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IndustryArena Forum > WoodWorking Machines > DIY CNC Router Table Machines > New Machine Build - Massive CNC router for timber components
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  1. #1

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    New Machine Build - Massive CNC router for timber components

    I am about to begin building a very large CNC router for creating timber components and have had quite a bit of difficulty finding information on this forum, or anywhere on the internet, about building very large scale cnc machines. Lots of the machines I see being built are quite a few steps smaller than the machine I need so I am having quite a bit of difficulty deciding on the the details and design.

    I will be using the machine to create joinery in large solid wood timbers (8x8, 6x12, 6x6 etc), I use everything from white oak to pine so the machine must be able to handle the hardest of woods. I will mainly be using a 7 inch long, 3/4 inch diameter carbide cutter head. My goal is to be able to use this cutter head to create 1/2'' - 3/4'' depth of cut which will allow for very aggressive material removal.

    I see lots of build threads on here where the original post has lots of the design and details figured out, or at least a strong direction for the machine, I unfortunately cannot decide which way is best to approach this build.

    I am posting in hopes the talented people of this forum can guide my decision making, so here is where I am at now:

    -Spindle HP: 10 minimum (I have been in contact with a forum member who has a used 12 HP komo spindle which seems to be a good for for this machine)
    -Work envelope: 48'' X , 120'' Y, 16'' Z
    -Gantry style design
    -I am really hoping to use large stepper motors instead of servo's, accuracy is not extremely critical in this application
    -I am thinking rack and pinion to create movement
    -square linear motion rails
    -Welded steel frame
    -Rapid feed rates and very quick movements are not critical, the depth of cut is much more important. I have seen that a lot of builds decide what the rapids and feed rates should be and work from there, but on this build the aggressive depth of cut will be the starting point for feed rates. With this being said, it will be a machine used for my business, and time is money, so an efficient machine is critical.
    -Mach 3 controller


    So with this being said, I cannot decide on a starting point. I am torn between the following:

    -A gantry with high vertical uprights (I think this is referred to as low rail design)
    -A gantry that sits on high frame rails (I think this is high rail design)
    -A moving table (Table moves only in Y direction, Gantry moves in only X direction)
    -Some other approach I am not even aware of


    I am hoping the talented people of this forum can chime in and aid my design process!

    Thanks,
    George

  2. #2
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    Re: New Machine Build - Massive CNC router for timber components

    The first thing that comes to mind is Mach3. Due to it being unsupported I’d seriously would consider another solution. Thankfully there are many solutions these days.

    I’m by far no expert in large wood working spindles but isn’t 10 HP a bit of an over match for a 3/4” cutter doing 1/2” deep slots?

    We don’t have a lot of details here but RAPIDS are very important on large machines. This especially if you want to machine a feature at one end, one in the middle and one at the end. Slow rapids will destroy your cycle times. Again it depends upon what you are doing but for commercial use I’d be focused on good rapid performance.

    As for servos you might actually be better off with servos. When you have such a high horse power spindle you need to consider reaction forces in machining and maybe more importantly in a crash that might put far more energy into the system than normal cutting. Most of the machines built here are in the 2HP range so you have to consider thAt the common approach seen here might not fit your needs.

    In the same sense a 10 HP spindle really requires a more substantial frame than the common builds here. I’d go so far as to say don’t do it unless you have well developed fabrication skills. Well skills and a machine shop. The high Z clearance for example requires a bit of thought in the design.

    You will likely need rack and pinion for your long axis. You don’t need to make every axis rack and pinion though.

    As for table selection generally on large machine people go the moving gantry route to save space. However for large timber handling a moving table might be a safer option. Why? Easier loading without the back breaking error to get the timber under the gantry in a moving gantry solution. There are options though, you could do a moving gantry machine with a longer travel than needed to provide a gantry parking space. The goal is to be able to drop the timber in place with a minimal of shifting of the wood required. So if you intend to do 12 foot long beams, being able to drop them directly onto the table is a big deal.

    I mention the above based on experience one place I worked that Had a very larger planner mill. One thing that stood out was how easy it was to load the machine up with truly heavy stuff. That could be accomplished with fork lift or overhead crane. Now I don’t expect your timbers to be that heavy but they are heavy enough to cause injury. Side sign in the ability to load the machine easily.

  3. #3

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    Re: New Machine Build - Massive CNC router for timber components

    Thanks for the reply Wizard, I am going to research another solution instead of Mach3, although at this point software is lower on my list, not sure if I am making a mistake by considering software an issue to be dealt with later in the build?

    So for the 10HP, I spoke with an engineer from the company I get my cutting tools from and he suggested a 10HP spindle minimum for the 7'' long, 3/4'' diameter cutter with a 1/2'' to 3/4'' DOC. I should also mention that we'll be running other cutter heads with larger diameters, say 4inch diameter surfacing bits... We currently have a 3HP machine and are constantly stalling it, I would just rather be over powered with the spindle as it's an absolute nightmare when the machine cannot cut as fast as we desire.

    I am going to do a bit more digging into the desired rapids and feed rates before I get much more into that side of the conversation. But I think 300IPM rapids and 100IPM cutting would be the minimums.

    The more I look into designs the more appealing and realistic option seems to be a moving table with a fixed gantry (Table moves in Y direction, gantry does the X and Z movements). For me, space is plentiful, I am not worried about taking up space with a larger moving table and would like to ensure a safe and comfortable working environment for my employees and myself. Loading by hand is out of the question, crane or forklift is the only way for us to go, I cannot expect to load 200-300 LB beams by hand all day long. Installing a crane next to the machine is no problem for us.

    I should also mention I have a full welding fabrication shop and a half decent machine shop with a number of mills and lathes, so I am quite confident in our abilities to produce each component, but first we have to figure out the design haha!!!

  4. #4
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    Re: New Machine Build - Massive CNC router for timber components

    If you want to cut joinery on the ends of these beams, consider providing a tilting mount for your spindle. The options for cuts are limited if you can only approach the beam from the side; if you can approach it end-on, you've got more options. I've seen people provide a gap in their tables to fixture a board in vertically, but this is only going to work with short boards (unless you elevate your whole machine considerably). The tilting mechanism wouldn't have to be motorized; as long as you can shift it manually and get it to rotate 90 degrees accurately and fasten it firmly in place, this will make things like dovetails etc. a lot easier.
    Andrew Werby
    Website

  5. #5
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    Re: New Machine Build - Massive CNC router for timber components

    Hi George - I think Wizard has the clues here. You must think through your loading and unloading and this will give you clues on the machine style. A high rail design is the stiffest but does present loading issues. A moving table design with fixed gantry takes up space but does make a relatively easy to load machine and a very stiff machine.

    A style I think you should consider is a moving column design. So it's a one sided moving gantry design. This allows easy loading of long objects from the long side. Robot machining centres do this sort of thing and there are many moving gantry machines in aerospace due to long parts needed to be machined. So you have a double rail on one side of the table that the column moves along. The column can have two axis with the table fixed or the table moves in the short direction and the column moves long and Z. I'd consider the column to move in all axis and the table to be fixed. Then a forklift can be used easily for loading and unloading and the operator has full access to the job. can walk up and down the job to check or set things. Prior machines discussed all have part access issues.

    The machines you discuss have been developed for sheet work (8'x4') not timber work as you describe.

    I had a dig around but can't find a suitable image of a machine. Here's a mill that's sort of the right configuration. You have a fixed table at bench height for operator comfort. Two long rails behind the table(Y), a column with a saddle with the bearing pairs (X) and the Z. This gives you the opportunity to implement a rotary for the work piece/table as well. Steppers or Servos will be up to your budget either will work. A fabricated steel frame and components will do the trick. Aluminium components will be lighter and rapids will be easier if its light. Cutting timber does not require a significantly stiff machine. There's lots of discussion here about stress relief of the frame that will be good for you. I'd also consider making the machine a bit bigger then you expect as I've always found that no matter how big I build a machine or an oven or a thing it needs to be bigger 3 weeks after you finish it. The fixed table design can be extended very easily if you leave the space just add some more track. Good luck. I also suggest you fully develop the design in CAD and check all suppliers have what you spec before you start the build. Many builds start and buy stuff then change through the build or can't get something they expected to get. Throws quite a few spanners in the works. So fully resolve and cost/source your design in CAD then move fwd... Looking fwd to your design progress... Peter

    As Awerby says consider a spindle that can take aggregate tooling, this will then allow easy end or edge work.

  6. #6

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    Re: New Machine Build - Massive CNC router for timber components

    Hello awerby,

    I should have included this in my first post... I attached a picture of some gable accents. We create these by laying down a large glue laminated block of timber on the cnc and cut each individual piece from the large block, it works incredibly well but takes forever at 1/8'' depth of cut currently, hence the reason for this machine.

    If this machine build goes well I will start a secondary build right after, a horizontal cnc router for doing the end joinery on timbers, but that's for another day haha!

    We currently have a contract to build hundreds of these gables so its my current focus to develop an efficient building method for this type of work.
    Attached Thumbnails Attached Thumbnails image_full.jpg  

  7. #7
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    Re: New Machine Build - Massive CNC router for timber components

    Quote Originally Posted by George484 View Post
    Hello awerby,

    I should have included this in my first post... I attached a picture of some gable accents. We create these by laying down a large glue laminated block of timber on the cnc and cut each individual piece from the large block, it works incredibly well but takes forever at 1/8'' depth of cut currently, hence the reason for this machine.
    you can't run them through a bandsaw first then cut them on the router?

    i'm assuming you're talking about using a 7 inch long endmill to cut the profile of the 6" deep gluelam. so you are shaving off 1/8" of wood by 6" depth of cut correct? what is your feed rate?

  8. #8

    Re: New Machine Build - Massive CNC router for timber components

    The moving table is the best choice for machine rigidity. The downside is that the machine footprint has to be nearly twice the table travel so you would wind up with a machine that is almost 20 feet long.


    Next best choice is the high rail design. That keeps the distance from the rails to the gantry center line as short as possible so less possibility of flex.


    In either case a massive gantry is going to be required to overcome the bending moment of the 16 inch Z travel and the loads imposed by a 7'' end mill. My first choice for the gantry would be a 10 or 12'' square tube with a 3/8'' wall.

    As peteeng suggested above, an open sided machine is not out of the question. Given the shape of your parts, it would be a good fit. In fact picking up a used CNC bed mill might make a good base to start with. Most of the hard work is already done for you, wouldn't be hard to modify one to fit your needs. The older ones pretty much sell for scrap price or less. Since you would only really want the frame, the overall condition is not much of a concern. There are also a number of open side routers available on the used market in the sub $5000 range that would fit your needs, might have to modify the Z axis to get the required travel, but again, all of the hard work is done.


    Servos would be my choice for this application, especially considering 100 IPM cutting speeds with heavy loads. Not really much more expensive than good steppers. I would recommend DMM Technology products. https://store.dmm-tech.com/ I think somewhere in the 1KW range would be a good fit for this application. Perfectly compatible with Mach3 or Centroid Acorn. https://www.centroidcnc.com/centroid...ontroller.html
    Jim Dawson
    Sandy, Oregon, USA

  9. #9
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    Re: New Machine Build - Massive CNC router for timber components

    Buy a used Biesse ROVER.

    Building machines is fun, but you've got contracts and time is money.

    The learning curve on using a CNC is something to contend with, and it's tiny compared to the task of building, integrating and commissioning a CNC from scratch.

    As far as spindle HP goes, with CNC you can make several lighter cuts over the exact same path so you can optimize the cut to the HP available.

  10. #10
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    Re: New Machine Build - Massive CNC router for timber components

    I understand the reasoning behind most of the comments already given and I will add a couple of further points that might be worth considering.I used to program and operate a 15 foot by 10 foot machine with a 3 foot Z axis-it was a 5 axis machine-and I do have a fair idea of some of the issues that will arise.To begin with you need a reliable and safe way to load large pieces in a sensible amount of time.In reality it means either a forklift or a travelling overhead hoist.You also need a way to locate the piece repeatably and to hold it securely while the machining goes on.

    Am I correct in believing the Z axis travel you are seeking is dictated by the tool length plus the depth of the wood?You may need to edit the programs to make sure that the tool doesn't finish the job and then travel home through it.With hundreds of the same item it only needs to be done once.

    I have used a 2 1/2 inch long tool on a 3 axis machine to take 1 inch deep cuts but with the exceptionally long tools you are intending to use you will be applying a hefty amount of leverage to the spindle bearings and to the Z axis carriage and I would echo the advice given earlier to trim a bit off before the final machining.

    One other thought,what are you going to do about extraction?with lots of large sections being machined there will be a mountain of chips to get rid of each day and it isn't easy to organise extraction for anything other than panel cutting.

  11. #11

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    Re: New Machine Build - Massive CNC router for timber components

    Great replies thus far, much appreciated.

    I want to clarify how we are currently making our timber parts. We are using a 1/2'' diameter by 6'' long cutting tool, it has roughly 1'' of actual cutting length. Our timber assemblies are generally made of 6-12 parts which notch together with dowels and such. To make the parts we toss a large glue laminated block onto the bed of the machine and essentially "carve" out pieces... At 1/8'' DOC you can imagine it takes a very long time, our little 2.2KW spindle does not like its current workload! Some programs take 10 hours of cutting and the cut quality is not too good, the machine struggles with anything harder than pine.

    We want a machine that can plow through material.

    Based off the current response from the knowledge base on this forum, it seems my best options are as follows:

    -Change my design approach to a moving column design like peteeng suggested.
    -Buy a used machine I can upgrade/retrofit to do what I need.

    I should mention I am located near Toronto in Canada, and the used CNC market here is nowhere near as good as in the US. I have brought machines over the border before but it always ends up being way more money than I anticipate, and quite a headache to deal with. So with that being said I am still deciding if building a machine or retrofitting one is a better solution.

    The comments regarding loading were insightful and to be honest I had not really thought too much about it. The open sided sliding column design is an incredible idea I would most likely never have though of myself, the thought of being able to place a large timber block up against a "fence" of some sort which is parallel to the long rails of the machine is highly enticing.

    Another point to consider... I will have multiple people (Up to 5 at a time) helping me construct this machine, so once I have the design nailed down we are not intimidated by the scope of work.

    Forum member Jim Dawson has been kind enough to correspond with me via email and he suggested I take a look at a used Morbidelli Author 502 CNC router he came across on craigslist. I am very interested in this design, perhaps this machine can be retrofitted to my application, but I worry about the Z height as it seems to be a panel processing machine.


    Some other updates... DMM servos seem to be a great solution and I will be avoiding steppers.
    Mach3 is out the window, currently looking at Centroid solutions.

    Routalot has made a comment regarding dust collection. I have not spend much time thinking about this, I have a 10HP cyclone dust collector which I was going use solely for this machine with all of its available CFM targeted right at the cutting area, and perhaps add additional pneumatic lines which blow high pressure air at the cutting action to get the chips flying up into the collector.

    Our slowest months are January and February so my plan is to push as hard as I can to produce results before the end of February.

    Thanks,
    George

  12. #12
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    Re: New Machine Build - Massive CNC router for timber components

    Nice to see a fellow Canadian, I am a couple of hours north of Toronto myself.

    I agree with the posts that suggest a used machine as a starting point at least. I retrofitted a couple of used machines for a local company a few years ago. One was a moving table design with the a 5 x 10 ft work area. The other was the moving column style with a 16 ft long X-axis. Incidentally, both machines continue to work very well with the old Mach3 software. Both machines are servo operated with rapids in the 1000 IPM range.

    If you can find a functioning used machine, that would be the quickest solution by far, however, like you said, they are harder to find up here. How much Z travel do you need? Also, with a bit of creativity, you can use a moving table machine for parts that are considerably longer than the table.

    As for the HP of the spindle, a good industrial 7HP should chew through even hardwood plenty quick. On the other hand, a cheap 10HP unit may not measure up. The tooling is also an important consideration as they are not all created equal.

    You didn't mention the time frame that you are working with except that you plan to work hard on it for Jan & Feb. Are you planning on being fully up to speed after that?

    I am interested in following your progress. Keep on posting.
    Rick

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