Sturdy and Fast all Steel CNC , my first build

[Boyan Silyavski]

Would it be possible to lock one lead screw and put a dial gauge on the other side and measure how much (little) it can be moved?

As Geoffrey said, a purposeful looking piece of kit - very nice :-)

Interesting. I will do that tomorrow and report back. The gantry will not deflect for sure :-).

silyavski very good work and very helpfull thread.
I am planing a machine a little bit bigger than yours (X:1500mm Y:750mm Z:130mm real travel).
I have been inspired by your plans for my machine frame.
I have some questions about what i see.

1. How did your succeed to have Z axis rails in the same plane? Did you use epoxy, or did you mill the 6mm plates?

The Z axis rails are in the same plane for 2 reasons:
1. When i mounted the bearing blocks first, i checked the plate with straight edge. luckily it was almost straight. Some hits with big rubber mallet made it perfect.
2. Now having achieved to mount them on a plane surface, using precision square i squared 1 raw of them and tightened them. The rails were in the bearing blocks but not attached to anything else. cause when you measure long things, its easier to detect any error.Then using digital caliper i measured 150mm, tightened the bolt on the caliper and from both sides made sure the distance is the same . Tightened a bit, then with the digital caliper made sure its parallel to 0.01mm. Little bumps with small plastic hammer helped. Then tightened it finally.

2. Why you use 2x6mm plates instead of one plate 12mm?

I did not want to wast more time. That's what they had at hand at the metal shop. Luckily, cause they were not perfectly flat, so it took a lot of hammering to flatten them against straight edge.

3. What clamping system are you going to use?

Its up to my friend. On my small machine i have cast aluminum grind flat plate. With a lot of tapped holes. On top of it i mount 10mm hard plastic sheet using bolts at the corners and very very thin double sided glue sheet, the ones they use in photography printing to mount photos to lexan support. I Hot melt glue all jobs. When finished, i use alcohol to un glue the detail.

But with a strong and fast machine that will not always be possible. I know your doubt. I have it for my next machine and still not decided. My best bet will be to use plastic bed. I have to make some visits to the junkyard or an recycling center. And on top of it 5mm expanded PVC . However i plan to invest some money and maybe use steel channel , like a mill, but not on all the bed, just at the nearest side, so to say for fine jobs.

So that's my suggestion. Make 2 areas/ or 3 areas as i will do but my machine will be 3m long and 1.5 wide/ . One with a proper aluminum or steel bed and the other plastic.

Cause MDF will constantly need surfacing, i believe investment here will pay very fast in the future.

Vacuum i am not planning to use. The strength of vacuum is if you have production which is repeatable, or you work with sheets only. However in the future if needed you can make some removable vacuum fixtures.

4. What is the clearance from the lower part of z axis to the cutting surface. Also what is the real traver for your z axis.

260mm and real travel of 215mm

Now, careful cause this is still unconfirmed info and just a point of view. Its just what months of mind games told me. As i said it many times in the forum, cause that's my view for a DIY really multitask machine, i seem to find that the Z to bed/ frame without anything else/ 250-260mm is perfect. With the trade off that when alu sheet is routed it had to be risen another 100mm at least, using MDF, wooden or so, ribbed or solid, removable bed or fixture.

Below is how my z plate ended. As you see the solid bars combined with the rails reinforce the plate and is very doubtful it will bend, think of bending a solid steel bar ~50mm thick and at least 50mm wide, 500mm long. Another pint here is that i use 2 spindle mounts separated at spindle both ends. So the mounts and the spindle further reinforce the thing. No it will not bend in any way.

5. Finally what is the horizontal distance ( from left to right ) for y,z axis carriages and the vertical distance ( from bottom to top) for y and z axis carriages ( outer side of carriages)?
Thanks for you time
Vagelis

What i believe is the absolute minimum for a good strong machine- 240mm for the Z Spacing left right



The vertical is my minimum for such a long Z plate. The width of 150mm is the minial as i see it , again having in mind the length




Hope that helps.




Vagelis, something else.

I have been following your build with great interest, please let me tell you something. This also to the other people that aspire to build a machine. You will need to spend at least 100eur on the following things if you don't have them, to be able to accomplish the precision mounting successfully. They are a MUST. I don't see how it can be done without them and especially by one person.
Believe me on this. Not to mention the satisfaction you will feel when all is mounted precisely.


-1m straight edge or longer.Stainless better

The Must here is to be at least long enough that it can lay on both parallel mounted rails that the gantry slides on. In other words wide as your machine. Without this you will run at the moment of mounting and later at countless problems. The best will be if it has length of the diagonal of the bed or at least of the rail.

Many will disagree but Rectangular section is better than knifed edge, especially if you work alone. Much more cheaper also.

Here is my initial experience with links from where to buy. http://www.mycncuk.com/threads/6546-...o-straight-%29
To summarize it DIN 874 is the magic word. Whatever accuracy. Or Din 866 rule, especially if you go bigger machine build. Like my next one. You guessed right, i will buy at least 2 meter one.

-2x 30cm precision squares . Din 875 is the word here. these will help solder , square the gantry, the gantry to the bed, etc. Yes, 2 of them because many times you will clamp them together in clever ways.


-1x <10cm precision square , Din 875 is the word here. Stainless betterfor the tight fits, squaring the spindle, etc.

-2x cheap chinese squares

Once you have bought a really cool reference square, you go with it to the shop and buy cheap squares to use for soldering and damaging jobs. Once you reference them against the good one.