Second CNC table build, here we go again....

**Davek0974** · 22-07-2015

I had thought of that but seems a possible method may be to fit the rails as-is and then fit a stretcher bar under the slats to force the beams out a little, 3mm should be easy.

Could even use the middle slat support possibly, not got that far yet though.

**Davek0974** · 25-07-2015

Got the Y axis motion fitted and the gantry supports tacked up.

Even without the beam fitted the side supports are very rigid, most encouraging.

**Davek0974** · 26-07-2015

Got the gantry supports welded up - very little distortion which was great, impressed myself with that one

One thing I can now say is, that gantry beam is damn rigid, i put a dial indicator between the gantry and side beam and it's practically a solid object

Also got the X axis and THC mount welded up, came out nicely.

One question - I had to move the x motor rearwards, placing the rack on the back face of the beam - no biggy but, I had forgotten the rack bolts go across the rack face so are now screwing into nothing. Should i fit some short support angles like 10x20x4mm 100mm long and welded to the beam, and then mount the rack to them????

Or something better???

**njhussey** · 27-07-2015

Originally Posted by Davek0974

One question - I had to move the x motor rearwards, placing the rack on the back face of the beam - no biggy but, I had forgotten the rack bolts go across the rack face so are now screwing into nothing. Should i fit some short support angles like 10x20x4mm 100mm long and welded to the beam, and then mount the rack to them????

Or something better???

Looking good Dave, I presume that you mean Z axis motor not X? I'm not sure how much force the stepper will exert on the rack but I would think a long piece of angle tacked on to the back beam would be ok to mount the rack, just have to be careful that you don't distort the beam welding it but you seem to have done a good job of not distorting things so far

**Davek0974** · 27-07-2015

No definitely X-axis, the Z-axis is mounted on the THC unit, X-axis on the carriage.

I have opted to try the 3M VHB double sided tape for this - no distortion and easy to fit, seems to be getting good remarks on other builds.

**njhussey** · 27-07-2015

Hah...i meant Y axis not Z but I guess you call it the X....confuses me everytime!!!!

**Davek0974** · 27-07-2015

Ha :)

Depends on the table i guess, my one is x=left/right, y=front/back, z=torch

**Davek0974** · 27-07-2015

Reclaiming some motion distance....

After building the base frame and motion, I decided to build a new floating head using Hiwin and a single carriage - pretty much a standard design. However, this moved my torch 30mm closer to the front of the table than I had planned which left very little over-travel on a full 1250mm sheet - not good.

The first pic is a cross-section of the average torch mount with the Hiwin at the bottom and the circle being the torch clamp.

Now, as I am using wide/stable Hiwin rail, could this idea work?? It regains a valuable 30mm of spare travel on the Y axis.

**Davek0974** · 28-07-2015

Here we go, down to 27mm distance now, thats a little less than my existing unit

The side effect is that to get the torch back on centre, I have to shift the Hiwin carriage to the left a fair bit, luckily this will be over the machine side beams and will not affect anything at all - perfect

**njhussey** · 28-07-2015

That should be fine Dave I would have thought, it's not carrying any weight and ther are no forces acting on it after all. For complete ease of maintenance could you not turn the torch mount through 90° (gap facing the front) and use one of the fixing bolts (now coming in from the right and tightening into tapped holes in the 5mm steel plate) to tighten the clamp? I'm not sure from the drawing if there's ease of access to get to the torch mount?