First time build - Steel Frame CNC Router

[examorph]

Thanks everyone for the comments, please see below revised design showing modifications are per your suggestions (I think ).

Attachment 17114Attachment 17115Attachment 17116

Still need to figure out some of the finer details for fittings, positions, etc but think it will be OK for initial review.

JAZZCNC - I checked and checked again and its definitely 50x50mm box section drawn in SolidWorks all to scale (although spindle might be out as this was a copy/paste job ). Might look off because of the machine being quite small compared to others (750 x 400 x 100 cutting area).
The ends on the gantry are welded and don't go all the way as I wasn't too sure how else to get access to the bolts. Gantry is all steel, would 4mm box section for this be OK also?
To confirm, as the size of the machine is fairly small, would it still need the 20mm pitch screws or larger motor for the X-Axis or can it do without? If needed, are they 2020 ball screws?

Clive S - Sorry I have never heard of the mesa route before and still after reading up on it I have no clue does the 7i76 replace the BoB and 5i25 act as some sort of motion controller?

RouterCNC - Simplest way I could think of pulling up the X Axis screws was just to stick it onto some box section and weld wherever it needed to be as well as using a 5mm aluminium spacer to help align things as suggested, will this do the job?

Thanks again for the comments and guidance guys.

[Clive S]

Clive S - Sorry I have never heard of the mesa route before and still after reading up on it I have no clue does the 7i76 replace the BoB and 5i25 act as some sort of motion controller?

Ok This is the forum for Linuxcnc stuff. https://forum.linuxcnc.org/forum/index and this post will give you an idea https://forum.linuxcnc.org/forum/27-...d?limitstart=0.
This is where you can get them in Europe http://eusurplus.com/index.php?route...tegory&path=63.
.
Basically the 5i25 is the card that goes into a pci slot in the PC (Linuxcnc is a real-time op system and does the motion controller stuff) and the 7i76 is the BOB for all the input/outputs etc.

[examorph]

Thanks for explaining this to me Clive. Reason for LinuxCNC was really just because it was free, but after looking at the boards it may end up being cheaper and easier just buying a Mach 3 License and one of these boards.

I updated the design slightly to raise the Y Axis ball screw by sitting it on some box section, similar to the X Axis (not sure if it would be stiffer buying wider box section and turning it 90 degrees or maybe also taller and having it sit at the base of the 'L' ?). Another reason for doing this was that I found on kincreaky's build log that Chai could supply these so I added them to all 3 axis and will get them with the rails/screws as it will save shipping.

Attachment 17152Attachment 17153Attachment 17154

This also gives me enough space to go with a belt to drive the gantry screw which might be better?
I remember reading somewhere that 25mm end machining is recommended when using pulleys, will this be enough in my case or do I need more?

[routercnc]

The X axis bearing connection looks better now. For info you can buy ballnut mounts off e-bay which are longer than the one you have drawn so give a bigger footprint and are stiffer. They are connected by 4 bolts, not 2 which is better.
http://www.ebay.co.uk/itm/Ball-Nut-M...QAAOSwHnFVjdoi


On the Y axis the 2 ways of mounting the ballscrews you have drawn are probably similar in stiffness so go for what seems most practical to make - but how will you mount that box section end-on? You mention turning it around which would be better.

[examorph]

but how will you mount that box section end-on?

I was planning on welding it direct to the gantry box section as its all going to be out of steel, would this be ok?

You mention turning it around which would be better.

Ok thanks, will turn the ball screw supports on the Y Axis around and use 70 x 50 box section to leave some clearance on each side.

[routercnc]

[QUOTE=examorph;75595]I was planning on welding it direct to the gantry box section as its all going to be out of steel, would this be ok?

Sorry, missed that it was a steel gantry. Then end-on as originally drawn in post#7 would be slightly stiffer. Go easy on the welding to minimise the gantry warping.

[examorph]

CannonGuy - Thanks for spotting the upside down rails on the one side, it was me being lazy and mirroring everything along the mid plane!! Will probably leave it as a mirror as the feature tree on the SW assembly is already starting to get crowded.

routercnc - Thanks for confirming. I read on a few build logs that people have been keeping the temp below 60C to reduce warping, so will probably stick to this. I have a stick welder but can get a mig arranged if you guys recommend it?

Speaking of welding, do you guys recommend the epoxy leveling route on the x axis for a build this size? With the Y and Z axis do you normally not do this?

[Clive S]

Examorth The board that you linked is the pmdx Is an excellent BOB but for the best results it will need a motion controller like say the Ethernet smooth stepper as the PP on pc's these day are flaky to say the least. There will be more support on this forum with Mach3. Good luck with the build.

[DigiSoft]

You can check out my thread I am almost finished with my machine.
It is 90% steel

http://www.mycncuk.com/threads/5237-...LD-please-help

[examorph]

Dean - Thanks for clearing things up for me, I will be doing some aluminium work on it but was going to go down the route of using a mist rather than flood cooling, will this still be OK with the ply wood sealed base and spoil board setup? Also, probably a silly question but what are the typical depths for the ply wood base and spoil board? Just checking as I want to make sure I leave enough space bellow the spindle.

DigiSoft - Thanks for the link, I remember seeing it previously. Really nice buildd!