Advice sought on new Mill build

[embraced]

Good suggestion regarding the weight.

For the spindle, the motor I will be using has a max speed of 8000rpm. The spindle has a max speed of 12000rpm.
I will put a 60T HTD5M pulley on the motor and a 40T on the spindle. I will still get a large amount of torque on the bottom end - 15.7N.m. I don't really imagine I would need more than this, given that the BF20 I have only has 3.6N.m. with a 1.8kw servo - and I have not managed to make a cut using all the available power yet.

As for the counterweight, originally I was going to have the counterweight slide on a round or HIWIN rail at the back of the column. With the new changes on the column I am starting to think that I may be better with a gas spring next to the ballscrew to push the column up.

Thoughts?

[JAZZCNC]

If your using thick enough plate for the main structure braced correctly then you shouldn't need to mess around with epoxy etc. Esp if your mainly HSM as the cutting forces are much much lower.

I wouldn't use a Gas strut and would go with counter weigth down the column centre running along some cheap round rail. Every industrial machine I've ever seen use's this method inc £250,000 5 Axis machine I recently worked on.

I'm interestd to see the spinlde and motor your going to use can you post links to it.?

[Boyan Silyavski]

I think he is talking about that , cause that's what i was looking at not long ago, when contemplating future mill build.

[Boyan Silyavski]

Sorry, i have problem editing posts,

These bearings doesn't have to be conical roller bearings instead of angular contact ones?

They seem to be exactly the same bearings used on the water spindles.

[Robin Hewitt]

And fix those rails to the table and the linear blocks to the saddle. No point in adding overhangs if you don't have to.

[Boyan Silyavski]

Here is the Chinese solution, machine only, cast iron , without motors , smaller envelope, seems its quite worth to DIY it, price wise .



This below also should be taken in consideration when designing the head. In fact you will need the motor, the spindle and the air cylinder in your hands, before you continue further with your build after a certain point.

2Ton( 2000kg) air cylinder 13mm cnc piston cylinder for BT30 ATC Spindle of CNC milling booster cyliner FL003D

[Boyan Silyavski]

Sorry for hijacking the thread , but its very interesting to me .

I gave it a lot of thought and believe i have the answer, at least for myself on my next build. My usual is "achieve maximum result with minimum materials" and easy to do it at home.

So here is what i have come with:

1. on the left is what i would do, on the right is the easier way, concerning soldering and so. Note that on the left side each cross is done separately and rotated 90 degree to the previous. The profile is 100x100x4, i don't believe bigger is needed.




2. The results in weight





3. So the final result , now taken in account the cut loss when cutting the 6m beam. Additional benefit is that can be used plates 100x10, for ease of soldering. So final size 300x300mm. Weight can slide at the back or additional extension of the plates could be made, without compromising the basic structure.

As you can see we are talking about 150kg total weight, easy to do and something like many many more times than the initial design. Also all the mixture of small stresses of soldering + the cellular structure will kill all vibrations at the same time the hollow place behind the rails will absorb the vibrations into the beam.

And as for the braces near the bottom, understand that if done correctly a structure needs only small braces to protect the soldering and the forces to go there smoothly. With the above design you will need only triangles with sides 100 and 100mm. if the base is done correctly i mean.




I don't know what you think, but i don't see how can be done better with less weight and easier. I am happy with the exercise.