Quite an Unusual one

[Boyan Silyavski]

Hi,

i am still in the middle of my 1st build for a friend and here comes the second already

This would be a brainstorm so , help and ideas will be highly appreciated. In fact i depend on it

Basically with some hard earned money from my day job and a bit profit from the other build i want to start slowly to build this machine.

If i succeed it will be my dream machine

Before some months i asked the same question at the zone, but did not get any help there. So i have done some preliminary research alone.


So here are the details:

1. What i would like to achieve:

-Now comes the crazy part.
If its possible i would like to have a very sturdy and rugged router table with work dimensions 700x700x200mm. At the same time i would like to be able to mount a pneumatic impact hammer and form metal sheets on it. I would like to form a wok-like shape circle with aproximately 53-60cm diameter to shape it from flat to 15cm deep. The metal is soft, mild sheet 1.2mm thick. Now i shape them manualy.

Dont ask me why, its another 200 page explanation, but i want to be able to make this sheet into form using impacts, not any other method. Not spinning, not waterforming and so on. This is 100 percent shure. No doubt here. So big or small impact hammer head mounted on air rammer moved by CNC.
The impact are known frequency of 700 to 1000 impacts per minute and the impact head size ideally will be from 10 to 25, 30 mm in diameter and should not coincide, so there is a minimum speed that should be maintained.
For that task the main goal is not accuracy but repeatability! means the metal is springy, and so and so, what matters is the final shape to be same all over again. As i do it by hand now, and do it well, i am quite capable of programming the hits afters certain experimenting so that is not an issue.

Can this be done? Yes, i have seen a document where 30cm dish is achieved using unsupported round rails and 10mm hammer head.

What i want to achieve is good repeatability with a machine that will not break after a year doing this all day. And if at the same time i can use it for Wood and aluminum routing will be perfect. As i dont have money for 2/ even for one now


Here is a video how it is done by hand by a guy/not me, i do it for now with normal hammer/. The 1.2mm sheet is quite ductile in fact, not as people could imagine. The goal CNC-ing the process is repeating the same shape over and over again, in other words eliminating variables.
the thumper the guy uses on the video is bigger by one size that what i will use. The weight will be 4kg. He uses 35mm head , i would be happy even with smaller as i would CNC it, not be in a rush i mean.







2. What i figured till now

I hope and i would like to be with moving gantry. Making a mill like, will be last resort.

Basically i have no problem with the general design. Big steel profile, sturdy table, double gantry as Johnathan build but with added 3rd rail somewhere higher as normal gantry for additional strength. Eventual Z box in the middle with 3 or even 4 No money will be saved for the sturdiness of the gantry and the table. Welded steel. I will design it so to resist a direct hit from a truck

I said rails. Now here is where i need help.
After a lot of thought and checking specifications and so i came to 2 conclusions. There was a bit consideration for the price also.
I decided that my best bet will be HIWIN Roller guide square supported rails , medium to heavy preload, 30 size.

The other choice i meditated a lot , was a big SBR rails like 30-50 size with double Plain Frelon carriages which are not cheap. Same price as big Hiwin roller carriages.


Then the movement. Here i am lost. Ball screws possibly with 2 nuts each on every axis, also 2 ballscrews for x, 2 for y and 2 for Z. Driven by short belts and so.

I also contemplate the possibility to make a floating Z plate and dumpen it with adjustable bike suspension, to imitate the rebound of the human hand when doing the same process, that could further lower the stress on the rails.

I will start posting the current design and will need your help here

Also it would be interesting if there is a chance to make it a separate machine with some kind of cheap heavy duty stuff instead of expensive Hiwin roller motion.
moved by belts or so.

One thing to me is clear though. It should be moved by at least Closed Loop Steppers, which i thing will be best.