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    Default severe vibration and runout when cutting steel on router

    I recently bought my 1st router/engraver similar to this one

    It's more than adequate for plastic, MDF, and wood. But not steel, which suffers from severe vibration and runout. Here's a video of cutting mild steel with a 6mm carbide bit @ ~4000RPM = 247 surface feet/minute. Radial cut is ~2mm and depth of cut is < 1mm. If depth is increased, vibration gets worse. Also doing a climb cut.


    Notes: the movement is jerky because I was manually jogging by 0.1mm. Also I mounted the machine on spring loaded feet to reduce vibration. Using the stock feet causes the steel shelf to vibrate like crazy.


    I know routers aren't meant for steel, but is it hopeless or are there mods or ways to do it? Is my work holding sufficiently rigid?

    The main problems I see are:
    1. The spindle speed is too high. I can go lower but then torque is lost, causing end mill to get stuck.
    2. The 3 axes are stacked, amplifying the play in the axis that has to support the most load. I don't know if this is a fundamental problem. If I had realized this earlier, I might've went for a Bridgeport style mill.
    3. The distance from the bottom of the spindle clamp to the end mill tip is 12cm. Is that unbraced section causing a lot of play?

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    Default Re: severe vibration and runout when cutting steel on router

    The main problem is that your using the wrong type of machine to cut steel.
    Your only real option is to reduce the depth of cut.

    Gerry

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    Default Re: severe vibration and runout when cutting steel on router

    Quote Originally Posted by spacesaver View Post
    I recently bought my 1st router/engraver similar to this one

    It's more than adequate for plastic, MDF, and wood. But not steel, which suffers from severe vibration and runout. Here's a video of cutting mild steel with a 6mm carbide bit @ ~4000RPM = 247 surface feet/minute. Radial cut is ~2mm and depth of cut is < 1mm. If depth is increased, vibration gets worse. Also doing a climb cut.


    [COLOR=#222222][FONT=Arial]Notes: the movement is jerky because I was manually jogging by 0.1mm. Also I mounted the machine on spring loaded feet to reduce vibration. Using the stock feet causes the steel shelf to vibrate like crazy

    I know routers aren't meant for steel, but is it hopeless or are there mods or ways to do it? Is my work holding sufficiently rigid?

    The main problems I see are:
    1. The spindle speed is too high. I can go lower but then torque is lost, causing end mill to get stuck.
    2. The 3 axes are stacked, amplifying the play in the axis that has to support the most load. I don't know if this is a fundamental problem. If I had realized this earlier, I might've went for a Bridgeport style mill.
    3. The distance from the bottom of the spindle clamp to the end mill tip is 12cm. Is that unbraced section causing a lot of play?
    You can't run your spindle at a lower RPM, these spindles have a minimum RPM of 6,000, if you have the correct Parameters set it won't run below 6,000

    This is a good example of why steel machining is not suitable for a CNC Router with this type of construction, the spindle is also not designed to cut steel, you can engrave steel with these spindles, for that you would be running at 18,000 RPM to 60,000RPM

    You will see some cutting steel with there routers, this is very misleading, as they are just showing eye candy, that is misleading and not a reality

    Mactec54


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    Default Re: severe vibration and runout when cutting steel on router

    So many things to consider. There is no rigidity in any of that machine for cutting steel. What kind of cutters are you using? What kind of steel do you want to cut. That spindle isn't made for torque. It is probably just stopping at 4000 RPM and bouncing off the teeth of the cutter. My only suggestion would be to blast that spindle fast and take tiny depths of cut and tiny stepovers like you would with a Dremel tool.



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    Default Re: severe vibration and runout when cutting steel on router

    As has been noted, your machine just isn't suited to the job of machining steel. Manual incremental jogging isn't the way you'd want to do it even if you had the right machine. Yes, your spindle speed is too high for that tool, but no - you won't be able to run that spindle any slower because of the torque loss you noticed. Your best bet would be to use a much smaller tool (<1mm), and higher spindle speed, as well as the low depth of cut and smaller stepovers already advised.

    Yes, the stacked axes do contribute to the problem. A Bridgeport type mill is much better for machining steel. That vertical distance wouldn't be a problem for a Bridgeport, but for a router like yours, it only exacerbates the problems caused by its inherent lack of rigidity.

    [FONT=Verdana]Andrew Werby[/FONT]
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    Default Re: severe vibration and runout when cutting steel on router

    the likelihood of successfully cutting steel on that router like that is slim to none . Knock your depth at least in half . There's a misconception to always climb mill on a cnc , it's especially so on a sloppy or less rigid machine , conventional mill rather than climb . If you have a decent coated end mill then you may be able to bump up the rpm and feed , otherwise if your just using a standard carbide then chances are that your burning your tool at 4000rpm

    A poet knows no boundary yet he is bound to the boundaries of ones own mind !! ........


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    Default Re: severe vibration and runout when cutting steel on router

    OK, I think we all agree that routers aren't meant for steel. You might as well say what I'm trying to do is laughable. But are there any hobbyist routers/mills with 3 stacked axes that can handle steel?
    BTW, I don't need to cut steel often. I'm trying to make a magnetic box/pan brake so the magnetic cores have to be steel (but soft steel like A36 used in flat and angle iron).

    Your only real option is to reduce the depth of cut.

    Yes, I'll try that. These 2 machines manage to cut steel with high RPM router type spindles and low depth of cut. But they should be more rigid from not having 3 stacked axes.



    (9000 RPM ? how is the end mill not melting? Seems as noisy as my attempt but with less vibration)

    But low depth of cut is going to wear out the end mill faster. These days, low radius of cut and high depth of cut is the way to go.


    Is there a spindle with more torque I can install? Actually, I don't know if I'm losing torque by using lower RPM. It might be that spindle torque stays the same, but more torque is needed to cut at lower RPMs.

    Also, I was quite shocked after reading about the othermill. How does a mill with a plastic frame and lead screws (PTFE coated though) manage to have higher precision than one with an aluminum frame and ball screws?



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    Default Re: severe vibration and runout when cutting steel on router

    Quote Originally Posted by spacesaver View Post
    OK, I think we all agree that routers aren't meant for steel. You might as well say what I'm trying to do is laughable. But are there any hobbyist routers/mills with 3 stacked axes that can handle steel?
    BTW, I don't need to cut steel often. I'm trying to make a magnetic box/pan brake so the magnetic cores have to be steel (but soft steel like A36 used in flat and angle iron).


    Yes, I'll try that. These 2 machines manage to cut steel with high RPM router type spindles and low depth of cut. But they should be more rigid from not having 3 stacked axes.



    (9000 RPM ? how is the end mill not melting? Seems as noisy as my attempt but with less vibration)

    But low depth of cut is going to wear out the end mill faster. These days, low radius of cut and high depth of cut is the way to go.


    Is there a spindle with more torque I can install? Actually, I don't know if I'm losing torque by using lower RPM. It might be that spindle torque stays the same, but more torque is needed to cut at lower RPMs.

    Also, I was quite shocked after reading about the othermill. How does a mill with a plastic frame and lead screws (PTFE coated though) manage to have higher precision than one with an aluminum frame and ball screws?
    I just new you where going to post these videos

    As I said, these videos are very misleading, to the inexperienced machinist, they are just showing eye candy, that is misleading and not a reality

    The steel he is cutting 2nd video is free machining, and is nothing like A36 to cut, which is tough and rough on cutters

    Both of these machines have way more rigidity than your machine

    Mactec54


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    Default Re: severe vibration and runout when cutting steel on router

    Quote Originally Posted by spacesaver View Post
    [COLOR=#333333]

    But low depth of cut is going to wear out the end mill faster. These days, low radius of cut and high depth of cut is the way to go.
    Suppose that depends upon who you talk to . Over the years I've done a lot of fast material removal rates on steel , and my preference is less depth at very high rpm's with high feed rates , which ultimately adds up to less tool wear and more material being removed .
    Your more or less trying to do the impossible so the information that we have given you will get you that much closer to achieving what your wanting to . As it stands burning tools is probably the least of your troubles because the lack of rigidity is likely fracturing your carbide at a higher rate than heat issues . Less depth and engagement means less cutting force , something that you need for 2 reasons , spindle torque and the lack of rigidity

    A poet knows no boundary yet he is bound to the boundaries of ones own mind !! ........


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    Default Re: severe vibration and runout when cutting steel on router

    There might be hope. I reduced the huge slop between the tool tip and where the spindle is braced from 12cm to 4.5cm. Before, when I pushed the tool tip with my finger, I estimate the tip could deflect almost 1mm in X & Y (and could hear a creaking sound). According to beam theory, the deflection of a cantilever is proportional to length^3 (not exactly true here since the spindle brace itself isn't completely fixed).

    Now the vibration feels like it has halved. I was able to mill my flux concentrator (to make a capped magnet) for a few passes @ 0.5mm depth of cut before the work slipped. The slip is because I had to greatly raise the work since the tool tip's lowest reach is much higher now.
    severe vibration and runout when cutting steel on router-reduce_slop-jpg

    Next I will do more surgery by reducing the height of the gantry (with the X & Z axes). I'm not sure if that will reduce deflection. I listened if cuts in X direction are noisier than in the Y direction, but didn't notice any significant difference. But reducing height is worth it so that the tool tip can touch the bed.

    I don't understand why the gantry is so high in the 1st place. I suspect it's to allow the 4th rotating axis (lathe chuck) attachment to be placed on the bed. Even if the gantry height is reduced, the 4th axis should still be usable, but the max work diameter will be reduced.


    Suppose that depends upon who you talk to ... my preference is less depth at very high rpm's with high feed rates

    Here they suggest high DOC at low radius.
    Introduction to High Efficiency Milling - In The Loupe - Machinist Blog

    I won't be trying it soon. I'll be happy if even 0.5mm works.

    Attached Thumbnails Attached Thumbnails severe vibration and runout when cutting steel on router-reduce_slop-jpg  
    Last edited by spacesaver; 05-21-2018 at 03:50 AM.


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    Default Re: severe vibration and runout when cutting steel on router

    Yes, but your machine needs to be capable of doing it.
    Hobby grade machines will almost never be able to do what tool manufacturers recommend. Even when cutting wood.

    Gerry

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    Default Re: severe vibration and runout when cutting steel on router

    Quote Originally Posted by spacesaver View Post
    [/COLOR]Here they suggest high DOC at low radius.
    Introduction to High Efficiency Milling - In The Loupe - Machinist Blog
    .
    once again it's a matter of opinion and who you talk to , I've done numerous methods on high end and lower end milling machines and what I said earlier is what I stand by for many reasons , especially on steels . Also keep in mind that for high efficient machining variable flute and variable helix mills are far superior to standard end mills
    your using a wood router which has no torque or rigidity to it , and typical milling practices aren't necessarily going to apply .

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    Default Re: severe vibration and runout when cutting steel on router

    I just did a small job in mild steel with my little 800W spindle.

    I took 0.1mm depth of cut at 15000 rpm with a two flute 3mm (1/8) carbide end mill.

    250mm/min. steady as it went, it vibrated a bit but I managed to hold size and the endmill survived.

    It was a pocketing job. hope this info helped.

    Last edited by CaistorAl; 05-24-2018 at 12:27 PM. Reason: additional information


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    Default Re: severe vibration and runout when cutting steel on router

    Hurray, I finally succeeded in making my part after getting a proper machining vise and lots of trial and error:

    2mm, 4900RPM, 0.5mm depth, 200mm/min: tool snaps on 1st outer perimeter
    2mm, 4900RPM, 0.5mm depth, 120mm/min: snap on 2nd or 3rd layer when starting to clear pocket from inside. 4 flutes tips were all severely chipped.
    2mm, 8700RPM, 0.5mm depth, 120mm/min: lasts longer, but still SNAP ! only 1 flute tip was chipped

    4mm, 6800RPM, 0.5mm depth, 120mm/min - success!

    as before, tool tip distance to spindle brace was minimized to 4.5cm.
    Note: I have no way of measuring actual spindle RPM, so I estimate by (VFD frequency / 400) * 24000 RPM / 1.1

    severe vibration and runout when cutting steel on router-dsc00665-jpgsevere vibration and runout when cutting steel on router-dsc00673-jpgsevere vibration and runout when cutting steel on router-dsc00678-jpg

    lessons learned:

    1. using a tool with <= 2mm diameter is almost certain to break for steel, no matter how fast it's spin
    2. need to use high RPMs to prevent tool from chipping or breaking - can't rely on those figures like 100 feet/min for steel that's intended for much stiffer machines
    3. don't always use carbide if there's noticeable vibration? I wasted a lot of carbide bits. Maybe I would've been better off with HSS or cobalt steel?

    Other notes:
    The most vibration happened when the Y axis (with most load) was the furthest away from an end - about 1/4 of the way. So I should've cut with Y closer to the ends or reducing gantry height might also help

    liquid cooling unecessary? I tried sulfurized thread cutting oil when experimenting with 2mm bits. It reduced vibration, but I don't know if the thermal shock contributed to the flute tip chipping. I didn't use any cooling for 4mm and it turned out OK.

    Attached Thumbnails Attached Thumbnails severe vibration and runout when cutting steel on router-dsc00665-jpg   severe vibration and runout when cutting steel on router-dsc00673-jpg   severe vibration and runout when cutting steel on router-dsc00678-jpg  
    Last edited by spacesaver; 05-31-2018 at 02:09 PM.


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    Default Re: severe vibration and runout when cutting steel on router

    Your depth of cut is still too deep, imo.

    Gerry

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    Default Re: severe vibration and runout when cutting steel on router

    Quote Originally Posted by spacesaver View Post
    Hurray, I finally succeeded in making my part after getting a proper machining vise and lots of trial and error:

    2mm, 4900RPM, 0.5mm depth, 200mm/s: tool snaps on 1st outer perimeter
    2mm, 4900RPM, 0.5mm depth, 120mm/s: snap on 2nd or 3rd layer when starting to clear pocket from inside. 4 flutes tips were all severely chipped.
    2mm, 8700RPM, 0.5mm depth, 120mm/s: lasts longer, but still SNAP ! only 1 flute tip was chipped

    4mm, 6800RPM, 0.5mm depth, 120mm/min - success!

    as before, tool tip distance to spindle brace was minimized to 4.5cm.
    Note: I have no way of measuring actual spindle RPM, so I estimate by (VFD frequency / 400) * 24000 RPM / 1.1

    severe vibration and runout when cutting steel on router-dsc00665-jpg

    lessons learned:

    1. using a tool with <= 2mm diameter is almost certain to break for steel, no matter how fast it's spin
    2. need to use high RPMs to prevent tool from chipping or breaking - can't rely on those figures like 100 feet/min for steel that's intended for much stiffer machines
    3. don't always use carbide if there's noticeable vibration? I wasted a lot of carbide bits. Maybe I would've been better off with HSS or cobalt steel?

    Other notes:
    The most vibration happened when the Y axis (with most load) was the furthest away from an end - about 1/4 of the way. So I should've cut with Y closer to the ends or reducing gantry height might also help

    liquid cooling unecessary? I tried sulfurized thread cutting oil when experimenting with 2mm bits. It reduced vibration, but I don't know if the thermal shock contributed to the flute tip chipping. I didn't use any cooling for 4mm and it turned out OK.
    I love the affect the finished part has

    A torchered piece of metal, if you wanted to get that hammered affect you would not be able to get it, it's a piece of art

    As for tool size, 2mm is an ok size if you needed it that size, I have used .004" diameter cutters to cut Inconel, much tougher material than EN36

    Mactec54


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    Default Re: severe vibration and runout when cutting steel on router

    This experience has been a serious revelation about life for me. I realized, you gotta cut into your problems, not bouncing around and scratching the surface . Look at all the energy wasted when there was vibration - it was shaking the machine wildly and the steel shelf underneath.

    I don't get why people use the expression, "can cut mustard". It should be, "can cut steel".
    I'd like to meet someone who can cut tungsten - figuratively

    Hmm, I wonder what would happen if I try machining tungsten on this router ...



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    Default Re: severe vibration and runout when cutting steel on router

    Quote Originally Posted by spacesaver View Post
    This experience has been a serious revelation about life for me. I realized, you gotta cut into your problems, not bouncing around and scratching the surface . Look at all the energy wasted when there was vibration - it was shaking the machine wildly and the steel shelf underneath.

    I don't get why people use the expression, "can cut mustard". It should be, "can cut steel".
    I'd like to meet someone who can cut tungsten - figuratively

    Hmm, I wonder what would happen if I try machining tungsten on this router ...
    You have to know your machines limits, you say it was shaking the steel shelf underneath, you don't have a steel shelf underneath, it called a table and yours is made from extruded Aluminum, if you notice in the video the side arms of the gantry are flexing, this machine is only good for light machining of wood and plastic, as it is built

    I doubt that anything would happen at all, if you tried to machine carbide, on your machine,, you could grind it on your machine, with a diamond wheel, but machining is a different beast, I have machined carbide dies, this is a common practice, and is quit easy to machine, if you know how, plus have the right equipment, machining carbide on your machine, is not going to happen, that would be a stretch of your Imagination

    Mactec54


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