[Tadas25]

Hi All,

I'm in new CNC project. This time with steel base ( X and Y axis from steel, Z axis from aluminum)
Base will be welded from 80 x 80 x 5 mm (3.15" x 3.15" x 0.2") tubes.
Y axis (1400mm or 55") wil be from 140 x 80 x 5mm (5,5" x 3,15" x 0,2").
Overall dimensions 1600 x 1400 x 300 mm (63" x 55" x 15").

For X and Y axis travel I plan to use Ahrens (aka. cncrouterparts) R&P system.
Hiwin HGR20 Profile Rail will be used for linear gear for all axis.

But, I was wondering what stepers I need to use nema 23 (3Nm) or nema 34 (8.6 Nm). I cant imagine what force will be needed for steel frame.
From that choice depends other electronics choose.

Here few early design renders:




Thanks for any advice !

[cnc3678]

Hi Tadas,

I'm new to the cnc scene as well, so I'll leave it to a more experienced member to comment on the question about the type of stepper for this load.

I'm curious about your choice of steel for the X-Axis - any reason why you are not using aluminimum as this will add significant weight?

Regards,

Richard

[Tadas25]

cnc3678
reason of choice metal tube instead aluminum plate is because all structure will be welded (to get rid of any bolts and nuts on main structure). Looking in weight - aluminum weight about 54 kilos on square meter. So on X axis would be about 30 kilos (if take 20mm thickness aluminum). Metal tube weight's about 27 Kilos.
Attaching some updated Z axis design.

I'm new to pulleys - NEMA23 motor with 20 teeth and other pulley is 40 teeth. So reduction will be 2:1 ?

And maybe someone can help with electronics:
What about this setup:

• PM752 Microstepping Driver x 4 Stepper drivers
• SY60STH88-3008 Nema 23 stepper motor x 4 Steppers
• UIM2901-5A Mach3 breakout board with spindle speed control x 1 BreakOut board
• The PS408-5 - 500W linear (Unregulated) power supply with three main outputs at 36V (8A) and a single auxilary output at 5V (1A) Power supply

T.M.

[cnc3678]

Very impressive drawings TM! You've obviously had some experience with Solid Works. How much were your linear rails?

RM

[lamesh99]

like cnc3678, i too am new on this scene. but i have one question, why welding? i had some steel frames built (welded) for me, and i always found, no matter how well it was welded and/or built, it (the frame) has absolutely never been totally accurate. with larger frames, the loss was up to several milimetres, even 6 or 7mm sometimes. for me it was not crucial, as it was merely for a stand, or a makeshift table, but for something like a CNC, that needs accuracy...
please, don't think i am being a smarta$$, i'm just asking. and if i'm wrong, by all means, tell me

[Tadas25]

lamesh99,
welding can be accurate. I'm not welder, but my friend has a welding company. They have "zero assembly table", that means they assembles (by welding only one dot where needed) on that table and makes adjustments as needed and than welds permanently. But sure, they cannot be 0.001 accurate. that's because I'm using 5mm thick tubes - the steel tubes can be grind'ed to be very accurate.

cnc3678
HiWin rails price's.

Attaching updated Z axis pic's.

For spindle motor I will use this

What about backlash for R&P ? is there 0 backlash or I misunderstood something about R&P ?
Can anybody help with stepper choice ? Does my choice - nema23 stepper is good ? is it powerful enough to drive this design ? I really need to know - I need to order parts. THANX !

[Tadas25]

Here is an update.

Is there possible to eliminate unused table area (what design is most efficient in cutting area usage) ?

someone ?

[DonFrambach]

Is there possible to eliminate unused table area (what design is most efficient in cutting area usage) ?

Move the uprights on your gantry back. This would also better balance your gantry where most of the weight is currently on the front bearings.

[PaulRowntree]

What is the target Z range? It looks like the gantry is extended very high, and the Z plate extends way down from the gantry beam to compensate. If this is correct, both extensions add flex. Most folks here have 5"-6" of Z motion for woodworking, and could probably survive with less.

[PEU]

you will learn that having the base larger than the cutting area is a good idea to clamp big jobs.

[Tadas25]

What is the target Z range? It looks like the gantry is extended very high, and the Z plate extends way down from the gantry beam to compensate. If this is correct, both extensions add flex. Most folks here have 5"-6" of Z motion for woodworking, and could probably survive with less.

Z reange is 9.5" little to high. Thanx ! I will fix this.

[Tadas25]

New X and Z axis design.
Let me know what you guys thinking about this design ?


p.s. if someone need's any solidworks model that you see in my drawings - just ask. I will share.

[ger21]

The profile rails are a much better choice, but they do cost twice as much.

While it is very thick, the spindle back plate is unsupported below the bottom bearings. I'd mount some side panels on each side of the spindle to stiffen it up. This would allow you to use a thinner plate, which should be cheaper.

[Tadas25]

The profile rails are a much better choice, but they do cost twice as much.

While it is very thick, the spindle back plate is unsupported below the bottom bearings. I'd mount some side panels on each side of the spindle to stiffen it up. This would allow you to use a thinner plate, which should be cheaper.

Yeah, profile rails are great. But when I added all parts to shopping cart - I saw amount that I can't afford for now. But, I will think about profile rails, and maybe I will be able to buy them.

For unsupported spindle back plate - can you mark the point on pic what do you mean ? (I need to understand it correctly).

Thank you !

[ger21]

Like this

[Tadas25]

Like this

Thank you.

Here is latest Z and X axis design. Missing some bolts, but construction is clear.

Overall design is form 20mm sheet. Only stepper mounting plate is from 12mm and side supports are from 5mm sheet. Does this seem to be enough for robust design of Z axis ?

T.M.

[Tadas25]

What you guys recommend to use. and what main difference between BOB, and CNC controller (except connection interface) ?

UIM2901-5A Mach3 breakout board with spindle speed control

or

CNC USB Controller

What should I buy ?

Thank you

T.M.

[PaulRowntree]

Just to be clear, I think ger21 was referring to the back plate that moves up/down on the drive screw. If you give it some stiffeners it can be made out of lighter material : less mass gives faster response. Some 3/8" AL plate bolted on-edge perpendicular to the back plate, running the full height of the plate, would suffice.

[ger21]

Paul is right. Reinforce the moving plate of the Z axis, not the parts that you added.

[Tadas25]

Paul is right. Reinforce the moving plate of the Z axis, not the parts that you added.

I think I have reinforced Z axis plate with fully supported rods. They must give great stiffness. Don't they ?

+ attaching few new renders.