Help with Clarke CL500M Milling Aluminium

Hi, I am 47 and started my working life in engineering working on capstones and lathes and then went on to sheet metal fabrication and welding till I was about 22 then ended up in sales which is what I do now.

I have always enjoyed making things and have just got into making nixie clocks and have always wanted to make one similar to Nixie Machine II Exclusive edition M.A.D.Gallery if you have a look,

So I have now bit the bullet and bought myself a little Clark CL500M and am about to start working on my clock legs, they are being made out of 12 mm aluminium plate that I've had cut to the blank sizes I need.

My legs will look a little like spider legs and will have curves and straights to machine out.

I have various end mills of all HSS sizes 2 mm - 12 mm some 4 flute some 2 & 3 flute that I will mostly use to mill out these parts, I have bought a 6" rotary table for my curves but it has been a very long time since I used any kind of milling machine so could do with some advice.
As I understand it with aluminium I don't necessarily need coolant but I have got a compressor to constantly blow away chips.
I have it on its fastest 1630 rpm
I know this is not a professional machine by any capacity it is just a hobby machine but hey this is my hobby.
Can anyone advise what is reasonably the most I can remove on each pass, so how deep into the 12 mm plate and how far in - so can I do 5 mm deep and 5 mm into the plate or less or more, what would be a safe speed to operate my power feed - should I even use the power feed

I will be grateful for any advice that will save me burning and breaking cutters until Iv'e learned the hard way

Thanks

Edited By JasonB on 06/11/2018 07:54:33

Some info for you, FWIW, sorry not very clear but readable; It will give you the general set up for depths / widths of cut etc. Aluminium can differ in content, some are 'soft' others 'hard' so surface speed differs & is adjusted accordingly but if you are above 800+ rpm you'll be in the ball park. Air mist blast coolant / WD40 are the better methods of cooling especially if you have 'soft' aluminium material, helps stop it 'sticking' to the teeth tips.



George.

Aside from the cutters, make sure the plate is clamped accordingly, so that there is no possibility the vibration will throw it off.

The success of a job for milling will often depend on how securely the work is being held, the same rule applies for all machines whether it's a bridgeport or an emco doing the job.

E.g using multiple clamp pieces if directly bolted on the table or a machine vise. 

Edited By Michael-w on 06/11/2018 09:44:24

2 or 3 flute cutters best for Ali, more room for the swarf to escape. In my experience, best keep the speed up, hot chips seem to shake themselves off the cutter better.

The Clarke is not known for being the most rigid of machines so you may not be able to get the typical d/4 cuts. Firstly I would help the machine by removing the waste to withing a couple of mm of the line by sawing or stitch drilling and then take light full depth cuts. Try something like a 10mm dia cutter for its rigidity full height but only 0.5mm per pass.

A small amount of paraffin or WD40 will give a better finish than dry and help stop metal sticking to the cutter.

Avoid coated cutters even if the gold colour looks good, a 2 or 3 flute uncoated one would be best and if you are going out to buy one then look at an aluminium specific cutter which will have better geometry for dealing with the swarf.

Get a feel for what feed cuts best by hand and then select the power feed to suit, at the depths I mentioned above and your 1600rpm around 150-250mm per min

Thank you all for your advice I have listened to you all and will take a little from you all

Keep it coming

Simon

Unless taking very light cuts you will find it best to avoid climb milling if your machine has any backlash in the screws, this is when the material can be dragged by the flute action to make very large cuts.
When cutting on the flutes (rather than end) you avoid climb milling by making sure the cutter flutes are always trying to push the work away from the tool.

Emgee

Whatever you do, Simon, post a picture of the finished clock! (I have a soft spot for nixie clocks!)

Will do though I expect it will take me any many months to complete

Some form of cooling/lubrication is needed when machining aluminium, I use a spray on cooking oil( the type for cake tins and frying pans) when the mess of coolant pumps is not needed. Aluminium will easily weld itself to cutting tips forming a false edge ergo bad finish. Try to use 2 flute mills if possible to give more space for swarf removal

Simon, all of my current build to date has been machining aluminium, I,m a beginner and I started out with the (gold colour) TiN coated 4 flute HSS cutters. That was a mistake on my part as they are not best suited to aluminium, they will cut ok but I found only if they were lubricated and only light cuts.

Jason suggested I consider one of the ARC Premium 2 flute uncoated Carbide end mills which are intended for aluminium. Well I got myself a 10mm one and have found it to be excellent, a superb cutting tool, not that cheap but I think worth every penny. Arc also do pretty much the same in 2 flute uncoated HSS but for some reason only in long series.

I dont know what you are considering if buying any cutters but just thought I would mention it.

Ron

Thanks for the advice, I have a couple of carbide 2 flute cutters for aluminium, there not branded or expensive so don't yet know if there any good but will give it a go this weekend with some WD40 and report back

This was my last Nixie build it looks much better in real life, the nixie tubes are just timeless and getting hard to get now, the new old stocks are running out and apart from one guy in the Czech republic Dalibor Farny who makes the huge R|Z568M tubes that I will be using in my new clock though they aren't cheap at $145 per tube and I need 6 plus the colons

.

NewsFlash for nixie fans: **LINK**

https://www.bbc.co.uk/news/uk-england-humber-46252838

MichaelG.