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10th March 2014, 02:12 PM #1GOLD MEMBER
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Best way to round aluminium bar corners
I have some 30 x 3mm aluminium bar, and would like to shape the ends of the bar with 15mm radius curves on the flat surface, so the ends are nicely rounded in a semicircular shape. I can cut them to approximate shape with a hacksaw working on tangents of the curve, but want to have a nice smooth curve.
I understand that aluminium will clog up a linishing belt or a belt sander, bench grinder wheels and some files.
Not being a metal worker, I would welcome any suggestionsregards,
Dengy
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10th March 2014 02:12 PM # ADSGoogle Adsense Advertisement
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10th March 2014, 02:38 PM #2GOLD MEMBER
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How many you have to do?
Turn up some 30mm dia discs say 10mm thick. clamp one either side of the bar. File until you rub the steel. How badly the file clogs depends on the aluminium and how new your file is. Some chalk rubbed on the file after each clean can help. I use a spray of WD40.
(works better if you have a hole in the bar so you can use a bolt, but you cant always have everything)
Stuart
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10th March 2014, 03:35 PM #3.
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Round over router bit in a router table
Rub wax on the corner.
Practice
Watch out for the shards they are razor sharp.
Whoops I realise you want 15mm, could be a hard bit to find, 1/2" will get you a fair way there.
You can sand ally on a linisher (I do it all the time), use a new belt, gentle strokes, keep the belt clean by applying a piece of PVC pipe to the belt.
Practice first
Grinding some chalk on the belt is supposed to work but I find it just makes a mess.
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10th March 2014, 04:29 PM #4GOLD MEMBER
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Thanks for sharing this experience. BobL. I will head over to my son in law's shed and give it a go.
Do you put the flat edge of the PVC on the belt to clean it, or just the lay the pipe across it so the curved surface is against the belt, or doesn't it matter?regards,
Dengy
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10th March 2014, 04:55 PM #5
I'm a little confused, perhaps you can clarify some dimensions... is that 30mm diameter bar?
Where does the 3mm dimension come into it?
When you say the radius curves on the flat surface? Do you mean the curve is only in one plane? Or is the end like a half sphere?
A picture or sketch would make it a bit clearer.
Ray
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10th March 2014, 06:45 PM #6Philomath in training
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It's 30x3 flat bar.
The other simple one is a flap disc in an angle grinder. Trim the end to an approximate radius and then use the flap disc to blend.
Michael
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10th March 2014, 07:22 PM #7
That all makes sense now... How accurate? or is it just for visual effect?
If it's just for visual effect, find something 30mm diameter, and use it as a template to scribe a line on the aluminium, then roughly chop the majority of the waste with an angle grinder and thin cut off wheel, then finish sanding to the line in a disk sander, or linisher.
Angle grinders don't like aluminium generally speaking, but small cuts like this should be no problem.
Ray
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10th March 2014, 07:50 PM #8GOLD MEMBER
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Thanks for your input everyone, very much appreciated. I should have clarified above, the profile is more elliptical than semi-circular.
Following on from the suggestions above, I drew the required profile on the flat ends of the aluminium bar using a cardboard template, then chopped it with a 1mm disc on a 4" angle grinder to a rough approximation of the required shape, and did the final shaping on the linishing wheel. Used BobL's suggestion of a PVC pipe to keep the linishing belt clean, worked perfectly.
Very pleased with the result, having done a practice run and taking it slow and easy, frequently checking against the cardboard template of the profileregards,
Dengy
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10th March 2014, 08:15 PM #9.
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10th March 2014, 09:17 PM #10GOLD MEMBER
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The absolute best way to prevent ally clogging linisher belts, flap discs, grinding wheels and cutoff discs is candle wax.
simply set your linisher, angle grinder or sander going and then apply candle wax to the wheel or belt.
I am a boilermaker who has worked extensively with ally and that is what I use to this day. In fact, I will not touch a tool to ally without waxing it first with the exception of TCT saw blades and carbide burrs. I use metho sprayed on for the former and CRC/WD40 for the latter. Either of these work well for bandsaws and jigsaws as well, just remember to clean off the CRC/WD40 if you are welding the component. If you are sanding finer than say 80 grit then use velvet soap, (slightly moist is best, but dry works too).
I would not generally use finer than a 60 grit flap disc with 40 being my preference.
One final word of caution. Blow out sanders and grinders with compressed air on a regular basis. Ally dust penetrates everywhere and you do not want to be hanging onto a grinder that becomes a jet engine complete with flames exiting the vents, (yes, I have seen it happen and no, his undies did not survive the encounter).
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11th March 2014, 07:41 AM #11GOLD MEMBER
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Thanks for this valuable information, Karl. Where is the best place to get non scented candles?
As I'm a non-metal worker, can you pease tell me what are carbide burrs?
Also, is metho sprayed around a drop saw with TCT teeth safe, on account of the sparks generated inside the saw with the brushes etc.?regards,
Dengy
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11th March 2014, 09:50 AM #12.
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Good infö there Karl.
The tip for using soap on fine sanding belts for ally sounds like a good one for ally, I'll tuck that one away for future reference.
I found hard wax works a bit better than candle wax as candle was is a bit soft and melts too quickly and gets flung off high speed tools.
I don't know where to get hard wax, I just get it from my ally working BIL
I use metho sometimes in the way you indicated but as I found I am restricted to delivering it with a squirt bottle and that is not easy if both hards are needed on the tool so I tend to use wax on CT tools as well. One way to to get continual wax delivered to on the cutting edge is to rub the cut line or surface with wax,
I do use metho when using a drill press (one hand is usually free to hold a squirt bottle) and also on lathe work, and also when using taps and dies - works great.
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11th March 2014, 10:41 AM #13GOLD MEMBER
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Carbide burrs are tools used in die grinders instead of grinding stones. They are available in a range of shapes and sizes with cylindrical, ball and christmas tree shapes the most common. There are from memory 3 basic tooth styles used on burrs ranging from a coarse single cut tooth designed for fibreglass through a less aggressive single cut tooth aimed at ally and other soft metals then progressing to a finer double cut tooth style more in keeping with steel and cast iron usage. In thinking about it just then, I reckon they could have some applications in the woodworking field too.
Metho is quite safe around saws due to the fact that when sprayed on the blade, (we generally use a squirt bottle and give a couple of squirts with the saw running, this is generally sufficient to prevent clogging of the saw teeth), it is largely contained by the guard and doesn't reach the brushes etc. I have never witnessed or heard of a flash or fire caused by metho. Unless you leave it next to where you are welding, but that's another story in itself.
We generally aren't too fussy where we get our candles, (scented work fine too and probably provide a calming aura in one's workshop into the bargain . Wherever candles are on sale cheaply is where we source them.
Using the velvet soap and rotary sander method with say 80 then 180 then 400 grit paper, you can almost get a polish finish provided you use plenty of soap and particularly with the 400 grit, change the paper when it smears the ally rather than cuts. A quick buff with a lambswool mop and cutting compound will see a beautiful polished finish produced.
Hard wax may possbly be better as far as fling off goes, but due to the availability and pricing of candles, we have stuck to them.
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