Seeking some practical squaring advice.

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.

Attachment 11015 Attachment 11016

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

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

Thanks for any advice!

Wal.

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.

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

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, 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.

Fashion something like a fly cutter, mount a dial indicator on its long arm and rotate around or something like this, which is better and use the long arm, then rotate. or something simpler, but on the same principle.

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..!

Attachment 11201

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

Wal.

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

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

re 'squaring' - have a look at this video, the sections on squaring the head and squaring the vice. While not directly what you need it should give you some clues...

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.

Quote:

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Originally Posted by Wal

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

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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.?

Quote:

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Originally Posted by JAZZCNC

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.?

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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!