Steel frame cnc router design/build

[CraftyGeek]

There is one inner brace already - 15mm plate & then 20mm outer on the end.

I'll look at doubling up that inner brace later.

I have to keep an eye on the cost as its already adding up to way more than I originally intended...& its going to take me months & months to sort out the finances for it - so yes, the budget is important. I appreciate that its not worth cutting some corners - but I can't shove a bottomless pit of funds at it.

[JAZZCNC]

There is one inner brace already - 15mm plate & then 20mm outer on the end.

I'll look at doubling up that inner brace later.

Yep but the more towards the centre you can support it the better, bring that inner triangle inwards the gantry side does the same job so it's not needed there. On mine it's only built like that for ease of fitting it's piece on it's own that bolts on could have easily done it like suggested you do and would work just the same.

I have to keep an eye on the cost as its already adding up to way more than I originally intended...& its going to take me months & months to sort out the finances for it - so yes, the budget is important. I appreciate that its not worth cutting some corners - but I can't shove a bottomless pit of funds at it.

Yep completely agree and understand but just understand it's here at this point when building frame you can't afford to cut corners. If you have a weak structure you have a Weak machine and it will always be weak or hard to correct without major hassle and expense at later date.
I've seen this often where folks think I'll do it on cheap then upgrade later only to find out it's not that simple or easy and end up scrapping and starting again. . . . It's called learning the hard way, I'm just trying to help steer around that.!

[CraftyGeek]

Right, the gantry is moving along nicely - i'm at the stage now where i'm starting to add the Z-axis. Its probably time to finalize rail/leadscrew choices before I go much further.

My thoughts have been
X - SB20 rail with 2x 1605 screw
Y - SB20 rail with 1605 screw
Z - SB16 rail with 1605 screw

I've seen mentions of clearance issues/fiddlyness when using SB16 with, I assume 1605 screws...should I just use SB20 for Z as well?
All axis will have a single Nema 23 motor & be driven by belts/pinions. Initial power setup will only be 24V - but I plan on upgrading this to at least 48V in the relatively near future.

Does this sound ok?...what about the Z axis setup?

[JAZZCNC]

No don't use 5mm pitch for X & Y you want 10mm so RM1610. Use Rm1605 on Z axis.

Either rails will work but your correct the 16mm are lower so very close without machining the plates to allow clearance for ballnut.

Dump the 24V ASAP.

[CraftyGeek]

That'll teach me for posting when i'm tired :-p
Brain said 1610, fingers typed 1605.

Ok - i'll go SB20 all round for simplicity sake.

24V will be upgraded - but it means upgrading the stepper driver boards as well...so it won't happen immediately, but as soon as its possible.

[CraftyGeek]

As i'm getting further into the design now & tweaking parts sizes to make leadscrew bearing housing line up etc i'm wondering about methods of assembly & tweaking the fit of parts.
This is a 2 pronged question..

Firstly - I see many mentions of shimming parts to get accurate spacings & alignment....what is normally used for shimming?

Secondly - some of the parts that i'll be constructing have a length of steel box with an end cap plate that needs to be welded on.
On the design, i'm drawing this as a neat, flush fit like this:


Given that i'll be completely new to welding (yes i'll be practicing first), the tutorial video that i've watched suggests fitting parts together like the next image so that the actual weld can fit between the box & plate.

That obviously makes getting accurate positioning very tricky & i'm guessing a bit of a nightmare.

So I was wondering if something like this would be a better approach...grind out some notches on the end of the box section - sit the plate flat on the end, then tack weld into the gaps that were created by the grinding...this should help keep alignment more straightforward & accurate?


If i'm missing something here please fill me in...or I could be missing something entirely

[Clive S]

Could you not just make the green bit a bigger so that you can weld it from the other side to get your fillet weld ..Clive

[Old Silver Fox]

JazzCNC

Where would you recommend as a source of rails and RM1610 ?

[Boyan Silyavski]

JazzCNC

Where would you recommend as a source of rails and RM1610 ?

BST automation, Aliexpress, Fred. http://www.aliexpress.com/store/314742