Here's another link from someone who made a similar unit.

    http://www.*******.com/forums/showthread.php?t=33819

    Good luck!

    Jim
    Thanks, That looks very helpful. Amazing what one can learn on this forum.

  17. #17
    5thwheel is offline Stainless
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    This is a spring leaf I am bending for a model vehicle. The materials is a steel cast off (found in the street) from a street sweeper brush. It is some kind of high carbon steel. I need to get a little more bend in it but it slips because ther is no way to pinch the material while it is being fed in the rolls. That is why I am trying to design pinch rolls. They should do the job better.


  18. #18
    Doug is online now Diamond
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    Try this. Shown is a Di-Acro slip roll with the third roll backed off. The material is rolled using only the two rolls with a piece of rubber or urethane under the material.

    The rubber forces the material to wrap the upper roll.

    With this method you also don't have the flat at the start of the rolled material.
    Attached Thumbnails Attached Thumbnails slip-roll-trick.jpg  

  19. #19
    Racer Al's Avatar
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    Doug, that's a great tip! Thanks for sharing it.

    I'm also planning to build a new slip roll, mine is too light duty.

  20. #20
    5thwheel is offline Stainless
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    Quote Originally Posted by Doug View Post
    Try this. Shown is a Di-Acro slip roll with the third roll backed off. The material is rolled using only the two rolls with a piece of rubber or urethane under the material.

    The rubber forces the material to wrap the upper roll.

    With this method you also don't have the flat at the start of the rolled material.
    Doug, I use a similar method now using a dowel (by hand as in rolling pin for baking) against rubber but I get kinking in the tin.

    I see your rolls have the third (deflecting) rolls running verticle rather than at an angle. (also similar rolls posted by bosleyjr)
    How well do this type work?

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