Seeking some practical squaring advice.

[Wal]

Hi all,

I've started my fixed gantry mini-mill build and so far so good. Here's a pic of my bare x-axis and one with the machine table loosely fitted.

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It's a simple build made up of three linear stages, with the x riding on the y. Here's a 3D visualization:


http://youtu.be/2XRB4kylHHs

Looking ahead, I can see that I'm going to have a bit of a challenge when it comes time for me to square the rails on my x/y gantries.

I'm pretty confident that I can get each pair of rails running parallel, but I'm wondering if anyone has any suggestions on how I can ensure that the two sets of rails run perpendicular to each other.

I'm aware of the millkins script (which is an X-Y skew correction script) available from here:

LinuxCNC Documentation Wiki: ContributedComponents (http://wiki.linuxcnc.org/cgi-bin/wiki.pl?ContributedComponents)

but if I can get it close to start with, then that can only be a good thing.

Thanks for any advice!

Wal.

[irving2008]

What I did to check perpendicularity on my mill was to clamp a good known 8" engineers square to the table and mount a lever arm dti in the spindle. I then adjusted the square to achieve 0 deviation on the x traverse, rotated the spindle 90° and measured the y deviation by traversing the other leg of the square. In your case you could use the x & y reference edges to do something similar. A set of good parallels would allow you to check y alignment at various x positions. Obviously you don't have a spindle yet so you'll have to synthesize some sort of temporary and fairly rigid fixed height z axis.

[GEOFFREY]

Hi Wal, your pics are looking good. Well done and keep those pics coming. G.

[EddyCurrent]

Wal, For a machine that size it looks like a much better and easier route than the moving gantry design. If it is out of square what are your options for correcting it i.e. means of adjustment ?

[Wal]

>Wal, For a machine that size it looks like a much better and easier route than the moving gantry design.

I wanted to keep things as simple as possible, so opted for 3 semi-autonomous linear stages along with off the shelf parts (like the motor mounts) - all I really had to do was buy the rails/ball-screws (as per the specifications recommended here) and then work out where the holes needed to be to mount 'em... The work area comes out at approx 200x200mm - or 200x300 if I re-position the pillows on the machine table. The footprint is a lot bigger than that - about 800x600 - and the weight of the frame/aluminium/plates/hardware is knocking on 100kg... eek.

>Hi Wal, your pics are looking good. Well done and keep those pics coming. G.

Thanks Geoffrey. I'm a long way off yet, but I hope to get a build thread up. It won't be a diary, more of a 'here's what I did' type thread. Heh. That's if it works..!

Irving, I'm having a bit of trouble visualising the squaring process - no sooner than I get an inkling, another thought comes along and de-rails (pardon the pun) it. I'm gonna have to draw some pictures..!

Wal.

[Boyan Silyavski]

Fashion something like a fly cutter, mount a dial indicator on its long arm and rotate around or something like this (http://www.ebay.es/itm/Dial-Co-Axial-Centering-Alignment-Indicator-Mill-Rotary-table-Center-Imperial-/390719342191?pt=LH_DefaultDomain_3&hash=item5af8b0066f&_uhb=1), which is better and use the long arm, then rotate. or something simpler, but on the same principle.

[Wal]

Picked up the (70Kg!) frame from the steel fabricator earlier today. A friend helped me get it into the basement - door and banister had to come off temporarily (and will now probably stay off for the foreseeable future as I devote all my time to putting it together - heh!). In theory I now have everything I need, just a case of tapping, assembling and squaring the beast..!

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I feel a week off work is in order...

Wal.

[Clive S]

Looking good Wal, I don't think that will flex much :star: ..Clive

[Wal]

It's Dean's fault. I'm paranoid about deflection...!

[irving2008]

re 'squaring' - have a look at this video (http://techtv.mit.edu/collections/ehs-videos/videos/127-machine-shop-4), the sections on squaring the head and squaring the vice. While not directly what you need it should give you some clues...

[Wal]

Cheers Irving, will have a proper look at that over the next couple of days. Looks like I could learn a few things from it..!

Wal.

[JAZZCNC]

It's Dean's fault. I'm paranoid about deflection...!

Hey what.??? . . . . Don't be blaming me I had nothing to do with it you read into my posts what you will.!!!. . . To quote Manuel from faulty towers " I Know Nothing". . Lol

Just want to ask why you had that diagonal brace put so low down.? . . . . Looks to me like could be in the way if you have larger material on the bed or use a vice etc.?

[Wal]

Just want to ask why you had that diagonal brace put so low down.? . . . . Looks to me like could be in the way if you have larger material on the bed or use a vice etc.?

That is a good point but I doubt it'll affect me too much. My work area is 30x20cm max and most of what I do will be smaller than that. If I need length I can go across but I can't conceive having to work on large bits of stock. Famous last words and all that - heh, this is just a mini-mill that's ended up a bit over-engineered!