Rotary file advice needed please

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idkhow2diy
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Rotary file advice needed please

Post by idkhow2diy » Tue Sep 24, 2019 6:53 pm

Hi

I need some advice please on how to cut / grind within a slot in steel (see pic - this is a section of the lever frame in a signal box).

I know a grinding disk in an ankle grinder will cut the material easily when the various bits are disassembled but I need to be able to grind within the slots when the frame is built to ensure the levers work properly. I can manage to cut it with a rough file but it’ll take ages!

See the pic - the area in the centre (the sort of + shape) is where material needs to be removed. That stepped section to the right was cured with a file so it’s not so tough that it will not cut. But I still need to take about 1.5mm more out of the lower part of that area and the file is just too tiring. Maybe with a decent bass rhythm, some better gloves and a day…

So I wonder if a rotary file / rasp will be any use? eBay / Amazon throws up all manner of shapes and sizes, some of which say only good for soft metal. It doesn’t matter about the fact the edges would be curved provided enough material can be removed, and addressing the curve with a decent file is a lot easier than trying to file down the whole approx. 1.25” width in one go. It’s a bit hard to explain.

The thing is of the 27 of said slots, each is going to need adjusting by hand individually, which is why they cannot be cut before assembly. Each is slightly different. Any advice / suggestions of types / parts etc. greatly appreciated!
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Dave54
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Rotary file advice needed please

Post by Dave54 » Tue Sep 24, 2019 8:30 pm

What is it? Fabricated steel or cast?
If it's steel the old fashioned way is to chip the bulk out as near as the line as you can get it with a cold chisel, (or air chisel I suppose) and then use files.
Wear goggles for the chipping obviously.
If it's cast then as far as I know you can't chip it away.
I've used rotary files a long time ago, they work, but they're not the be all and end all (or at least the ones I used weren't) and still take time.
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Rotary file advice needed please

Post by idkhow2diy » Tue Sep 24, 2019 10:29 pm

Dave54 wrote:
Tue Sep 24, 2019 8:30 pm
What is it? Fabricated steel or cast?
Ah I thought I added that in - definitely castings. Also the adjustments needed are not large, a few mm or less here and there, and not all the same place. So I was hoping a rotary file of some sort to rough it out and then file to make it neat.
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Rotary file advice needed please

Post by big-all » Tue Sep 24, 2019 11:16 pm

the signal lever will be steel
what happened to the origional lever in the slot cut down for electric ??
we are all ------------------still learning
idkhow2diy
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Rotary file advice needed please

Post by idkhow2diy » Wed Sep 25, 2019 6:17 am

big-all wrote:
Tue Sep 24, 2019 11:16 pm
the signal lever will be steel
what happened to the origional lever in the slot cut down for electric ??
The slots are not cut any different for mechanical or electric - and the photo is before the levers were fitted. Not touching the levers but so much of these frames are clearly modified when built that adjustments are still needed to the castings now.
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Rotary file advice needed please

Post by Dave54 » Wed Sep 25, 2019 10:15 am

Are those numbers stamped on the front for the assembly order?
Stuff like this is often made as almost a "one off"
And then "fitted" in the old fashioned sense of the word.
That is they are actually made close to the finished size and then individually fitted together by hand, and then often numbered for assembly.
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Rotary file advice needed please

Post by idkhow2diy » Wed Sep 25, 2019 10:25 am

Dave54 wrote:
Wed Sep 25, 2019 10:15 am
Are those numbers stamped on the front for the assembly order?
It's a mixture of bits from about three different frames which is unfortunately unavoidable. There would have probably been adjustments even if the frame was all complete due to it being installed / bolted down etc. but it's made worse by that fact. Even those bits that were originally mated up had visible differences. So I need to do these minor adjustments but I don't want to buy a / the wrong sort of rotary file if it's of no use.

As I can file it by hand I'm guessing a rotary will have some effect and perhaps enough, and save my wrists!
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Rotary file advice needed please

Post by Dave54 » Wed Sep 25, 2019 10:47 am

As I said, I've used them before, but only with an electric drill. I had to make a reasonably accurate slot in a pair of motorbike handlebars for the throttle twist grip, some machines have that setup where a piece moves in a slot and pulls the cable. Drilled, sawed and filed the bulk of the waste out, but it was very awkward because the slot was one side of the tube. We had some decent rotary files. They worked of, but they were slow, even on the relatively thin stuff of the handlebars. My impressions is that they are really for removing material in really difficult places like mould or die making perhaps. It has been a long time ago though. Worth a try.
What about some sort of flexible shaft grinder?
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Rotary file advice needed please

Post by idkhow2diy » Wed Sep 25, 2019 10:57 am

Dave54 wrote:
Wed Sep 25, 2019 10:47 am
As I said, I've used them before, but only with an electric drill. I had to make a reasonably accurate slot in a pair of motorbike handlebars for the throttle twist grip, some machines have that setup where a piece moves in a slot and pulls the cable. Drilled, sawed and filed the bulk of the waste out, but it was very awkward because the slot was one side of the tube. We had some decent rotary files. They worked of, but they were slow, even on the relatively thin stuff of the handlebars. My impressions is that they are really for removing material in really difficult places like mould or die making perhaps. It has been a long time ago though. Worth a try.
What about some sort of flexible shaft grinder?
Ok so I'm back to wondering what type of rotary file as eBay and Google throw up different types and patterns, some of which say only for soft metal, other say nothing at all. As to the flexible shaft grinder - a sort-of grown up Dremel? I have a Dremel and all sorts of wheels, and a flexi shaft, but it seems like attacking the thing with a toy so I've not tried it. The right sized wheel, a decent drill (got) and a flexi shaft may well work nicely and I'd not considered that so thanks! Of course I don't have one (other than the Dremel) - but then nor do I have a rotary file as I don't want to buy something useless.
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Rotary file advice needed please

Post by Dave54 » Wed Sep 25, 2019 2:32 pm

I don't know there days. The ones I used back then were good quality. Might have been Starrett, but I can't see that they do them any longer, if they were by them of course.
They were files rather than rasps.
I wonder if you could do something like clamp a plate onto packing on the face, dead square to the side of the slots being worked on, and use a mag drill with something like an end mill to remove as much of the waste as you can. Just a thought though really.

I've got a mate who was in engineering all his life, I'll probably see him at the weekend and will ask him if he can think of anything if you haven't got it sorted.
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Rotary file advice needed please

Post by Bob225 » Wed Sep 25, 2019 5:45 pm

You will get in there with die grinder but you will lose the square corners but you can use a b*stard to get them back in shape

You could use a powerfile but there 16mm wide and the belts tend to let go if you get them too hot
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Rotary file advice needed please

Post by idkhow2diy » Wed Oct 09, 2019 5:35 pm

A bit of feedback on this - I did get what appeared to be a decent rotary file off eBay and it does a good job at roughing out, followed by the equally decent flat b'stard file I also purchased. I used the rotary on the one awkward area then filed flat (the file has filey bits at one edge too), and the file alone on all other areas (about 15 of the 27 castings needed fiddling). So it seems the file I was originally using that was taking ages was so doing purely because it was rubbish!

The rotary is pretty uncontrollable on the flat surface as you'd imagine but it gets the bulk out ready for the file, so it all worked out ok. It has a tendency to make a cut and then stick in that cut but angling it afterwards gets past that. A guide of some sort would help but there's no way to make one.
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Rotary file advice needed please

Post by Bob225 » Wed Oct 09, 2019 6:54 pm

The old b*stard, file works wonders i needed a smaller one a few months ago and end up with a bahco from wickes, a file card keeps it good as new
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