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How to machine out a metal channel by hand?

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John Doe 224/06/2022 16:43:59
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100 forum posts
15 photos

Hi folks,

I need your advice. I am making stands for our rocking horse, but the channel I glued in, made from some metal pipe, is a slightly too small ID for the support hoops' OD. (I know, schoolboy error!).

How can I relieve the channel neatly to allow the hoop to seat properly?

I have no workshop or milling machine etc, so need another way to do it - filing by hand would probably be too hit or miss?

I was wondering about something I can put in my 1/4" router and move along, grinding out the channel from above, or maybe a parallel reamer?

The channel measured 10.00mm ID and the hoop OD measures 10.20mm, (I originally thought they were the same).

Any thoughts?

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Edited By John Doe 2 on 24/06/2022 16:48:18

Dave S24/06/2022 16:47:20
374 forum posts
90 photos

Might be easier to make new hoops for the horse end.

Dave

JasonB24/06/2022 16:49:45
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23070 forum posts
2769 photos
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Probably easier to reduce the round hoop by filing

Tim Stevens24/06/2022 16:54:08
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1622 forum posts

Or perhaps find some straight tube with slightly thinner walls to lay in the wood slots? Perhaps brass - which as another option would be easier than steel (and a better bearing surface) to make from flat strip, as long as you get the thickness right first?

Cheers, Tim

Martin Connelly24/06/2022 16:56:39
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2183 forum posts
227 photos

Clamp the two parts together and run a Ø10.5 drill down the resulting hole, from both ends unless it is a very long drill.

Martin C

John Doe 224/06/2022 17:13:26
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100 forum posts
15 photos

Thank you so far, liking that last suggestion.

 

Just to reinforce, I have no workshop, so cannot make new hoops, and the channel is already glued in. (Yes, I know......it's a cock-up on my part).

 

Edited By John Doe 2 on 24/06/2022 17:15:21

SillyOldDuffer24/06/2022 17:34:41
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8903 forum posts
1999 photos

Assuming the channel is impossible to remove I'd file the hoop because it's easier to get at than the inside. Shouldn't take too long with a sharp coarse file. I'd roughly file a series of flats to get rather under wanted diameter, and then smooth the untouched parts a little more carefully to a pop fit.

The only good news is it isn't a precision job. The filed hoop doesn't have to be a circle or have an exact diameter. It only needs to fit where it touches and look as good as the woodwork!

If the channel can be removed, it could be spread more open by forcing a larger diameter rod into the slot with a big hammer or a vice. The wedging rod would need to be about 12mm diameter. The main difficulty is holding the job during spreading. The wooden frame it's already glued into would probably do, but it might get damaged.

You have my approval to use Strong Industrial Language. I often make 'nearly right' errors and the resulting extra bother drives me mad!

Dave

AdrianR24/06/2022 17:44:51
597 forum posts
36 photos

I assume you used epoxy to glue the channel in so I would heat the channel up to remove it from the wood.

Then heat the channel to red heat to anneal it.

To open the channel up I would cut a strip of metal from a drink can to wrap the hoop, then force the channel over the hoop and strip. After this, the channel should be slightly wider than the hoop.

DC31k24/06/2022 18:22:29
727 forum posts
2 photos

Broomstick, sandpaper, sellotape, cordless drill.

Bill Phinn24/06/2022 19:00:37
768 forum posts
114 photos

Maybe it's just perspective, but the channel and hoop diameters look substantially wider than circa 10mm to me.

As others have suggested, a long piece of dowel wrapped in sandpaper and a drill, or maybe an extended-shank drum sander if you can contrive one, would be my attempt at a solution.

old mart24/06/2022 20:04:55
3912 forum posts
268 photos

I would cut up some empty aluminium drinks cans for shims and try fitting it between the channel and the hoop. Use clamps or mole grips to squeeze the parts together. You may have to carefully separate them with a hammer and drift. The object is to stretch the channel slightly. Extra shim thickness mught be needed. If you have a vise, the job would be much easier.

Calum Galleitch24/06/2022 20:15:19
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194 forum posts
65 photos

What glue did you glue it in with?

Simon Williams 324/06/2022 21:04:06
662 forum posts
82 photos

It's not without its perils, but hammer the tube side to side to flatten it slightly. So long as it can move through the limited arc of the rocking horse movement, it won't matter if the tube is oval. The height isn't an issue as the receiving channel is open one side.

Nice exercise in planishing...

Good luck

Simon

Ian P24/06/2022 22:37:45
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2595 forum posts
114 photos

Not really solving the problem but your woodwork looks to be to a very high standard but how did you make it without a workshop?

My thoughts on a solution to the diameter problem are that if the U channel really cannot be removed then reducing the diameter of the bent steel hoop by filing would be the best option. Even if its already painted then just file the 'sides' of the hoop so its ends up slightly oval leaving the upper paint intact.

You could use an angle grinder with a metal grinding (rather than cutting) disk to carefully widen the gap in the steel channel but it would need to be done slowly to avoid heating the metal (and therefore destroying the bond of your adhesive)

Ian P

Hopper24/06/2022 22:39:18
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6694 forum posts
347 photos

You need to remove 0.2mm off the diameter, or 0,01mm off the wall thickness. Largest round file you can fit in there will do it in no time. Anything with emery paper will take longer.

Paul Lousick24/06/2022 22:55:39
2078 forum posts
728 photos

I have used grinding stones and rotary burrs in a router to remove metal which did an excellent job UNTIL the bearings gave out. (warning: wear safety gear, routers spin at 20,000 + rpm and stones can shatter)

So I would recommend that you do as advised and use a file, emery paper and elbow grease. Removing 0.2mm from either the channel or pipe should not be too hard.

Edited By Paul Lousick on 24/06/2022 22:58:53

Hopper25/06/2022 00:18:52
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6694 forum posts
347 photos

Correction: 0.1mm off the wall thickness,not 0.01!  Still easily file-able.

But it would be just as easy, or easier, to file down the round bar with a flat file, as Jason suggested. You can finish it off with long strips of emery tape wrapped once around the job and pulled back and forth to make a nice smooth and round finish.

 

Edited By Hopper on 25/06/2022 00:21:40

David George 125/06/2022 07:43:09
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1873 forum posts
505 photos

I would look at heating the metal channel to soften the glue and remove it. It would be a bodge to do any other and so simple with a hot air gun not a flame.

David

Brian Wood25/06/2022 08:37:32
2579 forum posts
39 photos

It might be possible to spread the channels progressively by hammering in a short section of larger diameter bar, levering it out and moving it along as you go.

Brian.

Edited By Brian Wood on 25/06/2022 08:37:58

Pete White25/06/2022 09:00:06
174 forum posts
16 photos

The answer is in the name, "ROCKING horse", we are talking a toy here, not fine limits IMO, It is easy to overthink things....0.2 mm? Remove a little bit of metal from somewhere and make it "fit" cool

Edited By Pete White on 25/06/2022 09:01:19

Edited By Pete White on 25/06/2022 09:04:36

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