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  1. #1
    Hi All.

    Just thought id offload one of those worries I have knocking round in my head. Its in regard to wood router cutters.

    Something like this


    I seem to go through them like hot dinners. and I wondered if anybody else has the same problem, or can perhaps advise me if I am missing something

    Im using a standard 2.2kw chineese spindle, spinning at top wack 2200rpm? Ive checked its spinning in the right direction. all Im cutting is 3mm ply.

    the workpeace is securely fixed down, and im only moving at around 2500mm/min @ around 4mm a pass

    I seem to go through about one every hour, sometimes quicker. and at about 12 a pop its starting to take the biscuit

    I even bought a couple of really expensive ones from ltc tooling http://www.itc-ltd.co.uk the guy said, he has never known one to break... my machine broke it in minutes

    there doesnt appear to be any slop in the machine... (you can grab the neck of the spindle and hang on it, without feeling any play or movement)

    any ideas, no matter how trivial they sound... would be appreciated. may have to post a video

    in anticipation of your replies gents, thanks in advance

    matt
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  2. #2
    Ger21's Avatar
    Lives in Detroit, United States. Last Activity: 13 Hours Ago Has been a member for 5-6 years. Has a total post count of 508. Received thanks 68 times, giving thanks to others 0 times. Referred 1 members to the community.
    What diameter is the cutter, 6mm?

    Drop your rpm to 13,000, and they should last longer.

    Also, try using the shortest bit you can find. The longer it is, the more stress it will have on it.
    Last edited by Ger21; 02-08-2015 at 01:54 AM.
    Gerry
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  3. #3
    Clive S's Avatar
    Lives in Marple   Stockport, United Kingdom. Last Activity: 14 Hours Ago Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 5-6 years. Has a total post count of 2,309. Received thanks 403 times, giving thanks to others 35 times. Made a monetary donation to the upkeep of the community. Is a beta tester for Machinists Network features.
    Im using a standard 2.2kw chineese spindle, spinning at top wack 2200rpm? Ive checked its spinning in the right direction. all Im cutting is 3mm ply.
    Matt As Gerry has said drop your rpm down and feed rate up. 2500mm/min seems slow to me. Gwizard indicates with a 6mm 2 flute carbide slot cutting 4mm DOC 18450 rpm 7790 mm/min feed. rate
    ..Clive
    The more you know, The better you know, How little you know

  4. #4
    Hi Matt,

    Have a look at the cheap and cheerful cutters on toolstation http://www.toolstation.com/shop/Power+Tool+Accessories/d80/Router+Bits/sd2579/Router+Bit+Straight/p83429 they may not last any longer, but at the price the pain is lessened.

    Cheers,

    Rob
    Last edited by cropwell; 02-08-2015 at 12:16 PM.

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  6. #5
    As you are breaking so many you may be able to answer this - are the bits breaking when you plunge into the wood or as its cutting along a length?

    The reason I ask is that the cutter does not have a cutting edge all the way along the bottom edge, so if you are plunging vertically into the wood as opposed to a ramp effect you may be putting loads of force onto the cutter! anyway that's my experience with that type of cutter.


    Earle

  7. #6
    Hi Matt, below are just two examples of the same problem you have. I even tried to go with 6mm with a 1/2" shank and that broke just as easy and trust me these on the photo were not the only two I broke:-) I even managed to break a quite expensive WP 1/4" x 1/2 shank cutter, it lasted a longer but not much. Unless I ran these 6mm straight flute cutters with air blast, at low feed and shallow depth of cut they broke long before they get remotely blunt. They break while slotting straight or curved sections and never broke during a plunge or ramp-in. If I want to break a brand new one within 10 seconds I just cut some of those dark brown HD fibre board at the feed/speed/DOC you mentioned above. Gmmf, they die so gracefully, no real nasty sounds, nothing gets flung across the workshop, the spindle just leaves half the cutter behind in the slot... :-)

    Earl has a point, not all of these straight flutes can plunge straight down. I normally bought the ones that can plunge but it did not make much of a difference in the results I got, nether did changing brands.

    I don't know but I think its got to do with limited chip clearance or something. I'm not saying this type of cutter is junk but I for one, had no luck with them in 6mm. The larger ones like 1/2" x 1/2" straight flute cutters never breaks and lasts till they are blunt but they also don't like aggressive cut depths while slotting, in my experience. On the larger diameter ones it takes quite a but if cutting force at more aggressive DOC. Try one in a hand router and you'll understand what I mean.

    For 6mm dia go for single flute or even two flute spiral cutters and you will have MUCH more joy, faster feeds and you'll cut them till they are properly blunt without breaking and you'll save money.


    I would be curious to know if other CNC'ers are using these straight flute 6mm cutters at reasonable feed/speed/DOC with success in ply or harder types of wood.
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  8. #7
    You would think it was inability to clear swarf, but that is not really a possibility in 3mm ply.

    Next favourite is a build up of gunge that dulls the edge so it stops cutting and starts bending.

    Perhaps it is the material. Is the glue in the plywood transferring to the cutting edges?

  9. #8
    Hey Matt,

    Try the classical 16000rpm feed 60IPM 1 diameter cut depth. 17000rpm for harder wood. Thats a speed feed depth combo that must work on any machine even a crappy one. Works even on chattering machine and i use the similar cutters until they stop cutting at all.


    Its spinning on the right or correct direction?

    Do you climb cut or conventional? I climb cut natural and conventional cut man made wood.
    project 1 , 2, Dust Shoe ...

  10. #9
    Clive S's Avatar
    Lives in Marple   Stockport, United Kingdom. Last Activity: 14 Hours Ago Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 5-6 years. Has a total post count of 2,309. Received thanks 403 times, giving thanks to others 35 times. Made a monetary donation to the upkeep of the community. Is a beta tester for Machinists Network features.
    Boyan In post one the op has said it is cutting in the correct direction. If the feed rate is too low that could gum the cutter up
    ..Clive
    The more you know, The better you know, How little you know

  11. #10
    Quote Originally Posted by Clive S View Post
    Boyan In post one the op has said it is cutting in the correct direction. If the feed rate is too low that could gum the cutter up
    The rate i suggest will not clog the cutter, rest assured Clive. I am cutting same on flimsy machine all day long for 2-3 days until i waste a cutter. He is not cutting with 200$ cutters, big spindle and perfect hold down to go industrial fast like 400IPM. I am just suggesting to try that and see if that still happens.
    project 1 , 2, Dust Shoe ...

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