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Thread: Newbie trying to figure out Onsrud Feeds and Speeds - Cant find the data

  1. #1
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    Jun 2015
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    Default Newbie trying to figure out Onsrud Feeds and Speeds - Cant find the data

    I know there are a lot of posts on here, but all they do is direct you to an Onsrud page with a bunch of data sheets. On the data sheets they seem to have chipload information, but not feeds and speeds unless they are in some code I am not understanding. Can someone please send me a link with an explanation of where to look and what to look for! This is the link that everyone recommends http://www.onsrud.com/xdoc/FeedSpeeds and when I click on it it has a bunch of other links to the data pages. The data pages list the chipload, but as mentioned I need the feeds and speeds! I see a chart at the top with Good Better and Best and not sure if they are referring to the bit number or something else. I feel like an idiot that I can not seem to find that information. Someone please help me! Thanks!

  2. #2
    Join Date
    Feb 2013
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    River Fall WI
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    You are thinking too hard, it is just math.
    You have two things you can change (once your bit have been picked) to change your chipload, move speed or RPM's.
    http://www.shopbottools.com/mTechSho...pLoad_inch.pdf
    Kyle Stapleton
    River Falls Renaissance Academy
    Math/Technology Education Teacher


    PRS Alpha 96x60 2.2 hp spindle, Double Air drills, 6" indexer, Fein 5 zone vac table
    Desktop w/spindle
    Potter Pen
    Aspire 8.5, Creo 3.0

  3. #3
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    Thanks Kyle, but it does not tell me the RPM needed for the spindle speed or the feed rate. I have the chipload information but where are the speeds and feeds rates listed?

  4. #4
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    Nov 2014
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    DB,
    Have you looked in your shop bot control software under tools and used the chipload calculator? This may explain what all those numbers mean. It'll ask you to input user variables like number of flutes on the bit, etc. When you have the basic parameters set, you can then take that chipload and reference the chart and make adjustments to the calculator. Then make some practice cuts at the RECOMMENDED (which is all those charts are) feeds and speeds. If you see in the forums this: 1D, or 2X D, that means the depth of cut using the diameter of the bit as a reference. Eg a 1/4" upcut bit with a 1D cut would be cutting with a .25" depth. 2D would be 1/2" depth of cut or DOC. Start with the 1D depths until you have more experience. There are a lot of times when you will want to cut both more and less than that. 38% stepover is a comfortable stepover % to start with for me when doing things like pocketing or roughing.

    Even experienced guys will have to do trial and error when using a new material and/ or new technique in the same material.

    You can't really give ballpark figures because there are so so so many different materials, machine set ups, humidity levels, altitudes, hold down methods. Its really impossible. I think Onsrud and others give cutting parameters that they feel are safe and conservative, this is only my opinion.

    hope that helps.
    PRS Alpha 96" X 48" w/ 12" Z
    4hp Spindle
    6" Indexer
    Aspire 8

  5. #5
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    Justin - thanks so much. But this still does not help me I am afraid. I need to find the RPM's and Feed Rate recommended by the manufacturer according to the material I am using. Everyone says it exists, and I know it is only a starting place and I have to experiment, but I don't even have the starting place for the Onsrud bits. According to Shopbot and Onsrud the information exist at the link I listed in my original post. But I can't find them. So far no one has been able to point me to the right place.

  6. #6
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    Nov 2014
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    This might help but these are completely for me.

    Hardwood F/S:
    1D DOC
    2 flute across the board

    3/8" 3 IPS/ 10k
    1/4" 2.5 IPS/ 12k
    1/8" 2.5 IPS/ 15k
    1/16" 2 IPS/ 18k

    This completely varies, but It seems to me like these RPM or "speeds" work as very good generals or starting points and you vary the feed rate depending on material hardness you're cutting. No one here knows what you're doing and would be hesitant to give you any specifics like this because it could be completely wrong for what you are doing. Please keep that in mind. If there is a lot of heat, you should move your feeds faster, if the machine is bogging down when you move it faster, take a smaller bite by lessening the DOC. If you do not have an alpha and push it too hard, you may lose steps as I understand it.

    Hopefully the more experienced guys can chime in with a little more science/ know how.
    PRS Alpha 96" X 48" w/ 12" Z
    4hp Spindle
    6" Indexer
    Aspire 8

  7. #7
    Join Date
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    DB, You're not understanding the use of the chart properly. The chipload is the recommendation and the RPM/feed rate is back calculated from that. The actual RPM's and feed rate depends on what your machine is capable of. To get to a chipload of 0.014 (for example) could be achieved by moving at 5ips with an RPM of 11,000k but for someone with a fixed speed router that's not possible. Just as higher feed rates might not be possible for someone with a smaller machine.

    Chiploads are nothing more than ballpark figures to give you an idea of where to start. Your eyes, ears and touch are the most important thing to use after that. It's all about keeping the heat down.
    The answers to a lot of questions can be found at http://www.shopbottools.com/ShopBotDocs/ or http://support.vectric.com/

  8. #8
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    Apr 2013
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    Kennebunkport, Maine
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    Don,
    Did you buy spindle or router?
    Did you buy the starter set of bits?
    In your tool database, there should be the starter set of bits with a Shopbot default feed/speed in the "Wood" category. I might start at 1/2 Diameter pass depth to start with those feeds/speeds so you don't break a bit and get discouraged. Exclusively hard woods and usually exotics here so they're a little high for me, but a good starting point until you get a feel for it. If spindle, most likely rpm's will be between 10-16K and between 1-2IPS for Desktop for hardwoods(Rough guide).
    You've gotten some good advice, but need to cut some so you recognize your "Sweet Spot" for material/bit/machine.
    http://www.precisebits.com/tutorials...s_n_speeds.htm
    I kinda like Brady's VERY General start point for natural hardwoods of 1.5(IPS MoveSpeed X,Y), .5(IPS MoveSpeed Z), 14K(14,000 RPM) at 1/2Diameter passes and keep a hand on the VFD (or keyboard feed shortcut SHift <> if router) and watch to make sure I'm getting chips NOT sawdust, feel bit after cut(should be room temp to slightly warm, but you should be able to leave your finger on it), and have an edge quality I'm happy with.
    May want to stick with the species you're most likely to be cutting and dial in the bits you have so you get a Feel for your machine, and then you can adjust feeds,speeds,pass depth to optimize cut times afterwards.
    Scary at the very beginning(and you'll have "Learning Days"), but fairly quickly you'll be "Guessing" the correct settings for brand new bits/woods closer and closer
    Might recommend sitting in on a couple of TJ's training classes as there's almost always some cutting going on, and you can ask questions afterwards.
    You may also want to watch some of his recorded classes, as a lot of times he's using the Desktop and you can listen to it.
    http://www.shopbottools.com/mSupport/tutorials.htm
    2 cents.
    scott
    Scott P.
    2013 Desktop/spindle/VCP 10
    Maine

  9. #9
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    Jun 2015
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    Thanks Scott and everyone, I understand now. I purchased the spindle. I was a little sad that I found out that the spindle RPM was not software controllable and that you have to use the dial. I love everything automated! But that is another discussion. I was confused about the feeds and speeds because in a couple of places it said Onsrud provides this information for every bit. However, they only provide chipload and thanks for the information on where to start. Also Tom at Shopbot support sent me another document this morning as a starting place. I have attached it here for anyone who wants it! Now I can start experimenting on my own materials. I am appreciative of the help. Shopbot Feeds and Speeds Chart Email.pdf

  10. #10
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    I would by no means turn a blind eye or ear to what your machine and material are telling you while cutting @ these chipload numbers. Don't be scared to come up with your own numbers. Start at MS,2,1 and 13,000 to 15,000 RPM for any material and adjust as needed. Chipload means squat if your hold down method is weak and parts move around or lift on you. About 70% of the challenge with CNC is keeping the parts down properly while being cut.

    Chipload numbers are rarely achieved on light CNCs. Chipload is nothing more than the speeds required to get the longest tool life. They are by no means the ideal speed for cut quality. That needs to be understood. Now, I won't say that carbide is dirt cheap, but it's cheap enough because it lasts a long, long, long time as long as you don't overheat it.

    If you are an engineer that just has to have the 'right' number, then run your tool without dust collection for a few inches at a given RPM/MS and rooster tail some chips into your hand. Measure the thickness of the chip with a pair of digital calipers....THIS is your actual chipload & what the magical mystery charts are referring to...

    You will gain more insight and expertise with your machine and be better off if you just abandon the idea of running @ chipload. Some adhere to it like it is a religion...but few mention the inevitable variables that you will encounter while trying to run at those values. I've met many people who paint themselves into the proverbial 'gotta run @ chipload' corner only to shortchange themselves along the path of being a good, dynamic machinist...so keep this in mind while you build up your skills.

    -B
    High Definition 3D Laser Scanning Services - Advanced ShopBot CNC Training and Consultation - Vectric Custom Video Training IBILD.com

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