A slighly iffy Rockcliffe machine...

I felt it was only fair to post some pics of my machine. Having had the bits quietly rusting in the kitchen for some months I had a sudden motivation rush and hacked it together over a weekend and it never occurred to me that it would be worth photographing the process so apologies for the lack of 'in-progress' pics.

I bought the linear components from Marchant Dice - standard 16mm bearings and blocks. 12mm ACME screw and nut. The stepper motors/drives and psu are from Motion Control Products.

My intention was to 'knock' this machine together quickly and cheerfully to play with then move the linear components over to another better machine when I had a better idea of what I wanted.
With that in mind I cut out the wooden parts and bolted the linear components onto them inside a couple of hours - I'd no intention of painting them or doing anything fancy.
I decided to simply cut the holes for the slides a tight fit and make them in pairs so that there was no need to use Rocklciffes 'end plate' (which makes final adjustment easier) if I'd thought on I could've made the parts slightly wider to give me an extra 36mm movement.
I then spent a day or so machining the ends of the screws, making the stepper/bearing mounts and the ACME nut holders (shown below). I didn't want to support the screw using the steppers bearing (again my intention was to move all this to a 'better' machine) so my stepper mount holds a pair of bearings back to back to take the load.
Finally I roughly bolted it all together, hacked the wiring, sellotaped a pen to it for testing (first pic) and tried writing 'Hello World'.

Although my idea was to re-use the parts in practise this didn't turn out to be as useful as I'd imagined. Now I know what I want my next machine will have a moving gantry, be much bigger and probably use ball screws and HiWin bearings. However I priced up the relevant parts and got to £1500 just for the linear components - so I'm now temporarily on plan B.

Plan B is to remake the machine using some aluminium plate for the xz axis. Use the extra 36mm on the XY axis. Move the bearings inboard a bit on the Y axis and allow the table to overhang the front and rear of the machine. At the moment the table range is around 13 by 12 inches. I think I can improve this to 14.5 by 19.5 without changing the linear components.
Hopefully I'll make a 'nicer' job of this machine and document it's construction...

Things I learned:-

No matter how big the cutting area it won't be big enough.
Watching a CNC machine is better than watching the tele.
A decent stepper and screw have no problems destroying an MDF machine if it jams.
Fit limit switches (see above).
Fit limit switches (seriously).
Just do it, the first machine is a learning experience - you'll want to build another.

Looking good, i am going to start making a flying gantry machine based on the Rockcliffe design.
I got the plans, and i am changing them to make a 1000x1000mm work area with proper guided rails.
Will be made off Ally so should be very rigid.
With all that metal, will most likely cost a bit, but when i start i will also put some pics up as well.

Wow your machine looks really nice ! "iffy" ?

Nice job on the motor mounts, i plan to do somthing like these for my machine. I was thinking about using Delrin to make them for my first machine, however ali would be much nicer !

Regards,
CM

Quote:

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Originally Posted by CheekieMonkies

Wow your machine looks really nice ! "iffy" ?

Nice job on the motor mounts, i plan to do somthing like these for my machine. I was thinking about using Delrin to make them for my first machine, however ali would be much nicer !

Regards,
CM

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Hi - by iffy I mean a bit rough round the edges and unfinished... It was just a rough job, although by using a couple of simple jigs to ensure holes were square and parallel it did mean I didn't need the end plates and the whole thing is accurate to around a thou (obviously ignoring sag, load deflections etc). MDF may be 'industrial cardboard' but it's amazing how accurately you can machine it.

I should think the Delrin would be fine - I used ali because that's what I had. This is my 3rd attempt at building a CNC machine - the first two reached various degrees of completion before dissatisfaction caused me to take them apart again.
I think it's possible to get too precious:- "is this the right material?", "will this be stiff enough?" etc etc. Hence my 'just do it' comment.
If I'd designed the Rockcliffe machine myself I think I'd have given up on it long before completing it for all the same reasons, however the simplicity of the design and the fact that people are already out there using them meant I could just ignore my misgivings and try it.
It's not the stiffest machine in the world, but just like the real world you simply compensate by taking smaller cuts. After all you wouldn't expect an X3 to cut like a Bridgeport...

Now it's built and in use I reckon in the past I've been way too precious, I'd happily build machines now using drawer slides, skate bearings etc. Reading various forums most people are simply too finicky and they're not helped by the 'money's no object' groups who rubbish any design not using 'brand x' linear bearings and 2" thick ali plate at some astronomical cost.

Good luck with your build anyway! You're only a few miles up/down the motorway so if you need any help...

Well to be honest with you I’m only couplers off having everything I need, I’m sure you’ve looked at my build log by now. I’ve done a bit more since then but I’ve had to do other things, I’m really getting pea’d off now because I want to start using my machine. The point I’m at is making the drive nuts from delrin I have the delrin, I have the taps I just don’t have a bench drill or a proper setup I can use to get them right the first time. I was going to ask you if you would be so kind as to drill and tap them for me in my last post, then I just thought no your being silly you can do it yourself with the hand drill but the fact is I’m putting off doing anymore because I want to get it done right and as well as the rest of the parts I’ve made. At the start I did have a bench drill however it was my father in-laws and he’s since taken it back.

If you do/have seen my build log you will see what I’m talking about when I say “perfectionist” I’m just putting off doing anymore to it until I can use the right tools and get everything spot on like I have done so far, I don’t have a “workshop” I’m using a brick out house. loll it doesn’t even have work bench’s everything I do I have to do on a workmate !

I will crack on though I think I may have to nip down to B’n’Q and get myself one of the £40 Bench drills some time in the week, don’t know if the bus driver will like me getting on the bus with it ! loll Sounds a bit sad and desperate but that’s my situation at the moment, I’m not working right now ether so money is somewhat non nonexistent right now but ill come out the other side with a working machine that can help me to make the items I hopefully will be selling and earning a living from.

Small steps as someone once said to me, I would defiantly be up for meeting up/coming to yours and seeing a working machine and all that, so ill leave it with you !

Right that’s enough of the tears I’ve got stuff to be getting on with.

Kind Regards,
CM

Quote:

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Originally Posted by CheekieMonkies

Well to be honest with you
{snip}

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There's no problem if you want to come up and have a look at mine, we can tap your Delrin too if you like. Sadly I'm working (money or time but not both eh?) so weekends are best for me. Sounds like your car'less so we can sort something out if you like (just pm me).

Your machine looks great - all the more so for the lack of workshop facilities! Very impressive. How are you going to couple the stepper motor to the rod? If it's a rigid coupler we could knock some out pretty quickly...

I'm pretty lucky in that I have the machines. What I don't have is the space - I need to rationalise my workshop a bit. At the moment my CNC machine is hogging my workbench, I'm going to have to get rid of my router table in order to have somewhere to put the MKII. I should be starting on the MKII in a few weeks when we start cutting up material for a friend of mine who's also building one - may as well try and do all the cutting in one go...

Regards
Steve.

Steve any chance you can re-attach your pics to your original post, another member has reported this to me.

I will also get back to your above post soon mate, hows things?

Sorry guys, I've looked but it doesn't look like I have those shots anymore.

Found these:

This is a rockcliff machine !

Cant find any other sorry.