#201 cutter not that sharp! :)))

I thought I would post a cautionary tale…
T6 6061 651 4mm sheet is not wood!

I was going to square up a small piece I had kicking around. Set the job up and taking the feed rate and speed from the tool library in CC, I was ready to start. I changed the step down to a smaller .250. My thinking was how much kinder it would be to the tool. I was taking 1mm off the size all around

It was on the 6th pass that I knew things had gone awry. The change in the cutter tone from nice single pitch and regular to something tortured sounding had let me know that it would not be a happy experience.

I stopped the machine and found out that aluminium sheet gets hot. Now I know why they use it as a heat sink. Anyway, the chips have welded themselves comprehensively to my nice blunt cutter and I binned it. I captured a couple of images for posterity and my idiot’s scrapbook. These horrific images serve to underline my inept bumbling and general numplitude. You can be sure that the lesson is leaned.

Be kind… laugh quietly behind your hands. :grin:

Not much accuracy from this cutter.

Comprehensively F*%£@D!!!

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It should be sharp underneath that — just use lye (it’s the active ingredient in most drain cleaners) to remove the aluminum.


Thanks Will. :+1: I have decided that on this occasion, I am not going to remove all of the trash from the large bins that our local authority collects each week. I will let it go this time around and try and stay awake next time. Lye is fairly toxic. I did replace our drain cleaning gunk recently and I bought a new pair of chemical resistant gloves. Hmmm… never thought that lye would be a useful adjunct for milling aluminium. :grin:

Lye is the main ingredient in drain cleaner but you can usually just buy lye on its own without the other chemicals drain cleaners have. Use a glass container with a lid.


Lye must be the same as Caustic Soda (or the same thing by a different name).

A good friend of mine once had a side line in cleaning ovens, he used LOTS of caustic soda to remove the accumulated gunk. One day he was cleaning an expensive oven and as the parts were so dirty he left the parts to soak overnight. When he came to remove them the next morning they were gone. What he hadn’t realised was the expensive oven used aluminium parts, they had dissolved!

An expensive mistake he didn’t make again.


It just needed a good Lye down to recover :wink:


Not half as much as I did. :grin:

?? Rub-a-dub-dub, gets too hot when it rubs?

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Also, big chunks like that can be popped off with an old knife tip. I saved a number of mills when learning aluminum cutting. I also learned to learn with no more then 2 flutes, ideally with a single flute.

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For sure it got very hot, Andy. I thought a 3mm x .250 skim off the edge would work well. It certainly seemed ok until it wasn’t.

I think that criminals would have loved the fingerprint removal technique of just touching the finger pads to the metal workpiece after this sad attempt at milling. :grin:

The silly thing is this, Griff. I had bought several single flute bits in preparation for milling a complex 3D part. I had figured (so very wrongly) that the standard #201 bit would be able to handle a little sideways milling and edge material removal.

It couldn’t and didn’t and I was just lulled into a false sense of security by listening to the good milling sound and watching the bit make the first 5 passes without any apparent difficulty.

When I stopped the machining process and looked at the forlorn looking cutter, I realised that there is a whole lot more to cutting metal than wishing for it to happen. I think I should experiment a bit with lots of scrap pieces and save cutters by the methods detailed in this thread by yourself and @WillAdams.

I think I will also need to look out a friendly cutter supplier while learning to carve metals. Chip clearance is what killed this for me. It seemed to me that I was making quite small chips and I guess they just welded themselves together and then inevitably the clumps of chips blocked the cutter flutes and finished by generating too much heat and stuck to the cutter.

I’m no expert, but I have learned BIG chips are what you want. Among other advantages they carry away heat.

Set aside a day or two to read.


I’ve found these HQ Master 1/8” single flute end mills to be good for experimenting since they don’t break the bank.

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Not a chance! :rofl: :rofl:

Did you bin it in a fit of pique? Patience, my man, patience! You should know @WillAdams would have an answer for you! :+1:

Thanks for the reference, Griff. I have read much of Vince’s work. Hmmm… I wonder if he needs an apprentice. :thinking:

Snap! I bought these a little while ago and I now understand that I should have used them.

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Aha! I can see I am dealing with a Brit. :wink:

Yup! The air was blue and you would be forgiven for thinking I had lost £1000 and found a penny! :grin:

The “oh wow” moment of using single flutes after mucking up a couple multi-flute end mills is real.

I’m so busted! No wait, isn’t that an Americanism? :rofl:

I don’t believe that of you, Jeff! :innocent: :point_left: @jepho

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Think dockside harridan. :rofl: Genuine cockney lad from Whitechapel here… :grin: