Accurate Strong Gantry

[JAZZCNC]

Hi,
Incredibly detailed piece, very nice done.
The patterns are so sharp even in a mm .
What sort of material is it?

Aluminium 6082T6 cut with a simple 90degree spot drill nothing fancy.

Regards the belts and cutting conditions let me just say my machine 99% of the time it's been built has cut nothing but aluminium and the belts are completely uncovered being exposed to millions of flying sharp and very hot chips so are working in the worst enviroment and I've only ever had to replace two belts. This wasn't because of wear it was because I left a pulley loose which fell off after adjustments for a bracket for sensing belt breakage. (It was a very good real world test of my new belt E-stop.!)
The other I trapped and damaged moving the machine due to not being covered. (So do as I say, not do as I DO, and cover your belts from the start other wise it never get done.!!)

[vargai]

at first sight thought painted wooden, but it cannot be done so sharp

[JAZZCNC]

at first sight thought painted wooden, but it cannot be done so sharp

Yes probably because of poor video done with phone camera.! . . .Looks much better in real life and very shiny.

[Sven]

I have a similar set up just 90 mm wider. I would not do it again, setting it up without backlash is a pain.

Next one wil have a dual stepper, a leadshine easy servo, which is a stepper with encoder.

In this design I would box up the 4 beams so they become one, that is much stiffer.

[vargai]

Hi Sven,

Yes , the four box should be redesigned somehow, originally I wanted to tie the boxes with 3, 4 plates to work together after placing the
ball screw
What does the similar exactly-how did you make the synchronising?
Nothing is written in stone-just thought to skip the step with stepper and make higher grade machine but do not know too much about stepper.
I hear of lead shine and certainly stepper technology becomes better so if there is an reliable option instead the more expensive servo why not.
My friend who is member of a CNC DIY group made a 5axis machine with steppers for woodwork upon order.
They mates from the group says: everything is ok but why did not you use servos.
Probably stepper is undervalued in public awareness.

[Sven]

I have the second setup in your diagram, with the motor in the middle. It is impossible to get enough tension in the belt without putting big loads in the spindle bearings.
I added a guide to push the middle section of the belt above the motor to reduce floppiness. still not good.

[vargai]

So you are a doubter of using belt based on your experience.
Others have well working machine with this set up.
I am just an outsider at the moment, the best thing is to ask Dean to show a short video of a working machine .
Would you be so kind to do it, Dean?

[vargai]

I have the second set up in your diagram, with the motor in the middle. It is impossible to get enough tension in the belt without putting big loads in the spindle bearings.
I added a guide to push the middle section of the belt above the motor to reduce floppiness. still not good.

Let me know about the data bearing type, size, belt type, size and experienced phenomenon
angular bearing on drive side it can bear more load than single row
20/10 ball screw with Dia 15 machined end -bearing can hold let's say max 1 Tons here

[Boyan Silyavski]

Let me know about the data bearing type, size, belt type, size and experienced phenomenon
angular bearing on drive side it can bear more load than single row
20/10 ball screw with Dia 15 machined end -bearing can hold let's say max 1 Tons here

Hey,
no tons here!! You have to read well the belt documentation! Find the belt tension formula on Gates web, calculate the tension for your exact setup and then using guitar tuner / or app on your phone/ tension the belt to the proper tension . This is a must to do it properly.

So the force you apply is not tons. Lets say its the force i can apply with one hand and using as a lever say 15mm screw driver against the motor and the frame. With say 20-25cm screw driver i exceed that force and over tighten the belt easily. Of course i have done it at the beginning with tuner, but now just know how a properly tensioned belt feels and sounds.

That means you have to design it so that you could lever somehow the motor with a wrench , screw driver or make some tightening mechanism. That does not mean introducing unnecessary idlers and tensioners.

I have the second setup in your diagram, with the motor in the middle. It is impossible to get enough tension in the belt without putting big loads in the spindle bearings.
I added a guide to push the middle section of the belt above the motor to reduce floppiness. still not good.

Now if you have read what i posted before and belt documentation may be you don't have the proper belt cord or you have not designed it to be tensioned properly. I tension the belts with one hand only and a screwdriver or a wrench, using them as a lever against the frame. So if you don't have where to lever them, drill a hole and fix something to be used as a support for the lever.

So are you idlers bigger than 20 tooth pulley as per belts specification? Cause if they are smaller, misaligned or whatever not properly followed, may be thats the problem.

Yeah , i advised against long belts exactly cause people don't bother to read carefully 300 pages belts manual and maybe they miss something or do some basic mistake. Yeah, Deans machine works, but he has knowledge and experience so his machine is an example that there is no problem with the design, not that if say you, me or sb else could do it with the same success.

I will give you an example - Honestly how many people know point 6 below. About the idlers size and placement. Most people i have seen on the forums think that they could place idlers where they want and 99% of the idlers are made by 3x 608 bearings stuck together, which in diameter a much smaller than 20 tooth pulley/which is ok for 10mm wide belts but not 25mm as is this case/


Also look at number 4. The machine sides should be stiff enough.




What i mean is RTFM, do everything properly and all will be smiles and sunshine.

[vargai]

Next one wil have a dual stepper, a leadshine easy servo, which is a stepper with encoder.

Hi Sven,
I read a short 20 page long description of leadshine easy servo and did not find mentions of dual purpose.
Can you point to it ie. link or so?
Thanks
István