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end milling does my Doreen needs a blast

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brian jones 1109/07/2021 06:30:51
292 forum posts
54 photos

As I am getting into proper milling on my DW, stoopid boy Pike has just realised that tools need cooling and oils dont cut it

You need air blast cooling from compressed air - as I have seen on these CNC millers. I have seen how the small swarf particle congeal around the tip and quickly obscure the work ( magnetism?)

I have a shop vac to suck this away but it interupts work.

What kind of air flow do I need for this duty?

Ive seen another user with a silent shhh compressor (£350)0.9cfm 1/4 hp

My own workshop compressor is a noisy bstd and only for intermittent use - inflating car tyres etc. I wouldnt use it full time I am sure it would burn out - it was only £60

Then another issue arises - as reported by another member = this will blast metal particle around the place, hence its no coincidence that CNC mills have a ventillated enclosure

OMG where it this going

anyone else been down this route?

looks like going down a country road in E Africa at the start of the rainy season

Edited By brian jones 11 on 09/07/2021 06:35:19

JasonB09/07/2021 07:07:00
21307 forum posts
2419 photos
1 articles

Small paintbrush should do for you.

As your DW does not have the high spindle speeds of CNC machines it will not be able to generate the volumes of swarf that they do or the heat such high volume of metal removal can generate. You are also unlikely to be using the same machining strategies that use the full flute length of the cutters.

You can apply a small amount of Paraffin or WD40 with a brush when machining aluminium which helps stop the material sticking to the tool. For steel a little cutting fluid will help when using HSS cutters but there is no not much need for flood cooling of a fogbuster type system. The air only tends to be used on the CNC machines when cutting harder steels that are best cut dry using a shallow depth of cut and high feed rate.

David George 109/07/2021 07:16:12
1636 forum posts
497 photos

Brian you don't need air blow for standard milling and drilling you will be just spreading swarf around the workshop unless you have totally enclosed guarding. I have a small bottle of paraffin for aluminium a pot and brush of cutting oil for steel and you don't need anything for brass.


brian jones 1109/07/2021 08:12:57
292 forum posts
54 photos

My spindle speed is 1500 max

well thats reassuring, i was having visions of entering a black hole and indeed I am only do small jobs gently does it.

Reading up about the Axminster (siegel) KX3 was a shock and awe experience - but then so is rocket science

must keep my feet on the ground and not aim for the moon


not done it yet09/07/2021 08:21:28
6272 forum posts
20 photos

Just a few questions that you might consider?

Mill Aluminium (or brass) - no worries about magnetism?

Use carbide end mills - no worries about magnetism?

Use carbide insert tooling - cooling generally unnecessary for hobby work?

Use flood cooling - would be much cheaper than £360 for a compressor?

Make a connection to the outlet of your vacuum cleaner?

I would be surprised if the other user gets 25l/minute at any decent pressure (work it out?)

Surely the issue of blasting swarf all around the place could be overcome by use of a valve?

My conclusion is that huge air blasts are not really required for hobbyists. My compressed air receiver contains over a thousand litres of free air. It does not take long to fill. It lives in a separate area to my workshop, is not that noisy (I don’t need ear defenders while it is running!) but I still use just use cutting oil as that is sufficient for most duties (it reduces the heat generated during cutting and cools the work - magnetism is not a problem I have very often (even when cutting steel. I do have a demagnetiser but have not used it for end mills.

I recommend you replace your noisy compressor if it runs continuously at the required rate because it’s probably worn out.

Water has a specific heat content four times that of air. That is increased hugely if that water is evaporated (Latent Heat of change of state). That is why many use mist cooling, not compressed air only, if cooling is required.

SillyOldDuffer09/07/2021 08:58:24
7476 forum posts
1648 photos

I agree with David George - compressed air solves a problem you don't have!

Is something else adrift? Are you expecting to remove metal faster than is sensible? The Dore Westbury is a good small machine, but it's for precision work rather than hacking metal quickly. Most hobby machines are too weak for prolonged hard work: the operator has to drive within their capabilities, thus swarf control and cooling can be managed by ordinary means. Excessive caution also causes problems, maybe worse; if rpm, depth of cut and feed-rate are in the zone, swarf tends to come off sensibly: too slow, and swarf gets stuck under the cutter where the resulting mincing soon blunts the edge.

CNC machines often use compressed air to combine cooling and swarf management. When a machine produces a couple of tons of swarf per shift, removing it efficiently becomes important. Oil soaked swarf is costly waste, while clean swarf retains value because it's easy to recycle. In a machine centre compressed air is applied in an enclosed system and carefully directed to blow swarf ready for collection rather than showering it around the workplace! The air may contain a dash of atomised oil making it dangerous to breath. On these machines compressed air is a special case and carefully managed. Elsewhere, using compressed air to clean machines is often a sacking offence. It blows metal particles under slide-ways, into motors and electronics, and maybe someone's eyes. And blowing dirt around to hide it doesn't keep the workshop clean.

I bought a flood cooling system for my mill (an 1100W WM18) and consider it a poor investment. Two problems: I rarely cut metal hard and fast enough to justify turning it on, and it makes a mess! Only gets used when I hack large lumps of steel with carbide, which might be what Brian wants. For most ordinary jobs removing swarf and splashing coolant/lube as necessary with a brush is 'good enough'. Cutting with carbide I often don't use coolant at all: carbide is cracked by thermal shock, so it's best cooled all or nothing - don't splash hot carbide every so often.





Edited By SillyOldDuffer on 09/07/2021 08:59:50

Nigel McBurney 109/07/2021 10:15:34
910 forum posts
3 photos

Whats wrong with soluble oil,its cheap,and works either applied by brush or a tank and pump. Compressed air will blow fine swarf particles into the slide ways ,and slideways will soon wear out,Modern industrial machines are designed to cope with various coolant problems , small hobby machines are not nor are older UK machines.Cnc machines use coolant systems to cool the work and to remove the large volume of swarf produced.Forget about using compressed air. Is the use of carbide tooling without a cooling lubricant a good idea,the work piece will heat up, expand so accurate measurements cannot be taken until the work cools,so keep it cool in the first place. When machining cast iron coolant is not required ,and clean the lathe/mill of cast swarf before switching to a material that needs coolant as soluble oil will cause the iron swarf to rust and difficult to remove and not do the machine any good.

Dave Halford09/07/2021 11:33:59
1669 forum posts
19 photos
Posted by brian jones 11 on 09/07/2021 06:30:51:

I have seen how the small swarf particle congeal around the tip and quickly obscure the work ( magnetism?)

looks like going down a country road in E Africa at the start of the rainy season

Edited By brian jones 11 on 09/07/2021 06:35:19

I get the swarf sticking to the cutter, a cheap (very) paint brush fixes that even though it gets shorter.

If you get blue chips then slow something down.

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