Cost per axis in the UK...

[digits]

Hi guys - I am considering putting together my own CNC mill/router and I'm trying to work out what it would cost me...

Having checked ebay etc, so far it's looking like £150 per axis just for 16x4mm trapazoidal screws,bearings,nuts and supports and another £150 or so for a pair of round rails and 4 bearing blocks - so about £300 per single screw axis.

I think I'd probably need double screws on X and Z - which would make them about £450+VAT each!

Do these prices seem sensible - or is there a way to build a sub £1000 router of decent accuracy?

Cheers.

[diarmaid]

Hi. Im building the small solsylva router and am hoping to get my ACME rods from here, Im not using ball screws on this machine but dont know what postage to Ireland is yet:

http://www1.mscdirect.com/cgi/nnsrhm

...because I also have been having trouble finding screws locally.

If my router goes over €1000 I'll be very surprised and €300 was already spent on the control system. I suppose its very dependant upon what size your router is and what its built out of.

If your going with good quality ball screws and they are each 10ft long and 2inches diameter, then yeah, your going over £1000. Plus obviously you'd be putting these onto a heavy all metal large machine which is also expensive. For my next machine, I'll be doing just that, but hope to keep the overall cost under €4000.

How big do you want your machine and what will it be cutting? (i.e: Cutting metal will require a heavier more 'stiff', and hence more expensive construction)

[digits]

Originally Posted by diarmaid Hi. Im building the small solsylva router and am hoping to get my ACME rods from here, Im not using ball screws on this machine but dont know what postage to Ireland is yet: http://www1.mscdirect.com/cgi/nnsrhm ...because I also have been having trouble finding screws locally. If my router goes over €1000 I'll be very surprised and €300 was already spent on the control system. I suppose its very dependant upon what size your router is and what its built out of. If your going with good quality ball screws and they are each 10ft long and 2inches diameter, then yeah, your going over £1000. Plus obviously you'd be putting these onto a heavy all metal large machine which is also expensive. For my next machine, I'll be doing just that, but hope to keep the overall cost under €4000. How big do you want your machine and what will it be cutting? (i.e: Cutting metal will require a heavier more 'stiff', and hence more expensive construction)

Cheers diarmaid - I'm not planning a huge machine, but I do want it for cutting metal - mostly aluminium.

I haven't gone for ballscrews or the top spec bearing blocks etc, it's just that everything seems to cost multiples of £20 and everything adds up very quickly:

For one axis:

1 Trapazoidal screw with machining for nuts and bearings etc: £60
1 trapazoidal nut £20
1 fixed bearing £45
1 floating bearing £20
2 supported rails (500mm long) £70
4 linear bearing blocks £80
1 motor coupling £10

which comes to £305 + VAT = £360 for a single 500mm axis! All the parts are very good quality - I've already got the parts for my X-axis, but if I put together the other two axes it will cost me well over £1000 which is right up there with some of the mid range commercial machines.

I haven't however seen anything under £2000 which with a cutting envelope of 500x300x300 mm that will cut metal, so I guess I might just have to eat nothing but baked beans for a while

[mr_mocap]

Bit late in this thread I guess to be posting, but I was interested in this prior to starting the build on my mill. The intended travel is 450 x 300 x 120 and I would say I am about half way through. The machine is scratch-built (not from plans, not a conversion) using new steel section which I am welding together. The axes travel on round rail and are driven by ballscrews all of which have been purchased new from Marchant Dice. I originally estimated the cost of everything (rails, screws, motors, drives, etc etc) to be 1200UKP. However the cost has now exceeded 2000UKP and looks like going to 2500UKP.

At this stage I am wondering whether it would have been cheaper to convert a machine or use ally section building blocks. However I still feel justified as the end result is promising to be extremely rigid, and will include automatic coolant pump and spindle switching etc etc. So, in my opinion, better than the alternative... but I would say that, wouldn't I!?

[digits]

Originally Posted by mr_mocap Bit late in this thread I guess to be posting, but I was interested in this prior to starting the build on my mill. The intended travel is 450 x 300 x 120 and I would say I am about half way through. The machine is scratch-built (not from plans, not a conversion) using new steel section which I am welding together. The axes travel on round rail and are driven by ballscrews all of which have been purchased new from Marchant Dice. I originally estimated the cost of everything (rails, screws, motors, drives, etc etc) to be 1200UKP. However the cost has now exceeded 2000UKP and looks like going to 2500UKP. At this stage I am wondering whether it would have been cheaper to convert a machine or use ally section building blocks. However I still feel justified as the end result is promising to be extremely rigid, and will include automatic coolant pump and spindle switching etc etc. So, in my opinion, better than the alternative... but I would say that, wouldn't I!?

Cool - have you got any pictures you could share? I am just about to give all my money to MarchantDice - I'm aiming for 500x400x400mm travels, using aluminium extrusion and Hiwin rails and trucks, so it's not going to be cheap, but it should be nice!

[mr_mocap]

Yes, I do have pictures. I have started this blog which I will add to as and when I am able. I intend to document the build as I go.

The blog is at http://uk.360.yahoo.com/mr.mocap, let me know what you think if you visit, I have enabled comments from 'anyone' as well on that site.

Kevin at Marchant Dice is great, he is as friendly as he can possibly be. Usually quite quick, he's taken a bit longer to deliver my balscrew assemblies although I have it from him that they will be with me tomorrow! Let's hope so. The assemblies (screws, nuts, bearings etc) for all three axes came to a whopping 900 pounds - by far the biggest single outlay for this machine. However, as a result of my spec, Kevin is now planning to make this set available complete via ebay so this may help others in building something similar. Possibly it will be a bit cheaper this way too ;-).

[digits]

Everything costs a fortune doesn't it - the parts are very nice, but £50 for a bearing still hurts!

What sort of deflection are you going to get with your unsupported rails? I'm probably being paranoid, but I'm planning to have everything supported in my design - if I ever get it off the ground.

I look forward to seeing more of the blog - you're two weeks behind - telly hasn't been that good recently

[mr_mocap]

Originally Posted by digits Everything costs a fortune doesn't it - the parts are very nice, but £50 for a bearing still hurts! What sort of deflection are you going to get with your unsupported rails? I'm probably being paranoid, but I'm planning to have everything supported in my design - if I ever get it off the ground. I look forward to seeing more of the blog - you're two weeks behind - telly hasn't been that good recently

Yes, deflection is certainly a problem with this design, but it's a lot cheaper of course. As it happens, I was offered some Hepco slides for FREE(!!!) after I'd started the work and had gotten well into it... and I didn't want to backtrack. Deflection is a compound problem, as it's a compound slide that I'm building, but my thinking is that with roughing and finishing passes during actual operation (the latter being exceedingly light) I will minimise problems of this nature. I haven't tried putting a dial gauge on the slide yet but may do, I just don't want to become too depressed! One idea would be to add bearing wheels that rest on guides on the bed to minimise this; something that will be easier to do when the machine is operating (i.e., making parts for itself). If it's really bad, I can retrofit the Hepcos. Two 20mm rails are pretty sturdy though, I have to say; the real downside as I understand it is the increased wear rate that you get from this type of bearing. And the kind of thing that I wish to make has also to be taken into consideration: shiny bespoke bits for Harley Davidsons mainly, where actual accuracy is less of an issue than how nice it looks!

On top of all of this, it's also fair to point out that the ball screw itself will add some extra support as well and this is a 16mm shaft.

As for not keeping up with the blog: yes, I am behind but there hasn't been much progress lately due to several factors. Not least of which being that my company has just won a contract to scan / resurface the entire product range of a major car manufacturer for a web project! I should be making more progress this weekend, assuming that my ball screws arrive this morning as promised. And I will keep the blog as up to date as I can.. maybe you should start one too, it's free!

[digits]

Glad to see you've got your ballscrews - now he can get on and make mine

[mr_mocap]

Originally Posted by digits Glad to see you've got your ballscrews - now he can get on and make mine

How far have you got with your build then? Do you have any pictures, or renders of your design maybe? I thought that I would have everything done in less than two months, start to finish - but that was back in the days when I thought the total cost was going to be 1200 quid!

My blog is now only one day behind, I did do some work on Sun but not much - my sister's visiting from afar this coming weekend, so that probably means I won't get much done then. On top of everything else my Harley's still in bits, and the SUN IS SHINING??? What happened to all that lovely rain?? And so it goes...!!!

[digits]

Originally Posted by mr_mocap How far have you got with your build then? Do you have any pictures, or renders of your design maybe? I thought that I would have everything done in less than two months, start to finish - but that was back in the days when I thought the total cost was going to be 1200 quid! My blog is now only one day behind, I did do some work on Sun but not much - my sister's visiting from afar this coming weekend, so that probably means I won't get much done then. On top of everything else my Harley's still in bits, and the SUN IS SHINING??? What happened to all that lovely rain?? And so it goes...!!!

The design isn't quite finished, but it's costing me already! I still have to finalise my order for aluminium extrusions and plate,not to mention about 300 T-nuts and bolts, so I guess I'll be busy CADing tonight! I will post some CAD images when I've finished frantically ordering everything!

Cheers and happy building!