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Tube Notching

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Andy Joyce 104/03/2019 09:28:57
11 forum posts
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Need to notch joint multiple lengths of thin wall stainless steel tube prior to silver soldering to form a fuselage.

Have 6.35mm OD tube with a wall thickness of 0.2mm which is to be joined to 7mm tube. So how best can this be done?

wondering if I could use a 7mm 4 flute milling cutter in a pillar drill with the 6.35mm OD tube supported in a larger diameter tube to hold it. Would this work?

Tried making a simple grinder as pictured but this did not work at all. Perhaps a different stone type would be better

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Hopper04/03/2019 11:39:14
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3774 forum posts
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Your Dremel rig with a 7mm carbide burr instead of the grinding stone?

JasonB04/03/2019 11:47:16
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My only worry about using anything with coarse "teeth" would be that it could catch the leading edge of the very thin walled tube and draw it into the cut. Could be solved by slipping a thicker walled tube inside the main one to add some support.

Brian Sweeting04/03/2019 13:39:14
385 forum posts
1 photos

AJ 1, very many years ago I worked for a firm that made tubular steel trolleys and the tubes were notched on a machine providing a similar method to the one that you are proposing.

If memory serves, it had a rotating cutter like a milling tool but mounted horizontally The tube was clamped into a movable vise and pushed onto the cutter.

Maybe make a sliding plug to go inside your tube so that a spare(?) drill chuck could be used to hold the non cutting end of the tube and improve your grip.

David George 104/03/2019 14:11:50
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I used to make motor cycle frames and the joints were milled with an aluminium plug inside the plug was inside when the first one was was machined and then the same plug supported the tube as each one was milled.

David

Trevor Drabble04/03/2019 14:27:34
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205 forum posts
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Suggest careful use of a tube cutter such as items 59799 or 27996 from Toolstation.

Trevor Drabble04/03/2019 14:49:15
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205 forum posts
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Sorry , forgot to say , the tube should obviously be supported by inserting wooden dowelling inside it in order to prevent distortion during cutting .

Andy Joyce 104/03/2019 18:01:21
11 forum posts
4 photos

Trevor

Those tools are no use as they will produce right angle cuts. What is required is a lap joint as pictured.

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Andy Joyce 104/03/2019 18:13:28
11 forum posts
4 photos

Tried another technique this evening which was very simple and quick. Using a standard 6 inch bench grinder, I ground an simple arrow shape on the end of the tube with an tip angle of about 90 deg going back no more than a 1/4 of the diameter, then cleaned up the shape with a round file of similar diameter to the pipe.

Result was not perfect but it was very quick with little burring of the tube.

Tim Rowe04/03/2019 18:13:33
26 forum posts
4 photos

Andy

I am intrigued - A fuselage for what? I wonder how strong those joints are going to be?

With a 0.2 wall you are removing very little material. I would be inclined to insert a suitably sized wooden dowl and use a fine round or half-round file. Unless of course you are doing hundreds!

Tim

Colin Heseltine04/03/2019 18:20:42
345 forum posts
87 photos

Could you use the small jewellers diamond core cutters. See link below

**LINK**

and make similar tube /pipe notcher as picture below.

Woodward-Fab-SPPIPENOTCH-2-034-Pipe-and-Tube-Hole-Saw-Notcher

Colin

Andy Joyce 104/03/2019 19:02:51
11 forum posts
4 photos

Tim

Aircraft is a 1/4 scale Zavage Bobber which has an open construction so you see all the fuselage construction from the instrument panel backwards to the tail

Would guess a 100 of so joints have to be made so need a system that forms each joint quite quickly. Will post a link that shows the construction shortly.

Andy Joyce 104/03/2019 19:06:12
11 forum posts
4 photos

This site shows the construction of a 1/3 scale build Link

Andy Joyce 104/03/2019 19:07:20
11 forum posts
4 photos

Page three shows a metal construction

Andy Joyce 104/03/2019 19:13:11
11 forum posts
4 photos

Colin

Your diamond core cutter could be an option, but they are not cheap are they. Note they don't say they are suitable for metal. More tempted to try a carbide burr.

Will talk tomorrow to the guys in our workshop at work to see if they have any suggestions particularly with regard to the use of a 4 flute milling machine cutter.

JasonB04/03/2019 19:35:48
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You could probably do similar with diamond coated tile drills which are dead cheap if you can wait a week or two.

Just hold tube in a vice and see if you can plunge down as you would with a holesaw

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Andy Joyce 105/03/2019 19:52:00
11 forum posts
4 photos

Jason, Do you think this tool would work?

f:0">link

JasonB05/03/2019 19:57:16
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I'll try one of mine in the morning and let you know.

Chris Gunn05/03/2019 20:07:50
284 forum posts
16 photos

Andy, full size fabricators use a linisher with a long belt, and a roller at the business end which will give the right radius when the tube is radiused. the tube is presented to the roller at the appropriate angle to give a right angle or any other joint angle by an adjustable tube rest. I wonder if you could make a small version using the 1/2" wide linishing bands that are used on the power files. These can be bought at Screwfix and Toolstation, (belts or files) my power file has a roller about 1/2 " diameter at the end, too big for what you want. It would all depend on how small a roller the belt would go round.

Chris Gunn

JasonB06/03/2019 08:50:02
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Put a used 6mm diamond coated "holesaw" as per my earlier link into a drill chuck and tried it on the nearest stainless tube that I had which was 1/4" dia and about 0.5mm wall.

Fed down with the quill, they need running fairly slow say 500rpm and need cutting oil but not too bad once the burrs where tidied up.

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