I am in the process of designing the bed for my CNC machine and would appreciate any guidance regarding frame dimensions and material choice.
My plan is to weld a steel frame together with 10mm * 50mm plate welded to the sides of the upper rails, which will then be milled by a local machine company in readiness to accept the linear guide rails. They have quoted £800 to mill the side rails and drill all of the holes.
Their machine is super accurate and will ensure that the rails are 100% parallel and level to each other, resulting in super accuracy. Whilst £800 is expensive it will save me the headache of getting the rails aligned
My plan is to base it on the axyz 4000 series machine as shown below.
First can I ask the main intended use.?
I don't want to use aluminium profile section as I think those machines have poor resale if you ever decide to build another one.
Do you have any suggestions that might be of help ?
Getting the rails parallel is not a problem - once you have the gantry mounted and put a couple of bolts in one rail the other will self align. Either that or you can use a DTI to align them by affixing it to one carrage with the needle against the other rail.
Another way to get them parallel in the vertical plane is to mount them on (the right type of) epoxy. Pour the epoxy on the rail mounting surfaces with a channel (or several channels) in between and gravity will level it 'automatically' with very high accuracy.
I don't want the machine bolted to the floor, I just want it to sit on the levelled feet.
Do you think that once a frame is constructed from 80mm * 80mm * 6mm box section and then machined it will still be able to distort ?
80 x 80 x 6 box section can still distort. The size of the machine you are building will be rather heavy, 80 x 80 x 6 box section aint light. Unless you level it very well it will still move. If you decide to bolt it down then make sure it is perfectly level on its feet or you will pull it out of alignment with the bolts.
We would certainly be interested in hearing the personal experiences of anyone who's used epoxy et al to level the top rails of a larger frame. Our Mark-3 machine will be for 8' x 4' sheets. (That said, we're still assembling the bits for MK-2).
Heavy frame = good, as long as you don't have to move it!
For a machine purely for woods it does seem a bit excessive, however you seem to want to use it for milling aluminium too in which case it pays to make it as strong as you can.
What sort of tolerances do you require as that it what determines if machining the rail surfaces perfectly parallel is necessary? You can compensate for it perfectly well in software.
BUILD LOG: Steel frame cnc router design/buildBy CraftyGeek in forum DIY Router Build LogsReplies: 110Last Post: 06-05-2015, 09:00 PM
By fatguyslim in forum Machine DiscussionReplies: 41Last Post: 08-02-2014, 10:37 PM
By Gytis in forum Metalwork DiscussionReplies: 11Last Post: 18-08-2013, 09:35 AM
BUILD LOG: 7' X 4' Steel frame buildBy Ricardoco in forum DIY Router Build LogsReplies: 6Last Post: 28-10-2012, 05:02 PM
By icedfusion in forum Machine DiscussionReplies: 11Last Post: 13-01-2012, 05:39 PM