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

[Jonathan]

I wasn't sure if I should put this in the mill or router cattagory, so I've been ambitious and put it in mill since I'll be using it for metals.

Progress so far...
Base - check
X-rails - check but need rotating I think
Z-axis - got the bits
Y-axis - in progress

Today the 900mm/600mm supported 20mm linear rails and bearings arrived from Hong Kong. Barely adequate packaging caused the bearing blacks to be skuffed, negligible really. Seller despatch very slow but DHL very fast.

Also the 20mm aluminium plate for the X/Y axis arrived. It's certainly heavy stuff!

I went to a small local metals supplier and picked up a meter of 80x3mm aluminium box section for the Y rails to mount on, along with 1m of 3"x1"x0.25" alu angle since it was cheap and looked handy for mounting stepper motors and stuff. Also picked up (barely) a piece of 4"x2" steel channel for the gantry sides. Two meters far £10 and it's heavy stuff :)


I'll post some more pictures soon. Here a couple of the base and X/Y/Z axis' I made which will not be used for obvious reasons...

Drawing....disregard the plywood gantry sides as above.


Frame without top 18mm MDF sheet. Screws are M20x2.5


Didn't want to be spinning those 2m long screws, so antibacklash nut placed between two tapered roller bearings. Those pine side bits are temporary until I make aluminium ones.


Er, not much here....am I right in thinking I should rotate the X rails by 90°? At the moment the bottom one possibly doesn't really do much?


Old Z-axis ... ditched that plywood idea! Do note the alternative to a nut i'm using for the drive on the screw though - bearing. More on that later.


Mount for stepper on Z-axis (will still use this) and screw. Note thrust bearing etc...

[Jonathan]

Been busy making router today and Friday...some photos of progress:

Gantry...layout of the parts just to check it looked ok:


Closeup of Y/Z axis'


My milling machine...

[routercnc]

Some good progress there, keep it up . . .

[Jonathan]

Some good progress there, keep it up . . .

Thanks :) I'm at home 24/7 atm (and in the workshop 10/7) so it shouldn't be long!

I'm using the PM752 drivers from Zapp at 70V with their 3N.m motors. Two motors on the X axis. 1Nm motor for 4th axis, but with same driver.

http://www.slidesandballscrews.com/p...ml?cPath=44_97

[ecat]

Looking very nice, I can't wait to see how the 2x X motors work out.

[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.

[Wobblybootie]

Now that got my attention ... have you detailed it elsewhere?

[irving2008]

What have you done there? Can you give some more detail


edit: *** must type quicker ***

[Jonathan]

Now that got my attention ... have you detailed it elsewhere?

Haha, thought it might!

I've not detailed it elsewhere, shall I start a new 'thread' about this?

[Jonathan]

What have you done there? Can you give some more detail

Er, not much more to say really? Standard thin section bearing with bore bigger than the thread (20mm here, but more would be better to get less axial load on the bearing) placed on the thread at an angle. I'll use a strong spring to pull the bearing against the thread so that it rides over any imperfections. That's what the tabs are for on the mount, to mount the spring.



I'm toying with the idea of pressing a brass insert into the bearing lathed to better fit the 60° thread profile. It's tricky to work out the exact dimensions though...