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cropwell
07-03-2014, 11:36 PM
Hi,
I shall be starting a new build soon, I had a project, and I bought a CNC machine to do some light machining in acrylic to make parts for it. It didn't help. I just got the bug.

So this week I had the steel delivered to make a new machine frame (7 metres of 50x50x3 hollow section) plus some other bits.
I have the leadscrews (2 x 600 1605's, 1x500 1605, 1x300 1204), ballnuts and supported rails from Chai.

Next week Amadeal are delivering :-
AMA290VFF Metric Bench Lathe 2 axis DRO
Stand for AMA290VF Bench Lathe
Face plate for the AMA290VF Lathe
160mm/4jaw/Independent Chuck
Backplate for AMA290VF Lathe
Fixed Steady for AMA290VF
Travelling Steady for the AMA290VF
Quick Change Tool Post - Piston Type 200
9 piece Indexable lathe cutting tools 12mm
ER32/MT4/Metric Collet set 12 piece

I have already made a milling table for the lathe from the short bed of a Clarke CMD10 and I have fitted that machine with a long bed. I have already got a MIG welder and a 14" Evolution cut-off saw. For the smaller ali parts, I have the MD A4 crapezoidal machine I bought 2 years ago.

The design will be similar to Jonathans new build for Sasha, but with a fixed table, and probably nowhere near as robust.

Now all I need is the time, patience, skill and health to get on with the build.

But I have one starter question :- How do I ensure that the frame is square ? I intend to set up individual corners of the box section so they are clamped to the CMD10 bed, but overhang for welding. With a bit of careful tacking and strategic sequence and placement of welds, I hope to keep it square. The top and bottom frames should be (relatively) OK doing it this way and then I was thinking about drilling the corners and clamping the uprights with threaded rod through the middle.

I would welcome any ideas to help ensure that I don't end up with a twisted mess of scrap for the frame as I feel that this has to be the foundation of the whole machine.

Cheers,

Rob

BTW my original project is still ongoing, but in a hold state

PSG
08-03-2014, 06:37 AM
Hi mate.

Build yourself a big square out of some wood, and clamp the ieces to it to ensure squareness. Make a few if its for a complex corner, then you know it is square before you tack.

JAZZCNC
08-03-2014, 09:28 AM
Rob don't get obsessed with squareness of the frame because mostly it's not critical and just measureing across the diagonals will be enough. Whats VERY VERY important is that you don't set the frame in Twist.

Reason why frame squarness isn't critical (To some degree depending on design!!) is because it just holds the rails and the Gantry rides on the rails so you affectively set "Cutting" squareness with rail and gantry alignment not the frame. It's also why Twist is VERY bad because rails sit on the frame and Twist means they won't be on the same plane. This is why Epoxy levelling is good has it levels out any twist.

EddyCurrent
08-03-2014, 09:50 AM
That's right measure the diagonals and to avoid my issue set up your 4 corner legs and get them all at the same height using a long spirit level before welding the joining bits between. Keep checking as you tack bits into place before final welding.

JAZZCNC
08-03-2014, 09:57 AM
That's right measure the diagonals and to avoid my issue set up your 4 corner legs

To save me or Us trawling thru your thread what was your issue eddy as I haven't really closely followed your build has you seem very capable.

EddyCurrent
08-03-2014, 10:07 AM
One corner was 3mm lower than the other because I just started building from the garage floor assuming it was level.

JAZZCNC
08-03-2014, 11:50 AM
One corner was 3mm lower than the other because I just started building from the garage floor assuming it was level.

Ah I see so you effectively put it in twist. But ounce positioned the epoxy will have levelled this out for you won't it.

That's a good point for Rob and others thou because while it may be obvious to others not everybody thinks that you need to start building from a FLAT level surface. It often pays out to spend a little time making a platform to work from or spend the time setting the bench level.!

EddyCurrent
08-03-2014, 08:05 PM
Ah I see so you effectively put it in twist. But ounce positioned the epoxy will have levelled this out for you won't it.

Yes, the fact that my top beams were bolted to the frame meant I could shim them to near as damn it level, then the epoxy on top was the icing on the cake so to speak.

JAZZCNC
08-03-2014, 09:35 PM
Yes, the fact that my top beams were bolted to the frame meant I could shim them to near as damn it level, then the epoxy on top was the icing on the cake so to speak.

Good That's why I like the top rail adjustable, yes it needs to be done right and takes a bit of time but gives that flexabilty if or when needed. Said it so many times but I'll say it again it's that important I feel.!! . . . Adjustment is the KEY to successful DIY machine.!!

EddyCurrent
08-03-2014, 09:40 PM
If the top rails hadn't warped through welding the 10mm thick steel plates for the bolts, I think I would have been able to shim it without the epoxy.

JAZZCNC
08-03-2014, 10:00 PM
If the top rails hadn't warped through welding the 10mm thick steel plates for the bolts, I think I would have been able to shim it without the epoxy.

Yes I agree and it was the thick plate and current required to weld it that caused warping.
I don't weld plates to the top rail I just insert thick plate on inside and tack to hold then bolt thru it. That's also why I use Epoxy putty to give a nice matting between top rail and mounting plate on frame along with setting rails on same plane.
Often I don't need to use epoxy but I do anyway has it forms a kind of register, the only thing you need to take care with is that the top rail doesn't lean but that's easy sorted with holding plates until it's set.