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  1. #37
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    Default Re: What Part To Start ?

    Quote Originally Posted by peteeng View Post
    Hi Jake - I think your overcooking the frame for cabinetry work. With your cabinetry background I'd build a timber machine as your starter or at least a timber bench. I'd use linear bearings however not the extrusions and wheels on lots of these. Peter

    https://www.buildyourcnc.com/CNCMachineKits.aspx
    Your link is not for anyone that is serious about building a machine for business

    Mactec54


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    Default Re: What Part To Start ?

    Quote Originally Posted by JakeInCharlotte View Post
    My frame design has changed as I have dug in deeper. The one I posted earlier seem great to me, but I saw a lot of welding. To me that equals heat, shrinkage, and distortion. I started searching pictures of high end machines and found their bases to be a simpler design using big rectangle tube. The big tube will require less welding for sure. The part that got me was the fact that the table heights are around 34" from the floor to spoil board, and that needs tall tube. I'm sure I could build something out of smaller material, but Im not looking to reinvent the wheel. I have been buying steel from Howard Steel in Charlotte for years and I find their prices to be pretty competitive. They seem to charge based on weight, well sort of. The frame will be close to 3000lbs as designed.




    Yes and yes. Not sure where at the current time. I'm following the table flatness thread and bookmarked Precision Grinding Inc. in Alabama. They are only 6 hours away from me. Otherwise I plan to use the cedar shim scraps my trim guys leave everywhere.




    Thought about it. I even tried to buy just a frame. I just could not find anyone interested in a frame only sale.

    Im looking at the Acorn system for sure. I like the fact it is from a company that builds bigger systems. Has Centroid always been a supporter of open source DIY systems? If so, I think it's pretty cool.
    Gary Campbell is a Pro and does this for a living, located in NW Michigan. He can sell you one perhaps he has already done. I would trust his judgement 100%, but please do not ask for "free" help. https://www.camheads.org/showthread.php?t=7830

    Retired Master Electrician, HVAC/R Commercial. FLA Saturn 2 4x4 CNC Router Mach4 Kimber 1911 45ACP


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    Default Re: What Part To Start ?

    Quote Originally Posted by JakeInCharlotte View Post
    14 x 10 x 3/8 = 58lbs. per LF @ $62 per LF

    14 x 10 x 5/16 = 49lbs. per LF @ $43 per LF
    Here is a machine that was built by a friend, it is quite well documented here on the Zone, he had his frame made in China to his Design they also machined it, let be know if you do want to out source the basic build

    He spent a lot of money to do this build, but it payed for it's self in a very short while, He used the best of everything Drives Motors Etc it has rapid speeds up to 2500 IPM

    Note the concrete feet, these where required to keep the machine from moving around under acceleration , it is 12' x 6'

    https://www.cnczone.com/forums/cnc-w...ediculous.html

    Attached Thumbnails Attached Thumbnails What Part To Start ?-router-build-jpg  
    Mactec54


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    Default Re: What Part To Start ?

    Have you thought of looking on ebay for an older machine to retrofit a modern controller to?Even if you have to replace some worn components,the prices are often startlingly low and you have the basis of a machine that can be customised to your requirements.I find the discussions on this board about massive frames for people engaged in hobby activities tend to lead to massive and overbuilt frames,with correspondingly massive costs of materials in pursuit of levels of accuracy that would be in order for components in chronometers.If your ambition extends to making a dozen kitchen cabinets a month,what is a realistic amount of deviation from utter perfection?A solid table is a necessity and the legs are there to keep it off the floor,adjustable feet are a help if the workshop has a slightly bumpy floor.



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    Default Re: What Part To Start ?

    Big question of the day. Is the end result going to justify all the expense?

    You will have a 3,000 lb machine, with extra heavy duty motors and everything to carve out wood kitchen cabinets. But not on a production basis. In other words perhaps $30,000 or $40,000 and for all practical purposes is going to be white elephant.

    A production shop can purchase a new one with factory support and parts cheaper than your custom built one. Same way on larger machine, they want support and factory training. A hobby user will not have room for it, and the standard 4 inch thick concrete floor is going to crack under that weight. So that means a new reinforced base floor / foundation.

    As one poster said, if you want something solid that will not move, bolt it to the floor. Industrial machines are leveled and bolted to the floor, why not yours?

    Retired Master Electrician, HVAC/R Commercial. FLA Saturn 2 4x4 CNC Router Mach4 Kimber 1911 45ACP


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    Default Re: What Part To Start ?

    Just for kicks, give JD squared a call and get a price on their new router that is coming out. The thing is a beast and their plasma tables are very reasonably priced. You couldn't build one for what they sell them for. Here's a couple pics from their Instagram. You might be surprised with the price compared to what your build cost is. I'm planning on getting a plasma table from them.

    Dan

    Attached Thumbnails Attached Thumbnails What Part To Start ?-screenshot_20190405-131141_samsung-internet-beta-jpg   What Part To Start ?-screenshot_20190405-131145_samsung-internet-beta-jpg  


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    Default Re: What Part To Start ?

    Dan, Is that steel or aluminum? Thats down in Mactec54's home town?

    Retired Master Electrician, HVAC/R Commercial. FLA Saturn 2 4x4 CNC Router Mach4 Kimber 1911 45ACP


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    Default Re: What Part To Start ?

    Hi Jake - looking at your "rectangular construction is easier" comment. Rectangular construction is not as stiff as triangular construction. (hence it needs to be heavier) Plus rectangles have lots of vibration modes. Since you will have to move this machine it needs to be light or dismantlable. Look at a design that has bolt in triangular bracing. This will be much stiffer, eliminate many vibration modes and can be made lighter for transport. Even think about making a base section and a top section that bolt together. The top section then is lighter for transport to your stress reliever and machinist etc. If you choose an easy path there are consequences for that convenience. Figure out the best way to do something vs the easy way. This forum is full of the best answers once you filter through the dross. Personally I'd buy a chinese machine get it going and if you have to, rebuild it. Seems to be the way to go for a starter machine these days. Plus you have to learn CAD, CAM, tooling... you have a lot on the plate to chew before you get to sawdust, the machine is just the starting blocks. I think you need a starter machine not a Rolls Royce (Cadillac in USA?). Perhaps consider building a simple half sheet machine for small stuff to get you going.... Peter



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    Default Re: What Part To Start ?

    Hi All- To look at the heavy bench argument a little further. The only reason to have a heavy bench is to stop it from moving around. Weight and stiffness are not connected so lets just assume that we need a heavy bench to stop it from sliding around. I looked for some acceleration figures on commercial machines and they range from 0.5g to 2g so lets pick 1g as a nice number that can be scaled easily. If someone out there can give us a real number that Jakes sort of machine would run at that would be excellent. So the calculation attached is to find out the ratio of gantry weight to table weight needed to achieve no slip on the floor. I've also assumed a friction co-efficient of 0.2 but it could be 0.1 (slippery steel to steel) or 0.3 rough. Its a simple calc neglecting moments and some other factors. So upshot is the bench and gantry have to weigh 48x the gantry weight to not slid. So if the gantry assembly weighs 50kg then the entire machine has to weigh 2400kg. Looking at some of these machines they weigh just over the tonne so perhaps 0.5g or less is more like it? But if you bolt the machine down then it weighs what the earth is so bench weigh is irrelevant. So what accelerations are out there? Peter

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    Default Re: What Part To Start ?

    Pete, thank you for the calcs.

    However, I think it is not about actual sliding of the machine on the floor but any flex or distortion on the base relative to the gantry, no?



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    Default Re: What Part To Start ?

    Quote Originally Posted by peteeng View Post
    Hi Jake - looking at your "rectangular construction is easier" comment. Rectangular construction is not as stiff as triangular construction. (hence it needs to be heavier) Plus rectangles have lots of vibration modes. Since you will have to move this machine it needs to be light or dismantlable. Look at a design that has bolt in triangular bracing. This will be much stiffer, eliminate many vibration modes and can be made lighter for transport. Even think about making a base section and a top section that bolt together. The top section then is lighter for transport to your stress reliever and machinist etc. If you choose an easy path there are consequences for that convenience. Figure out the best way to do something vs the easy way. This forum is full of the best answers once you filter through the dross. Personally I'd buy a chinese machine get it going and if you have to, rebuild it. Seems to be the way to go for a starter machine these days. Plus you have to learn CAD, CAM, tooling... you have a lot on the plate to chew before you get to sawdust, the machine is just the starting blocks. I think you need a starter machine not a Rolls Royce (Cadillac in USA?). Perhaps consider building a simple half sheet machine for small stuff to get you going.... Peter
    Now you are talking, have been making small machines this way for a number of years sure does help with the machining, it's like everything though there is a limit when you come to build a big machine like this which is better built as one piece, stress relieving and Machining is not really an issue for a big machine as those that are building them have the machines to machine them as well, it actually costs less to build as one piece also

    Mactec54


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    Default Re: What Part To Start ?

    Quote Originally Posted by davida1234 View Post
    Pete, thank you for the calcs.

    However, I think it is not about actual sliding of the machine on the floor but any flex or distortion on the base relative to the gantry, no?
    Correct

    Mactec54


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