MDF CNC Router plans / parts for home build beginners

[Zephyr]

I'd like to say that I think this idea is brilliant and just what I needed.

I was just about to start a new thread about a newbie being in a difficult position - especially one with practically no machining experience, no previous knowledge of G-code or CNC, no machine-filled workshop and very little money to spend etc.. I include the contents here so you can see where I'm coming from.

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"I've designed a machine and think it should do what I want (machining hard-wood). It's a moving gantry type and will have a working area of X=610mm Y=900mm Z=200mm.

I don't have a workshop so I either have to pay people to make the parts for me or buy a ready-made machine or a kit.

The prices of new ready-mades are high (money is another problem of course) and none that I've seen have the Z-axis travel that I need. In short, I need a machine to make my machine.

I'd welcome any suggestions about this as I'm sure others have this problem. Would anyone want to make parts for me, does anyone have a machine for sale or know where I can get one (or a kit) at a reasonable cost?"

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I've reached pensionable age without a half-decent pension so I'm doing this because I need to earn money. I plan to make wood items and (hopefully) sell them at craft fairs around the Berwick upon Tweed area where I now live. (I'm from Nottingham so I know many of the places mentioned in posts).

The machine I want to build will eventually have to make long parts and this is why I want a large size although I could start with one smaller and then, maybe, scale it up.

My thoughts are that 1 Nm motors will be too small (for my sized machine) but I accept that using larger size 3Nm will increase the cost.

I was also thinking of using Roys drivers and BOB because they seem to be reliable and the last thing I want as a newbie is an unreliable driver problem to sort out. There are too many problems for a novice like me and I need to reduce the potential for problems. Personally I would want a driver system that would control the larger 3Nm motors.

In answer to HiltonSteve's question, I think £350 is a reasonable price to pay for something (electronics) that will probably work and not give problems but I know other people might find that price too high.

Like Wobblybootie I want something I can afford and that works.

I'm not sure about using threaded-rod for leadscrews though as I think this would produce too many accuracy problems.

I hope me throwing my 3pennorth in helps. If you want to ask anything please do. I'm filling up with enthusiasm and hope again - after getting despondent about all the complexities of this project.

I use Ubuntu GNU-Linux and also EMC2 (both free of cost) and it seems to work very well in simulation mode. I use QCAD and recommend this as a cheap yet execellent 2D package (the book that came with it was essential for a novice like me). I don't use MSWindows so any expensive Windows-only software is out.

It's good when someone with experience offers his knowledge and help to people like me with very little experience but a definite need and a lot of enthusiasm - and I appreciate this.


Sorry if this is a bit rambling. I'm normally a bit more logical than this but it is a long, exciting thread - and I think it's got wings.

Regards,


Keith.

[irving2008]

Loads wont be that high. more critical is friction. By way of example, using four 10mm W-series (2 x WS-10,500, 2 x WJ200UM-01-10, 2 x WJ200UM-01-10 LL) spaced 100mm apart on 500mm long rails 250mm apart for a gantry where the drive is central and the cutting force approx 50mm above the bearings. A 15Kg gantry accelerating at 10m/s^2 will need 200N of force to overcome friction- thats about a third of what you'll get from a 1Nm motor on a 12x3mm screw, and will be ok on wear for 15years continuous running (at a max speed of 900mm/min)!

Thats £80 approx for rails and carriages (RS prices)

[Wobblybootie]

I think the IGUS 'N' series may come out a little cheaper but I am not sure how mounting the gantry to them would work. The holes / clearance do not appear that big (well, I know what I mean)

[Robin Hewitt]

Okay, hows about put the gantry on rollers? A pair of widely spaced ball bearings at either end riunning on a steel bar glued to the base, plus one sprung roller between each pair to hold it down.

To hold it square, a similar arrangement, turned through 90 degrees and close to the screw.

Wouldn't work so good for the Y but it fixes the big axis and gets your overall cost down.

You'd need some powerful springs which would want to bend the MDF, but an iron inclusion would fix that. Goodbye friction

[mel_earp]

OK - this is from the perspective of someone who hasn't built anything, but I have read loads. When I had some time to look at my potential router, I looked up and down the cost scale of every option I could find for the slides. The cheapest of all was drawer slides, but clearly not good enough.

It seems to me that you are on the path to re-invent the skate bearing on angle solution. You can see them all over the place. Here is just one example, albeit a crude one with the skate carriages riding on round rails - er pipes actually. Most examples ride on inverted angle.

With a set of 8 bearings at a fiver or less, this is pretty cheap and low friction.

[8iggles]

Skate bearings have to be the best all round DIY solution for me, low cost, the effectiveness of them, 8mm shaft.....the tubing is a little harder to find (for free) I'm up to 38 skate bearings now with 4 more shortly on the drive reduction

Another thing that has worked well for me is the 12mm threaded rod across the table as this way only needs sides making - crude but easy to adjust and mount things from etc

Cheers Shaun

[HiltonSteve]

Right, I have been listening to what everyone is saying and after looking at the IGUS slides again I have decided to go with the Drylin N 27mm version, this is mainly for ease of assembly and they should be more than up to the job. At RS prices it will cost around the £80 mark for everything which is 12 carriages and 2m of rail, these are at RS prices so I should be able to get it cheaper after I speak to my IGUS man in the morning. This may seem expensive to some but you have to bear in mind the lack of skill and tools that will be required to get your linear rails sorted which are a very important component.

I know the skate bearing idea will work out cheaper but for a first time builder I am not so sure that it is the way to go, using the igus drylin N will make assembly so much easier and I have got a cunning plan as to how it will fit in with the design and a simple way to mount it...

Also been thinking about the leadscrews and may go for M12 trapezoidal (depending on the cost) with some simple anti-backlash plastic nuts. May cost a little more than standard M12 threaded bar but I think that the benefits will outweigh the cost.

17 size steppers should come in at around £10-£12 each so total build cost is not looking too bad.

MDF will either be 18mm or 25mm, not sure yet until I get something drawn up and see what fits best but hoping that 18mm will be good enough.

Table size looks like it will end up at 500mm x 300mm with 2 rails on the X and Y axis as this way all the linear rail will be used without any waste, the remaining 400mm can be cut in half and used for the Z.

I think at this stage I need to get the design done and get something made to see how it performs, enough talking about it, lets get something put together and see what happens. Yes there will be issues but we have to make a machine to find them, some of the issues will have to be acceptable for a low cost machine but I want to get it as good and as simple as possible for a reasonable build cost.

Drawing tonight/tomorrow so will get the designs up on here when I have something to show you all.

[pjl83]

With a set of 8 bearings at a fiver or less, this is pretty cheap and low friction.

Can I ask where you found this price? I was looking at the "piece of angle skate" option but couldn't find a price like this??

Thanks
Paul

[irving2008]

Can I ask where you found this price? I was looking at the "piece of angle skate" option but couldn't find a price like this??

Thanks
Paul

Try here... how good they are I dont know... or good old fleabay

[HiltonSteve]

Has anyone ever built any of these skate bearing linear guides and had decent results?

Just don't like the look of them but not had any experience with them either.