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  1. #1
    Hi all. Currently awaiting a build so in reality not even a new CNC user yet!.... But, doesn't stop me thinking and planning. So one thing I've been reading is about mistakes, some minor, some more costly. Snapped bits seem a common issue. I'm assuming this is down to incorrect feed rates or more likely errors in the programming and plunging too deep. Hopefully this is short lived and checking your toolpaths thoroughly is a must early on. Anyone experienced this when a novice? Or still experiencing this? How much is down to user error or can it sometimes be hardware error?

    I have a few carving/inlay projects planned. Hopefully in some nice hardwood. I'm thinking of during early days running the project on some cheap pine or ply first as a test before buggering up an expensive piece of oak. Is this a reasonable idea or am I thinking over cautious?

    I already have a decent dust extraction system in my new workshop. Dust shoes seem a good idea as carving produces a lot of chips/dust. But again as a novice user, I'm thinking I want to be watching the cut, firstly out of interest, but secondly out of safety. Are you all confident enough in your cutting to be blind to the cutting bit? Are you confident enough to leave your workshop while cutting is in progress or would you at least want to be in the workshop doing other things so you can hear an issue and stop it swiftly? Do you expect issues or is it now rare when experienced?

    Maintenance. Apart from keeping clean and dust free, what general maintenance is required? greasing ball screws? I'd guess that attracts dust sticking? WD40? silicone spray?

    What were your first projects? Why? Anything nice and simple that teaches a new user a thing or two or just blast straight into what you are after doing and make mistakes to learn?

    Any other tips/tricks, need to know, nice to knows?

    Cheers

    Mark

  2. #2
    Hi, There is a free program called Camotics https://camotics.org/ which is a 3 axis simulator, this can be used as an initial toolpath check.
    Instead of cheap pine you can use Kingspan insulation boards (though I haven't looked at the health and safety rules regarding machining this) it is firm enough to cut yet soft enough to give if you accidentally plunge in too fast/far.

  3. #3
    Quote Originally Posted by Pilsbury View Post
    So one thing I've been reading is about mistakes, some minor, some more costly. Snapped bits seem a common issue. I'm assuming this is down to incorrect feed rates or more likely errors in the programming and plunging too deep. Hopefully this is short lived and checking your toolpaths thoroughly is a must early on. Anyone experienced this when a novice? Or still experiencing this? How much is down to user error or can it sometimes be hardware error?
    Broken bits are just part of the learning process and they can and probably will happen from a mixture of all of the above, however the one error I see most often from new users is forgetting to reset the Z axis offset (Zero) after changing tools.
    Checking toolpaths carefully with a simulator is a good pratice to get into however then it won't always stop crashes.? Common things that can and will bite you at some point are Clamps and screws which hold the material.
    Many jobs require the tool to move around between cuts and the code doesn't always move in ways you'd expect so it's very easy to hit a clamp when it moves locations or hit the head of a screw you are using to hold waste material etc which doesn't show in the simulation.

    This can and does happen even for experienced users, but obviously I've never done this.. . . . It's 99.999% user error most of the time.


    Quote Originally Posted by Pilsbury View Post
    I have a few carving/inlay projects planned. Hopefully in some nice hardwood. I'm thinking of during the early days running the project on some cheap pine or ply first as a test before buggering up an expensive piece of oak. Is this a reasonable idea or am I thinking over cautious?
    I'd advise at first to cut Air by setting the Z zero in Midair. This will prove your code is working as expected.
    Then I'd practice on soft materials like Dense foam(kings span) or MDF. However, you will have to tweak the speeds n feeds, DOC, etc, to suit the material your using and MDF is a better practice material than foam because it's harder and closer to Real wood.

    Quote Originally Posted by Pilsbury View Post
    Dust shoes seem a good idea as carving produces a lot of chips/dust. But again as a novice user, I'm thinking I want to be watching the cut, firstly out of interest, but secondly out of safety. Are you all confident enough in your cutting to be blind to the cutting bit? Are you confident enough to leave your workshop while cutting is in progress or would you at least want to be in the workshop doing other things so you can hear an issue and stop it swiftly? Do you expect issues or is it now rare when experienced?
    At first, it's ok to watch the cutter for the reasons you stated but I'd advise putting one on ASAP because while it does obviously lower dust it does a more important job in that it stops chips from getting recut giving a poor finish and excessive tool wear.


    Quote Originally Posted by Pilsbury View Post
    Maintenance. Apart from keeping clean and dust free, what general maintenance is required? greasing ball screws? I'd guess that attracts dust sticking? WD40? silicone spray?
    Keeping it clean and greasing the screws and bearings is often enough, bit of light oil on the rails won't hurt either just don't go crazy.

    Quote Originally Posted by Pilsbury View Post
    What were your first projects? Why? Anything nice and simple that teaches a new user a thing or two or just blast straight into what you are after doing and make mistakes to learn?
    My first CNC job was making new gantry sides to replace the MDF ones.!

    KISS is the best advice and in MDF to start off with. Start with simple 2D shapes with a few pockets and holes. If your feeling confident maybe try a bit of V carving.

    A good practice exercise that will have all of the above plus more and will be useful is a Collet holder.
    If your feeling really confident instead of collet pockets with straight sides make the pockets tapered and use a 2.5D toolpath with a ball-nose cutter. Also, try putting chamfers on the edges.
    This will give you all the major tool-path types in one Job and will teach you how to do tool changes in the same job. Just about every job you do from then one will have one or a combination the tool-paths used in this practice piece.
    -use common sense, if you lack it, there is no software to help that.

    Email: [email protected]

    Web site: www.jazzcnc.co.uk

  4. #4
    Quote Originally Posted by ngwagwa View Post
    Instead of cheap pine you can use Kingspan insulation boards (though I haven't looked at the health and safety rules regarding machining this) it is firm enough to cut yet soft enough to give if you accidentally plunge in too fast/far.
    Whilst nowhere near as toxic as say spraying polyurethane varnish, if you're making fine dust it's still potentially a bit nasty so some form of extraction wouldn't be a bad idea.

  5. #5
    Cheers ngwagwa. I shall check out that program. Looks like a good check to see nothing ridiculous will happen. I shall also consider things like kingspan after looking into it.

  6. #6
    JazzCNC. I have no doubt I’ll be cursing broken bits. Already have a few cheapo Chinese ones to lessen the blow. Some of the recommended bit sites are still rather expensive for a novice to be using in my opinion. I’ll treat myself when I’ve got over the worst! And yes, clamps and screws are going to be a giggle. A vacuum bed is way above my station!
    “Air cutting” is also a good idea, as is mdf. Can see that being much better than pine being very fibrous.
    I have dust collection now hard plumbed into my workshop with a branch and blast gate ready for where my cnc will sit. Putting up with dust and crap is now almost a phobia to me since my recent workshop build. All clean and tidy but takes minutes to destroy!
    Like your first project ideas. Already thought of drill bit holders, router bit stands etc. Will take the KISS advice. Have some rather intricate projects in mind I’ll try my best to postpone until I’ve covered the basics. Had in mind I’d be producing show stopping work in a short time. Might be in for a rude awakening I think!

    One further question for you, perhaps the only man on the forum who can answer ..... when do you think I’ll be making a simple collet holder? 😉

  7. #7
    Voicecoil. It’s amazing how only until fairly recently dust extraction has become a big thing. I’m on that. Health is important especially when cutting stuff like MDF. Plus my workshop is all new and tidy. Even went to sand outside the other day. Won’t last!

  8. #8
    Removed.
    Last edited by Zorbit; 27-09-2020 at 02:11 PM.

  9. #9
    Quote Originally Posted by Pilsbury View Post
    One further question for you, perhaps the only man on the forum who can answer ..... when do you think I’ll be making a simple collet holder? 😉
    At this moment I can't say as I'm still waiting for the slow boat but when the boat lands you are the first on the list.!
    -use common sense, if you lack it, there is no software to help that.

    Email: [email protected]

    Web site: www.jazzcnc.co.uk

  10. #10
    Zorbit. Interesting about clearance planes. Shall bear that in mind. Also good to hear about HSS being more forgiving. The few bits I have bought are carbide as I thought they were the holy grail.... at least that’s what they said they were on Banggood!

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