Comments sought on new build: A CNC Router for RC Gliders and Planes

[EddyCurrent]

How do you plan to get the gantry at exactly right angles to the rails ?

[njhussey]

How do you plan to get the gantry at exactly right angles to the rails ?

I am going to clamp a piece of Aluminium sheet to the gantry back and use a large engineers square off the reference rail (bolted down) to square it.

The reference rail will be parallel to one 100x50 x axis rail so I might get a DTI and reference the 100x50 rail carriage off the rail side and then bolt that down firmly (threadlock) to the carriages before referencing the gantry.

[EddyCurrent]

I think I'm going to use a combination. What you said plus a digital angle finder plus a 3-4-5 triangulation measurement.
If they all arrive at the same point, great, if not, I'll do it again, have a rethink or maybe take an average reading.

[Neale]

How about setting it up as accurately as possible by measurement, then cut two right-angles in a piece of panel material - one cut across the bed to give a straight edge, then one cut along X at mid point of gantry to divide it in two. Flip over one piece on to the other and the difference between the two "right angles" is twice the gantry alignment error. I was thinking this one through the other day as part of my "how would I set it up accurately?" musings but not sure how it would work. I was also wondering how and where I would build in the necessary adjustment for correction.

[EddyCurrent]

Neale,
That's how I would set an engineers square up, by flipping it over as you say but in this case I'm on about bolting the gantry cross member to the two carriages each side sitting on the long rails with the adjustment being in the bolts fastening that cross member to the carriages. So it's bolting three pieces together and ending up with the cross member at right angles to the long rails.

[njhussey]

I might just put the gantry piece on a flat table and bolt the carriage pieces at 90 degrees to that and then bolt to the carriages and see how the rail spacing is on the x axis box section. I'm not going to worry too much at the moment as I need to get the bulk of it built whilst I still have access to my works workshop and all the facilities there, only got 5 weeks left...

[Wobblycogs]

I've given squaring up the y to the x axis a little thought as well. I've seen Jonathan mention using dowel pins and long calipers but I was thinking a good first pass would be to fit a pen in place of the router and get the machine to draw a large square or rectangle. Measured corner to corner the two measurements should be the same if the gantry is square. This is how I square pieces up when working wood, it's pretty easy to get a good level of accuracy and it costs nothing.

[EddyCurrent]

. . . whilst I still have access to my works workshop and all the facilities there, only got 5 weeks left...

Neil, What's happening with the workshop ?

[njhussey]

Works will still be there, however I shan't...

[EddyCurrent]

How's progress ?