Hello all, I've never built a CNC router before, in fact I've never even seen one (unless you count Youtube). I'm a woodworker and I primarily want my machine to handle timber. Here's my end game...
1. The ability to handle 1/4" standard woodworking router bits
2. The ability to utilise a standard wood router or laminate trimmer (prob preferable due to their more uniform cylindrical body). I dont need to vary the speed during working - only for different materials. Provisionally I would use a Makita RT0700
3. The ability to hold and clamp a wide range of workpieces - maximum size laterally of 1220x606 working area - although I might consider a wider working are such as 1220x1000 to give me the ability handle the occasional table top. I would also need the ability clamp workpieces perpendicular (upright) to the table bed (for routing unusual joints or ancathus leaves on table legs etc) so the machine should have an open/through bed to the ground when the bed sheet material (prob MDF as its easy to level and v stable) is removed. My initial concept is to have sliding bed support cross sections that can be easily loosened and so adjusted to fit a vertical workpiece - they would also provide support for clamping.
Initial provisional choices:
* Speed: A wood router might prove heavy to a cnc so I see the gantry being both strong and as rigid as possible - this will all add weight and affect speed. However, a router can only travel so fast through wood without charring it whatever its means of travel so I suspect I will be making motor decisions more based around torque than speed
* Materials. Obviously I would like the machine as rigid as possible. Working steel is out of the question for me as I do not have the tools or the skills to weld (I have enough tools for 2 lifetimes already and my list of wants is long enough without venturing too much into a whole new field of metal work equipment). So I will be limited to using a bench press drill, my wood bandsaw, hacksaws, files and possibly my mitre saw (If I can bring myself to cut anything other than timber with my beloved Festool Kapex mitre saw) - otherwise I will use my bandsaw. So, with those restrictions I believe I will be limited to working with wood, acrylics/plastics and aluminium profile. I have discounted bolted steel frames - I have many machine stands for my table saw and Planer thicknesser that are bolted steel and they flex and work bolts loose all the time.
Therefore, initial choices are as follows:
Wood for the frame/stand. I have a glut of white oak timber - its very well seasoned and very heavy and stable wood. I can dimension it exactly on my planer thicknesser and seal it. It's as strong as steel imho and I can work it to a fraction of a mm. Of course wood breathes even when endgrain is sealed but as a base with slotted fastening to the CNC framework (for seasonal movement) it will be very well suited and provide significant dampening and low end weight.
The framework of the CNC machine (the axis and gantry) will be predominately aluminium profile (sizes not decided - I know zero about aluminium profiles yet) - and I will also use sheet/plate alu of a thickness of at least 10mm for manufacturing the various templated parts (gantry, support etc). I assume I can cut 10mm thick alu on my bandsaw on its slowest setting using some cutting oil spray - any advice suggestions would be appreciated - I dont expect the blade to last more than a single project.
Design. I am new to CNC and so know very little except what I have read recently but it strikes me a rack and pinion for the x and Y and some kind of lead screw for the gantry would be my best choice for rigidity. I also admit that I am leaning towards that choice simply because I cannot imagine that a allthread lead screw is worth the bother or can deliver - seems that a ballscrew would need its ends machining unless I went for a standard size and I am confused by their assembly and mounts etc to be honest. One thing I do know is that I want 2 motors driving my X axis - one central drive just looks and feels problematic for a larger machine and my gut tells me it's going to struggle and sprain especially where any cut is being pushed along the X axis with the router to the far left or right on the Y axis. I like the idea of using a steel angle profile with v bearings to run the gantry down the X as it looks hardwearing and stable - strikes me also that standard bright steel solid round bar would also work very well as rails once polished up and tested for straightness - I cant imagine many machines capable of flexing a pair of 20mm cold drawn roundbars
Sketchup will be my friend as I plan on drawing out my full design first and then subjecting it to a barrage of public scrutiny on this site - I would rather not "reinvent the wheel" from scratch and so if anybody can recommend any sketchup plans that are reasonable examples to modify and resize I'd appreciate that as it's always easier for me to start with something even if I end up discarding and replacing every part of it.
I plan on making no decisions electronics - other than motor sizes - until I have made the mechanical machine. Likewise, I wont be buying anything other than raw materials (aluminium, timber etc) until I have built that.
Can anybody suggest a machine for me to look at for inspiration?
Sorry to start with just some ideas but the guy who taught me cabinetmaking always used to say that if you cant draw it, you cant build it - and there's a lot more to drawing than drawing pictures.
This might be of use; http://www.mycncuk.com/threads/8243-...ht=woodworking
And this; http://www.metabricoleur.com/t7858-f...eues-d-arondesSpelling mistakes are not intentional, I only seem to see them some time after I've posted
Wow I love the Festool laminate trimmer mount, beautifully done isn't it. An expensive router to smash into a table surface though :-)
I like your design for the table insert - do you have problems getting it to sit flush again after you have removed it? Any reason this is preferable to removing the entire bed?
Actually, a wood router is not heavy at all, when you compare it to better, more powerful options (spindles).
Weight is your friend, and shouldn't really affect speed if the machine is powered correctly.
You have the 3rd part backwards. The slower you go, the more likely it'll be to cause burning. The faster you cut, the cooler the bit will be, and the longer it'll last. If your machine is rigid enough, you'll find that the lack of spindle power will be the limiting factor in how fast you can go.
A cnc router for cutting wood with 1200x600 (or 1000) cutting area is entirely possible with aluminium extrusion but would need to be the heavy gauge type and around 80x160 in section.
My machine has a gantry of about 700mm width, using heavy gauge 80x80 section and I would go bigger next time.
Recent designs on this forum have also used an 'L' shape arrangement from 2 rectangular sections to get stiffness in 2 axes, which is certainly worth considering.
If going for the raised gantry style then 20mm side plates are a minimum, but I would recommend going all out for the raised X axis style with no gantry sides. It's not much more effort to make and will give better performance.
You mention 20mm round bars not flexing much but I'm afraid you would be surprised how much they do flex. My very first machine had 20mm chromed round bars and matching linear bearings and was one of the reasons that some of the holes were a bit oval. Instead I think you would be OK with supported round rail for wood cutting, but would look for profile linear rail on at least the Z axis (short therefore cheaper) as it is vastly superior.
You also mention rack and pinion but I would stick with ballscrews all round personally. In terms of how the end supports work - one end (usually the driven end) sits in a housing containing a pair of angular contact bearings. When the securing nut is tightened this supports the ballscrew, allows it to rotate, but prevents axial movement.
The other end is just a simple support bearing and just holds the ballscrew in place whilst it rotates.
If this is a bit daunting then rest assured that you can buy a ballscrew 'set' with the ballscrew, fixed bearing, floating bearing, retaining nut (special) and drive coupling all included. You can even request particular lengths machined to your requirements for very little extra - have a look on ebay or aliexpress for examples.
You can cut aluminium profile on a mitre saw if you fit a TCT aluminium cutting blade. Take your time and it will go through like butter.
From what you say i imagine you as an hardcore woodworker .
Let me break some illusions:
-the best Festool router is crap compared to the cheapest Chinese water cooled spindle. Once you run a proper spindle you will wonder why you ever considered a router.
-Wooden machine base is asking for problems and wasted money
-Aluminum profile gantry on that span is asking for problems. That can be cured by bolting steel back plate to reinforce the aluminum profiles though. Profiles, not profile.
There is a cheap way to make a steel gantry and more expensive way, to make aluminum plate gantry. On your intended span the gantry will be somewhere like 1450-1500 wide/for 1000mm travel/ . So you don't need to know how to solder. Just design it and have somebody made it for you. It will still cost cheaper than aluminum. And the aluminum also needs to be bought and machined. So it could be as simple as soldering 2x 100x100x3mm together
-in my signature is the link to my 1rst build. You could find it quit inspiring if you like that style of machine. Somewhere inside are the free plans in sketchup. You could use ball screws, mounts and so, as i have drawn them one by one checking against the real product.
In fact all your questions about PR, ball screws, Breakout boards, motors and so are answered there. I am glad that at the time Dean broke my illusion about the rack and pinion and i ended using ball screws
-I say it every time : until you have them in your hands, dont drill holes for spindle mounts, ball screw nut housings and whatever Chinese thing from aluminum, cause many times they look the same but come with different holes placement or if they are cast the holes are misplaced some times.
I wish you luck with the build!
Just to update you all on this thread, for some reason when I moderated a recent reply the result was the whole thread being removed.
This has happened to me before when using the mobile app so I think it's a bug in the software. As such I had to manually go in and restore each post by you - as you.
So if you've had notifications suggesting there has been new activity to this discussion but can't see anything new, now you know why. Please feel free to continue the discussion as normal.
Sorry for any inconvenience, have a great day.
Last edited by Lee Roberts; 19-03-2015 at 12:26 PM..Me
glynster - Did you get any further with this? Looks like we are trying to build a similar machine
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