fresh start 8x4 build

[JAZZCNC]

dont know if im being stupid but what i had in mind was to only bolt the top alu profile untill its square then had the bottom.

Sounds great in theory and will work treat in Cad but can tell you in practise it will be pain in the arse and you'll struggle to get linear rails to align and be parallel.
Fraction of degree error on wide machine shows massively at other end and you'll want easy way to adjust without affecting other areas of machine.

Then you have the fact that really you want to be bolting the bearing plates to the lower profile to stiffen the gantry.

Would be lot easier and stronger if you made the bearing plates longer and bolted to gantry. Also like whats been suggested you also want to move the gantry back to better balance the gantry on the bearings. Plus will bring the cutting area more into the machine foot print.

[reefy86]

i just roughed this out but is this what you suggest on the bearing plates? made the plate longer so can access bearing blocks and the aluminium profile is bolted to center of plate.

Ash

[JAZZCNC]

Ash easiest way is to have two plates. One bolts to the bearings and other is bolted to and part of the gantry. These then bolt together with the lower plate being threaded for bolts passing thru the upper plate and in location that is easy accessed. This way you can place gantry on bearing plate then lock into position when square. Then drill ream fit dowel pins to lock in place if wanted or just have tight fit.
Tight fit works well when first setting up and learning becuase if you bend the machine out shape can easily get back square by lossening bolts starting again.

[reefy86]

slap in the face lol. thanks dean :)

[JAZZCNC]

slap in the face lol. thanks dean :)

Was not my intention to slap ya mate.! . . . . I'll keep stum if you like.?

[Boyan Silyavski]

Or all this is just an indication that at the end you fill finish with too much spindle Overhang on gantry. My criteria is that in a good design, when looked from side, the bit should stay in the bearing spread or the sall called gantry side legs. Or at least not be too far in front of it. I don't see what you will be saving here? 5cm of rail?

[reefy86]

you mean keeping spindle bit more or less as centre to the bearing blocks or centre to the side plates as much as possible?

[Boyan Silyavski]

I mean D4 to be so long /260-300mm/ that router bit stays inside it. Its called -overhang/ how far from X rail is the spindle nose. There is center of gravity also. The nearest the bit to the center of gravity, the better. Ideally all should be designed so that is perfectly balanced .

you could read basic info about forces there http://www.cncroutersource.com/do-it...NC-router.html


But you could do it out of this concept as you like, if using Hiwing 20 rails and carriages. They are so strong that overhang is not a problem. Just i like things to be perfectly balanced and engineered