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  1. #13
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    Default Re: Building or buying?

    I started with a used machine (mostly just the frame), added steppers, wired the controls, and was delighted when it made first motions. I am still working on it, but i learn a little more about it with every bit of progress, and even every set-back. i am still not a master with CNC, but i learned a lot from doing, and researching what needed doing.

    I think what you start with depends entirely on your skill-level, and your time-span to get it done (if ever). starting with a kit, will give you a bunch of pre-selected parts, and all you do is put it together. no real research needed.
    Building from scratch is like a trial-by-fire. you will find a lot about the machines through researching what you need. but it can get expensive if you get it wrong.
    so value is in research on what you need your machine to do. what framework will be necessary to handle what you want your machine to do. and what motion components will be needed.

    at least, that is what i have learned. and there is always a chance i may be wrong.

    ~Travis

    Techno Isel Gantry III (?) base machine. EMC/LinuxCNC controller.
    about 48 X 48 X 5 inch working, Makita RF1101


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    Default Re: Building or buying?

    Quote Originally Posted by travis_farmer View Post
    I started with a used machine (mostly just the frame), added steppers, wired the controls, and was delighted when it made first motions. I am still working on it, but i learn a little more about it with every bit of progress, and even every set-back. i am still not a master with CNC, but i learned a lot from doing, and researching what needed doing.

    I think what you start with depends entirely on your skill-level, and your time-span to get it done (if ever). starting with a kit, will give you a bunch of pre-selected parts, and all you do is put it together. no real research needed.
    Building from scratch is like a trial-by-fire. you will find a lot about the machines through researching what you need. but it can get expensive if you get it wrong.
    so value is in research on what you need your machine to do. what framework will be necessary to handle what you want your machine to do. and what motion components will be needed.

    at least, that is what i have learned. and there is always a chance i may be wrong.

    ~Travis
    I agree and that learning experience has a huge amount of value. It means that, in future, you can also fix, maintain and upgrade your machine without huge costs.

    There are degrees of diy for a build. It will take the longest if you decide to fabricate and assemble every component yourself obviously but there are plenty of options for semi-homemade though. At it's core, a basic CNC machine is just 3 linear actuators bolted to a (hopefully sturdy) frame. eBay is littered with used precision linear actuators and, if you know what to search for, there are some awesome deals available. I found a THK actuator with 20mm rails (2 rail 4 blocks), 20mm ground ball screw and 54" of travel for $450 delivered.

    If I could go back and advise myself at the start of the project, I would have told myself to buy used actuators for all 3 axis and focus all my efforts on the frame. Aligning rails well is less my thing than building a quality gantry and base.

    There is also a lot of options for a ready made machine frame if you have some imagination and modest diy skills. I was particularly inspired by this guy's build:



    I like the smart use of off-the shelf parts, the incredibly simple construction and the level of precision he was able to achieve with a relatively modest budget.

    I can't pretend that I am not tempted by this table with built in gantry either:

    https://www.ebay.com/itm/Newport-30-...EAAOSwMVtZlxY8

    How much time would that have saved with it's ready flat and square mounting surface with aligned predrilled screw holes. I doubt that anyone here is capable of building a more precise base than that... I want one!



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    Default Re: Building or buying?

    Hi Travis;

    Great to hear from you!

    This is an interesting thread but I think people need to understand that even corporations struggle with the question of buying or building. Generally they never bother to build with off the shelf tooling (machines) which is what a router is in most case. But things like tooling and so forth, machine upgrades and improvements can be attacked with a combo of in house and contractor supported development. There are all sorts of factors that come into play so somebody asking this question needs to know it isn't uncommon.

    For me there are numerous reasons to DIY but for a home shop or even a small commercial business, the big one is self support as you so well point out below. You can't help but to learn about your machine as you build it. If you have to pay for a field engineer to come in and fix a machine you immediately drop into the realm of high costs and downtime waiting for the tech to come in. That could mean paying not only the techs hourly rate but his plane ticket, hotel stay, meals and lets not forget the parts. Even if a DIY build ends up with a problem that perplexes the builder he can post here with a reasonable understanding of his machine, the parts it is made up of and how it works - a big communications win.

    So I see the learning process leading towards ones ability to self support as being a big reason to DIY. However we also have to realize that that isn't what everybody is interested in. For those trying to decide which route to take I can only say think long and hard weighing the advantages and disadvantages, your skills and desires.

    Thanks for the post.

    Quote Originally Posted by travis_farmer View Post
    I started with a used machine (mostly just the frame), added steppers, wired the controls, and was delighted when it made first motions. I am still working on it, but i learn a little more about it with every bit of progress, and even every set-back. i am still not a master with CNC, but i learned a lot from doing, and researching what needed doing.

    I think what you start with depends entirely on your skill-level, and your time-span to get it done (if ever). starting with a kit, will give you a bunch of pre-selected parts, and all you do is put it together. no real research needed.
    Building from scratch is like a trial-by-fire. you will find a lot about the machines through researching what you need. but it can get expensive if you get it wrong.
    so value is in research on what you need your machine to do. what framework will be necessary to handle what you want your machine to do. and what motion components will be needed.

    at least, that is what i have learned. and there is always a chance i may be wrong.

    ~Travis




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    Default Re: Building or buying?

    Quote Originally Posted by Goemon View Post
    I agree and that learning experience has a huge amount of value. It means that, in future, you can also fix, maintain and upgrade your machine without huge costs.
    This is huge for somebody that wants a machine in their home shop. Even if you can get telephone support for a purchased machine you still need to understand the machine to communicate effectively with the on line service tech. The only problem with advocating the DIY approach is that some people just are not up to a machine build for whatever reason.
    There are degrees of diy for a build. It will take the longest if you decide to fabricate and assemble every component yourself obviously but there are plenty of options for semi-homemade though. At it's core, a basic CNC machine is just 3 linear actuators bolted to a (hopefully sturdy) frame. eBay is littered with used precision linear actuators and, if you know what to search for, there are some awesome deals available. I found a THK actuator with 20mm rails (2 rail 4 blocks), 20mm ground ball screw and 54" of travel for $450 delivered.

    If I could go back and advise myself at the start of the project, I would have told myself to buy used actuators for all 3 axis and focus all my efforts on the frame. Aligning rails well is less my thing than building a quality gantry and base.
    I would only qualify this by saying that the world of industrial actuators covers a massive array of capabilities. So if somebody goes this route be careful about what you buy as many slides simply don't have the rigidity to be used for routers or other CNC machines.
    There is also a lot of options for a ready made machine frame if you have some imagination and modest diy skills. I was particularly inspired by this guy's build:

    That is one beautiful build! It is a great example of somebody going his own way and doing so economically.
    I like the smart use of off-the shelf parts, the incredibly simple construction and the level of precision he was able to achieve with a relatively modest budget.

    I can't pretend that I am not tempted by this table with built in gantry either:

    https://www.ebay.com/itm/Newport-30-...EAAOSwMVtZlxY8

    How much time would that have saved with it's ready flat and square mounting surface with aligned predrilled screw holes. I doubt that anyone here is capable of building a more precise base than that... I want one!
    Those optical bench tables are an interesting breed, I'm not sure how they would work out for a machine tool build. The tables are optimized to minimize vibration. As such I'm not sure how thick the skins are on a table like this.



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    Default Re: Building or buying?

    Quote Originally Posted by wizard View Post
    This is huge for somebody that wants a machine in their home shop. Even if you can get telephone support for a purchased machine you still need to understand the machine to communicate effectively with the on line service tech. The only problem with advocating the DIY approach is that some people just are not up to a machine build for whatever reason.

    I would only qualify this by saying that the world of industrial actuators covers a massive array of capabilities. So if somebody goes this route be careful about what you buy as many slides simply don't have the rigidity to be used for routers or other CNC machines.

    That is one beautiful build! It is a great example of somebody going his own way and doing so economically.


    Those optical bench tables are an interesting breed, I'm not sure how they would work out for a machine tool build. The tables are optimized to minimize vibration. As such I'm not sure how thick the skins are on a table like this.

    Optical tables / optical breadboard / laser tables (and a bunch of other names for the same thing) come in a wide variety of thicknesses / strength. You can definately find ones that are (more than) thick and strong enough for a CNC router.

    The thickness is usually linked to the size, ( like with surface plates) because they also need to maintain very high precision flatness for optics / laser applications. The requirement for precision and stiffness in some of those industries exceeds ours (but for different reasons). They need to maintain flatness to the same .00001" as surface plates.

    They also come in a range of materials. I've seen them in stainless steel, aluminum, granite and composite honeycomb structures (which are very strong).

    The limitation to be aware off for the tables with built-in active vibration isolation using pneumatics, is that there is usually a weight limitation for that function and it's quite a lot less than the max weight the table could otherwise hold. I've seen 4000lb granite tables that can only hold 600lb with active vibration isolation turned on.

    I was looking at a deal on a 30" x 48" aluminum breadboard and it was 1.5" thick. That's about the same thickness as the aluminum sub plates sold for the Haas VF2. In other words, It would cover most needs here. It takes a lot of force to bend 1 1/2" of aluminum, even at 48" long....

    I think the large over-looked advantage for the diy builder is that many are designed to reduce vibration using lighter materials like aluminum. Commercial machine builders use cast for it's damping properties but, even a relatively small piece of iron weighs far too much for the average diyer to move around.

    The precision flatness and perfectly positioned thread holes on some of those plates is a huge plus too. Depending on what parts people are working with, I bet many people could start assembling and mounting rails as soon as they arrive. Who enjoys threading holes....



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    Default Re: Building or buying?

    Goemon wrote:


    "There are degrees of diy for a build. It will take the longest if you decide to fabricate and assemble every component yourself obviously but there are plenty of options for semi-homemade though. At it's core, a basic CNC machine is just 3 linear actuators bolted to a (hopefully sturdy) frame. eBay is littered with used precision linear actuators and, if you know what to search for, there are some awesome deals available. I found a THK actuator with 20mm rails (2 rail 4 blocks), 20mm ground ball screw and 54" of travel for $450 delivered.

    If I could go back and advise myself at the start of the project, I would have told myself to buy used actuators for all 3 axis and focus all my efforts on the frame. Aligning rails well is less my thing than building a quality gantry and base."

    I built a machine like that a few years ago; it worked out pretty well. The length of the actuators was a limiting factor, although the ones I used seem plenty rigid. It's nice not to have to deal with aligning rails and screws - the actuators have all that done already - although we did have to get the two X axis actuators lined up with each other. Building or buying?-picture-020-jpg I'm back at the drawing board now, trying to come up with something about twice as long and a little wider.

    Andrew Werby
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