approximate budget for CNC mill/Drill?

Interested to hear experiences and total costs to purchase and convert a machine to CNC for small jobs (less than 6in square)

Cheers!

A bit more information required to make an informed guess, I think.

"Less than 6" square", but how thick ?

What material & what kind of operations are envisaged ?

What degree of accuracy / repeatability required ?

How long do you want the operations to take ?

How do you envisage holding the component ?

Nigel B.

I bought a Denford Novamill off eay for £600 without electronics and built the controller, basically 3 drivers, a PSU and breakout board for less than £200 buying from eBay. My S7 lathe conversion cost around £150 for 2 drivers, steppers and sundry components. I also got a Dell desktop from a local s/h computer store for about £80 plus a flat panel display. Mach3 at the time was about £100 but I wouldn't recommend it any more, it hasn't been supported for years. LinuxCNC is free but reputedly harder to use. There are other controllers, UCCNC for example that many people recommend.

Are you a total beginner who wants to learn to use a machine then later convert it to CNC or do you intend to step straight into CNC machining? The latter may be problematical.

Do you need another computer? Which operating system/software? Or a purpose built controller may be what you want.

Are you going to use stepper motors, hybrid servo steppers or servo motors?

Do you want automatic tool change?

Lots of things you need to know about before you embark on a project like this.

There is useful information here CNC cookbook DIY machine blog

Martin C

Hi all,

some useful food for thought and questions I need to properly consider many thanks!

I really need to get it down to a quantifiable list of what exactly I am after - seen a lot of the Grizzly/Sieg/Clarke etc mini mills and look like with a bit of fettling they can produce good parts, which is what twigged my interest...

I have a spare desktop machine that I could run the Gcode/CAM off and am a proficient CAD user with a fair(open to interpretation!) experience designing for manufacture of turned & milled parts.A Dream scenario would be getting a machine I could plan to convert in a year or so's time so I at least understand the fundamentals/limitations of the machine a bit before whacking some steppers on it and sending an endmill ploughing through god knows what!!!

John H - it is likely I would follow that sort of approach too (or that what I had envisaged in my head) - thanks for giving some ideas for costs - have you got any photos of the setup? would be really interested to see.

In terms of material, it would be predominantly free machining aluminium, engineering plastics and maybe some mild steels - I cant imagine milling anything more hardcore at the moment.

In terms of accuracy, I think <100microns I would be very happy with - its predominantly for me to learn as much as I can about the process!

thanks for the attached links too - any further reading to this is much appreciated.

Kind Regards,

Toby

Toby, I'll take some photos of the mill.

You won't get 150mm + travel on the Y axis of a mini mill - the Sieg SX2P (£811) sold by Arc Eurotrade has 145mm travel & you have to go to the SX2.7 to get 180mm travel (£1370-£1470 depending on table size).

My ex-industrial Denford Triac 200 (which cost me £100 without the original drives, servo motors & Heidenhain control) only has 150mm Y travel, so it will be unable to mill around the periphery of a 150mm component.

Not sure you could get better than 0.1mm accuracy without changing to ballscrews. Relatively cheap ballscrews & support bearings are available from China via the likes of Ebay, but you will probably have to do some machining of the base machine's castings to get them to fit. As the Triac was built as a CNC machine, it already has ballscrews & angular contact support bearings all round - one less job for me to do !

I have 3 off 2.2Nm stepper motors (around £35 each) 5.6A digital stepper drives (£13 each) and a 48v 12.5A PSU (£23) . If I hadn't already bought these, I would probably go the closed loop stepper route (and may yet do so & move the other parts on) at around £90 an axis. I already have a suitable inverter for the spindle drive & intend (initially at least) to control it with an Arduino Uno (around £5) running GRBL (free) fed by Universal G Code Sender (free) on a laptop (already owned).

Nigel B.

The other things to think about with a conversion is that the base mill is unlikely to be as rigid as one that started out being intended for CNC use. My KX-3 is about 80kg heavier than my similarly sized X3, not all that weight is in the steppers and controls, all the castings are a lot beefier allowing for heavier cuts to be taken without deflection or vibration.

As Nigel mentions spindle bearings on a CNC will again be better spec, mine are a matched pair that would cost several hundred pounds to replace unlike the lower spec ones in the average benchtop mill.

Finally spindle speed needs thinking about unless you want to spend a long time cutting due to slow feed rates, the materials you say you want to machine would really want a spindle capable of 7,500rpm or better still 10,000rpm. I often run out of revs on my 5000rpm spindle and hate to think what it would be like on a typical benchtop mill with only 40-50% of that. You may want to cost in removing the head and replacing with a high speed spindle with auto change as this will also solve the bearing issue

Edited By JasonB on 23/12/2020 16:47:37

Hi Nigel,

Thanks for the info - may I ask how you found a mill in that condition? I feel I would be up to the challenge of reccommissioning something provided that all the guideways were in good condition and nothing needed substantial repair. At the moment to be quite honest I dont really know what to look for (ie brand/name/websites etc) I think the size I had just plucked with what I am familiar with - my 3d printer is 150x150x200 and I havent really been bottlenecked yet by the useable workspace... Again, really useful to see an idea of costing as it gives some context to me as how much money id expect to throw at it... Arduino and open source is the future of most stuff for makers I think!

Cheers,

Toby

may I ask how you found a mill in that condition?

Luck - right place, right time.

My former employer's son started buying CNC machine tools to break for their control and drive parts. Small Japanese, Taiwanese & Korean vertical machining centres were the usual purchases from auctions - all the control parts, axis & spindle drives and motors were removed and the carcasses sold for scrap. He had no interest in any of the mechanical bits, or tooling (usually some flavour of ISO40). Most of the machines came from failed company closure sales & were frequently still tooled for the last job they made. I used to pop the tools out of the carousels & eventually got a couple of hundred, which we did sell to a tool dealer for a pound or so each IIRC

One such purchase was the Triac. I did a deal with him that I would remove the parts he wanted (a couple of lunch breaks) & he wanted £100 for the rest. It has been is storage for several years & came home this year when the storage was NLA. I had to completely strip the machine to bring it home & I have started to clean up the parts to get it back together again.

WRT the 3D printer - you can make parts up to the table size on those as you don't need to take account of the cutter dimensions & workholding requirements working around a part, unlike a milling machine. And you will probably also (probably unknowingly) be using GRBL, as I understand that GRBL is at the heart of many 3D printer control boards movement control.

For me that main disadvantage of using GRBL is the lack of tool radius compensation. This will make using some form of CAM package a necessity on anything other than very simple parts. I see that FreeCad (which I am using after a fashion for 3D printed parts design) has a CAM module built in, so will probably try that initially. Fusion 360 is the usual recommendation for part design & CAM, but I will have to upgrade computer to use that and FreeCad works on the current one.

As you have a 3D printer, how about 3D printing a GRBL controlled Dremel spindle router for a low cost "toe in the water" ?

Nigel B.

Thanks for the context re the Triac - it had sounded an absolute bargain for a standard ebay purchase!

I had considered the cutting head - but not the workpiece clamping so much with respect to workable area. I think I was primarily highlighting that the majority of parts I would make would be under that (at least until I get an idea of what I am doing!)

RE Grbl, yes - plenty of printers and some router setups also run off something called marlin, which allows people to build one off printers and do all sorts of cusom control. I havent been too restricted with the firmware and control methods on mine yet, but I am sure I will eventually have a tinker! Open source stuff in that field is great, primarily because of the RepRap community.

I am fortunate enough to use solidworks both at work and in my studies, which has built in toolpath generation and machining simulation, so providing I could build a profile for the machine, I think I would have some idea for the command/control side. Ive used it a bit to get an idea of design elements for manufacture previously, and is certainly a handy feature. A couple of colleagues talk highly of autodesk software, although I have no experience of it it sounds like its a powerful tool too.

Re a Dremel router, I have spent many months umming and ahhing. after floating about on the MPCNC forums for a bit, I decided it wasnt for me - they sound great for woodwork and acrylics, but nobody has really cracked anything more - The current frame designs have too much compliance and look like they arent quite up to it. The alternative I considered was designing a much much smaller frame and build area to have much more rigidity. I spoke to a couple owners of them and with the question of mini mill or router, the majority went straight to mini mill conversions....

It does tempt me still, so may well look into it again!

Toby

Thanks for the context re the Triac - it had sounded an absolute bargain for a standard ebay purchase!

I had considered the cutting head - but not the workpiece clamping so much with respect to workable area. I think I was primarily highlighting that the majority of parts I would make would be under that (at least until I get an idea of what I am doing!)

RE Grbl, yes - plenty of printers and some router setups also run off something called marlin, which allows people to build one off printers and do all sorts of cusom control. I havent been too restricted with the firmware and control methods on mine yet, but I am sure I will eventually have a tinker! Open source stuff in that field is great, primarily because of the RepRap community.

I am fortunate enough to use solidworks both at work and in my studies, which has built in toolpath generation and machining simulation, so providing I could build a profile for the machine, I think I would have some idea for the command/control side. Ive used it a bit to get an idea of design elements for manufacture previously, and is certainly a handy feature. A couple of colleagues talk highly of autodesk software, although I have no experience of it it sounds like its a powerful tool too.

Re a Dremel router, I have spent many months umming and ahhing. after floating about on the MPCNC forums for a bit, I decided it wasnt for me - they sound great for woodwork and acrylics, but nobody has really cracked anything more - The current frame designs have too much compliance and look like they arent quite up to it. The alternative I considered was designing a much much smaller frame and build area to have much more rigidity. I spoke to a couple owners of them and with the question of mini mill or router, the majority went straight to mini mill conversions....

It does tempt me still, so may well look into it again!

Toby

HI

I feel that John has covered the cost about right , though I will add to this conversation from my experience.

I bought an Emco PC50 mill [work area 200x115x150ish] and PC50 Lathe from a college that were having a clearout. The machines had been in storage for a couple of years and had rusted surfaces though the guides had been oiled/greased so cleaned up nicely. These set me back ~£400.

I decided to scrap the existing electronics as there was no dedicated interface cards /software/cables/manuals with the hardware.

On the Milling machine I replaced the stepper motors for around £30 each [3 off] and ordered up an All in One Mach3 controller with stepper drivers based on the Toshiba TB6600 [cost ~£70] . I ran the copy of Mach3 that came with the board and an old PC I had . The 3phase spindle drive came from Ebay ~£60, I got the machine working and was able to run cutting tests successfully .

I decided to purchase a Licenced copy of Mach3 [~£130] and have been running the set up without issue for a few years now.

I use Fusion360 for my CAD and CAM generation [£0 currently !]

I then spent around £400 on machine vices, tool holders , clamp set, air -mist cutting chip clearance and cutters.

Total Cost to get started around £1250

I have probably spent half as much again on various bits for the cnc workshop over the intervening years [4th Axis more cutters [HSS and Carbide, stub drills ,High Speed Spindle etc etc ......]

I have since built a CNC Router Mill with a work area of 700x400x100 based on 40x40 Aluminum T slot framework [~£100], linear guide rails and ball screws[[~£150] with 12mm Aluminium CNC cut plates[~£100] [guess what machine they were cut on ?] The Stepper motors were a similar price [~£100] to the original Emco PC50 Mill , the drivers are DM542 based units [~£75] and the controller is a DDCSV2.1 stand alone unit .[~£170] .The spindle will be an air cooled 1.5kW 3 phase unit with ER11 collet [~£150].

Total cost of this setup is around ~£ 850

The purpose of this Router is to cut larger objects [ wagon and carriage sides from MDF /Plywood] Instrument Panels [3mm Aluminum]  model bases 50mm Hard Wood , Engraving Plaques Brass etc etc

[Photo is of the initial prototype , using parts from the "Come in Handy Cupboard" , 3d Printed components and plywood !!]

Good luck with your endeavours and welcome to the "Rabbit Hole" of CNC

Steve

Edited By The Novice Engineer on 03/01/2021 20:05:50

Hi Steve -

thanks for adding your experience for ref. That cnc setup looks great! have you got an example finished pieces from it? would be really interested to see. I think I have ultimately tried running before walking, as I am currently still getting myself setup proper. I have made a start with a humble drill press, which isnt much but a start! Nevertheless, its really helpful to see how others have tackled more DIY setups and I feel more confident that I would take this approach. I think another critical thing I need to work out is allocating the space for such a machine too...

The cnc router setup looks like its coming along nicely too - would be really interest to follow how it gets on cutting aluminium and harder stuff. the "mpcnc" seems to be quite a widely used platform that people work off that ive also been following closely. The more I look into it, I think this may be my first proper CNC endeavour ( - that is, a cnc router) as it is something I could build up from rexroth profiles or other bits and bobs I can cobble or print.

I certainly feel inspired having a look through this and the other posts... but also makes me realise how much space I need to make!! one can dream...

Toby

It's a bottomless pit of cash as you up the specs, from 1000 to 50000

DIY will save a lot of money but that route is a lot of effort

...and then there's the software...

Whichever route you choose it's a major commitment that needs foresight

Ebay is littered with the corpses of unfinished CNC dreams