Author Topic: Bending rolls  (Read 30190 times)

Offline Jasonb

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Re: Bending rolls
« Reply #15 on: January 22, 2016, 12:19:51 PM »
It certainly does not look as smooth as turning a geared one :-\

Looking at the video there are cranks at both ends and they are also at 90degrees to each other which would stop you getting stuck at TDC, stop the video at 3.12 when the handle end is up the near end is horizontal.

I think I have also seen chains and sprokets used.

J

Offline Firebird

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Re: Bending rolls
« Reply #16 on: January 22, 2016, 12:34:24 PM »
Hi

I think your right Jason, gears are the way to go. I have not yet delved into the black art of gear cutting so I will have to try and source some.

Cheers

Rich

Offline tangler

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Re: Bending rolls
« Reply #17 on: January 22, 2016, 01:52:22 PM »

I think I have also seen chains and sprokets used.


There's a build for such a beast in the current Model Engineers' Workshop magazine.

Rod

Offline Jasonb

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Re: Bending rolls
« Reply #18 on: January 22, 2016, 02:54:06 PM »
Could well be where I saw it then Rod, issues 236 & 237

Offline Firebird

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Re: Bending rolls
« Reply #19 on: January 22, 2016, 04:51:56 PM »
Hi Thanks everyone.

Plenty for me to chew over there. I think what I will do when I'm well enough is go through my available material box and see what I come up with and get back to you then.

Cheers

Rich

Offline Jasonb

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Re: Bending rolls
« Reply #20 on: January 22, 2016, 04:54:51 PM »
Rich, what size wheels are you thinking of as ERW tube is a cheap way to get a round ring

Offline Jo

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Re: Bending rolls
« Reply #21 on: January 22, 2016, 05:12:56 PM »
Like GHT I would recommend solid rollers, tube is likely to distort  ::)

Jo
Enjoyment is more important than achievement.

Offline Jasonb

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Re: Bending rolls
« Reply #22 on: January 22, 2016, 06:04:50 PM »
I was thinking of using it for the wheel rims not the tool which is why I asked "what size wheels"  ::) ::) ::)

These are 5.5"


Offline GWRdriver

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Re: Bending rolls
« Reply #23 on: January 23, 2016, 12:57:56 AM »
Nothing fancy just practical. Anybody made anything along those lines?
Hi Rich,
I'll vote with Jo and Jason on the GHT rolls, gear driven, with solid rolls.  My set was begun some time ago and interrupted by . . . well, just about any excuse that came along but I've recently pulled my "modified" rolls out and begun to finish them up.  The "mods" involve enlarging the design to make best of some orphaned steel shafting I was given.  The main rolls were increased to 1.5" diameter and the width to 12-1/4".

Suitable gears weren't available ex-stock so I had my first go at cutting gears.  Once the details were worked out, and a cutter was bought, it was a fairly straightforward milling exercise.  I cut a length of "pinion" and sliced individual gears (4 ea) off that.  I'm still shaping and fitting the working bits so the work looks a bit rough :embarassed: at the moment.
Cheers,
Harry

Offline Hugh Currin

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Re: Bending rolls
« Reply #24 on: January 23, 2016, 01:18:33 AM »
Sort of on topic. A few years ago I needed to bend some 1" x 3/16" aluminum the hard way, i.e. put the radius in the 1" direction. Finally bought one of these high quality benders from Harbor Fright. Some of you must be familiar with this top quality outfit. I then turned some new rollers with a 3/16" slot. It worked for the purpose.


It was for molding on a 1955 Shasta Trailer renovation:


If you're rolling tractor tires something like this might be OK. For a boiler shell, this is way too narrow.

Hugh
Hugh

Offline Ian S C

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Re: Bending rolls
« Reply #25 on: January 23, 2016, 12:33:31 PM »
A good few years back there were plans in "Model Engineer" for a set of rolls that used no gears, just a system of con rods and cranks.
Ian S C

Offline Firebird

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Re: Bending rolls
« Reply #26 on: January 23, 2016, 06:54:34 PM »
Hi

Some more good info, thanks,  :ThumbsUp:

Not sure what size wheels yet Jason, the portable engine is very much make it up as you go along.

But anyway I have decided this must be a joint effort and enrol you all on this joint project so keep the ideas coming  :help: :Lol:

I think the 4 gear type is looking favourite. Have a look at my crude drawing



Am I correct in saying that the handle would be attached/keyed to roller 'A'.  Rollers 'B' are fixed position idlers. The 4th gear would be fixed/keyed to the upper moveable/pinch roller. I am assuming that the upper roller gear stays in mesh when the upper roller is adjusted up and down, within limits.

Just trying to get my head around this :thinking:

Cheers

Rich

OOPS!!!!! sorry about the size of the drawing, got to figure out how to make it smaller  :thinking:
« Last Edit: January 23, 2016, 07:05:13 PM by Firebird »

Offline Jasonb

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Re: Bending rolls
« Reply #27 on: January 23, 2016, 07:58:26 PM »
Sounds about right to me.

Offline Firebird

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Re: Bending rolls
« Reply #28 on: January 24, 2016, 04:01:07 PM »
Hi

The somewhat oversized drawing? has gears of 1.5" diameter. Thats just a guess at the moment as I haven't sorted through the available materials department yet so I don't know what size the rolls will be and their spacing.

But a question about gears if I may. I have just spoken to my mate Julian and he has 3 involute gear cutters.

They are:  16 DP    21-25
               16 DP    35-54
               20 DP    35-54

I know nothing of gear cutting as yet but would any of those 3 put me in the ball park?

Cheers

Rich

Offline Jasonb

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Re: Bending rolls
« Reply #29 on: January 24, 2016, 04:13:24 PM »
I would stick with the larger size teeth as they will stay in mesh for longer before they start jumping so thats the 16DP.

If the centre to centre distance of two gears is 1.5" then you will need 24T gears but if you only find 1.5" material to cut them from the ctr distance will have to be 1.375" with 22T

A quick guide to what you can cut can be found on HPC's site, this PDF lists all the 16DP sizes


http://www.hpcgears.com/pdf_c33/23.120-23.125.pdf
« Last Edit: January 24, 2016, 04:57:34 PM by Jasonb »

 

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