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Old 10-16-2016, 12:43 PM   #1
pmdevlin
 
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Default cooling slots in aluminium problems

Hi all,

I have been asked to cut cooling slots in a small cylinder head from a rc plane engine. The slots will create the fins to aid cooling.

I am using 1.5mm cutters on my siege xl mill, and they are 4mm in depth.

I'm a bit of a novice, so we agreed for me to practise on scrap alloy, see how it looks, then if all agreed attack the cylinder head. The problems are these:

I have snapped 3 cutters, now on the last one, I am using a medium speed with no lube/cooling to prevent swarf from sticking to the cutter. I am told the aluminium is T2, this info means nothing to me !

The cutter where just cheap things, should I but a specific type (not expensive as I am on a tight budget) what speed should I be using, slow or fast (sorry no means on measuring rpm) and should I be using a cooling fluid?

With regard to the job, I don't have any digital measuring scales so its pretty much by eye, is there any way I can manually determine the distance between cuts, I cant seem to get these the same, even when following a careful measurement marked on the metal

Many thanks

Paul


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Old 10-16-2016, 01:00 PM   #2
Brian Rupnow
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Use spray on WD40 and keep it wet while cutting the slots. Run the lathe at about 120 rpm. Make sure the tip of the tool is exactly at center height.--Sorry Paul--I thought you were doing this on a lathe. If you are doing it in a mill, then if the cylinder is round you are going to need rotary table. If it is square or rectangular, then yes, the slitting saw is best. In fact, if it is being done in a mill at all, a slitting saw if the correct tool to use.


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Old 10-16-2016, 01:52 PM   #3
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Lots of back clearance on the tool !
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Old 10-16-2016, 02:04 PM   #4
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In a mill, I would be tempted to use a slitting saw if available if not a high speed low feed rate and a wee bit of WD40
To space the fins out equally use the machines graduations find youre starting position by using a bit of bar in the chuck Advance towards the part until a cigarette paper just nips then move half the diameter of the bar This is youre 0 position . Keep the cuts small as its a small machine
cheers
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Old 10-16-2016, 03:03 PM   #5
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Default Slitting saw.

I agree with the slitting saw, it is a bit more forgiving than small end mills and providing you are cutting straight lines, it can be quite neat.

If you have only got a small mill cutting tool, then lots of shallow passes with the tool turning at high speed, and use WD 40

Steve
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Old 10-16-2016, 06:01 PM   #6
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If using a milling cutter then run the mill flat out, it will still be too slow but better than nothing, kerosene or WD40, 2 flute cutter.

As said above it will be better to mount the head sideways and use a slitting saw.

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Old 10-16-2016, 06:10 PM   #7
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The one thing you can do above all else is to get some TapMagic for Aluminum. Just a little of this in the cutting zone makes everything else not as critical. You will get good surface finish and the aluminum won't stick to the cutting tool. Works great for all non-ferrous metals too, such as brass and copper.
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Old 10-16-2016, 08:49 PM   #8
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many thanks!

I have slitting saws, been in the packet for two years, like a scary monster at the back of the tool drawer

Ill have a practise, lots off practice first, on review, looks like I was way too slow with the speed, and wasn't using wd40 thinking the swarf would clog up the cutter. I think I preferred the cutter as I was cutting from above, and could see the work better, the slitting saw is from the side.

Is it a similar high speed with the slitting saws, and wd40 again?

Thanks

Quote:
you are going to need rotary table
Brian, strangely, questions about this on another post!
paul
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Old 10-16-2016, 09:11 PM   #9
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Slitting saws need to run pretty slow, depending on the diameter. Maybe 150 - 300 rpm. Kerosene, WD-40, etc. is not nearly as good as TapMagic, but a lot of people won't spend the money (not that much) if they already have something else sitting there.
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Old 10-16-2016, 09:19 PM   #10
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is tap magic an American thing, doesn't seem to appear on any GB websites after a google search?

thanks


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