CNC Extremely loud when cutting

[David Buchhauser]

I stand corrected. Sorry - I missed the reference to the Etsy shop.
David

[Ronald Blue]

Ear plugs are relatively inexpensive. Buy a brand that you can trust. They will have a NRR on them. What are you using now? There are things to bargain shop for and hearing protection isn't one of them. That said a decent set of 3M or similar ear muffs isn't all that expensive.

[David Buchhauser]

Right on Ronald!!
David

[Jim Becker]

The OP is using hearing protection...he states that clearly in the originating post.

[David Buchhauser]

As he should. Better to save your ears.
David

[Ronald Blue]

The OP is using hearing protection...he states that clearly in the originating post.

That's not disputed Jim. However if the ear protection isn't a quality product then you will find it inadequate. I use ear protection in my work all the time. Equipment that can be much louder than 104 on the decibel scale. Ear muffs are usually sufficient. Doubling up is an acceptable option. Once you reach a certain sound level and it seems like it's approaching 140 you can't muffle it. It is being reverberated through the bone of the scull. It might be lower than that I don't recall now. 104 isn't that high a number. Typically ear plugs or ear muffs will have a NRR around 30. I would never trust a cheap pair to deliver that though. That was the basis for my original comment.

[David Buchhauser]

I agree - perhaps his "ear protection" is not sufficient for the noise level. I have heard that 100 -105 db is pretty typical for a large sports event like a Dallas Mavericks game in the arena (per Mark Cuban).
David

[Mark Bolton]

I dont have much problem at all around my machine with or without ear protection. That screaming/rattling sound in your ear drums on a CNC (in my limited experience) comes solely from too much exposed tool and too high an RPM. Sadly if you need the tool projection there is nearly nothing you can do about it. We have occasion to cut 2.5" deep pockets in hardwood with a 1/2"x2 1/2" brazed tool. It doesnt matter what you do the noise and the chatter are going to be there.

If your tool is short, reduce your RPMs and increase your feed until it goes away or you start breaking tools. If you cant feed harder, smaller tool, if you need the depth, you just have to live with it.

[Ryan Williams]

I know this is an old thread, but I wanted to add some clarification for anyone reading through this. The issue here is feedrate not being correct. Most cnc bit manufacturers will give a feed/speed chart with a suggested feed/speed and chipload. You need to make sure your chipload is within the suggested range for the bit to work properly. CAM software should show you the chipload when you setup a bit. If you are moving a bit too slow at too high of an rpm, the bit grinds its way through the material - it chatters, cuts poorly, is very loud, creates a lot of heat and wears fast. The bit needs to be allowed to take a big enough bite to slice off chips instead of rub its way through the material.

For example, say a bit recommends 180ipm at 18k rpm, if you want to go slower than 180ipm, you need to drop the rpm proportionately as well, so you could change to 120ipm at 12k rpm, and still be at the proper chipload.

Once you have the chipload figured out, you then need to adjust your depth of cut. That is dependent on the material you're cutting, spindle power, material hold down, stepper/servo power, and machine rigidity.

Proper bit selection is key. for lighter duty machines, check out single or "O" flute bits, the feedrate is half of a standard 2 flute bit.

It is a very common mistake for new cnc users (I made the same mistake) to run the feedrate way too slow. You're just going to have to experiment with settings for your machine, just remember that the most important factor is to make sure you are at a feedrate and rpm that puts the bit you chose in its designed chipload range

[Bruce Page]

Welcome to SMC, Ryan. Thanks for the informative post.

[David Buchhauser]

I know this is an old thread, but I wanted to add some clarification for anyone reading through this. The issue here is feedrate not being correct. Most cnc bit manufacturers will give a feed/speed chart with a suggested feed/speed and chipload. You need to make sure your chipload is within the suggested range for the bit to work properly. CAM software should show you the chipload when you setup a bit. If you are moving a bit too slow at too high of an rpm, the bit grinds its way through the material - it chatters, cuts poorly, is very loud, creates a lot of heat and wears fast. The bit needs to be allowed to take a big enough bite to slice off chips instead of rub its way through the material.

For example, say a bit recommends 180ipm at 18k rpm, if you want to go slower than 180ipm, you need to drop the rpm proportionately as well, so you could change to 120ipm at 12k rpm, and still be at the proper chipload.

Once you have the chipload figured out, you then need to adjust your depth of cut. That is dependent on the material you're cutting, spindle power, material hold down, stepper/servo power, and machine rigidity.

Proper bit selection is key. for lighter duty machines, check out single or "O" flute bits, the feedrate is half of a standard 2 flute bit.

It is a very common mistake for new cnc users (I made the same mistake) to run the feedrate way too slow. You're just going to have to experiment with settings for your machine, just remember that the most important factor is to make sure you are at a feedrate and rpm that puts the bit you chose in its designed chipload range

Very well put! I agree - and this same principle applies to cnc machining metal parts as well.
David