[cyberkeith]

Hi everyone!

I am going to start my first CNC build project. I have wanted to do this for several years.
I have been reading on this forum for a long time and thank you to CNCzone and everyone here for all the information they have been sharing.

Parts have started to arrive this week and I am started to look towards the build start.
So far the Rails are all: SBR20's 1000mm 800mm and 340mm.

stepper motors are from Kelinginc... very fast shipping!
I ordered 2 of the KL23H2100-30-4BM 495oz dual shaft
and 2 KL23H276-30-8B 282 oz dual shaft motors.

drivers are the M542 for the 282 oz and I ordered two m982's for the larger motors.


I plan to use and have a solid aluminum plate for the gantry which is 3/4 thick and 36 x 8 inches.

I will post some photos as things get going, and will have many questions to ask.

thanks to everyone again,

Keith

[PaulRowntree]

Hi Keith! Congratulations for taking the plunge! Do you have working sketches to share before you start cutting pieces?

Cheers!
pr

[JerryBurks]

Sounds like a plan!

Without knowing more about the design, I would re-consider the massive aluminum plate. It would surely do the job but large cross-section square tubing of reasonable wall thickness would cost and weigh less and be more rigid.

A solid plate, even 3/4" thick dos not have that much bending and torsion stiffness. The further away you place the material from the axis of the beam the stiffer it gets. If you want to do a numerical comparison of shapes, the formulas are out there on the web.

[Mr.ChronoM]

This can be very interesting, I recently started build a machine with the same dimensions. The topic is also on this forum. I'll keep following progress for sure

[cyberkeith]

I have some drawings, but need to convert them to Auto-cad or something on the computer.
JerryBurks- I will consider the info on the 3/4 inch plate... I am planing to reinforce it in a design that has the rails rotated 180 degrees from each other, hard to describe... so I will work on getting the design posted here.
it would be far easier to change now before the drilling starts.

That is why I am here, to help avoid mistakes and to share ideas.

Hi- Mr ChronoM.. I saw you design and will follow your build also, great work so far!

I have ordered the 8020 for other parts and some more aluminum for mounts and supports.

I plan on using this in my wood shop. the size was driven by the things I build, although I am planning on adding not just a router, but do some simple laser engraving and maybe even playing with a 3d printer head.
I would have made it bigger but, budget and wanting to do small things cut it down.

I will get some pictures up soon!
Thanks everyone
Keith

[cyberkeith]

Some of the parts so far...
Rails SBR20 1000mm, 800mm and 342mm
Motors 495oz and 285 oz
Aluminum flat bar 6 x 36

Mainly testing my picture upload ability.

[Mr.ChronoM]

Nice looking parts so far, rails look very similar to mine

[aarggh]

Good luck with your build Keith! I get what you mean about 180 degrees for the rails, that's good, but as has been pointed out, thicker material on it's own isn't always the best solution. In some cases it can actually go against you. For example on my import machine, the walls are only 1/2" thick, doesn't sound much, but they have a lot of reinforcing to stop any flexing in any direction. This is important to consider for the sharp changes in direction where momentum can want to twist or "rack" the gantry, Or when it's under load doing a heavy cut and the Z axis wants to twist up and sideways, etc, etc. I can tell you my machine doesn't have any measurable flex at all no matter what i've thrown at it.

I'd go 12mm thick myself, and then use lots of solid bracing. 19-20mm thick means lots of inertia to overcome which can limit your speed, and also really stress the construction.

cheers,
Ian

[cyberkeith]

The 8020 arrived yesterday, surprised how beefy this stuff is, I have 80 x 80, 40 x 80 and 20 x 20.
I see why so many machines are made from this!

Also 2 of the 2m542 drivers and a stop switch.

Have been learning to use google Sketchup the last couple of day and slowly importing my parts into a file to work on the final design.

Lots of learning still to do for me!

[cyberkeith]

Thank you aarggh
I am working on this issue and will be adding cross-members. The span is only 34" with a cutting area on the Y of 26", so I am wondering if the weight should be ok for the 495 oz motors. 8020 would weigh less for the span.
K.

[louieatienza]

Nice stuff! I don't believe 3/4" aluminum is necessarily "weak" especially with your linear rail supports bolted to it. Also depending on your setup, I don't think a 495in-oz stepper is necessarily too weak to get it moving, less so if you're using a dual stepper on that axis. Of course there are advantages and diadvantages to building your gantry bridge out of solid plate or an extrusion of some kind.

I'd say it's far easier to over-estimate the stepper size needed or over-build where not necessary.

[cyberkeith]

This is my basic first design for the Z-axis with the parts I plan on using.

I would love some comments before the drilling starts

The front plate is 6" x 4.5" 1/2 thick, and a router plate will mount onto this with a DeWalt 618 to start. I plan on changing to a 2.2 kw spindle latter.

The back Carriage plate is 3/4

The spacing right now on the rails is at 4" on center, which puts the outside edges right at the 6" mark.

Thanks everyone!

Still learning google Sketchup, this is a basic download from their site and I changed the measurements and rails to what I am using. Not completely my work yet.

[PaulRowntree]

Would you be able to extend the top & bottom plates out to the sides by a few mm to allow you to put sides on the stationary frame? It would stiffen it enormously.

Do you have a coupler between the stepper and the acme? It would reduce the stresses on the motor bearings and increase the life of the motor.

How do you plan to fine adjust the orientation of the spindle during tramming?


Cheers!
pr

[cyberkeith]

Yes Paul,

I will try extending the plates and add some side support
I will be using a coupler between the motor and lead.
For the tram adjustment I was thinking of using set-screws in the router mounting plate.

Keith

[cyberkeith]

Changed slightly from previous post, added sides.
Keith

[cyberkeith]

working on plans for the gantry build

[cyberkeith]

Working on the layout for the CNC controls. Using a case from old test equipment, sonet test set.
I will put the power supply in another case.
You can see how much larger the 2m982 stepper drivers are over the 2m542.
I am using a very small BOB that should work with mach3, and I am going the leave room in the design to upgrade to another breakout board.
Fans will draw air in from the bottom front and exit bottom back.
All drivers will be fused.

[cyberkeith]

Most of the design now in the computer.
I just need to add the dual lead screws on the x-axis and some cross members in the table frame along with the Underside of the Y-axis tie bar.
pretty basic in design, anyone see any major flaws?
Thanks, Keith

[CarveOne]

Most of the design now in the computer.
I just need to add the dual lead screws on the x-axis and some cross members in the table frame along with the Underside of the Y-axis tie bar.
pretty basic in design, anyone see any major flaws?
Thanks, Keith

It will help to have another cross member or two in the middle because the plunge loads will make the table top bow downward a little in the middle if there is no support under it. Even two layers of MDF will bow when an end mill is not ramped into the project being cut. You don't always have room to ramp the cuts sufficiently.

[cyberkeith]

Power supply to get me by....
I have used parts from a lambda power supply, an old inverter and now have a basic 40 volt 12 amp supply. Need to add a bleed resistor yet, but this should get things running when ready.