Feeds and speeds. Some tips for a newbie please!

[Richard]

I am looking for a little guidance on feeds and speeds with a 2kw 3040 size gantry router (not chinese - this one has 20mm hiwin linear rails).

I want to take a light skim over a large area of ali plate. (no idea what grade it is).

So after googling about and looking at the feed and speed calculator on littlemachineshop's site, it appears that if I am using an HSS 12mm 4 flute endmill, the spindle speed should be very slow at 1600 rpm and the feed also slow at 275 mm/min.

Switching to a carbide endmill, a much higher spindle speed, 7200rpm and much much faster feed of 2800mm/min.

Does that sound right?

I have seen people using very fast spindle speeds and feeds (16k prm, 4000 mm/min) but not sure with a 12mm cutter?

Any general advise regarding this topic?

Obviously lube/cooling comes into play here, but initially I would like to run the machine dry or with a minimal mount of lube.

I am looking at taking a very shallow cut as I am just getting the plate flat, so no more than a 0.1 or 0.2mm cut.

Any advice welcome.

Cheers!

[Chaz]

I am looking for a little guidance on feeds and speeds with a 2kw 3040 size gantry router (not chinese - this one has 20mm hiwin linear rails).

I want to take a light skim over a large area of ali plate. (no idea what grade it is).

So after googling about and looking at the feed and speed calculator on littlemachineshop's site, it appears that if I am using an HSS 12mm 4 flute endmill, the spindle speed should be very slow at 1600 rpm and the feed also slow at 275 mm/min.

Switching to a carbide endmill, a much higher spindle speed, 7200rpm and much much faster feed of 2800mm/min.

Does that sound right?

I have seen people using very fast spindle speeds and feeds (16k prm, 4000 mm/min) but not sure with a 12mm cutter?

Any general advise regarding this topic?

Obviously lube/cooling comes into play here, but initially I would like to run the machine dry or with a minimal mount of lube.

I am looking at taking a very shallow cut as I am just getting the plate flat, so no more than a 0.1 or 0.2mm cut.

Any advice welcome.

Cheers!

For me, Id run max spindle speed. So 24K, Id start with 1500mm/min and work up from that. For shallow cuts you can probably go faster but 1500 - 2000mm/min is decent. How accurate do you need and how much material are you removing?

[Dave_stoke]

Google feeds and speeds calculator , it will take you to the little machine shop, input max spindle speed, material, mm/inch, cutter size and material and flute count. Hit calculate

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[Richard]

For me, Id run max spindle speed. So 24K, Id start with 1500mm/min and work up from that. For shallow cuts you can probably go faster but 1500 - 2000mm/min is decent. How accurate do you need and how much material are you removing?

Hi Chaz,

24k rpm and 1500mm/min, sounds crazy fast! (comming from a manual knee mill!)

Only a 0.1mm-0.2mm cut.

How much slower would you go with an HSS cutter of the same size?

[Richard]

Google feeds and speeds calculator , it will take you to the little machine shop, input max spindle speed, material, mm/inch, cutter size and material and flute count. Hit calculate

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Yes, I have already looked at that. It's telling me 7k rpm and 2800mm/min for carbide and 1.6k rpm and 275mm/min for HSS. I was surprised at the difference beween the two cutter materials.

[Dave_stoke]

Yes, I have already looked at that. It's telling me 7k rpm and 2800mm/min for carbide and 1.6k rpm and 275mm/min for HSS. I was surprised at the difference beween the two cutter materials.Carbide can take more stick as you can imagine. I didn't see the part you mentioned little machine shop sorry.

Can you override feed rate while it's running? If so use the slider to find the sweet spot. Then use that Feed rate.

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[Richard]

Carbide can take more stick as you can imagine. I didn't see the part you mentioned little machine shop sorry.

Can you override feed rate while it's running? If so use the slider to find the sweet spot. Then use that Feed rate.

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I'm running Mach3 (learning to drive this too!) so yes I can ramp up the feed.

I think that coming from using HSS and an old manual mill, the feeds and speeds mentioned seem a bit hair raising to me! LOL!

[Dave_stoke]

I'm running Mach3 (learning to drive this too!) so yes I can ramp up the feed.

I think that coming from using HSS and an old manual mill, the feeds and speeds mentioned seem a bit hair raising to me! LOL!I'm using 0.1-3mm Mills I have a bin full of shafts without ends lol.
It's scary when it looks like it's smashing side on into a piece of brass stock. But in all honesty since I used the calculator I just back the feed off slightly. It's fine. Then I let it run at the feed rate... Still fine.

My cut depth is 0.5mm I cut at 1mm but scared the shit out of me.

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[Dave_stoke]

Oh not with mills below 0.5mm I broke all those, my machine isn't quite gentle enough [emoji23] [emoji23]

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[Richard]

Just found GWizard.

It's telling me, for a 12mm 4 flute endmill in cast ali, 4148rpm and 427 mm/min for HSS.

For Carbide 6222rpm and 525 mm/min.

That seems very consvative.

If I set the surface finish from 1% to 30% the feed rate doubles.


If the tool size drops to 4mm then the RPM goes up to 18666!

[Dave_stoke]

Little machine shop can now suck my plums!
Just had a new 2mm flat 4fl endmill delivered.
Out of the box and broken in 3 minutes!

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[Chaz]

Little machine shop can now suck my plums!
Just had a new 2mm flat 4fl endmill delivered.
Out of the box and broken in 3 minutes!

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What speeds and feed? What material?

4 flute?

[Dave_stoke]

What speeds and feed? What material?

4 flute?Exactly this 25105

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[Chaz]

Exactly this 25105

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I wouldnt be using 4 flute for brass / alu. 3 at most, 2 is better. Did it snap on first engagement or did it cut for a bit?

[Dave_stoke]

I wouldnt be using 4 flute for brass / alu. 3 at most, 2 is better. Did it snap on first engagement or did it cut for a bit?It got this far but very aggressive. I suppose I should have dragged the feed slider down. But a calculator should be accurate no? https://uploads.tapatalk-cdn.com/20181115/f7bc8ae288618f2f4bc67acaf082aaa2.jpg

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[Chaz]

It got this far but very aggressive. I suppose I should have dragged the feed slider down. But a calculator should be accurate no? https://uploads.tapatalk-cdn.com/20181115/f7bc8ae288618f2f4bc67acaf082aaa2.jpg

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From the pic, it looks like you plunged directly into the stock or did it do a helix down? If you plunged then that would be an issue, not the best way to engage a cutter into material. When I cut at new speeds I turn the feed down to 10% and then ramp up once I have done the helix down and then started to make the cuts I expect. Sound / vibration / noise is key.

[Dave_stoke]

From the pic, it looks like you plunged directly into the stock or did it do a helix down? If you plunged then that would be an issue, not the best way to engage a cutter into material. When I cut at new speeds I turn the feed down to 10% and then ramp up once I have done the helix down and then started to make the cuts I expect. Sound / vibration / noise is key.It's actually a helix entry.

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[Chaz]

It's actually a helix entry.

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Material looks a bit gummy. Did it clog up the bit? Id say 4 flute is to blame here (IMHO / 2p).

[Dave_stoke]

Material looks a bit gummy. Did it clog up the bit? Id say 4 flute is to blame here (IMHO / 2p).Honestly I started with 4fl when I got the machine, this was done with 4fl 2mm a while ago. But without using the calc https://uploads.tapatalk-cdn.com/20181115/bbd75f4167cef194311a71ba0600c1d5.jpg

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[Chaz]

To me (and the pics arent very clear) it looks like the tool lacked lubrication and/or ability to clear material fast enough. A 2 flute is more forgiving.

[Richard]

Tried a new 12mm carbide bit today.

Lovely finish but degraded after approx 5m of cutting distance.

I tried upping speed from 8k and feed from 800mm/min

Here's some pics of the bit afterwards, some heavy wear.

Maybe I should have lub'ed...251062510725108

Am I still going too slow in rpm/feed or should I flood with coolant?

(the reason I did this dry was that I haven't got my cooland set up yet...)

[Dave_stoke]

To me (and the pics arent very clear) it looks like the tool lacked lubrication and/or ability to clear material fast enough. A 2 flute is more forgiving.I didn't have my coolant running. I doubt it would have made any difference tbh.
I can't slow it down it doesn't get near the stock. It's started acting up again. Losing steps for fun. Certainly doesn't like helix.
I think it's time to give up tbh. The machine is what it is cheap but not cheerful. But £800 isn't cheap.

Thanks anyway buddy

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[Chaz]

I didn't have my coolant running. I doubt it would have made any difference tbh.
I can't slow it down it doesn't get near the stock. It's started acting up again. Losing steps for fun. Certainly doesn't like helix.
I think it's time to give up tbh. The machine is what it is cheap but not cheerful. But £800 isn't cheap.

Thanks anyway buddy

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The issue is, in this world, £800 is not a lot.

[Dave_stoke]

The issue is, in this world, £800 is not a lot.It is when there's nothing left in the bank lol

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[Chaz]

It is when there's nothing left in the bank lol

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Agreed. Machining is an expensive hobby.

Can any of us help with machining this for you?

[Dave_stoke]

Agreed. Machining is an expensive hobby.

Can any of us help with machining this for you?Thanks buddy, I have listed it for sale. But also reminded the seller I bought it from that they must provide me with a solution as to why it doesn't do what they promised.

As for parts I might drop it for a while, have a break and finish up all the drawings in fusion. I wanted to make a scale hawker hurricane in its entirety with a 1.5mtr wing span. And then maybe a Lancaster. But watch tools were my main project. Haven't managed one yet.

I'll stay on the boards keep watching, reading and learning. Then maybe if things get better buy a proper mill and convert it to cnc.

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[m_c]

That looks like the cutter has been rubbing more than it's been cutting.

Speeds and feeds nearly always involve some experimentation to find what works best for your machine.
The key thing is tooth loading. Too much and the cutter will snap/spindle stall, too little and the cutter rubs. The smaller the cutter, the more precise the tooth loading has to be.

For most machines, two flute cutters are better, as it allows slower feed rates for any given spindle RPM (double the number of flutes, and you have to double the feedrate to achieve the same tooth loading).

Speeds and feeds calcs (I personally use FSWizard) generally only give you an estimate. If what they're suggesting isn't working, it can be worthwhile to look up the cutter manufacturer's specifications, and work out the figures manually to give you the recommended ranges. First work out the possible spindle speeds (manufacturer's will give a recommended surface speed range), then once you have the min/max RPMs, calculate the required feedrates at those two speeds for the min/max tooth loading.

[Richard]

That looks like the cutter has been rubbing more than it's been cutting.

Speeds and feeds nearly always involve some experimentation to find what works best for your machine.
The key thing is tooth loading. Too much and the cutter will snap/spindle stall, too little and the cutter rubs. The smaller the cutter, the more precise the tooth loading has to be.

For most machines, two flute cutters are better, as it allows slower feed rates for any given spindle RPM (double the number of flutes, and you have to double the feedrate to achieve the same tooth loading).

Speeds and feeds calcs (I personally use FSWizard) generally only give you an estimate. If what they're suggesting isn't working, it can be worthwhile to look up the cutter manufacturer's specifications, and work out the figures manually to give you the recommended ranges. First work out the possible spindle speeds (manufacturer's will give a recommended surface speed range), then once you have the min/max RPMs, calculate the required feedrates at those two speeds for the min/max tooth loading.

Hi m_c, assuming you're looking at my photos, that cutter cut beautifully for the first 5m of the cut (it was a zigzag path 350mm long, moving across 10mm each pass, doing 30 passes in all).

It left a very clean smooth cut then suddenly it seemed to get noisy and the surface finish got worse. I'm assuming this is when the edges went off for some reason....

This was supposed to be carbide, but no idea if it really is, it was a very cheap set, 2mm to 12mm, 8 end mills, for £25! LOL. (Just checked, the carbide bit is almost exactly twice the weight of the HSS one and it much less magnetic, so probably is carbide)

If there was a build up of aluminium on the tips, would that errode the edges like this?

[spluppit]

It's is pretty hard for anyone to diagnose the problem fully unless they are there. A few very simple and basic pointers that are basics you need to know and cover, if you you dont cover these then you are fighting in the dark.

Machining is a process of logic and forethought. If those are not applied when you are trying to learn and its going wrong, stop and think to yourself, 'apply logic and forethought.'

1) What is the brass you are trying to machine? I'm fairy sure i know the grade looking at your pics, without seeing it in person, but the point is do you know? It's so important SO important to know the material you have to machine. Different material have different properties and are for different purposes. I think what you have there is known as 'half hard' ... and the clue is in the name, half hard meaning it's ductile, Not gummy (No such material property has ever existed) This means it can be bent and is not generally used for machining. You should be using CZ 121 which is a fully hard and free machining brass and is the go to brass for general machining. It chips beautifully and there is no need for coolant, brass self lubricates and tools should last a very long time. The only real need for Coolant is for chip removal if making a lot of swarf or an air blast, It will add little to nothing to machining ability in this instance. Softer brasses are totally machinable but its not the right stuff to learn on, experience counts for everything in this game. Brass is one of the simplest materials in the world to machine, so if its not going right, then something is radically wrong.

The way your image shows the brass burring up indicated either: It's half hard or a soft brass or tool tool was blunt from the outset. You said the tool was new tool (assuming an acceptable quality) so go back to the material and look again

2) Your cutting tools. Only buy from reputable seller. If you have crap tools then expect crap results. Just because it's carbide doesn't means its good..and there is a lot of crap carbide out there. It's pretty simple fundamental basics. You don't have to spend fortunes, go to somewhere like shop apt (google it) The quality is fair for the price point and perfectly usable for home and small business. The odd problem can occur with cheaper produced cutters from places like apt but its pretty rare from my experience.


Generally when using a helical entry into the part the (pending software also) you should denote X and Y feed rate and a Z feed Rate. The Z federate is the helical plunge rate and pending machine, cutter size, cutting conditions will be about half of X, Y feed rate.(this doesn't apply to larger heaver machines where this can be wacked up) The info from speeds and feed calcs unless they ask for a machining strategy will not take things like helical entry into account.. Its a big learning curve I'm afraid

If you cover the basics and its still not right, then you need to start looking else where.

A small vid of brass being machined with small tools, a light air blast only is used and see how cleanly it cuts with the slotting using a ramp strategy. The slot is 2mm.

https://www.youtube.com/watch?v=pGAoW4KAGeA

[Dave_stoke]

It's is pretty hard for anyone to diagnose the problem fully unless they are there. A few very simple and basic pointers that are basics you need to know and cover, if you you dont cover these then you are fighting in the dark.

Machining is a process of logic and forethought. If those are not applied when you are trying to learn and its going wrong, stop and think to yourself, 'apply logic and forethought.'

1) What is the brass you are trying to machine? I'm fairy sure i know the grade looking at your pics, without seeing it in person, but the point is do you know? It's so important SO important to know the material you have to machine. Different material have different properties and are for different purposes. I think what you have there is known as 'half hard' ... and the clue is in the name, half hard meaning it's ductile, Not gummy (No such material property has ever existed) This means it can be bent and is not generally used for machining. You should be using CZ 121 which is a fully hard and free machining brass and is the go to brass for general machining. It chips beautifully and there is no need for coolant, brass self lubricates and tools should last a very long time. The only real needs for Coolant is for chip removal if making a lot of swarf or an air blast, It will add little to nothing to machining ability in this instance. Softer brasses are totally machinable but its not the right stiff to learn on, experience counts for e Everything in this game. Brass is one of the simplest materials in the world to machine, so if its not going right then something is radically wrong.

The way your image shows the brass burring up indicated either: It's half hard or a soft brass or tool tool was blunt from the outset. You said the tool was new tool (assuming an acceptable quality) so go back to the material and look again

2) Your cutting tools. Only buy from reputable seller. If you have crap tools then expect crap results. Just because it's carbide doesn't means its good..and there is a lot of crap carbide out there. It's pretty simple fundamental basics. You don't have to spend fortunes, go to somewhere like shop apt (google it) The quality is fair for the price point and perfectly usable for home and small business. The odd problem can occur with cheaper produced cutters from places like apt but its pretty rare from my experience.


Generally when using a helical entry into the part the (pending software also) you should denote X and Y feed rate and a Z feed Rate. The Z federate is the helical plunge rate and pending machine, cutter size, cutting conditions will be about half of X, Y feed rate.(this doesn't apply to larger heaver machines where this can be wacked up) The info from speeds and feed calcs unless they ask for a machining strategy will not take things like helical entry into account.. Its a big learning curve I'm afraid

If you cover the basics and its still not right, then you need to start looking else where.

A small vid of brass being machined with small tools, a light air blast only is used and see how cleanly it cuts with the slotting using a ramp strategy. The slot is 2mm.

https://www.youtube.com/watch?v=pGAoW4KAGeAWow thanks for that,

I hadn't even considered the brass hardness. It's just a strip off ebay. I know the bars I had cut an awful lot better. But there's never really a spec on those ads.

The tool was from ew in Stockport. It's where I get them all from.

The machine really doesn't function very well in helix you can hear the motor clunk back like it's hitting resistance just before it gets to a full step. Yet mach is counting down so it can register - 0.9310mm when it's still at +2.5000. Which might also be the case when it does actually plunge. It might be over plunging?
It's set for multiple depths of 0.5mm looking at the piece it seems deeper than that.

So it must be partly the machine or software and the rest the user.

I have a great deal to learn before I can work a machine even half decently. And if I don't do something with the steppers, the software and myself. I'll be forever buying bits.

I did think it can't be that hard. Usually very quick at picking things up. But if it was that easy, everyone would be doing it.

What I need is a source of income now. And stop fkn about. That way I will have a clearer frame of mind and I'll grasp it better.

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[Richard]

So anyone any ideas why that carbide endmill is showing so much wear?

Feeds and speeds were not a million miles away from G-Wizard.

I am surprised how ali can erode carbide so easily!

[Chaz]

So anyone any ideas why that carbide endmill is showing so much wear?

Feeds and speeds were not a million miles away from G-Wizard.

I am surprised how ali can erode carbide so easily!

We havent ruled out that you are using cheap / crap endmills. Try with something semi decent first (https://www.shop-apt.co.uk/) would be the supplier for me for something 'OK'. Id select a 2 flute uncoated endmill to start with. Plus, as Mr Ward suggests, the material might be the problem. Dont focus on the blunt endmill.

[Snapper]

Thanks buddy, I have listed it for sale. But also reminded the seller I bought it from that they must provide me with a solution as to why it doesn't do what they promised.

As for parts I might drop it for a while, have a break and finish up all the drawings in fusion. I wanted to make a scale hawker hurricane in its entirety with a 1.5mtr wing span. And then maybe a Lancaster. But watch tools were my main project. Haven't managed one yet.

I'll stay on the boards keep watching, reading and learning. Then maybe if things get better buy a proper mill and convert it to cnc.

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What machine is this Dave? Sounds like a chinese ebay special router.

They don't really work well out of the box and need a bit of wiring doing to get them to work fairly stable. Spindle or machine frame needs earthing, a star point earth helps too, and the spindle cable at least pretty much needs swapping for a shielded CY cable, otherwise you will have all sorts of havoc. Doesn't hurt to do the switch and stepper wires either although not really neccesary.

[Snapper]

So anyone any ideas why that carbide endmill is showing so much wear?

Feeds and speeds were not a million miles away from G-Wizard.

I am surprised how ali can erode carbide so easily!

Is that end mill coated? Looks like it might have tialn coating, which will cause build up pretty quickly, that's probably not erosion but almost certainly a build up of aluminium on the cutting edge. You want uncoated cutters really for ali. And yes find out what the material is, even different batches of the same grade can cut differently but stuff like 1 series ali is horrible for machining.

[Dave_stoke]

What machine is this Dave? Sounds like a chinese ebay special router.

They don't really work well out of the box and need a bit of wiring doing to get them to work fairly stable. Spindle or machine frame needs earthing, a star point earth helps too, and the spindle cable at least pretty much needs swapping for a shielded CY cable, otherwise you will have all sorts of havoc. Doesn't hurt to do the switch and stepper wires either although not really neccesary.It is an eBay special lol. It's the cncest 3040T.
Where do I earth it from to? https://uploads.tapatalk-cdn.com/20181116/1fdb9b4d8b8334c4915212c4f5035c39.jpghttps://uploads.tapatalk-cdn.com/20181116/1120e875a34270cbc56e969fd9a3b1dc.jpghttps://uploads.tapatalk-cdn.com/20181116/90c71e5fc699dd1d67d2d91d27d43fff.jpg

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[Richard]

Is that end mill coated? Looks like it might have tialn coating, which will cause build up pretty quickly, that's probably not erosion but almost certainly a build up of aluminium on the cutting edge. You want uncoated cutters really for ali. And yes find out what the material is, even different batches of the same grade can cut differently but stuff like 1 series ali is horrible for machining.

OK, I'll get a 2 flute uncoated from APT and see how it goes. The cutters I have are coated but I don't know what with.

The part I was machining is the bed of the machine, so no idea what grade it is. I just wanted it flat(er) and level.

Once I get the new 2 flute cutter, is 6k rpm and 500mm/min, dry, still in the right ball park for taking a shallow finishing cut at say 90% engagement?



Just for my own interest, if there is build up on the tips of the cutter, how does that erode the tip?


Thanks for the input!

[Chaz]

OK, I'll get a 2 flute uncoated from APT and see how it goes. The cutters I have are coated but I don't know what with.

The part I was machining is the bed of the machine, so no idea what grade it is. I just wanted it flat(er) and level.

Once I get the new 2 flute cutter, is 6k rpm and 500mm/min, dry, still in the right ball park for taking a shallow finishing cut at say 90% engagement?



Just for my own interest, if there is build up on the tips of the cutter, how does that erode the tip?


Thanks for the input!

What is the highest speed your spindle can rotate at?

[Snapper]

It is an eBay special lol. It's the cncest 3040T.
Where do I earth it from to? https://uploads.tapatalk-cdn.com/20181116/1fdb9b4d8b8334c4915212c4f5035c39.jpghttps://uploads.tapatalk-cdn.com/20181116/1120e875a34270cbc56e969fd9a3b1dc.jpghttps://uploads.tapatalk-cdn.com/20181116/90c71e5fc699dd1d67d2d91d27d43fff.jpg

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Every chinese spindle I have seen actually has a 4 pin plug on top so you can hook that up on the bottom to a bolt inside the spindle housing (under the cap) and then if you get a 4 core CY cable for your spindle you can run your earth with that, which is the best and tidiest way to do it imo. For a quick fix for now just take any bolt out of the frame (away from the cutting area and any moving parts) and get a piece of cable, crimp a ring terminal on the end of it and bolt it down to the frame, connect the other end to earth. That 'may' help your problems a bit short term, but shielding that spindle cable is going to be of more help. VFD emits a lot of EMI, and doesn't play nicely with USB or other low voltage electrics.

Your problem could also be mechanical, misalignment somewhere or something, or even a weak PSU that is struggling to drive 2 axes properly simultaneously. The power supplies they send out with these things really are a pile of crap (mine ended up setting on fire :highly_amused:)

[Chaz]

Every chinese spindle I have seen actually has a 4 pin plug on top so you can hook that up on the bottom to a bolt inside the spindle housing (under the cap) and then if you get a 4 core CY cable for your spindle you can run your earth with that, which is the best and tidiest way to do it imo. For a quick fix for now just take any bolt out of the frame (away from the cutting area and any moving parts) and get a piece of cable, crimp a ring terminal on the end of it and bolt it down to the frame, connect the other end to earth. That 'may' help your problems a bit short term, but shielding that spindle cable is going to be of more help. VFD emits a lot of EMI, and doesn't play nicely with USB or other low voltage electrics.

Your problem could also be mechanical, misalignment somewhere or something, or even a weak PSU that is struggling to drive 2 axes properly simultaneously. The power supplies they send out with these things really are a pile of crap (mine ended up setting on fire :highly_amused:)

Also, where are you based? Someone from this forum might be able to pop in and take a quick look.

[Snapper]

OK, I'll get a 2 flute uncoated from APT and see how it goes. The cutters I have are coated but I don't know what with.

The part I was machining is the bed of the machine, so no idea what grade it is. I just wanted it flat(er) and level.

Once I get the new 2 flute cutter, is 6k rpm and 500mm/min, dry, still in the right ball park for taking a shallow finishing cut at say 90% engagement?



Just for my own interest, if there is build up on the tips of the cutter, how does that erode the tip?


Thanks for the input!

Noooo. Don't cut the bed.

Get a board, sheet of ali, whatever you want to use and stick it on top. The bed is made of several independent pieces of extrusion and even if you machine it 'flat' they will flex independently anyway. Also you're then tied in to the cutting area, you can't really load a bigger piece in and clamp it outside the work area.

[Dave_stoke]

Every chinese spindle I have seen actually has a 4 pin plug on top so you can hook that up on the bottom to a bolt inside the spindle housing (under the cap) and then if you get a 4 core CY cable for your spindle you can run your earth with that, which is the best and tidiest way to do it imo. For a quick fix for now just take any bolt out of the frame (away from the cutting area and any moving parts) and get a piece of cable, crimp a ring terminal on the end of it and bolt it down to the frame, connect the other end to earth. That 'may' help your problems a bit short term, but shielding that spindle cable is going to be of more help. VFD emits a lot of EMI, and doesn't play nicely with USB or other low voltage electrics.

Your problem could also be mechanical, misalignment somewhere or something, or even a weak PSU that is struggling to drive 2 axes properly simultaneously. The power supplies they send out with these things really are a pile of crap (mine ended up setting on fire :highly_amused:)Thanks mate, so run the earth into the control box and connect to an earth point there?

Can I use hdmi for the spindle? I have a thicker rca shielded somewhere. I presume most of it is just signal wires?

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[Richard]

What is the highest speed your spindle can rotate at?

Man this thread is getting confusing! LOL!

I don't know how fast it can go. I will have a look at see what it actually tops out at.

It's a Schneider altivar 12 VFC with a water cooled 2kw spindle.

[Richard]

Noooo. Don't cut the bed.

Get a board, sheet of ali, whatever you want to use and stick it on top. The bed is made of several independent pieces of extrusion and even if you machine it 'flat' they will flex independently anyway. Also you're then tied in to the cutting area, you can't really load a bigger piece in and clamp it outside the work area.

Not on my machine. The bed is actually a big thick slab of cast iron, onto which is bolted an ali plate, which is drilled and tapped for tooling. It's basically sacrificial. As this is used machine, the plate had a few cuts in it and after transit and moving ect, it needed leveling.

[Dave_stoke]

Man this thread is getting confusing! LOL!

I don't know how fast it can go. I will have a look at see what it actually tops out at.

It's a Schneider altivar 12 VFC with a water cooled 2kw spindle.Yes sorry richy I somehow derailed and hijacked your thread.

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[Snapper]

Thanks mate, so run the earth into the control box and connect to an earth point there?

Can I use hdmi for the spindle? I have a thicker rca shielded somewhere. I presume most of it is just signal wires?

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No. It's a 3ph motor in there so what you should have currently is just the 3 U V W power wires. I can't remember off the top of my head what the optimal core diameter is for the cable but depending what power spindle you have it isn't hard to figure out the max current and find out on google.


Not on my machine. The bed is actually a big thick slab of cast iron, onto which is bolted an ali plate, which is drilled and tapped for tooling. It's basically sacrificial. As this is used machine, the plate had a few cuts in it and after transit and moving ect, it needed leveling.

Ah, I see. Very nice. Likelihood is it's a cast 5 series aluminium. In which case try drop your RPM by 20%. Have to feed a bit harder in that stuff.

[Dave_stoke]

No. It's a 3ph motor in there so what you should have currently is just the 3 U V W power wires. I can't remember off the top of my head what the optimal core diameter is for the cable but depending what power spindle you have it isn't hard to figure out the max current and find out on google.



Ah, I see. Very nice. Likelihood is it's a cast 5 series aluminium. In which case try drop your RPM by 20%. Have to feed a bit harder in that stuff.It's 800w the spindle. So I need initially a shielded cable capable of 1500w

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[Richard]

Man this thread is getting confusing! LOL!

I don't know how fast it can go. I will have a look at see what it actually tops out at.

It's a Schneider altivar 12 VFC with a water cooled 2kw spindle.


I just tried 20k rpm. VFD says 326hz and spindle was going at 19600rpm.


This is what the bed looks like and what the finish was initially and after the tool degraded.

[Snapper]

It's 800w the spindle. So I need initially a shielded cable capable of 1500w

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No, it's 800w @ 220v over 3 phases so, roughly 270 watts per phase or about 1.25 amps. Maybe you could get away with repurposing some sort of signal cable... but I wouldn't personally. Get a proper flexible copper braided cable and do it properly.

[Dave_stoke]

No, it's 800w @ 220v over 3 phases so, roughly 270 watts per phase or about 1.25 amps. Maybe you could get away with repurposing some sort of signal cable... but I wouldn't personally. Get a proper flexible copper braided cable and do it properly.OK being an ex mechanic and a crafty bugger, I have shielded the original spindle cable and run it separately from the rest. I have also earthed all bodies.

Let's see how it fairs. Its running a program now its always struggled with. Lego block lol.

Anyway after reading and thinking about what you said it dawned on me. Yes before I was running spindle speeds above 5000 rpm there wasn't much current so little interference, since its been running upto and beyond 15000 rpm that's when it started going haywire.

Let's see if my DIY shielding worked



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[m_c]

If you've only been taking a light surface cut, then the wear on that cutter would be as expected, especially if chip clearance has been poor along with no lubrication.

If chips start getting re-cut (I.e. not cleared from the cutter), then in soft materials they will start welding to the cutter. As soon as that happens, your nice sharp edge is now covered by a blunt layer of material, and the problem will compound from there as heat builds up at an ever increasing rate, until something finally fails.

I never realised you were machining aluminium with that cutter (I'd assumed you were still working with brass), but in aluminium you want polished cutters so there is as little roughness as possible on the cutter to avoid chips sticking (coated cutters are often rougher, but in aluminium coatings make little difference, which is why uncoated polished is usually preferred). You also want a bit lubrication to help stop things sticking. Lubrication can vary from an occasional spray of WD40, to mist, to full flood coolant.

On something like that bed surfacing job, a light spray of WD40 across the part at the start along with just enough air to clear chips would be more than ample to keep things running smoothly.

[Richard]

If you've only been taking a light surface cut, then the wear on that cutter would be as expected, especially if chip clearance has been poor along with no lubrication.

If chips start getting re-cut (I.e. not cleared from the cutter), then in soft materials they will start welding to the cutter. As soon as that happens, your nice sharp edge is now covered by a blunt layer of material, and the problem will compound from there as heat builds up at an ever increasing rate, until something finally fails.

I never realised you were machining aluminium with that cutter (I'd assumed you were still working with brass), but in aluminium you want polished cutters so there is as little roughness as possible on the cutter to avoid chips sticking (coated cutters are often rougher, but in aluminium coatings make little difference, which is why uncoated polished is usually preferred). You also want a bit lubrication to help stop things sticking. Lubrication can vary from an occasional spray of WD40, to mist, to full flood coolant.

On something like that bed surfacing job, a light spray of WD40 across the part at the start along with just enough air to clear chips would be more than ample to keep things running smoothly.

Thanks m_c.

The brass part was someone else's post in this thread! (it did get a bit confusticated...)

I need to get some side plates made up to keep the chips and coolant under control.

The machine has a pipe running down to a small thumbscrew valve with a copper tube going down to the cutter (see attached). If I run compressed air to it, I think it will draw coolant down another tube, plugged in where the red arrow is and make a mist spray.




Interesting how a buildup of ali on the tip of the tool will erode carbide! I guess there is very high localised heating due to increased friction.