[Mister H]

I already started a thread but now I see that it is in the wrong section (http://www.cnczone.com/forums/showthread.php?t=30066), my appologies.

So now in the right place

I have recently started designing my first CNC machine
The dimensions the cutter can reach are about 90cm x 70cm x 10cm

As for the linear bearing I use the following parts:
20mm steel rod for the x and y shafts. for the x axis I will support this rod in the middle to prevent bending.
the bearing itself consists out of 2 bended (120 degree) plates (4mm thick) welded on a plate for fixture. on these plates i connect some bearings (6 on every side)

for the Y axis i'm not sure weather I'll use a sliding bearing or the same bearing as described above.

The z-bearing is a sliding bearing on a 15mm shaft.

I already bought 3 1.7Nm steppers and for the drivercard i'm building the PICstep at the moment. I have some trouble finding a shop that sells the IC DIGIKEY LMD18245T-ND for a reasonable price over here in Holland. I can order them at digikey, but i don't know if i have to pay taxes and importing costs etc. Does anybody know where to find them in europe?

every comment on the design is welcome since i'm not sure weather the design is stiff enough.

Many thanks

Hendrik

[edit] added a picture of the linear bearing i want to make

[bp092]

what did you model that in?

[joecnc2006]

On you bearing slides, what are you going to use to prevent the Gantry from lifting up?

[Madclicker]

On you bearing slides, what are you going to use to prevent the Gantry from lifting up?

120 degrees will wrap the pipe.

[svenakela]

I already started a thread but now I see that it is in the wrong section (http://www.cnczone.com/forums/showthread.php?t=30066), my appologies.

Hendrik,
I moved your other thread from the engineering forum to one of the DIY forum. At least a little bit better place for the thread.

Regards,
Sven, moderator

[Mister H]

Hendrik,
I moved your other thread from the engineering forum to one of the DIY forum. At least a little bit better place for the thread.

Regards,
Sven, moderator

Thanks, i couldn't figure out how to do it myself.

@bp092, I modelled it in Solidworks and rendered it to make it more realistic.

What is everybody's opinion about my Y-axis. Should I go for the home made bearings or the sliding bearing. The advantage of the home made bearing is that I can make a construction to support the rods.

[Brunow]

Zeer mooi begin. Wegens dat je van nederland bent ken je toevallig http://www.mijncnc.web-log.nl/ zijn mannen die ook al een tijdje bezig zijn.

Nice start! Where did you buy those steppers?

[joecnc2006]

120 degrees will wrap the pipe.

Oops, you are right, don't know what i was thinking, guess we all slip sometimes.. lol

[Rance]

Hendrik, All looks well, except as has been mentioned before with stiffening the gantry sides. how do you plan on building your bearings (Post #1 last pic)? Welding?

[Mister H]

Hendrik, All looks well, except as has been mentioned before with stiffening the gantry sides. how do you plan on building your bearings (Post #1 last pic)? Welding?

yes I''m going to weld this. maybe I have to put some reinforcement ribs in it

[Mister H]

so what do you guys think about this set-up for tha gantry (it is just a principle sketch, it isn't completed, no place for z-axis yet!!)

And would you go for 20 or 30 mm rods?

[Guldberg]

If they are supported like that, 20mm will do, proberly less if you like or a hollow pipe. The solsylva has proven that concept

[Mister H]

Ok, now i'll have to make a choice... make everything from 20mm or 30mm rods. the rods on the gantry can be 20mm, as Guldberg already suggested. But what about the rods carrying the gantry. i think they have to be 30mm to be able to carry everything without bending to much. Or maybe i will have to support them like this as well.

For me the major disadvantages are the construction. How to make a round profile on the mdf where the rod can be glued / or whatever on.

Greetings Hendrik

PS: somebody has an idea where you can buy the LMD18245T for the PICstep in europe for a normal price?

[dan dimock]

Keep up the good work, sure is looking nice - I am working on the computer end now, trying to learn it, soon I will be ready to start building my unit, if you have plans, I may copy yours, best of luck
Dan

[Mister H]

I've got the PCB's for the stepper ready now. Got almost all the parts for the stepper drivers... so next time i've got some spare time... its soldering time

I still have to make the interface board. Which interface board (with break out) do you think is ok to make?

I also got the parts to make the bearings, so i can make them as well. Havn't got time to make some photo's now. but will do that next week (i'm not home until then so building is paused as wel )

Hendrik

[vger]

As you mentioned early on, you intend to support the rods near the center. Take a look at the end on view of one of your bearings with the rod in place. 20 mm will do. At the bottom there is sufficient room to support the rod along it's entire length. Perhaps to a piece of flat bar on edge or angle or T extrusion. Not welded, but epoxy, or even screws all the way up from the bottom into tapped holes in the round bar. The end view would look like a lolly pop. One other thing you will have to deal with is a means of adjusting the bearings so they are in contact without too much load on them. Maybe an offset shoulder bolt going through the bearing? Took me a minute to find it again... http://www.buildyouridea.com/cnc/hblb/hblb.html might look familiar. Keep up the good work.

[jmytyk]

nice renderings, what software are you using? i noticed you even changed the textures on the edges. is the 'blotchy-ness' due to trying to cut your render times? -- man do i need to brush up my cg skills.

nevermind- just saw you say it's solid works...

[Mister H]

I rendered it in Solidworks yes. I didn't do anything with the edges, just applied material to it (I applied somehing that looked a little like MDF) and rendered it. Solidwork did the rest.

[Mister H]

I've been busy with the electronics and I've got the PICsteps ready (except for the LMD's). I have also chosen a interface (4 axis pminmo) where I already bought the parts for.
So now i'm back to the mechanical parts again. The spindels have arrived today (tr14x4 and hexagonal nuts).

As for the linear guiding... has anyone of you tried a concept like the included drawing? And if so, does it work ok or what are the drawbacks?

thanks in advance for the info

[Mister H]

some photo's of the parts I've bought and made.
The electronics aren't completely ready yet (still waiting for the LMD's to arrive). The spindels are tr14x4 spindels and the steppers are 1.7Nm from stappenmotor.nl