Pics of my metal cnc table (base w/rails complete)

[guru_florida]

Here is a pic of my firs cnc table so far. My goal is a precise/accurate milling machine for small robotic & various parts, proto pcb work, etc. I am designing in SolidWorks. I will also post my SolidWorks design in time too.

In the picture, the ballscrew is mounted to the carriage plate, but I havent secured either end yet. I am working on those parts now.

More detailed pictures are found at:
http://photos.colinmackenzie.net:81/cnc/

Comments and suggestions welcome of course!

Colin

[klick0]

Colin,

Looks good, I am planning on an 8020 aluminum extrusion based frame as well. How are the ballnuts mounted to the carriages? You said they aren't secured but just wondering what you are planning.

Also the link you posted doesn't seem to work.

Ross

[guru_florida]

I got properly sized blocks from the 8020 guy on ebay to make the support pieces. I have the carriage mount already done, thats what is holding the ballscrew in place. It wasnt too complicated. In my real model, the ballnut fit through the carriage mount/stanchion for better support. I havent had a chance to update the SolidWorks model to reflect the change yet.

The fixed-end bearing mount is somewhat complicated because of the large holes. The floating end is easy.

I tried the link from a friends computer and it works. But you have to have the forward slash after the cnc too or the pictures wont come up right. Are you getting anything from the site at all? or a 404 completely?
C

[klick0]

The link works now, I'm assuming it's the same link, unless you changed it. Who knows, maybe it was nothing.

I see how you have the ballnut mounted now, granted i'm sure that's secure and strong, but if yer cutting aluminum or something I think that type of bracket might deflect a bit. I'm not structural engineer so I have no real idea. I'm basically trying to determine how strong I need to make my ballnut adapter. I'm sure there is no visible flexing to it, but hookup a digital caliper and apply 100 pounds of force and it might move a bit.

Do you have a mill that you are currently using to create the parts you have?

Ross

[guru_florida]

The blocks were cut when I got them. The guy at 8020 seems to have an accurate cutter. I checked the block and used the most square side. As for deflection, there are 3x 1/4 inch socket heads going down from the tooling plate (carriage). The bolts also travel down almost to the ballnut. I can use SolidWorks to simulate deflection I believe, but I dont think I will have enough of a work load to matter much...certainly not my main concern. hehe

I am using a dremel tool, a portable drill and occasionally I travel 40mins to get to a drill press for proper holes. NOT MUCH FOR TOOLS!!! haha

I am doing the best I can with what I have...following good assembly practises. I will have good precision I believe...then I will redo parts to achieve better precision when I understand more. I am a decent engineer but new to cnc, so I must build my first one, understand the problem more...then rebuild.

There is another thread I posted too that is getting some good posts:
http://www.cnczone.com/forums/showth...1&goto=newpost

Here I was asking how to secure the fixed end bearing to the shaft...there is no threading on the shaft I got off of ebay. I was hoping for some type of nobby to go on there without threading but I guess not.

C

[csrc]

If I may be so bold, have you consider using two flanges with a connecting tube instead of a billet solution? I have a design for mounting motors on my machine with a section cut out of the tube to access the coupler screws. Your bearing housing could bolt to one flange. Just an idea.

[guru_florida]

I didnt think about it, but I like the idea of drilling only 1 hole through thin fractional inch or so tubing than a square block. But the accuracy of the cut tubing concerns me. The part you saw was actually two parts a roughly 2" square block, and another roughly 2x2x1" flat block. The cut ends are on the sides so they do not affect the alignment (tho I am assuming on the factory extruded heights to be square --- will need to be checked.)

Still, I like your idea...I will think about it some more. What kind of tubing were you thinking?

[csrc]

I am building some motor adaptors from a piece of tubing and two welded flanges. One end mounts the motor and the other traps the bearing against the shaft shoulder. The coupler is inside the tube with a section removed from the tube to provide access to the coupler screws. Trapping the bearing this way allows me to shim the shaft either way using either large or small shim washers accordingly. Very easy to make. In your case, you could add a carrier plate to locate the bearing (6201rs 12mm ID 1.2594" OD on my shafts, works great with 5/8-.200 ballscrew shaft and 3/8" drive). 3/8" plate would work for the 6201.