Initial design advise wanted

[driftspin]

Hi,

I'am new to cnc and looking to build a steel gantry type machine, capable of aluminium, and wood.

Hobby use, although you never know.
3d work is a wish.


After reading build logs for months now i would like to bypass build mk 1 an mk 2 and go for a reasonably good machine.

Work area +/-1250mm x +/- 700 mm x +/- 150 mm (bed adjustable in height)

Constructed mainly out of steel box section (120x80x4 and 80x80x4)

Zaxis aluminium

Designed around 20 square rail , 1605 / 1610 ballscrews, 3nm nema 23 steppers. Watercooled 1.5 / 2.2 kw spindle.

I am reading up on electronics... i am not up to speed yet.
Digital drives separate stepper processor pc / software

I am also not sure if i will need flood, mist, spray or just airblast cooling.
Or how to put this in my design at this point.

I have not yet desided if the machine will be table top or on legs of its own.


One sides of the frame support will be removable to accept sheet material 4x8 sideways.

Not sure about belt or direct drive for y and x or slave motor for twin ballscrews.

I think y and x will see some epoxy before mouting the rails.
Although for the gantry (X) i am still considering having the rail and block (Y) mounting surfaces machined parallel and reasonably flat.

I have access to solidworks (had no training) and basic tooling.

My mig co2 welder is a 155 amp cebora 4mm is about the max it will do.

I will have to buy some measuring equipments like

a basic straight edge 1500mm,
90deg square angle and
0.01/0.001 mm indicator.



This is my first real post and or design please be gentle ☺.






https://cloud.tapatalk.com/s/57b7638dc5df3/total.JPG


https://cloud.tapatalk.com/s/57b76398...Gantry%20Z.JPG



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[driftspin]

https://cloud.tapatalk.com/s/57b76ac7...Gantry%20Z.JPG

https://cloud.tapatalk.com/s/57b76adb090cc/total.JPG


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[Clive S]

Hi driftspin and welcome to the forum. I can tell that you have been doing your homework and have got off to a good start.
Ask as many questions as you think fit. As usual the general advise is don't buy any electronics etc until you have a final plan sorted and keep away from kits. Good luck with the build.

[driftspin]

Thanx for having me 😅

For now i guess the ballscrews are going to be typical C7 rolled Chinese.

The 1st question i have at this point.
what would give best results.

A) Slave the 1600mm balscrew steppers or;
(i am not up to speed on how this actually works but i do get the general idea)

B) Connect the ballscrews through a belt and a single stepper.

And is then still a nema 23 3nm ?

Total length of this belt would be +/- 2300mm.




Verstuurd vanaf mijn SM-G7102 met Tapatalk

[Clive S]

what would give best results.
A) Slave the 1600mm balscrew steppers or;
(i am not up to speed on how this actually works but i do get the general idea)
B) Connect the ballscrews through a belt and a single stepper.
And is then still a nema 23 3nm ?

Well that question has been debated a lot on the forum and my answer would be non generally is better than the other.

Option B You would possibly need a nema 34 with a high voltage drive like 230V and also you are guaranteed never to rack the gantry. You would also need idler pulleys on the belt.

Option A. you use two drives similar to AM882 (they have stall detection built in) you also need two homing switches so that the controller can make sure the gantry is squared with the homing routine.

The screws in my opinion are best driven by short belts.

Both systems are used widely on the forum.

[driftspin]

Ok thanx for this awnser.

It looks like i can still place the screws so that both options stay possible.



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[driftspin]

I have a sound proofing question.

So i have this typical backyard shed.
Its roughly 4 by 6 meters.

Constructed with concrete floor.
Walls are made by stacking 44mm wooden interlocking planks.

I live in an urban area.. so lots of neighbours nearby. Row housing... yup its not ideal for a cnc hobby.

So what works best on insulating cnc cutting noise... maybe maybe rockwool and plywood /dry wall on the inside?

Anyboy got better solution / idea? Instead of moving of course :-)




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[Nr1madman]

Very good question! I have just built a shed for my future router. I went with 120mm insulation in the walls , then windprotection and 22mm woodpanels. Have not closed the walls on the inside, should I add something more before osb boards and drywall?

[driftspin]

Haha it will never be cold in there 😊😊😊

I would definitly go for a layer of wood on the inside of the wall... maybe drywall over it.

The wood makes mounting stuff easy...



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[routercnc]

Hi driftspin

Noise reduction is related to how heavy the walls are. Look up 'mass law sound reduction' for more info.

There are some basic calculations on this site:
http://www.engineeringtoolbox.com/so...ls-d_1409.html

Let's say with the cnc machine running noise levels inside the workshop are 90dB. If the surrounding urban noise levels near the workshop are 50dB (with the machine off) then you need to achieve 40dB reduction.

With concrete at 2300kg/m3 and 0.2m thick this gives surface mass of 460 kg/m2. This gives an average noise reduction of 52dB, which would be enough.

With wood at 400kg/m2 and 0.044m thick this gives surface mass of 17.6 kg/m2. This gives and average noise reduction 28dB, which is not enough on its own.

Assuming you are stuck with wood, this can be improved by adding another wall with an air gap in between. Using the air gap you get more noise reduction than if you just stuck the walls back-to-back with each other - but they must not touch each otherwise the vibration will pass easily from one to the other and the benefit is lost. So mount them on separate vertical studs. The larger the air gap the better the performance, but workshop space is lost.

Finally you can add absorption material in-between the walls which takes out the high frequencies (it does nothing for mid to low frequencies which is why you need the double wall first). This can be anything fluffy, so rock wool is fine.

Make sure you seal any gaps otherwise lots of the noise benefit is lost. Make sure the roof, door and window specs are considered as well (plus floor if it is just suspended wood).