Dave's Router

[daveshorts]

I emailed gary from zapp and he said to ring him when he was back from his holiday. So that sounds positive. I have plenty to keep me occupied in the meantime.

[Ross77]

Hmmm refilling ballnuts. Fun lol

I got some from ebay for mine. have you got enough to check the size?
I would suggest a tray and lots of caffine

[daveshorts]

Yeah I have about 3/4 of them and have managed to put 2/3 back in without too much difficulty. I will then have to try threading it back on the screw which might mean starting again... I guess there is nothing special about the balls, just their size is important.

Should they be lubricated? And how much space should there be?

[Ross77]

I've only rebuilt one so I'm defiantly no expert. I had an old worn ballscrew so thought I'd give it a go. I don't think the balls are anything special except that they should be softer then the ball screw and nut so its the balls themselves that wear out. the ones I got where advertised as suitable for ballscrews so I just had to trust them..........

Reloading the balls isn't to bad . I assembled mine on the screw itself tho. i took off the cover and dropped each one down the same feed tube and then every 2 or 3 pushed them down and around the screw with a small bar. Eventually they appear at the other side of the return tube, that way you know there are no gaps. use plenty of oil. Setting the preload is the difficult bit and will require a box of different sizes to get it right. you might be lucky as yours is new and just be able to fill it with them all the same size.

NSK do a good guide for ball screws, (cant find it at the mo tho.) You will want to check the sizes as I believe some are set up so it is only ever other ball that is the correct size (drive ball) and the intermediate ones used to set the preload. This lowers the drag but also reduces the load capacity.

Like i said mine was basically scrap before I started so didn't have anything to lose. If in doubt wait for Gary....

Good luck

[daveshorts]

I seem to actually be getting somewhere after last weekend.

I have mounted the Y axis on the X-axis rails, and built a Z-axis minus a motor mount which will have to be bodged somehow.

The z axis ballscrews are binding slightly, I think because the plastic inserts (where the balls are returned) are getting squashed by the linear bearings when I do up the bolts on the ballscrew mount. It is fine when they are loose, so for the moment I might get away with some shim under the mounting block and moving the whole ballscrew out a touch.

I am getting to the point where I want to get the thing working, at least so I can use it to make more accurate replacement parts for itself...

Gary is apparently sending me some replacement balls, free of charge... thankyou!

[daveshorts]

If you look closely at all the unimportant bits which are just left with rough sawn edges it would possibly look less tidy. It is big and shiny though.

Right I think I have fixed the Z-axis binding problem - it was just not aligned right - rather than adding shim I shaved a couple of mm off the ballscrew support block and it is now good.

However it is running so smoothly compared to the Y axis, it rather indicates that there is something wrong with the Y- axis... I need weekends with less work in them.

[daveshorts]

It moves - have finally got it wired up and moving! I have even routed something - the emc default gcode, so not very imaginative.

It seems quite noisy though, should you be able to hear the steppers over the top of a Kress router going?

Next job is some limit switches and probably some kind of optical home switches, then I might be a bit less stressed when driving it around... Has anyone any experience in accurate home switches?

[Tom]

Hi Dave,

I can hear my MDF router over the kress, especially on rapids. When the vac's on too though I can't even hear myself think!

Looking good... What's the first project going to be?

[daveshorts]

Ok I will worry a bit less then, I am slightly worried that some of the ballscrews are not quite aligned, which probably isn't very good for them...

Most of the first few jobs are going to be building bits of itself - I need to make a baseplate for it, and now I have a way of drilling accurately positioned holes it seems stupid doing them by hand. I also want to drill lots of holes to tap in the plate. Which may as well be automated. I will also experiment with milling some pcbs.

After than, some science demos, probably some bits of the van de graaf I am building, after that there will be many others...

[daveshorts]

Have spent the weekend drilling and tapping a scary amount of M10 holes in half inch aluminium plates, for the base. In the process discovering various issues. The oldham couplings were slipping on the Z axis, so I added some grub screws which has largely fixed that problem. Plus the nuts holding the ballscrews into the bearing got loose... which was not ideal! So had to take it all apart and tighten them up. If it wasn't for this though my forearms would be significantly more painful from tapping...

I also discovered that one end of my X-axis ballscrew supports was 0.7mm further out than the other and the ballnut, which might have been making the couplings work harder than they should. There is a definite wobble to the screw now...