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

[Jonathan]

looking good jonathan (the router that is, you need a hair cut :)

:rofl: thanks

hows it getting on with thet much Z ?
have you made a provision to drop the whole gantry down for your smaller /finer jobs ?
it is a good feeling when the thing springs into life :)

It seems fine. There's a bit of wobble visible on the latest part (see below), but I think other factors are contributing such as the whole router wobbling madly due to the floor not being strong enough...

I have measured the Z deflection parallel to X. I can bend the Z axis by about 0.06mm if I push as hard as I can with little finger, so a reasonable force but not huge. It takes a lot of force to bend it more than that which makes me think it's the linear bearings that are a bit sloppy. Not much I can do about that.

I've not made it so I can lower the gantry, it's far to heavy to be doing that sort of thing. I think I'll make a raised bed and machine aluminium stuff on that. It's a compromise, but the gantry sides are very strong.

Yes one X motor is much stiffer than the other. It's limiting my feedrate...

Anyway, at last here's a video of it running:



(I'll post the first test video tomorrow when I've edited it)

[blackburn mark]

Splendid!!!! im surprised how fast its cutting

0.06mm

thats a lot better than i would have thought :)
i had to try your scientific test, im getting about 0.03mm but i only have 120mm cutting space so your gantry sides were a good choice over plate

Yes one X motor is much stiffer than the other. It's limiting my feedrate...

i removed the drive from one side (in order to find the one that was stalling/binding) and it ran better on a single stepper than it did on both which i found pretty bizzar
i could only think that there was some kind of sympathetic (machanical) interference between the two with there being more drag on one side and because i was lazy when i fitted the the standard brearings (the fit is to tight) i cant back the pre-load off... the diffrence in drag between each side isnt massive but im hoping that its that causing the problems

my double row A/C bearings have turned up so ill give them a try at some point but for now ill stick with 1500mm/min

[Jonathan]

Well done Jonathan and good to see you up and running :-)

congratulations lad

Thanks, I'm glad it's working at last!

Splendid!!!! im surprised how fast its cutting

What feedrates do you/other people normally use with MDF? I looked it up and found the chipload should be about 0.3mm. That would mean with my router at 11500rpm (lowest) it needs to be fed at roughly 6.9m/min ... which is huge! I wanted to get it fast enough to make chips, not dust, and in doing so reduce wear on the cutter.
I accidently cut all the way through 18mm ply with 6mm cutter at 2m/min last night. The cutter survived but the finish was poor/wobbly.

thats a lot better than i would have thought :)
i had to try your scientific test, im getting about 0.03mm but i only have 120mm cutting space so your gantry sides were a good choice over plate

Er, I wasn't testing the deflection of the gantry sides - the DTI was stuck to the side and touching on the back of the Z axis. I'll see how much the gantry bends today.

My problem with the X motors is one of the nuts is stiffer than the other, and the screws are a bit bent. I put them under tension to remove the bend, however that doesn't help when the gantry gets to the end of the bed since there's no give in it and as a result it often stalls.

my double row A/C bearings have turned up so ill give them a try at some point but for now ill stick with 1500mm/min

Hmm, I thought 3600mm/min was tedious
Y is happy at 5000, maybe more - not tried. The backlash seems to have increased slightly on Y. It's now 1/2 a step - 0.012mm.
Z still works at 10000, and X seems reliable at 3600mm/min...but not at the end of travel.
I think my toroidial transformer is too small now I've got an extra motor.