Aluminium Profile Type Router - Initial questions

[AndyUK]

Would you mind expanding on this?

Hah! Yes, "Unless you're going down the linuxCNC route in which case I have no idea" :P

Reading it back it sounds like I'm saying don't use ethernet with LinuxCNC - it was meant as an "if you're using LinuxCNC there may be more appropriate options like onboard PCI cards".

[CNCRY]

Thanks Andy,

I'm trying to figure out whether 2005 or or 2010 ballscrew would be better, or 1605/1610 (which seems to be less available pre machined). I don't plan to use pulleys.
Problem is all calculations seems to lead to other values which I don't know what I'm aiming for!
So filling out a speeds and feed calc for say hardwood @ 20,000rpm spindle I get min/max of 9-11 M/min speed. Assume this is the cutting speed and the rapid people refer to are movement between cuts.
I also used zapp calculator to get critical speed of 20mm diameter ballscrew with 750mm spacing between supports giving 1548 RPM.
From forums someone gives 2010 screw @ 1348 RPM = 2.15m/min, so would the motor need to at appox 6740rpm to achieve that?
But also the motor Voltage driven needs to be known to get an idea of rpm which can be achieved?
I also don't know the final weight of the gantry, I'd estimate say 20Kg based on extrusion weight + spindle and alum plate.

On another note - have I already got off to a bad start using the non-heavy type of aluminium profile. This was from KJN, I intend to add plate/strengthening to make it more rigid.
Just installed fusion 360 to see if I can learn to create my design in diagram form:)

Ryan

[AndyUK]

I'm trying to figure out whether 2005 or or 2010 ballscrew would be better, or 1605/1610 (which seems to be less available pre machined). I don't plan to use pulleys.

Meh, get a custom quote from Fred and he'll machine whatever you want, it'll still probably be cheaper than the pre-machined, and you'll have a quality product from a trusted vendor.

So filling out a speeds and feed calc for say hardwood @ 20,000rpm spindle I get min/max of 9-11 M/min speed. Assume this is the cutting speed and the rapid people refer to are movement between cuts.

Yep. No feeds and speeds calculator will ever give you rapid speed recommendations. Do remember that it will also depend on how many flutes your cutter has.

From forums someone gives 2010 screw @ 1348 RPM = 2.15m/min, so would the motor need to at appox 6740rpm to achieve that?

Then that someone is a tit and can't do maths. It was probably me. The 2010 means that the outside diameter of the screw is 20mm, and the pitch is 10mm. In one turn of the screw, the ballnut will move 10mm. So 1348 turns per minute equals 13480mm/min = 13.48m/min.

But also the motor Voltage driven needs to be known to get an idea of rpm which can be achieved?

Its less about the voltage, more about how much torque you have left when you get up to those RPMs, which then dictates how quickly you can accelerate and decelerate. Whilst I spent a lot of time doing the calculations, I still ended up with the same motors as everyone else with the machine size, so for starters find a decent build about the same size and steal their motor and PSU configuration :P Work forwards from that.

I also don't know the final weight of the gantry, I'd estimate say 20Kg based on extrusion weight + spindle and alum plate.

Quite machine dependent, but I'd guess you're lowballing it. A 2.2kW Spindle is approx 8kg alone. Rails + Ballscrews + Plates + Motors + Extrusion should be a good ballpark. Maybe nearer 30-40kg?

[CNCRY]

Thanks for bearing with me, now I have the whole idea in my head I'm keen to start building , but want to do it right first time so remaining patient, and re-thinking the design.
Is Fred the BST automation aliexpress store? What sort of lead time do people get with him and is there a ballpark % amount of import duty etc to be expected?
That RPM calculation was from a U.S forum in IPM, and was clearly wrong then. Thats clear now, so with the 10mm pitch I'd need to aim for 1000rpm to get 10m/s cutting speed, which should be about right for a 2 flute cutter in hardwood. While Aluminium would need to aim for 5m/s or 500rpm at the motor?
So from most similar builds I have seen everyone ends up with 3/4NM Nema 34 motors, but there is variation in how they can be driven.
Trying to pin down some aspects so I can then design around those.
You are right on gantry weight . Profile is 8kg + 8Kg spindle + perhaps 10kg rails and carriages + aluminium plate + motor - more like 35Kg.
Ryan

[Kitwn]

Is Fred the BST automation aliexpress store? What sort of lead time do people get with him.
Ryan

Ryan,
Yes, Fred is BST Automation. I fell of the sofa when my leadscrews and rails arrived in remote western Australia only 4 days after I paid for them. It often takes longer than that to get stuff from the state capitol Perth. You do pay quite a lot for delivery though and it's worth checking the different total cost for item + postage and 'free' postage for the same thing.

Don't forget that many Chinese businesses are closed at present because of the virus so delivery times at the moment are anybody's guess.

I don't know about import duties to Pommieland but make sure you know the total cost before comparing suppliers.

[guciTaums]

I would like to know what kind of forum is this? phpbb? Guci

[JAZZCNC]

Hi Ryan,

Let me just say from the start that the Heavy Mill 3DTEK as got some serious issues and it's far from its name suggests.

First off scrap the Z-axis altogether it's load of rubbish and far too flimsy. The Z-axis is THE most important part of the machine because it's where all the action happens. If it's weak then it doesn't matter if the rest of the machine is built like a tank your cutting will always suffer.
Also, no point using Hi-win profiled linear rails on other axis if going to use a round rail on Z-axis, use either all-round or all profiled. You are wasting your money mixing them.

Next is the Gantry sides, they are also weak and flimsy. They will resonate and flex which again transfers into the cut. To be honest the whole gantry is on the weak side and could easily be made stronger with a design change. Even the Light profile will work if you used an L shaped design.

Regards the ball-screws you will be better with 16mm x 10mm pitch for a wood router at this size. 10mm pitch will easily allow you to cut aluminum without any problems. Whereas 5mm would be too slow for cutting wood correctly.
You don't need 20mm for a machine this size and it will only rob you of power and speed because of the extra inertia of the ball-screw. It takes more power to accelerate and deaccelerate than 16mm and it does make a big difference to performance.

Regards the electrics and controller then always go with Ethernet if you can afford the extra, it's much more stable than USB or parallel port.

Andy mentions Voltage isn't so important but I'm afraid he's wrong, It's very important to the speed and torque you'll get from a stepper motor. The torque you get from a motor is proportional to voltage so if you increase the voltage the torque will also rise, up to a point. To get high speeds from a stepper you need voltage which is why we try to use higher voltage drives so we can boost voltage. Obviously there is a limit dependant on motor/drive specs etc but in general, more volts = higher rpm which is better for a router.

Regards the Motor, drives and PSU spec then there is a well-proven spec for machines this size which has been used for a long time on this forum. Which I'm happy to help you with. However, I'd also advise you to consider looking at Closed-loop steppers as they have come down in price quite a lot and are much better than the standard stepper systems. This could change things a little regards PSU etc depending on which you go for. So go have a look at them if you haven't already and let us know your thinking.?

BIGGEST ADVISE is don't buy anything else until your 100% sure it's correct. Also don't buy electrics until needed as your wasting warranty and things change fast these days regards controllers/software and drives you could end up with a better system by waiting until needed.

Don't be afraid to ask questions no matter how dumb you may think they sound.

[CNCRY]

Hi Ryan,

Let me just say from the start that the Heavy Mill 3DTEK as got some serious issues and it's far from its name suggests.

First off scrap the Z-axis altogether it's load of rubbish and far too flimsy. The Z-axis is THE most important part of the machine because it's where all the action happens. If it's weak then it doesn't matter if the rest of the machine is built like a tank your cutting will always suffer.
Also, no point using Hi-win profiled linear rails on other axis if going to use a round rail on Z-axis, use either all-round or all profiled. You are wasting your money mixing them.

Next is the Gantry sides, they are also weak and flimsy. They will resonate and flex which again transfers into the cut. To be honest the whole gantry is on the weak side and could easily be made stronger with a design change. Even the Light profile will work if you used an L shaped design.

Regards the ball-screws you will be better with 16mm x 10mm pitch for a wood router at this size. 10mm pitch will easily allow you to cut aluminum without any problems. Whereas 5mm would be too slow for cutting wood correctly.
You don't need 20mm for a machine this size and it will only rob you of power and speed because of the extra inertia of the ball-screw. It takes more power to accelerate and deaccelerate than 16mm and it does make a big difference to performance.

Regards the electrics and controller then always go with Ethernet if you can afford the extra, it's much more stable than USB or parallel port.

Andy mentions Voltage isn't so important but I'm afraid he's wrong, It's very important to the speed and torque you'll get from a stepper motor. The torque you get from a motor is proportional to voltage so if you increase the voltage the torque will also rise, up to a point. To get high speeds from a stepper you need voltage which is why we try to use higher voltage drives so we can boost voltage. Obviously there is a limit dependant on motor/drive specs etc but in general, more volts = higher rpm which is better for a router.

Regards the Motor, drives and PSU spec then there is a well-proven spec for machines this size which has been used for a long time on this forum. Which I'm happy to help you with. However, I'd also advise you to consider looking at Closed-loop steppers as they have come down in price quite a lot and are much better than the standard stepper systems. This could change things a little regards PSU etc depending on which you go for. So go have a look at them if you haven't already and let us know your thinking.?

BIGGEST ADVISE is don't buy anything else until your 100% sure it's correct. Also don't buy electrics until needed as your wasting warranty and things change fast these days regards controllers/software and drives you could end up with a better system by waiting until needed.

Don't be afraid to ask questions no matter how dumb you may think they sound.

Appreciate the advice JazzCNC
Heavy Mill was my initial idea as I could see how it was constructed, plus I assumed must be a sufficiently good design to sell:) I'll not be copying it's Z axis in that case, and will design on the same rail setup instead. As I just mentioned in reply to Andy - im's trying to establish some "fixed" ideas and design around that, but X changes so does Y!
So one thing I did notice on heavy mill were weak side's so my design there is similar to Andys log = http://www.mycncuk.com/attachment.ph...3&d=1573338796 . That is rails on top on the extrusion, then a carriage and aluminium block which the gantry rail site on top of,and fixed using side plates .

I'll be looking into 1610 ballscrew based on both the replys now.
Do closed loop steppers work with standard nema motors ? I'll take a look.

I'll be trying to draw this in a shareable format soon. But design steps wise, can I design/build the X/Y axis and gantry to a good standard, then consider the Z axis as the next "module" or is that a bad idea!
If I know the motors to be used, I can pretty much leave electronics until the build progresses, and certainly won't buy anything related to that yet.
Will my existing 120 x 40 profile with 40x40 cross pieces suffice for X/Y axis with extra bracing?
And with the L design for gantry - just thinking how I can incorporate the 90x90 profile, perhaps a 60x60 attached to it at the back?

Ryan

[JAZZCNC]

So one thing I did notice on heavy mill were weak side's so my design there is similar to Andys log = http://www.mycncuk.com/attachment.ph...3&d=1573338796 . That is rails on top on the extrusion, then a carriage and aluminum block which the gantry rail site on top of,and fixed using side plates .

Yes, this is the L design I was suggesting, most of the L designs you'll see are based off my original design or someone else's who took from mine, it can be used both with or without Gantry sides and makes for a very stiff gantry with easy rail mounting etc. When mounting directly to the bearings just bear in mind access to the bearings bolts when deciding the bearing plate length. I've seen several designs that missed this little detail, which is why it's a good idea to draw it in cad to catch these things.

Do closed loop steppers work with standard nema motors ? I'll take a look.

No closed loop steppers have an encoder on the back which goes to the matching drives. Also often closed loop steppers are 3 phase steppers with smaller step angle of 0.9 or 1.2 deg whereas typical stepper is 2 phase. with 1,8deg step. The difference being closed-loop are smoother.

I'll be trying to draw this in a shareable format soon. But design steps wise, can I design/build the X/Y axis and gantry to a good standard, then consider the Z axis as the next "module" or is that a bad idea!

Yes you can but I wouldn't recommended it because your better designing the whole thing in CAD to see if anything clashes.

If I know the motors to be used, I can pretty much leave electronics until the build progresses, and certainly won't buy anything related to that yet.

All you really need to know is the motor frame size ie: NEMA 23 or 34. Now I've seen you mention Nema 34 is what you need.! This would be bad for a machine this size and mistake often made by new builders are thinking bigger is better, it's not.!
NEMA 34 motors require a much higher voltage to get the RPM needed for a router. A 4Nm NEMA 23 will perform much better than a 4Nm Nema 34 at the same voltage.

Will my existing 120 x 40 profile with 40x40 cross pieces suffice for X/Y axis with extra bracing?
And with the L design for gantry - just thinking how I can incorporate the 90x90 profile, perhaps a 60x60 attached to it at the back?

Yes, the 120x40 and 40x40 could be used for the frame with bracing.
Regards the Gantry then Bolting 60x60 onto the back won't do anything other than add weight. To get the stiffness and height you need one piece flat with the other bolted on top. So either buy a wider piece for the bottom and put the 90x90 on top or start again with 2 x 45 x 90.
I'm assuming that your using BR range profile because of the 90mm. This is good because when using 16mm screws then the BK End bearings mounting holes will line up with the 45mm slot spacing. If you used the IR with 40mm slot spacing then you would have to make plates or drill the profiles to bolt the bearings on.

It's these little things that catch you out and cause more work. Hence why drawing in CAD can save many wasted days and money.

[CNCRY]

Yes, this is the L design I was suggesting, most of the L designs you'll see are based off my original design or someone else's who took from mine, it can be used both with or without Gantry sides and makes for a very stiff gantry with easy rail mounting etc. When mounting directly to the bearings just bear in mind access to the bearings bolts when deciding the bearing plate length. I've seen several designs that missed this little detail, which is why it's a good idea to draw it in cad to catch these things.



No closed loop steppers have an encoder on the back which goes to the matching drives. Also often closed loop steppers are 3 phase steppers with smaller step angle of 0.9 or 1.2 deg whereas typical stepper is 2 phase. with 1,8deg step. The difference being closed-loop are smoother.



Yes you can but I wouldn't recommended it because your better designing the whole thing in CAD to see if anything clashes.



All you really need to know is the motor frame size ie: NEMA 23 or 34. Now I've seen you mention Nema 34 is what you need.! This would be bad for a machine this size and mistake often made by new builders are thinking bigger is better, it's not.!
NEMA 34 motors require a much higher voltage to get the RPM needed for a router. A 4Nm NEMA 23 will perform much better than a 4Nm Nema 34 at the same voltage.




Yes, the 120x40 and 40x40 could be used for the frame with bracing.
Regards the Gantry then Bolting 60x60 onto the back won't do anything other than add weight. To get the stiffness and height you need one piece flat with the other bolted on top. So either buy a wider piece for the bottom and put the 90x90 on top or start again with 2 x 45 x 90.
I'm assuming that your using BR range profile because of the 90mm. This is good because when using 16mm screws then the BK End bearings mounting holes will line up with the 45mm slot spacing. If you used the IR with 40mm slot spacing then you would have to make plates or drill the profiles to bolt the bearings on.

It's these little things that catch you out and cause more work. Hence why drawing in CAD can save many wasted days and money.

Thanks Jazz - going to spend the next week or so learning fusion 360 and actually drawing the thing:) Probably makes sense to learn to use CAD alongside building a CNC machine!
The Nema motor - that was me being a muppet. I do mean Nema 23 4NM.
I guess the hybrid steppers are perhaps £50 more each with a driver package then a normal stepper and decent driver, something like https://www.cnc4you.co.uk/Stepper-Mo...-Servo-Kit-4Nm. ?

RE: the profile, I spent a fair amount so far so would really want to avoid wasting . You are right its the BR as below with 45mm spacing, so will make mounting easier.



So do you mean
40x120L along the bottom with 90x90 on top. Notice the slot spacing on that is 40 so no way to direct join - but I guess joining plates at ends will do?



for BST automation shop, which as mentioned is probably not sending anything right now - something like
3 X Anti Backlash Ballscrew RM1610 -L1000mm with SFU1610 Ballnut + BK12 BF12 Support Unit + 1610 Nut Bracket + 6.35*10mm coupler shows as $141 + $107 shipping. $248 total. I've never order anything over a few £ from china - what import duty do people get hit with? Looks like VAT+2.5%?

Ryan