Small scratch build 3 axiz CNC

**bofred** · 07-03-2015

Hi all,

I will document my first CNC build here. I started this to learn about CAD, CAM and CNC carving. I am not in a hurry and it can take a while between the updates.
The parts used is mainly from the scrap yard and cheap Chinese electronics.

Machine goal: A small machine that is able to cut small aluminum parts.

**bofred** · 07-03-2015

Frame:
Mostly build of 80x80 heavy extruded aluminum rods. The linear bearings are mounted so that they are able to be adjusted in order to make things straight.

Electronics:
Motors: Used BoR NEMA 34 steppers, Flange size 86mm
Stepper controller: Wantai 80V 7A
Breakoutboard: Cheap serial port card
Computer: Old DELL with printer port
Powersupply: 80V scrapyard trafo (10-12A) with a small 24V built in. (edited)

Spindle:
None yet

Ball screws:
None Yet

**routercnc** · 08-03-2015

Looking good so far. You could use the machine to make reinforcement plates to brace the gantry (assume you don't have milling machine etc) as that profile is not as stiff as steel and it looks like you are using simple fasteners to hold it all together.

Once you get the weight of the y and z axis fitted and the spindle give the gantry a thump with a soft hammer and you will feel it vibrate. just something to think about as you progress.

**bofred** · 08-03-2015

Thank you,

I plan to make 10mm aluminum plates on the sides to fasten the Xmotor and make it more rigid. I have some friends that are building another kind of machine and I can use the same side plates they are ordering from the vendor. A plate behind the X is also under consideration.

Then I plan to reinforce the Y rods with a pair of brackets. Hopefully it will be firm enough.
The bolts are ordinary M8 and M5 for the linear bearings. But there is allot of them.

Next up is to choose what kind of ball screw Im going to use. Ill try the hammer

Originally Posted by routercnc

Looking good so far. You could use the machine to make reinforcement plates to brace the gantry (assume you don't have milling machine etc) as that profile is not as stiff as steel and it looks like you are using simple fasteners to hold it all together.

Once you get the weight of the y and z axis fitted and the spindle give the gantry a thump with a soft hammer and you will feel it vibrate. just something to think about as you progress.

**bofred** · 10-03-2015

I have started to plan how to measure and adjust the axis and I think I am able to get it fairly straight after a lot of adjustments. The frame is about 0.05 to 0.1 mm off before any adjusting. It might be different when I have all parts on the frame and tighten every thing up.

The linear bearing had a little banana shape so I straightened the first one up by clamping it to a straight surface and tightened it so it is real straight. The other side I plan to fasten after the wagon is mounted so that it will follow the one I straightened. That was a strange sentence, I'm sorry for my English..

I have also ordered three ebay 16mm diameter ball screws with bearings. Now the fun part begins

**GEOFFREY** · 11-03-2015

That looks nice and tidy. Don't worry about your English, it is pretty good and I am sure that is a thousand times better than most forum members Swedish. G.

**bofred** · 13-03-2015

Thank you Geoffrey. Its good practice and as long as I'm being understood I'm happy:) Min svenska är lite bättre dock ;)

**T0rnado69** · 14-03-2015

Originally Posted by bofred

Min svenska är lite bättre dock ;)

what he said........

what ever that means

looking good and keep the updates coming :)

**routercnc** · 14-03-2015

Min svenska är lite bättre dock - ‎My Swedish is a bit better though
(thank you google translator!)

Now I can see the side view of the gantry the lower gantry beam is actually supported underneath as well as at the rear - should be better than I originally thought from the first photo.

Once you get the side plates added it will be a nice machine. But before you do I would add kiln dried sand to the gantry beams to add weight and provide damping. As this is a fixed gantry machine there is absolutely nothing to loose and it will help with the finish of the cut. Add one end plate, turn the machine on its side and fill to the top with sand, then add the second plate.

On the electrical side - and I'm not an electronics expert so I might be worrying over nothing - is it good practise to put the stepper driver right over the top of the transformer coil (trafo in swedish)? Is there a risk of electrical interference?

**bofred** · 16-03-2015

Yes, google translate is spot on:)

And thank you for all feedback. I really need feedback since this is my first CNC.
The sand filled beams sounds nice. Problem is that I have so many holes to plug. The lower Xbeam has a total of 26 holes in it. 8 on each side to fasten it to the Zbeam and 10 for the linear bearing screws. I once had loudspeaker with sand filled stands and that worked really good.
I'm a bit worried that the Z moving part becomes weak but that is a later problem.

The electric cabinet could be as you say a bit noisy. Thank you. When I made it I figured the drivers had grounded houses and the "ring trafo" should not radiate that much magnetic fields. But I have the break out board unprotected and I don't know how sensible it is. I am able to fit a plate between the trafo and the drivers if I need. I planning on having shielded cables for the motors but the "on to the break out board cable" from the PC is unknown (cheap cable).

Here is a short video clip of when I test ran the motors. The wantai driver seems to have plenty of power. Cheers!

http://www.br-automation.com/downloa...MASMOT-ENG.pdf