CNC Router V1.0 (For Cutting Multiple Materials)

[biketrialsdave]

Little update... It doesnt look like much has changed but I've added a lot of minor details. Currently ALL aluminium plate is 20mm thick. Does anyone think this is overkill for the plate which attaches to the X axis carriages (on top of gantry) and the plate which attaches the motor mount to the Z axis?

My useable bed dimension is now 343mm x 434mm. I think that's fairly reasonable for what I will be cutting.




Dave

[JAZZCNC]

If I have read this correct, the top edge "registers" with the carriage (i.e. points it in the right direction?) but does not actually have a close/touch fit with the carriage?

Yes the top edge sits directly on the carriages, the edge acts has the register. If you have them already look at the carriages and at least one edge will be machined, this the the reference edge.
The rails will also have a Machined Ref edge, exactly the same applies with the rails regards Referencing against an edge thou in your case using profile you will only be able to do this if you machine the profile or have a separate plate machined which bolts to the profile.

Another question regarding clearances... I am in the process of adding milled out sections in the end plates to locate the extrusions. Should I allow an additional margin (say 0.5mm??) for the extrusion? Or should I design an 80x80 slot with 4mm radius corners as per the extrusion?

The only sure way is to measure the profile your using then machine to light interference fit. Wouldn't suggest you have them machined without the profile first if your wanting close fit.
Same goes for anything you want machined really, don't trust Cad or dimensional drawings where fit is important has there is always some slight difference waiting to bite you. Can't beat having the part in your hands and I won't machine anything were tight or close tolerance is important without parts in hand.

Currently ALL aluminium plate is 20mm thick. Does anyone think this is overkill for the plate which attaches to the X axis carriages (on top of gantry) and the plate which attaches the motor mount to the Z axis?

Nope it's perfect and will help reduce resonance. . . .Certainly wouldn't go below 15-16mm.

Can I suggest you change the position of the BK/BF bearing blocks and put them on the outsides of the gantry and End plates, or at least the motor side bearing.?
The way you have them on the inside will mean they are trapped between the gantry side and end plates which will make fitting very awkward and inflexible, will also mean they need to be done at the same time has bolting profile together.

Put them on the outside at the motor end and you can insert the screw thru the ends/sides after building frame. Notice you have the motor mounts has closed blocks like this so just machine the inside to clear the bearing block and fitting will be much easier and very neat, The bearing will also be protected from crap inside the motor mount so that's another plus.!!