I am about to start researching into building a CNC router to be able to cut up to 610 x 1220mm (not sure on the Z axis Travel yet!). I require to cut soft wood, MDF and Hard wood of varying thicknesses.
Any help would be very much appreciated, for the plans, parts required, electronics, etc etc. because at the moment I am a complete novice.
thankfully, being in the Royal Navy I have a friend that has offered the use of the workshop to produce any of the machined parts (for the normal payment of a packet of Chocolate Hobnob's of coarse!!).
Please help if you can.
Hi Rob, wellcome to the forum. I suspect your friend may well have an uncle on this site! Good luck with your build when you start. G.
I don't know, there should be a law against using Royal navy workshops in this way.
Welcome to the forum, it is always worth having a good read of the build logs to see what people are using and problems that crop up.
Router Build Logs
I'm not one of the resident experts but I have read a fair amount of the advice so I'll try to condense some of what you will probably find by doing lots reading.
For the dimensions and materials you have specified, 1610 ballscrews would probably be fine, you can order them from linearmotionbearings2008 on ebay.
If you can afford proper linear rail, buy it. If you can't afford it or don't need super accurate cutting, use supported round rail. You can order this from the same guy on ebay that sells the ballscrews. Do not even think about using unsupported rails or an angry Yorkshireman will beat you with them.
The popular 3.1Nm steppers from cnc4you will probably work for you.
Try to avoid the TB6560 stepper drivers, they generally suck.
The water cooled 2.2kw spindles from China (ebay again) are very popular here and should do what you want just fine.
If you can weld or swop hobnobs for welding services, make your frame and gantry out of steel box section, it's a lot cheaper and stiffer than aluminium extrusion. Make your frame and gantry very, very strong and include lots and lots of diagonal bracing.
If you have a good idea of what you are going to be using the machine for, don't put an excessively long z-axis on it. As you are building your own machine, don't be afraid of considering things like a future 4th axis or a gantry that can overshoot the end of the table for cutting dovetails or strange sized stock if these things would be useful to you.
If you only have a little workshop consider making a vertical machine to save yourself a lot space.
Use a dedicated PC if possible for your CNC machine. If you don't mind linux, linuxcnc is great and free, if you really want windows then don't forget to budget for a copy of mach3.
Once you have budgeted for all the big stuff like screws, rails, steppers, drivers, power supply, frame materials, spindle add about 30% to cover all the little bits like cables, tubing, water pump, bolts, paint etc.
Hope that helps you get started. :)
The Following User Says Thank You to D.C. For This Useful Post:
He's correct thou you would deserve a beating if you buy UN-supported round rails.
Given the relatively low work load and accuracy required for just cutting wood and If this machine is just for hobby use then supported round rail will be your best option for a few reasons.
1st they are much cheaper but more so they are much more forgiving than Profiled rails regards build tolerances.? Profiled linear rails are much better regards durability and tolerances but they also need much tighter tolerances regards mounting surfaces etc being very unforgiving of poor workmanship. For Hobby wood cutting use they are bit OTT, esp if your on a budget.
With the Design and materials then Again D.C is correct keep the Z axis extension to a minimum and if its within your skill range then using Steel box section is much cheaper and very strong.
To add to this regards design then try to avoid high gantry sides. My preferred way is not to have any gantry so to speak and mount the Gantry direct onto the rail bearings. This means designing the frame so it raises the rail mounting surfaces but unfortunately it mostly suits using Twin ball-screws on the long X axis. It could be made to use a single centre driven ball-screw but just not has clean a design and weaker.
This twin screw design is very very strong and ridge which helps eliminate Twist, resonance and flex which is the enemy and gives poor finish etc.!! DONT under estimate the forces required when cutting, Even wood.!! Weak gantry and Z axis will result in poor cut finish.
(Will attach render of wood cutting design to give an idea of what I mean regards gantry on rails)
ONLY use 10mm pitch or higher ball-screws for wood use, 5mm will be too slow. 16mm Diameter will be fine, 20mm max.
Don't use 25mm which are commonly available has they are too big for machine this size and require large motors etc.
Motors best suited will be 3 or 4Nm Nema 23 don't use nema 34 has again they are unsuited to machine this size and would actually give less performance not more has is commonly mistaken.
To get the best from steppers then Voltage is very important. Common mistake leading to poor performance is using too low voltage PSU. Lots of motor/driver kits you see often include under sized PSU mainly because they use off the shelf Linear PSU, it also suits the supplier because they are very comfortably within the Drives voltage threshold so less chance blown drives.
With Wood machine then speed is important so sizing the PSU correct becomes important this Sizing also impacts the drives you use. Won't go into all the Crap of why and how etc it's all repeated here on the forum if you want to search but I will tell you thru experience cutting out the crap buy 3.1Nm motors and run them between 65-70Vdc using 70-80V drives.
This leads nicely to Drives and Electronics.!! . . . If you can afford Digital drives then buy them the are worth the investment.
DON'T Skimp on the drives, PSU and to some extent the BOB (Brake out board) they are the Life force of the machine and the sizes I suggested will transfer to future machine giving some future proofing.
The control box and wiring are often skimped on by using unshielded wire and cheap switches etc but again this is false saving and will lead to hair pulling and head scratching chasing problems it also works out more expensive in the long run.
Don't be tempted to run out an buy the Drives motors etc first has lots do has your just wasting warranty and chances are it will be months before your anywhere near needing them. Same goes for WC spindles ETC wait until your ready for them.
Best advice is Design machine then show and Ask. Don't be afraid to ask or think outside the Box just don't try to do it on the cheap it never works.!!
Don't rush out and buy anything without very carefully checking you understand exactly what it does and if it fits your needs and again don't be afraid to ask.!
Unfortunately I can't be around has much these days with today being a rare morning to my self to catch up on things so if you do have any questions specific to me I may not answer straight away.
Good luck and happy building.!
The advice you have already had is worth a small fortune.Good luck wirh your build. G.
Last edited by GEOFFREY; 11-04-2013 at 09:12 AM. Reason: spelling
As far as I'm aware welded steel section and precision rail don't go hand in hand , you will need to grind the steel or shim the rails to ensure that the precision you have bought is actually achieved. I'm not saying that welded section is bad just that you need to be aware of the work required to get the best out of your rails. (bolting precision rails to bent steel = bent rails)
Cutting forces in hard wood can be high, what wood and depth of cut are you looking at?
If its mainly a router that you are building then I would make sure that the dust extraction is very good, one of the main problems is re-cutting of chips which can result in poor finish and short tool life. for example I have just cut alot of edges of a kitchen work top with cheap cutters, after each pass the dust was removed and the cutter had a clear pass. one evening in a rush I didn't bother with hoovering after each pass and the cutter was useless after one joint.......
Good luck with your build and the best advice I can give is to buy the best you can afford in the first place as you will only end up paying out double.
Thank you all for your advice. I have lots of research to do now.
I will no doubt have more questions soon as I start getting my head around it all
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