Am I being silly?

[AndyUK]

It just isn't going to happen. I need to find a easier route or just not bother.

Then you need to be looking at purchasing a solution. Although even those will require you to put some effort in to diagnosing and troubleshooting problems along the way.

[brman]

I won't criticise anybody for doing their best to make something work.I started with an MDF machine and drawer runners,which gradually got changed to SBR12 rails.I also use a much derided breakout board off a parallel port running LinuxCNC and it has never let me down.The crux of the matter is that we have the freedom to build with materials we are comfortable with and running software of our choice.If it doesn't meet our hopes,then clearly we made at least one wrong choice-at which point we get to decide what we do about it.

Thanks, yes, I have read enough to know what are the "best" ways of do things but "best" is not necessary most suitable for me at the moment. In my mind it is a compromise between making enough wrong decisions to learn and not making so many I give up

That one statement right there is why you should give up right now.!

If you don't have the budget to buy one and you don't the time or inclination to build one then just call it a day and save your money for when you do. If you proceed then it's highly likely you'll just blow money or as often the case when taken on half-hearted you'll fail and give it up.

I can see why you said that but I think we have different priorities. I see nothing wrong with experimenting for experimentations sake, even if it is not the "best" or conventional way of doing it.
Plus, there is no such thing as failure in my view. If I did nothing that would be a failure as I would have learnt nothing. If I do something and it does not perform as I hoped then fine, there is no failure there as the success is in the learning.

Then you need to be looking at purchasing a solution. Although even those will require you to put some effort in to diagnosing and troubleshooting problems along the way.

As above, I guess I should have made it clearer why I am doing this. It is not just to get a machine that makes parts I want. If that was the case I would just take my cad models to a cnc prototyping place and pay them. It would probably work out cheaper in the end! Lastly, time wise, I am not saying I don't have the time to tinker and fix things, just that I have to take that into account overall. ie. there is no point me spending all my available time making the best steel frame in the world but not having the time to sort the drives/control etc.

This might all sound like I am trying to justify to myself ignoring the good advice here. I am not, honest! I am still concerned about the effort of making a square and flat steel frame though, so I think I might need to consider ally extrusion again. Something for me to think about anyway. If I go that route then the choice between supported rod and profile rail is mainly one of cost vs performance.

Which I think leaves the other question. Fixed gantry, is that the right way to go for a small machine like this?

[ericks]

When i built my latest machine i used aluminium extrusion. However i had a reasonable budget so i used heavy duty extrusion. It's a moving gantry design but i have no problem with a fixed gantry type. Although my machine is made from extrusion it is very rigid, i machine aluminium very easily and also do steel plate on it. Although i prefer not machining steel cause of the mess it makes.

[brman]

When i built my latest machine i used aluminium extrusion. However i had a reasonable budget so i used heavy duty extrusion. It's a moving gantry design but i have no problem with a fixed gantry type. Although my machine is made from extrusion it is very rigid, i machine aluminium very easily and also do steel plate on it. Although i prefer not machining steel cause of the mess it makes.

Thanks ericks, do you have photos of the machine or a build diary?

[ericks]

Not latest cause i am constantly adding stuff, but this was taken a while back when i was busy adding a bit of guarding over the ball screws...I did do a few things on this build that i would change on the next one. My experience is more on panel building rather than machine building :)
I started by first building a steel stand.

[brman]

Thanks, that does look like a very nice, solid machine.

[ericks]

Thanks, yes it's heavy and rigid. There was opportunity to make it even more rigid but i found it is good for what i need atm. There are so many options re machine designs. My next one will look much different to this one. All the best with your journey :)

[brman]

Thanks, I am curious how you joined the extrusions. For my 3d printer I tapped the ends of of the exrusion and used bolts to clamp them together. I then braced the corners with plates underneath. Like this....

but I was never very happy with this. Ok for a 3d printer but pretty easy to pull the joint apart as it clamps only to the thin wall of the extrusion.

[ericks]

This is the best pic i have atm showing the connectors

[JAZZCNC]

I can see why you said that but I think we have different priorities. I see nothing wrong with experimenting for experimentations sake, even if it is not the "best" or conventional way of doing it.
Plus, there is no such thing as failure in my view. If I did nothing that would be a failure as I would have learnt nothing. If I do something and it does not perform as I hoped then fine, there is no failure there as the success is in the learning.

I try to help people avoid problems they cannot see by using all my experience of building machines and helping 100's no 1000's of people over 15yrs+ who have taken similar routes and nearly gave up due to either poor design and build frustrations or woeful under budgeting. You gave a Budget of £500 so all my advice was based on this. You also proposed design material that is neither cheap or suitable for a successful machine.!

I understand the experimenting for experimentation's sake I do it every week in some way or another. But what I don't understand is why to do it when you are being advised by an experienced builder that there are better ways which won't cost any more money and in fact, will probably cost less.? All it would take is to experiment with a Welder.?

I also don't understand why anyone would join a forum seeking advice then ignore it.? Also, don't get why someone would seek to build a machine but state they have no time or inclination to build one.? . . . This seems to me you just like wasting people's time so you'll get no more from me I'm afraid. Good luck.!!