build 2nd prototype Zoltar CNC 2012

[gait]

  All,

I was able to buy spare parts of the CNC 2012 machine from Chris, to build a 2nd prototype. A few parts were missing and had to be made. I was happy to have a colleague who's neighbour is working for a company doing laser cutting steal parts. He took care to make those to complete the kit.

The best of this kit is that the portal and the standers were already glued together. Furthermore  the portal structure contains two square parts so the it is more rigid to hold the weight of the Kress miller. To start I intend to use it with the proxxon miller so there is no direct need for it.

Chris advised me to buy the ball screw drives directly via E-bay and I did so. He supplied me with the drawings and I ordered them half of December. Within a week I received the spindles at home! all of this for a very reasonable price: â,¬ 165,00 ( I just got a tax receipt of â,¬ 10).



After collecting the parts just before Christmas I started assembly of the machine.

First clean the spindles:



Damn! what a lot of dirt was on it. Furthermore the t-nuts were not mounted on 3 of the 4 axis, as indicated on the drawing. The machining of the ball screw drives was good. The ends to fit the bearings needed a small sanding. I'm happy with the ball screw drives for this price!

To turn the t-nut on the screw drives I needed to unscrew from the spindle. I did so in a plastic bag to keep the balls together and don't lose one on the floor..

After that the t-nut was cleaned inside and I used a syringe with needle 0.9 to inject a small amount of grease into it. Shimano has very nice grease to lubricate the wheel axes and I used it for this purpose. There are 16 balls in each turn of the nut and the grease takes care that the balls do stick in place. Now I screw the spindle into the nut and hold fingers crossed that every single ball will stay in in its turn. Apparently I didn't succeed, after the machine made its first test run one of the axis was giving a terrible noise possibly because of a ball that was out of its own turn. So I cleaned the t-nut again and placed the balls again. I made a little tube of paper by rolling it up and shift it inside in the nut. Carefully unrolled it a little so the balls were forced to stay in place and then screw the spindle into the t-nut. That went well. With my battery operated drilling machine on the spindle I tried the rolling of the t-nut over the spindle. It was running fine, no strange noises or heavy resistance felt.

Next: some mechanical work to do.

[gait]

We continue with mounting the ball screw spindle in the Z-ax.
The step described here is repeated for all axis. To mount the T-Nut in the steel plates, you need to enlarge the  holes a little bit. They are slightly smaller (0.2mm) than the T-nut because of the laser cutting. The holes include also small pegs to adapt the igus ballscrews. For my machine I had to remove the pegs by filing. It is easy to do, but watch the size of your T-Nut!



On the left 3 of the 4 pegs are removed, only 1 to go. At the right the plate as delivered. You need to file the hole to fit the length and with of the t-nut.

Fitting the T-Nut for the Z-ax:



On the next picture you can see the assembly of the ball screw spindles with the nut for the Y-ax:



The nut is mechanically secured by the top plate and 4 screws on the frame of the Y-ax carriage. This solution is used on all axis. 

The two X-as t-nuts are placed in the lower part of the portal and will be placed later in the assembly process.

[OldRaven]

Looking good!

Great price on the spindels..  is that for all the spindles you need for the machiene including the nuts?

[gait]

@ Oldraven,

The price mentioned for the ballscrew spindles included all, so 4 machined spindles 1204 and 4 t-nuts.
It is an amazing price compared to ordering in Europe!
The machine run last Tuesday the first set of formers for an Guppy Mk2 elektro glider. You can see the results in the Dutch Mbf thread.
An update in zoltar forum will come soon.

regards,

Gerhard

[gait]

Next step is the assembly of the ball screw spindles for the X-ax. They will be mounted in the standers which together with the table top forms the basic frame of the machine. This is done only to see if all fits perfectly, after the gantry is put in place on he basic frame they will finally be assembled.



At the top the completely assembled stander. Below the parts needed: left and right frame, 2 ball screws at the end of the spindle. At the motor side we have 1 ball bearing, the pulley, ax coupler a distance part to mount the motor on the frame and the motor itself with an adapter to fit a Nema 17 to a Nema 23. Because I'm using a Nema 17 motor, as is used for the popular reprap 3d printers, I also had to fit an ax adapter on the stepper motor from 5 to 10 mm to fit the ax coupling.
The ball bearings are fit in between metal parts who are secured by screws and tighten to the frame. A simple construction but effective solution.

For the table top you have the choice of different solutions: an aluminum tabletop with slots, or a MDF tabletop. I decided for the last option and use a 22 mm MDF plate, 600 x 385 mm.
The MDF was prepared with polyurethane paint to lock the surface for any liquids so you use cooling liquids in case you want mill aluminium or bras.

The assembly of the table top with the side frames is easy to do: Clamp one side to the frame and drill the holes in the table top. The frame contains slits to fit the screw and you can adjust the frames, so they are parallel to each other. I measured the distance between the left and right frame so they were parallel and 3 screws were mounted at each side to hold the table top. Don't tighten them so we can move them aside if needed if we mount the gantry to the basic frame.

Now comes a tricky part: we have to mount the portal on the basic frame.



The machine on the workbench, note that the gantry was mounted allready.

First we have to take care that the X-ax spindles are removed. Then turn the basic frame upside down on the workbench supported by two wooden beams, see picture. The ball bearing support on the top the gantry is removed so the ball bearings of the bottom side can slide over the underside of the frame. Next step is bring the gantry over the feet of the x-ax frame and let the ball bearings run over the frame. If needed you can adjust the x-frames to fit the width of the gantry and try to shift the gantry over the support from one to the other side. It runs smoothly and I tighten the screws to the table top. Now the ball bearings at the upper sliders are mounted to the gantry. Again I tried the movement of the gantry to find out if it still was running smoothly. It did . If it doesn't you have to adjust the width of the table.



The result of previous steps: it is starting to look like a CNC machine!

Now it is time to mount the ball screws for the x-ax, the pulley for the synchronization of the x-axes and fit the t-nuts in the slots of the gantry. This synchronization is needed in case that one motor looses steps or doesn't run at all. It prevents the gantry from distortion on the x-ax.

Mounting the t-nuts into the lower part of the gantry went easy, all fit well. The tooth belt and pulley's have to be assembled before the ball bearing at the motor end is fitted into its holder. Otherwise you don't have any space to install the belt. In this step I also took care of positions of the hexagonal screw in the pulleys so that they are reachable at the same time, to tighten or loose.

The ball screws were fit in the holder and tighten to the frame. Job done so far for the x-ax.



here you can see the ball bearing of the x-ax at the motor side, the tooth belt and the protective shield for the tooth belt.
If the motors are attached to the x-axes and the pulleys are tighten to the axes we mount the protective shield to the frame.
A ball bearing will be mounted in the protective shield to set the tension of the tooth belt.

Next step is to mount the Z-ax on the gantry and the y-ax spindle.

To mount the z-ax support on the gantry I had to remove the green HDPE  slider blocks of the bottom. In these blocks 2 ball bearings are mounted who slide over the Y-rails the z-ax was already completely assembled in an earlier step. So we position the z-ax support on the y-rails. Next step is remounting the ball bearings on the bottom side and adjust the tolerance on the y-rails by gently tightening the 4 hexagonal screws in the upper and bottom slider blocks:



I tried to slide the z-ax support over the y-ax and this runs smoothly by hand.

Second step to do is mounting the y-ax spindle and t-nut.
This is easy to do, everything is open for assembly and I could easily put the ball screw in place and fit the t-nut.



This picture shows the fully assembled spindle for the y-ax. You can also see that the motor coupler is mounted. The ax-coupler is 30 mm long and has an inner diameter of 10 mm to fit the motor and spindle. Due to the use of Nema 17 motors I needed to fit a 5 to 10 mm adapter on the motor ax.

So that is all to do with the mechanics so far. Next thing to do is the mounting of the motors and test run the machine!

[OldRaven]

Looking good!

What controller do you plan to use?
Why did you pick nema 17 and not nema 23 steppers?

Peter

[gait]

Peter,

I'm using Nema 17 motors of 0.45Nm. These are populair in the build of 3d printers (reprap) Since I use these motors also for my foamcutting I'd loved to use them for this purpose as well: the same contoller etc. The update of this post doesn't follow the actual build. On the mbf is the actual status of the build and i'm translating the information from there into this forum.

The controller used is the Zoltar bie1900 controller with cnc-usb software.
The Nema 17 motors are performing very well so far. I have a feed of 400mm/min with 3 mm plywood,and a 1.9 mm end mill, without problems.
With the current proxxon spindle it is no option to go any higher(maybe also with respect to the limit of the end mill?), my proxxon spindle is at the end of its lifetime, after almost 20 years. I've ordered a Kress 800 fme spindle instead.

First results are very promising:



So far I've had a very nice experience in the assembly of the machine and starting up first tests to see how it is working. Besides that the inspiring talks with Chris learns that I have found a new challenges in building / constructing model airplanes by using cad cam. Lots of ideas are popping up and still have to work. So limited time is available to learn all these nice things !

Br,

Gerhard

[Chris@home]

Looking good Gerhard,

Next to the inspiring effect CNC machines have onto our hobby(s),
its also pretty addictive!
Be aware of this side effect ....
                         
            Your life will never be the same....

As for the time needed to learn actual cutting parts:
You are pretty quick so far.
But there is still a whole future ahead to learn even more.

Take the time and enjoy the journey!

-chris-

[cwoffenden]

This has been great to watch and I'm looking forward to starting mine! One small correction on something Chris said:

Your life will never be the same....

As a hobby it's so time consuming and addictive, your wife will never be the same... Yes, I spend too much time with my toys.

Carl

[Chris@home]

No problem, all fine here, as long as the dust & chips are kept far away, outside the house.

Brass chips have proven to be a real dealbreaker

Just keep that in mind.....

-chris-

[rikvancoolwijk]

You'll have to prove that your machine is an essential tool for her from time to time, by making something nice for the home 
look at the nameplates topic or the Christmas decoration form Peter(Oldraven). Afther that she’ll come with hare own ideas.
If you want that is another question

Rik

[gait]

Rik,

I wonder if my wife will come up with ideas to make on this machine. Although some small furniture and a doll house would be loved by her. I didn't tell her yet what the possibilities are. Just discovering my self!

Meanwhile I produced a nice set of formers for the fuselage of an electro glider "Thermy" see FMT October/November 2012.
The Kress mounted in the meantime on the zoltar performed very well and was less noisy as my proxxon spindel.

Just have to finish my build log here, the machine is now working and I'm the proud owner of it! Happy to start the many projects to come. Now first learning the use of CAD software and conversion to g-code.

Gerhard

[smarivoet]

Happy to start the many projects to come. Now first learning the use of CAD software and conversion to g-code.

know the feeling :-) same here...
yesterday I had once again some time to explorer autocad again. And I made a first exercise from scratch... I guess that starting simple and advancing towards a complex design is the only solution for us 

[gait]

All axes do have end- or ref switches. I mounted proximity switches 12 V. These are supported by the Zoltar Bie 1900 controller. It is possible to mount mechanical switches, or proximity swiches of 5 or 12 V as reference or max. switches.

I ordered mine by stappenmotor.nl



Above picture shows the proximity switches mounted for Y-ref and Y-max, at the back of the frame.



And at the front...

Please take in mind that the distance between the proximity switch and the activating metal should be within 2 mm. You also have to think about not less that 0.5mm otherwise the switch will be destroyed at your first test run. The adjustment to the proper distance was carried out by using a wooden stirring rod( roerhoutje), between the activator and the switch and then adjust the nuts to fit the distance.



As well as for the Z-Ax.

The stepper motors are mounted and shielded cable is used for wiring. The 4 pole connectors mounted, can directly be attached to the controller board.The motors mounted are the same as used on 3D printers. Specification: U=3,1V I=2,5A 200 steps/rev holding torque: 48 Ncm.



mounting of the X-ax motor and wiring. I used to glue a small box to the motor. Inside the box I made the soldered connections to the extended shielded wiring.

The cabeling of the proximity switches is 6 meters long, these will be cut afterwards to the right length.
All connected to the controller board, which I build in a nice stainless steel cabinet of Zoltar. I used a 24 V/120 W industrial switching power supply for the board.

Let's see if the portal can be moved along the X-ax, yes it did! I started at 25 mm/min and increased the speed to 2500 mm/min. This is approximately the max speed for this configuration.



Above you see the wiring is all fed thru the portal down under the table. A z bend aluminum piece will be mounted to guide the wiring to the end of the table. At above picture you see the proximity switches for the X-ax, they are mounted in a separate holder under the portal.

[gait]

As mentioned in previous posting I noted a cracking noise  when the machine was doing a test run.
To solve this problem I disassembled the spindles of the X-axes and demounted the t-nuts from their seats.

Normally if the t-nuts are assembled on the spindles, it will come with plastic tubes inside. With these tubes you can easily detach the nut from the spindle without losing the steel balls. Unfortunately I didn't have this tube, so the balls can fall apart when demounting. I detached the nut inside of a plastic bag so I kept all together. The 1204 has 32 balls inside the t-nut. After cleaning the balls and the t-nut I put a little bit of grease inside of the nut by using a syringe with needle. With a pair of scissors the single balls were placed inside the nut, 16 in each side. Finally I used a piece of paper, rolled it and gently moved inside the t-nut. Finally I unrolled it so the balls were pressed in place. Then I screwed the nut on the spindle and assembled them in the base.



Having the machine up-side-down I took a picture of the X-ax tooth belt couplings. This tooth belt prevents the protal of bending when one of the x-as motors is not activated or broken.
Again doing a test run. This was much better!
max speed achieved on the X-as was 2500 mm/min. I tried to go up to 3000 mm/min but this was too much!.