Aluminium profile cnc build

[valdis034]

Hello again. Now I am on Z axis design and I am thinking for which pulleys to go. As I found in a lot of threads that htd pulleys of 15mm wide and 5mm pitch are the most common, how many teeth should be? On RM1610 ballscrews it will be mounted with grub screws yes? Thinking how to mount the motor for z axis, we want z axis plates as short as possible. Yes? Here is what i have for the moment..





I am going for a bit smaller size than said in the beggining. Now I am using 1400mm length rail (x axis) and get 1190mm of travel from it leaving 5mm each end unused, in Y axis using 1150mm lenght rail and get 940mm of travel, the same using 5mm each end. Should I leave more in the ends?

All the plates seen in screenshots are 20mm thickness except motor mounting brackets and y axis ballnut housing attachment to z axis.

Thank you for any input!

[valdis034]

Hello again after a while. Had some interruptions, broken computer, but i am back again with in my opinion more or less final design. Mainly i am going to use it for woodworking, and hopefuly i will be able to machine aluminium at low speed. 2.2kW water cooled spindle should be capable doing that?

Lets start from main dimensions.

X(longer) axis. 1400mm lenght Hiwin 20mm rails with HGW20CC carriages. 200mm between carriages ends. It gives 1190mm of travel leaving unused 5mm of rail each end.

Y(shorter) axis. 1170mm lenght Hiwin 20mm rails with HGW20CC carriages. 200mm between cariages ends. It gives 970mm of travel leaving unused 5mm of rail each end.

Z axis. 330mm lenght Hiwin 20mm rails with HGH20CA carriages. 178mm between carriages ends. It gives 133mm of travel leaving unused 9mm rail each end.

The frame, legs, and gantry is from 80x80 extrusion. Frame cross bracing is 40x80 extrusion.

All the plates are 20mm thickness except Y axis ballnut housing connection plate (which is 10mm thickness) with Y and Z axis assembly.

For bed i iam going to use 20mm plywood sheet.

Have 4 adjustable feets in all corners. Do i need in the middle aswell?





All extrussions will be clamped with 50x50x3 steel brackets:



I am using 1610 ballscrews for X and Y axis, and 1605 for Z axis. Pulleys on all screws are htd 15mm wide 5mm pitch. Have 20mm slots for belt tensioning, and for ability to go for different gear ratios. I see that these pulleys are most comonly used. Are they the best option for me?



The question if it is enough of shaft inside the pulleys? With standard ballscrew end machining it doesnt go trough all the pulleys bore. I left 1mm gap between pulley and BK block. The same with motor, 1mm gap pulley and motors bracket.



Here it is at its max position in X axis:



And about Z axis. I have sandwitched ballscrew and mounting blocks between the plates so I have 9mm cutout in the front plate.



Z axis motor is angled because with sraight slots motor spacer was in belts way. So now the belt is going right between the spacers.


Another question is what spindles positioning is the best? Here Z axis is all the way up:


And all the way down:



Whats still left to do:

1. To decide which exact litmit sensors to use so i can desing them into the assembly.
2. To route energy chains routes, to have a trunking for them.
3. To design rail dust guards.

Before ordering all the mechanical parts would like to get some comments from all you. Maybe there are some weak points, or something. There is always something can be done better, so others can see it better.

I Dont have any parts bought yet, except i have high indtuctance stepper motor from my previous build and tb6550 drivers with BOB which i am not sure if to use them.

Thanks!

[Clive S]

I Dont have any parts bought yet, except i have high indtuctance stepper motor from my previous build and tb6550 drivers with BOB which i am not sure if to use them.

You would cripple the machine if you used them. Have a look for AM882 drives and nema 23 motors from Zapp or CNC4you.

Re the screws you will probably requite the F dimension to be about 30mm it doesn't cost much more to do it right.

[valdis034]

I changed ballscrews shaft to 30mm in it is sticking out a bit. And I saw quite a lot people are making it from 15mm to 30mm. It is not a standard? They can do any dimension i like or not?
And how about motor shaft? I could cut out a bit depper in the bracket but it will start to loose its strenght, isnt it? At the moment i am using 10mm plate and motor is 5mm in it. Do i need to go deeper?

How deep it is:

[Clive S]

I changed ballscrews shaft to 30mm in it is sticking out a bit. And I saw quite a lot people are making it from 15mm to 30mm. It is not a standard? They can do any dimension i like or not?
And how about motor shaft? I could cut out a bit depper in the bracket but it will start to loose its strenght, isnt it? At the moment i am using 10mm plate and motor is 5mm in it. Do i need to go deeper?

How deep it is:

The conventional way is like this so the the motor will stick through. The motor shafts are normally OK. 2-3mm is OK

[valdis034]

I opened the bracket the same like you showed me, but i still have 8mm left. I checked motors dimensions and pulleys dimensions all seems ok. Where that difference could come from? Maybe you are using different pulley?

[Clive S]

I opened the bracket the same like you showed me, but i still have 8mm left. I checked motors dimensions and pulleys dimensions all seems ok. Where that difference could come from? Maybe you are using different pulley?

The shaft on a nema 23 from Cnc4you is about 22.5mm long.