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6th September 2013, 02:42 PM #1GOLD MEMBER
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How do I make one of these (long thin metal thing)
Hi. This is my first post on the metalwork forum due to being a complete dunce at metalwork. Anyway, I want to make one of the saws like in the attached photo. I'm stuck on making the long thin metal arm. I understand its usually made from a length of brakeline - bent into a U shape. My question is, how do I bend it without it collapsing where the radius is smallest. I have a few bending springs at home which I have previously used when bending pipe but never with any success, and anyway, I think its way too thin for a bending spring. Is there another way of bending it ?
cheers
Arronmarqsaw.jpgApologies for unnoticed autocomplete errors.
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6th September 2013 02:42 PM # ADSGoogle Adsense Advertisement
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6th September 2013, 03:02 PM #2SENIOR MEMBER
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Seal one end of the tube.
Fill tube with water.
Seal other end.
Place in freezer.
When frozen to ice, take out and bend to shape.
Remove plugs and thaw out water.
Job done.
RobThe worst that can happen is you will fail.
But at least you tried.
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6th September 2013, 03:49 PM #3GOLD MEMBER
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Will it fit in the freezer?
With one of these?
3in1 Tube Bender Pipe Curving Pliers Brake Fuel Line 6mm 8mm AND 10mm UP TO 180 | eBay
Where are you going to buy the brake line from? Fair chance they will be able to bend it for you.
Stuart
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6th September 2013, 03:57 PM #4
If it won't fit in the freezer pack it with damp sand (and I mean pack it, not just pour it in) seal the ends, bend, flush the sand out. The ice works better though.
Ew1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.
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6th September 2013, 05:44 PM #5
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6th September 2013, 05:52 PM #6SENIOR MEMBER
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6th September 2013, 06:05 PM #7Distracted Member
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Any reason not to use solid rod?
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6th September 2013, 06:14 PM #8
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6th September 2013, 06:34 PM #9SENIOR MEMBER
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6th September 2013, 09:21 PM #10Novice
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Umm, I'd just use a brake line bender.
Just get your bit of brake line from a brake place and I'm sure they'd bend it for you on the spot.
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6th September 2013, 10:31 PM #11GOLD MEMBER
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Great, several ways that will work
thanks Guys,
I think the sand method will do the trick. I would use the ice method but we have no freezer.
I had thought of going to a brake place and getting them to bend it but I want the knowledge anyway as its a good thing to learn.
I was hoping to get the brake line from Repco or some other parts place. Havent rung them yet.
Why not use a solid rod ? I have no idea. Could it be because the brake line gives you the right amount of spring loading on the blade ????
cheers and thanks
ArronApologies for unnoticed autocomplete errors.
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6th September 2013, 10:40 PM #12Philomath in training
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I'm with Bryan here and ask why not use solid?
The only reason I can think of is that any extra stiffness may strain the motor - although when cutting I would have thought that in use the load from the cutting action would outweigh that consideration. Overcoming that may just be a matter of reducing the diameter slightly.
I know when making these devices there is a strong tenancy to follow the plans - especially if not familiar with the medium (metal) as Aaron admits he is, but if that metal bow is just acting as a spring there could be other things out there that may do the job - how about a laminated timber 1/2 span leaf type spring (I'm thinking of the limbs of my bow when I did archery years ago) another option may be a more solid framework with a tension spring of some sort. From what I can see the only job it has is to provide some tension on the blade on the return stroke so really there is not much force called for.
Michael
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6th September 2013, 11:15 PM #13SENIOR MEMBER
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Doesn't brake line have a very small bore giving a large wall thickness?
I would just try bending around a bit of pipe first and see how it goes. It might not deform as much as you think.
Phil
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6th September 2013, 11:31 PM #14
I have seen this idea before but a long time ago. I was surprised that brake line would be considered sufficient. There has to be enough tension in the "spring" to keep the blade straight in both directions when cutting and hopefully returning up. Seems flimsy to me but I don't really know. Another way would be to make the top bar out of vertical flat that extends behind a vertical support and has a spring to maintain tension. This method will enable the spring tension to be adjusted. The pivot between the support and top bar will need to be pretty close tho.
Be interesting to see it working. I have some spring type benders down to about 1/4 inch. I don't know if they are suited to brake line as they are meant for copper. Probably easier to go with previous suggestions. The springs can be hard to get off sometimes.
Dean
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6th September 2013, 11:57 PM #15GOLD MEMBER
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Yes, it is a matter of following the plans a bit slavishly when you have very little knowledge and not much time to experiment.
I should also clarify that there is no motor here. Its operated by hand - by pushing up and down on the handle you can see below the table. The handle is fixed to a vertically-mounted drawer slide - making it not nearly as complicated to make as it seems. Its actually a marquetry saw, and as such it's only used to cut sub 1mm thick veneers. The long metal bow is actually fixed to the drawer slide, not the table, and the whole thing moves up and down without any deformation of the bow. The spring loading is necessary to keep the blade tight, but the upper limb does not flex up and down as it might if the lower limb were fixed to the table.
Cheers and thanks for the help
ArronApologies for unnoticed autocomplete errors.
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