try to use a Worm gear after the stepper, it naturally hold the load when power off.

@routercnc9517

6 ай бұрын

I did look at worm gears in the original design but the output speed is very low. Would need gearing up again. Still could be an option though. Thanks

Another thing that might be limiting your top speed is the lack of acceleration. If you're able to ramp up the speed in your code that could help.

@routercnc9517

6 ай бұрын

OK yes that’s a good thought.

@nils1953

6 ай бұрын

@@routercnc9517 I've been nagging you for the past 4 vids about this, but if you add a accelstepper library to your code, the max amount of steps per second from your Arduino nano is going to take a hit :D

@sketchaus

6 ай бұрын

100%,came here to say this. There is an arduino library that will do ramped acceleration pulse generation. Also, more current will give more torque which will help overcome acceleration

@routercnc9517

6 ай бұрын

OK thank you. I was planning to write my own code for the acceleration but I’ll check out that library first. Do you remember the name of it? I’ve tend to run higher voltage and low / medium current on steppers to limiting heating but I may experiment with more current as it will only run briefly and occasionally. Thanks for the suggestions.

Glad u got that sorted

@routercnc9517

6 ай бұрын

Me too!

As usual, your methodical way approaching things gets you there eventually. Keeping everything clean and tidy pays off as well. 👌 If I only had half of that myself. 😬😉

@routercnc9517

6 ай бұрын

Thanks for that. I like to tinker and when not in the workshop I spend a lot of thinking so when I do get time hopefully it will work (eventually!)

Nice video. I suggest to use a stepper motor with break. Stepper motors provide huge torque at low speeds. You can lock the break after Z-positioning, so you can apply more drilling forces. If you're looking for cheap servos check out the products of JMC (just motion control).

@routercnc9517

6 ай бұрын

Thanks I’ve been looking at braked steppers but only found 2Nm braked so far at £60. I’ll keep looking.

If you lower the steps on the stepper driver from 1600 to 800 or 400 you will get more Torque. But you probably mentioned it already somewhere why it’s not possible… 😅

@routercnc9517

6 ай бұрын

That would help but it sounds terrible! Hopefully I can avoid that but it is an option.

Really interesting problem solving video, have you considered (I'm pretty sure that the answer is yes) a counter weight approach to take some load off the screw and stepper. I don't see how it could be integrated, but you know your machine way better than I do, considering I've only seen the last 2 videos. Anyway, I'm sure you'll find a solution that doesn't involve selling a kidney. Your videos are really interesting, I'm looking to seeing the next ones !

@routercnc9517

6 ай бұрын

Thanks for joining us. Yes I have looked at a counterweight but it needs to be about 50kg so there are issues with that. Hopefully you will see what I try in the next video. Thanks

Waow perfect..

@routercnc9517

6 ай бұрын

Enjoy!

Have you considdered about a counterweight to match / reduce the wight of the table, may allow you to get alot more out of the stepper already have and can locate the weright in the back where the ball screw was previously located and adding pully at the top

@routercnc9517

6 ай бұрын

That’s basically what I’ve been studying. Counterweight would need to be pretty heavy so I’ve looked at other options and got some parts on order. The calculations say it will help quite a lot, the remaining issue will still be backdrive when off however.

@bonio55

6 ай бұрын

@@routercnc9517 how about a solenoid based brake that releases when on?

@routercnc9517

6 ай бұрын

@@bonio55It's an option but I would need to work out and spec all the components so the solenoid was powerful enough to apply the brake, or operate a cam system to release the pressure and the main braking force was provided by a spring. By the time I have done all that working out and designing it a stepper with an integrated brake might be cheaper/more reliable. Still considering the options.

@rok1475

6 ай бұрын

Stepper motors are current driven. Increasing supply voltage to the driver has no effect on the current, which is controlled by the driver. If the supply voltage is matched to the inductance of the coils in the motor, you get the fastest transition rate from one state to the other, which affects max acceleration only, not the torque.

I think if anyone is thinking of building a cnc machine you can buy marble resin body for around $2000 or less and it will be a far better starting point, and have far better performance not that this build isn't worth it but you need to have some balls to see it through, I think anyway.

The stepper motors are current-driven. Increasing the voltage supplied to the driver has no effect on torque since the driver controls the current. You keep thinking of stepper motors as standard DC or AC motors where the supply voltage is delivered directly to the coils in the motor. Steppers are a very different animal. There is a formula for the “ideal” supply voltage based on the inductance of the coil. The perfect voltage doesn’t affect the torque still, but it does affect the angle of the rising slope of the current pulse released by the driver and thus the max acceleration of the motor. Not torque, only acceleration.

@routercnc9517

6 ай бұрын

That is great info thank you. I have always thought of voltage as being needed to get the current into the motor quick enough against the inductance. So I’ve gone for low inductance motors and high voltage. But matching them makes sense. For current I’ve always thought this was limited by the driver and I needed to not set it too high as this will heat up the motor. Once I’ve got the backdrive problem sorted I’ll revisit the driver current setting. Thanks for the info!

@rok1475

6 ай бұрын

@@routercnc9517 most steppers work just fine up to about 100 degrees C. Don’t be afraid to run them at max current, even if they seem to heat up.

@routercnc9517

6 ай бұрын

OK that’s great thank you. I’m pretty sure these have a low current setting when idle to hold position. I’ll play with the current and see what happens. Unlike CNC machines this stepper will only run periodically.

there was 1 thing you did change the 2 bearings for the rails that will change the lifting power you need i think !

@routercnc9517

6 ай бұрын

The drag force on the carriages is very low so I think it was mostly the bearing preload issue, thanks.

Drilling with a stepper motor will likely need alot of torque?

@routercnc9517

6 ай бұрын

Yes that is not an option with this setup. I have a cheap part on order which may help.

You can do drilling cycles with a stepper motor. I don't know why you think you'd need servos? They make steppers with encoders and/or brakes. You could employ a worm gear that would fix the problem. OR throw a relay in there and short the stepper to itself when it's not in use. It will act like a brake. Or just have it park at the bottom of its travel when it shuts down. The harder, more expensive way is not always better

@routercnc9517

6 ай бұрын

Ok thank you I’ll have a look at braked steppers. Parking at the bottom is an interesting option. Worm drive is ok for backdrive but output is very slow and would need gearing up. Lots of options!

@routercnc9517

6 ай бұрын

Shorting the windings could work with the correct control system to avoid shorting the driver. Nice idea!

You may be able to use a 4 pole changeover relay to short the stepper windings together using the NC contacts when the power is off to act as a rudimentary brake. Alternatively, look at some of the "integrated" hybrid steppers, iHSV I think they are called. I use them on my DIY pick and place machine wiht great success. They are about £200 ish. They also have no brake, so you'd still have to design round that. I wonder if a simple bike disc brake may work for this? Or some other concoction :D

@routercnc9517

6 ай бұрын

Ok I’ll take a look. I did talk about adding a brake disc and solenoid but edited it out as it was getting too long. I made one for my daughter’s ekart (see video series!) which used a Bowden cable operated disc brake. Could be an option but would need design work on the solenoid power, spring rate etc.

@routercnc9517

6 ай бұрын

Shorting the windings is a great idea. I think the arduino would need to manage the process as shorting the windings to the driver will damage it. I could rig something up temporarily and see if it will resist drilling. Great idea !

@alex13902

6 ай бұрын

@routercnc9517 my thought was to hook the relay coil to the incoming 12 or 24v power directly. That way, when the power is removed, the NC contacts close, giving the short. Obviously if you wanted programatic brake for drilling, having it controlled by the arduino would be helpful, but a little less failsafe. If you were to put the windings to the COM terminal, you could easily put the short on the NC side, and the driver on the NO side. That way, power on is driver connected, power off is shorted.

@routercnc9517

6 ай бұрын

Ok nice idea. I think I will go with the 48V power though so maybe put 2x 24V relays in series (2 poles each?). I’ll quickly try something by manually shorting and see what it offers.

@neverwipe

6 ай бұрын

Wouldn't that cause the z axis to just creep down slower since you're relying on the induction of an opposing magnetic field which is a function of speed?

Now I'm hitched, trying to figure out what kind of wonder part you're speaking of that'll help you fix your remaining issues!.. Well glad to see it finally moving. Hopefully either with your mystery part, or a 3Nm stepper, it stays that way when you put some heavier Material in the vise when drilling. Other than that, are you going to add a regular clamping brake into the system? Because even if you've got headroom now, I'd imagine when you drill, the forces on the table would be quite a lot higher.

@routercnc9517

6 ай бұрын

3Nm stepper is on the way (just to get the most of it without much outlay). But it will still back drive without power so I may need to design a brake. I added a cable driven disc brake to my daughters ekart (see videos) so would need to work out a spring and solenoid system or similar.

@routercnc9517

6 ай бұрын

The mystery part should help with speed and backdrive but not sure about drilling loads. We will see when it arrives!

@jacksat2252

6 ай бұрын

As someone already mentioned, a counterweight with approximately the same weight as the table on the back machine connected to the table would solve some problems very cheaply and easy to do with little effort and no drastic change or redesign. It would solve the weight of the table at least .😉

@routercnc9517

6 ай бұрын

Trouble is the table and knee weighs about 50kg which is a lot of material to fit. Still looking at options along this lines. Thanks

@nils1953

6 ай бұрын

@@jacksat2252 people on the last video mentioned the same. Firstly there is a space requirement with a counterweight, not only on the back of the machine, but you need clearance for the cable and pulleys. If there is no space for it, it's a difficult task to get to. And a counterweight would still not help when drilling, the forces on the stepper when pushing on the table during use are much higher than the table weight itself.

what about using dog teeth on the lift screw

@routercnc9517

6 ай бұрын

Not sure what you mean. Dog gears have teeth on the side. If you mean worm gear then that would stop backdrive but the speed would be very slow.

Hi. I have a question a little out of topic but i saw in the past you used UCCNC software. In Settings / Spindle there are these two parameters "M7 delay after on:" and "M8 delay after off:" but in the manual i read ......"M7 delay after on: This is a numeric value. The software dwells for the set amount of time in milliseconds when a M7 command is programmed and after the Mist output goes active. M8 delay after on: This is a numeric value. The software dwells for the set amount of time in milliseconds when a M8 command is programmed and after the Flood output goes active...... so which is the right one ? The ON and OFF in the screen or the ON and ON in the manual ??? Thanks in advance for your help 🙂

@routercnc9517

6 ай бұрын

Unfortunately I don't use either of those functions. I turn the spindle and mist on manually. Try asking on the mycncuk forum, or there is a UCCNC (CNCdrive forum?) which is pretty active.

@IceCreams62

6 ай бұрын

@@routercnc9517 I will try this path. Thanks a lot in any case 🙂

@routercnc9517

6 ай бұрын

@@IceCreams62 No problem. Here is the cncdrive forum: cncdrive.com/forum/viewforum.php?f=1

@IceCreams62

6 ай бұрын

@@routercnc9517 Hi. Here the UCCNC Support reply: ""You're right, it's a typo on the screenset. M7 and M8 turns on the mist and coolant and the delays are after turning them on. The M9 turns off the M7 and M8, so the delay after off is for it. We will fix the screen, thanks for the input. "" Hope this helps somebody else 🙂

@routercnc9517

6 ай бұрын

Ok great, thanks for sharing the info as it might help someone who has the same problem.

A cheaper fix to get higher speed could be changing your ballscrew and nut to 10mm pitch. Same higher speed at half the rpm. So you keep the torque. A screw and nut would be about £60 and should fit your current design without any changes.

@routercnc9517

6 ай бұрын

It would give more speed but half the effective torque and double the backdrive force. So not a great option right now.

@Nealieboyee

6 ай бұрын

@@routercnc9517 I don't follow. Running the stepper slower should give you its full torque no? But your mm/min goes up because you're using a higher pitch screw.

@routercnc9517

6 ай бұрын

I did consider lower pitch such 1604, I would need to see what was available. Thanks

@Nealieboyee

6 ай бұрын

No the other way around. Go up to 1610 from 1605. So one revolution gets you 10mm of movement. Half the rpm gives you the same travel speed, but without sacrificing the torque. ​@@routercnc9517

@routercnc9517

6 ай бұрын

It could work but the torque increase at lower speed would need to be double, I’ll maybe run the numbers and see.

A servo moter seems the best option here.

@routercnc9517

6 ай бұрын

Quite expensive but it would solve all the issues in terms of power and braking. But the Arduino will not put out enough pulses to drive a servo. Do you know of a cheap high frequency pulse generating microcontroller? The one I used on my lathe ELS (Clough42 kit) was around £50.

@klaasbloem

6 ай бұрын

@@routercnc9517 You could look into the Windows based UCCNC system or the free Linuxcnc software, in both cases an old laptop or PC will do the job in combination with a Ethernet (or USB) motion controller.

@nils1953

6 ай бұрын

@@routercnc9517 depending on how many ports you want or if you want to add a digital pin expansion, teensy 4.0 boards are very good and easily fast enough, even if you want to add touchscreens. The small one is 19£ i think. I'm not sure how well they work together, but you can use the Arduino IDE on raspberry controllers. The zero has a 1ghz processor, and is only around 10 bucks so possibly the cheapest controller with a lot of processing power you can get. Though I should add that both options obviously don't have perfect support for all off the shelf libraries, if you want that you'll have to go with Arduino boards like a Due or Giga, but those are 50€+, so yeah.

@routercnc9517

6 ай бұрын

There are 3 replies for this question but I can only see mine. If someone is posting here please try again, thanks

@nils1953

6 ай бұрын

@@routercnc9517 Repost: depending on how many ports you want or if you want to add a digital pin expansion, teensy 4.0 boards are very good and easily fast enough, even if you want to add touchscreens. The small one is 19£ i think. I'm not sure how well they work together, but you can use the Arduino IDE on raspberry controllers. The zero has a 1ghz processor, and is only around 10 bucks so possibly the cheapest controller with a lot of processing power you can get. Though I should add that both options obviously don't have perfect support for all off the shelf libraries, if you want that you'll have to go with Arduino boards like a Due or Giga, but those are 50€+, so yeah.

'Prove out'????

@routercnc9517

6 ай бұрын

Are you referring to the new part on order or something else?

@HeathLedgersChemist

6 ай бұрын

@@routercnc9517 No, the horrible Americanism you used.

@routercnc9517

6 ай бұрын

@@HeathLedgersChemistOh, OK not sure where I said that but I use that expression regularly. Maybe 'verify' would be more British!

@HeathLedgersChemist

6 ай бұрын

@@routercnc9517Prove is perfectly fine. The appending of 'out' to everything is an inane Americanism.