1.7*0.74*0.4m Mill / Router building...

**JAZZCNC** · 11-09-2012

That looks like an expensive piece of Ali make sure you don't Fubar .!! At least with strips if you do then it's a cheap repair.!

After fitting the strips are you going to fly cut it.?

**Jonathan** · 11-09-2012

Originally Posted by JAZZCNC

That looks like an expensive piece of Ali make sure you don't Fubar .!! At least with strips if you do then it's a cheap repair.!

Ascmetals are to blame for the good price. Not that bothered about marks to be honest - if I do mess up it's unlikely to cause more than aesthetic damage, which luckily I don't care about!

Originally Posted by JAZZCNC

After fitting the strips are you going to fly cut it.?

Not sure yet since the issue is I can't reach the full area with the spindle in one go. Once they're fitted I'll height map it and see how close it is. I can always put some aluminium 'sacrificial' strips on top (which could even make T-slots), but I think I've spent enough.

**JAZZCNC** · 11-09-2012

Originally Posted by Jonathan

Not sure yet since the issue is I can't reach the full area with the spindle in one go. Once they're fitted I'll height map it and see how close it is. I can always put some aluminium 'sacrificial' strips on top (which could even make T-slots), but I think I've spent enough.

90% sure you will.? . . . When I did mine I height mapped it with 45mm grid and was surprised at the differences.!! Thou mine was an easy surface has I only had to do the strips.
I had the same problem regards cutting the whole area but actually it works out good because the shoulder it leaves acts has a parallel reference edge for X & Y.

**Jonathan** · 11-09-2012

I tend to a agree with the 90%...

I reckon if the spindle on there, or the one I made, can support a big enough fly cutter I can easily get over both sides by moving the spindle to either side of the Z-axis especially since 2" wide around the border will be occupied by the aluminium angle unless I mill that down. The problem then is maintaining an accurate height between passes, but that shouldn't be too bad. On the previous bed it was very handy having the ridge left from surfacing for a parallel reference

TrickyCNC · 12-09-2012

Very nice machine you have there Jonathon !did you get anywher

e with the 'twisted bearing' screw drive setup ?

Rich

Originally Posted by Jonathan

Just got some M16 threaded rod for the Y-axis, thought I'd give a quick demo of the drive 'nut' as it's a little different...

I know I should probably use ballscrews, but I reckon using this method is almost as good - rolling friction, low backlash... I measured the backlash on the plywood Z-axis I made using this method and it was <0.005mm which I think is pretty good considering the cost!

I guess it'd be better to use trapezoidal and put an insert in the bearing to fit the thread better - I'll leave that for a later date though.

**Jonathan** · 12-09-2012

Originally Posted by TrickyCNC

Very nice machine you have there Jonathan

Thanks, but it's not that great really...quite a few things I'll be changing as the gantry is not strong enough for what I want to do next.

Originally Posted by TrickyCNC

did you get anywhere with the 'twisted bearing' screw drive setup ?

Yes, I mounted it and it worked well with low backlash:
http://www.mycncuk.com/forums/router...html#post16838

It's clearly not as good as a real ball-screw, but as something to get started it's excellent due to the low backlash and very low friction.

I cut the first piece with the new bed last night - just a pocket in the back of an aluminium motor mount and the finish was much better than with the [edit] MDF bed and I didn't need to do a finishing pass to get that.

TrickyCNC · 12-09-2012

Originally Posted by Jonathan

Yes, I mounted it and it worked well with low backlash:
http://www.mycncuk.com/forums/router...html#post16838

It's clearly not as good as a real ball-screw, but as something to get started it's excellent due to the low backlash and very low friction.

I saw you have mounted it, what I could not tell from reading the rest of the thread, is if you kept it / still use it ? and if so, how it was holding up ?

Rich

**Jonathan** · 12-09-2012

I used it for quite a long time, until changing to an RM1610 ballscrew. It was working well, although had caused some wear to the M16 rod (although not enough to be a problem) due to bearing inner ring being significantly harder than the screw, however I think if you used springs to push the angled bearing against the screw and/or used a trapezoidal lead-screw instead then it would last a long time.

**JAZZCNC** · 12-09-2012

Originally Posted by Jonathan

I cut the first piece with the new bed last night - just a pocket in the back of an aluminium motor mount and the finish was much better than with the aluminium bed and I didn't need to do a finishing pass to get that.

Surely that should read MDF bed.?

**Jonathan** · 12-09-2012

Originally Posted by JAZZCNC

Surely that should read MDF bed.?

Yes, thanks for pointing that out - fixed.

What size fly cutter do you use for surfacing yours?

I'm cutting the aluminium angle now to fit round the sides for the coolant barrier, then once I've got the bed aligned I'll get the router to cut a suitable hole in the bed at one end for the coolant to flow through and make a filter etc...

I seem to be able to cut 3mm per pass with the 6mm single flute cutter now :)