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NordicCNC's build log
Change log
10.3.2020 - Z-axis ratio changed to 2:1. Removed 48V power supply from component list. Added Delta 400W servo motors to component list.
4.3.2020 - Ballscrew dimensions changed.
4.3.2020 - Motor and power supply alternatives added.
Hello,
I’ve decided to start a build log in order to collect all the advice I receive in one single place. I found myself having to go back to all my posted questions, to refresh my memory quite often.
The idea is to build a good CNC milling machine for myself that I will use for my own projects. I plan to take a modular design approach when building this machine. What this means I can explain in another post upon request! Note that this just an approach that I will use for fun and it will not be a deal breaker if it turns out to be too complicated or doesn’t succeed for other reasons.
Machine requirements
The machine will be designed based on following requirements:
- The budget is undefined but I prefer to stay below 8000€.
- Stiff enough to machine aluminium with good tolerances and surface finish. What I mean with good finish is that the finished product should not have a terrible surface. If I can achieve the same surface finish as in this video, I would be more than happy: https://www.youtube.com/watch?v=xyVr35pgx7s
- Fast feed rates for machining large wooden sheets.
- Auto tool change spindle is preferred. Possibility to downgrade to a manual tool change spindle if the budget requires it.
- The footprint is not critical but is preferred to be as small as possible for the following working area: Y-axis (base frame): 1400mm, X-axis (gantry): 1000mm, Z-axis (spindle axis): 200mm.
Machine control and software
- I already own a Mach3 license and will continue using it. In the future I can upgrade to Mach4 if I find it necessary.
- Interface cards Ethernet SmoothStepper (ESS) https://www.cncroom.com/interface-cards/ess-mb3. This I already own. Breakout board will be MB3.
- MB3 breakout board: https://www.cncroom.com/interface-cards/ess-mb3.
- The MB3 and ESS will be powered with a 24V, 150W & 6.3A power supply: https://www.sorotec.de/shop/Power-su...A-Heng-Fu.html
- Delta servo motors (400W, 3000rpm) with brake (for Z-axis): https://www.aliexpress.com/item/3267...23d152a8ZJcwMZ. - Was JMC 180W servo motor.
- Delta servo motors (400W, 3000rpm) without brake (for X- and Y-axis): https://www.aliexpress.com/item/32671356516.html?spm. - Was JMC 180W servo motor.
- 3kW Auto tool change spindle with BT30 tool interface combined with a 3.7kW VFD: https://www.ebay.com/itm/3KW-220V-AT...r/264448370955
Z-axis design & components
The solution I will be using to allow for the heavy ATC spindle is to keep the Z-axis weight as low as possible. Linear rails, ballscrew & bearings, and servo motor will all be mounted on the rear plate. The ballscrew nut housing and guide carriages will be mounted on the front plate. This is based on the advice that there is not much difference between front/rear mounting when it comes to stiffness. Yes, it is slightly stiffer with front mounted linear rails, but this is a compromise I need to take. The gantry clearance will be 200mm. Anyway I will still be able to surface components up to a height of 240mm and with a diameter of around 160mm, since it will be possible to raise the tool above the bottom of the gantry. I could also decide to make the rear plate longer to further increase the height if I want.
Components that I plan to use:
- Aluminium tooling plates
- HIWIN linear rails: 20mm
- Delta 400W servo motor, with brake - Was JMC 180W servo motor.
- Ballscrew: 1605 - Was 1605 or 2005.
- HTD 5M pulleys with a 2:1 ratio Was 3:1
- 3kW Auto tool change spindle
X-axis design & components
The gantry will L-shaped and be made with 120x80 or 160x80 aluminium profiles. Aluminium keys will be inserted into the t-slots and then the profiles are bolted together from the bottom. Side plates will be used to mount the profiles together from the side. I am still debating if I will go for high gantry sides combined with aluminium profiles similar to JAZZCNC’s design, or with raised gantry. Linear rails with be top/front mounted to get maximum gantry clearance and maximum spacing between the guide carriages. It will also allow for Z-axis vertical tram. The ballscrew will be placed on the rear side of the gantry to stay clear of chips.
Components that I plan to use:
- Aluminium tooling plates
- Item equivalent aluminium profiles
- HIWIN linear rails: 20mm
- Delta 400W servo motor, without brake - Was JMC 180W servo motor.
- Ballscrew: 2010 - Was 1610 or 2010.
- HTD 5M pulleys with a 2:1 ratio
Y-axis design & components
I’ve learned that it is recommended to make a welded steel frame and use epoxy levelling to get flat surfaces for the linear rails. It is also cheaper. I consider myself a good welder and I have the possibility to make a welded steel frame. Does the welded frame have to be stress relieved or is that not required? I am not sure where I would find any local company that could do that for me. If I go for the welded steel frame, what are the recommended box section dimensions?
The machine will have be moved to my own garage at some point in the future (2-3 years from now), since I am building it in my parents garage. This is the main reason why I am still debating on using aluminium profiles for the base frame. With aluminium profiles I would be able to disassemble it and assemble it again once I move to my own garage. If I decide to use aluminium profiles I will probably use 120x80 or 160x80 aluminium profiles.
To allow for easier alignment of the linear rails I am planning to mount them to the top of the base frame. The guide carriages will be mounted together with separate aluminium plates, which will allow for some adjustment of the X-axis gantry to get the machine square.
Components that I plan to use:
- Aluminium tooling plates
- Item equivalent aluminium profiles
- HIWIN linear rails: 20mm
- Double Delta 400W servo motor, without brake - Was double JMC 180W servo motor.
- Double ballscrew: 2010 - Was 1610 or 2010.
- HTD 5M pulleys with a 2:1 ratio
Continuing forward
I will start posting updates of the design as it progresses. Any advice is very welcome.
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Re: NordicCNC's build log
Hi,
Some comments in no particular order, assuming you want to build a decent machine and not a toy:
- 1400 x 1000 x 200 mm is a _huge_ working area. I would expect a machine that size to weighs at least 1500 kg.
About servos:
- those 180W JMC servos are toys and seriously underpowered if you want decent speeds. If you want to go servos, use some proper ones. Delta servos are cheap and good. You need to size the motors depending on the max feed/rapid rates and accelerations you seek. 400W is probably the bare minimum.
- Personally I expect a router this size to be fast, I would target 30m/min (1000 ipm) and maybe 0.5g accel.
About ballscrews:
- 10mm pitch ballscrew would be the minimum I'd use, without any reduction. With servos direct-drive is the best and the cheapest. Good pulleys are expensive, and add unwanted inertia to the system. Servos are usually rated at 3000rpm, with 10mm pitch this gives you a max speed of 30m/min.
- 5mm pitch ballscrew is acceptable for the Z axis. Again without reduction. If you really want pulleys for space issues, use 1:1.
- Ballscrew diameter: you need to calculate it depending on the desired max speed. A ballscrew 1400mm long that don't whip at 3000rpm with fixed-floating ends is around 60mm diameter... If this sounds too big you can go with rotating ballnut (complex) or larger pitch. 20mm pitch would be ideal and you would only need 32mm ballscrews.
About rails:
- don't bother with anything less than 25mm. For the simple reason that 20 rails use M5 bolts and require tighter drilling positioning tolerances.
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Re: NordicCNC's build log
Quote:
Originally Posted by
jarjar
Hi,
- 1400 x 1000 x 200 mm is a _huge_ footprint. I would expect a machine that size to weighs at least 1500 kg.
Those measurements are all in MM you know? Do you consider that to be huge? That just seems a little bigger than AndyUKs and a couple of others I've seen on here.
EDIT: Are you saying it's huge for a MILL?
The reason I'm asking is because I was looking to build a machine that had a cutting area that could accommodate 1.2m X 0.8m and the proportions in Nordic's build are about the same as I was calculating.
Cheers
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Re: NordicCNC's build log
It all depends on your requirements.
But if you're after speed, good tolerances and surface finish in aluminium, it is, indeed, huge.
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Re: NordicCNC's build log
Quote:
Originally Posted by
jarjar
Hi,
Hi and thanks for your comments, very much appreciated! I will add my replies below.
Quote:
Originally Posted by
jarjar
Some comments in no particular order, assuming you want to build a decent machine and not a toy:
- 1400 x 1000 x 200 mm is a _huge_ working area. I would expect a machine that size to weighs at least 1500 kg.
Yes it is a huge working area! About the weight, I've quickly added all components to my build with assigned material weights etc. and it sums up to about 200kg right now. I excpect it to be around the 300kg mark once everything is mounted (with aluminium profiles as base frame). Not much is missing so I am not sure if you thought that the whole machine would be built out of steel? Then the 1500kg would make sense.
Quote:
Originally Posted by
jarjar
About servos:
- those 180W JMC servos are toys and seriously underpowered if you want decent speeds. If you want to go servos, use some proper ones. Delta servos are cheap and good. You need to size the motors depending on the max feed/rapid rates and accelerations you seek. 400W is probably the bare minimum.
- Personally I expect a router this size to be fast, I would target 30m/min (1000 ipm) and maybe 0.5g accel.
Yep, I realized this later (NEVER BUY PARTS BEFORE DESIGN IS READY) that I would've been better of getting either 400W JMC servo motors or 400W delta servo motors (seems to be pretty much the same price and specs!) or even stepper motors.
Targeted speed is 15m/min and about 0.25-0.5G acceleration. This I plan to achieve with a 2:1 ratio with 3000rpm and 10mm pitched ballscrew. I will also achieve some increased torque with the 2:1 ratio, which will be helpful for these small beasts of servos.
Here are some references where some people are testing these specific servo motors. According to description section he is running at 12m/min at 0.25G at a 2:1 ratio with a 10mm pitch.
https://www.youtube.com/watch?v=xyVr35pgx7s
https://www.youtube.com/watch?v=nd19IBllD2I&t=32s
Here is another one with some amusing testing. Same video in both links but at different time stamps.
https://youtu.be/ZMxzRn9GrKY?t=330
https://youtu.be/ZMxzRn9GrKY?t=420
Quote:
Originally Posted by
jarjar
About ballscrews:
- 10mm pitch ballscrew would be the minimum I'd use, without any reduction. With servos direct-drive is the best and the cheapest. Good pulleys are expensive, and add unwanted inertia to the system. Servos are usually rated at 3000rpm, with 10mm pitch this gives you a max speed of 30m/min.
- 5mm pitch ballscrew is acceptable for the Z axis. Again without reduction. If you really want pulleys for space issues, use 1:1.
- Ballscrew diameter: you need to calculate it depending on the desired max speed. A ballscrew 1400mm long that don't whip at 3000rpm with fixed-floating ends is around 60mm diameter... If this sounds too big you can go with rotating ballnut (complex) or larger pitch. 20mm pitch would be ideal and you would only need 32mm ballscrews.
I wanted to use belt drive to be able to experiment with ratios, mounting simplicity and to hide the motors so that they are not protruding. Using direct drive with 3000rpm and 10mm would be too much as you said for 16mm ball screws. This is another reason why I intend to use a 2:1 ratio, which would result in 1500rpm.
What calculator are you using to calculate those diameters (link or fomula)? I have not seen anyone in here that size of ball screws! I keep seeing the recommended sizes being 1610 and 2010. I will be happy with 15m/min anyway.
Quote:
Originally Posted by
jarjar
About rails:
- don't bother with anything less than 25mm. For the simple reason that 20 rails use M5 bolts and require tighter drilling positioning tolerances.
If I go for the aluminium profiles on the Y-axis (base frame), then I will only have to drill and tap the M5 bolts onto the rear Z-axis plate. This plate size fits well in my shitty CNC router that I built 10 years ago. It can handle the requires tolerances needed for those holes, I am pretty sure.
Anyway, do you think 25mm would be to prefer over 20mm rails for the sake of stiffness?
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Re: NordicCNC's build log
Quote:
Originally Posted by
jarjar
Some comments in no particular order, assuming you want to build a decent machine and not a toy:
Well that really depends on the definition of decent and a toy. Arn't all home machines practically toys when compared to industrial VMCs? Your line seems very arbitrary. Nordic has stated he wants a 'good' surface finish in Aluminium, which really he should be using a mill style machine for - so I see where you're coming from there, but again, define 'good'.
Quote:
Originally Posted by
jarjar
- 1400 x 1000 x 200 mm is a _huge_ working area. I would expect a machine that size to weighs at least 1500 kg.
... Why? This size is about standard for most of the build logs. Huge for a mill, still quite a small router. 1500kg? I think mines about 500kg... Sure added weight helps dampen vibration and makes sense, but there isn't any reason it must weigh that much. And hey - if its on rollers who cares? Lift and move with jacks.
Quote:
Originally Posted by
jarjar
About rails:
- don't bother with anything less than 25mm. For the simple reason that 20 rails use M5 bolts and require tighter drilling positioning tolerances.
That seems like a terrible reason to spend more money. A standard clearance hole for M5 gives you 0.5mm of wiggle. By marking out carefully, setting up the rails with clamps and a dial guage, then using a transfer punch, this is more than enough.
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Re: NordicCNC's build log
Quote:
Originally Posted by
AndyUK
Well that really depends on the definition of decent and a toy. Arn't all home machines practically toys when compared to industrial VMCs? Your line seems very arbitrary. Nordic has stated he wants a 'good' surface finish in Aluminium, which really he should be using a mill style machine for - so I see where you're coming from there, but again, define 'good'.
Hi Andy! Thanks for pointing this out. I will update the starting post with what my definition of good means. With good I mean that after my finishing pass, I want a smooth surface on which you should not/rarely be able to see vibration marks if you don't look extremely closely. The tolerances that you can achieve with a machine also very much depends on the machine operator. You cannot expect to get a good tolerance with roughing passes, even with industrial machines without using some tool compensation or adjusting the G-codes.
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Re: NordicCNC's build log
Quote:
Originally Posted by
AndyUK
Nordic has stated he wants a 'good' surface finish in Aluminium, which really he should be using a mill style machine for - so I see where you're coming from there, but again, define 'good'.
A "mill style" machine doesn't mean anything. The style of structure (C-frame, fixed gantry, moving gantry, ...) of a machine has nothing to do with its capabilities. Some are just easier to make stiff than others.
Quote:
Originally Posted by
AndyUK
... Why? This size is about standard for most of the build logs. Huge for a mill, still quite a small router. 1500kg? I think mines about 500kg... Sure added weight helps dampen vibration and makes sense, but there isn't any reason it must weigh that much. And hey - if its on rollers who cares? Lift and move with jacks.
Just some number I have in mind when someone tells me he wants to build a 8000€ router this size to do aluminium work. A Datron with similar working area is 2.5t for comparison. Stiffness comes with weight when using standard material (metal).
Quote:
Originally Posted by
AndyUK
That seems like a terrible reason to spend more money. A standard clearance hole for M5 gives you 0.5mm of wiggle. By marking out carefully, setting up the rails with clamps and a dial guage, then using a transfer punch, this is more than enough.
Indeed I was wrong about that. The clearance is the same for M6 bolts. Still the price difference is low and bigger is always better for rails... It helps for stiffness, ballscrew clearance, and the rails are better supported when mounted on T-slots profiles.
@NordicCNC
You still need a 32mm ballscrew at 1500rpm and 10mm pitch for 1400mm travel. Calculator for critical speed.
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1 Attachment(s)
Re: NordicCNC's build log
Quote:
Originally Posted by
jarjar
Just some number I have in mind when someone tells me he wants to build a 8000€ router this size to do aluminium work. A Datron with similar working area is 2.5t for comparison. Stiffness comes with weight when using standard material (metal).
I've added some clarification to what I mean with good finish. I am not looking to be competitive with a Datron machine, luckily! Maybe an even better description of what I mean by good finish is that the finished product should not have a terrible surface.The surface finish achieved in this video, I would be more than happy with: https://www.youtube.com/watch?v=xyVr35pgx7s
Quote:
Originally Posted by
jarjar
Indeed I was wrong about that. The clearance is the same for M6 bolts. Still the price difference is low and bigger is always better for rails... It helps for stiffness, ballscrew clearance, and the rails are better supported when mounted on T-slots profiles.
Yes, price difference seems to be only about 15-20% for either 25mm or 30mm rails. If it is bringing me added value and it isn't overkill, I think I am ready to go for the 30mm rails.
Quote:
Originally Posted by
jarjar
Many thanks for the link! Seems like if I would use fixed bearings in both ends, I would barely make it!
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Re: NordicCNC's build log
1. You need to add a safety factor.
2. The root diameter of a 16mm ballscrew is not 16, but 14-15 (outer diameter minus ball grooves).
3. Don't use fixed-fixed unless you know exactly what you're doing. The ballscrew needs to be pre-tensioned properly to account for thermal expansion or you will introduce backlash.
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Re: NordicCNC's build log
Quote:
Originally Posted by
jarjar
1. You need to add a safety factor.
2. The root diameter of a 16mm ballscrew is not 16, but 14-15 (outer diameter minus ball grooves).
3. Don't use fixed-fixed unless you know exactly what you're doing. The ballscrew needs to be pre-tensioned properly to account for thermal expansion or you will introduce backlash.
Good points. A 2:1 ratio resulting in the ballscrew rotating with 1500rpm, I will have to go for either 2010 or 2510 ballscrews, and decrease the ballscrew length to about 1100-1200mm.. This will give me a safety factor of around 1.2 with fixed-floating bearings.
Seems ridiculous to have to use any larger diameter ballscrews. I have not seen anyone else using that here on the forum. How does everyone else achieve 15-20m/min?
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Re: NordicCNC's build log
Quote:
Originally Posted by
NordicCnc
Yes, price difference seems to be only about 15-20% for either 25mm or 30mm rails. If it is bringing me added value and it isn't overkill, I think I am ready to go for the 30mm rails.
Don't forget to include the carriages in the cost estimate.
You'd be just about okay with a 1200mm 2010 screw @ 1500rpm.
Those of us using steppers rather than servos don't tend to go above 10m/min because the steppers will really lose torque above 1k rpm. My machine can just about handle 15m/min, but I'm leaving it at 10.
You'll have to find build logs for comparable routers using servos - I don't have any experience with them so won't advise.
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Re: NordicCNC's build log
Quote:
Originally Posted by
AndyUK
Don't forget to include the carriages in the cost estimate.
I quickly compared the 1100mm HGR20 and HGR30 sets offered from BST Motion on Aliexpress (I have seen them recommended a lot here, Fred was the seller) and the prices came down to 210€ vs 265€, if I recall the numbers correctly. Both sets included 2 rails and 4 carriages. Seems like a very good deal to me. Even with VAT added is only like 260-320€.
Quote:
Originally Posted by
AndyUK
You'd be just about okay with a 1200mm 2010 screw @ 1500rpm.
Those of us using steppers rather than servos don't tend to go above 10m/min because the steppers will really lose torque above 1k rpm. My machine can just about handle 15m/min, but I'm leaving it at 10.
Sounds good. I will have to see if I go for 2510 or 2010.
What diameter and pitch, ratio and stepper RPM are you running on your machine to achieve the 10m/min?
Quote:
Originally Posted by
AndyUK
You'll have to find build logs for comparable routers using servos - I don't have any experience with them so won't advise.
Good advice, thanks. I have looked around here and I will also browse through CNCZONE to see if I can find something similar.
Skickat från min SM-A530F via Tapatalk
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Re: NordicCNC's build log
Quote:
Originally Posted by
NordicCnc
The surface finish achieved in this video, I would be more than happy with:
Thought you said wanted a good surface finish.!!. . . . Any decently built machine will give you that finish.
Also:
If you go with 30mm rails and 25 or 32mm ball-screws then you can forget 180w or 400w servos. The extra inertia will freak a 400w servo motor when trying to stop 25mm screws from 3000rpm that are attached to a reasonably heavy Gantry which is sat on heavy bearings with a heavy ATC spindle hanging off it.
The best machines are those that have the right balance of power and weight which means getting the design and components matched. The choices you are looking at now will give you a very unbalanced machine.!
20mm screws and rails are more than enough for a machine this size. Regards the screw size and whip etc then forget whip calculators because they can't and don't account for the whole machine.
If you want proof if 20mm won't whip at 15mtr/min then just ask anyone who's using them on similar sized machine.! . . . . I've built dozens and trust me they don't if properly aligned and with correct end bearings. However, I've told you how to eliminate any chance of whip and still get the speed you require.
Also on that note, you have to factor in the Servos and the extra resolution and power they offer over steppers. This means you can use higher pitch screws and still end up with good resolution compared to steppers. Use this along with applying a ratio and the screw speed can be lowered greatly.
Regards the weight then I think you must have got something wrong because a machine this size will easily weigh more than 200kg, even 300Kg by time it's all finished.
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Re: NordicCNC's build log
Quote:
Originally Posted by
JAZZCNC
Regards the weight then I think you must have got something wrong because a machine this size will easily weigh more than 200kg, even 300Kg by time it's all finished.
Whats the maximum weight you'd expect though? I think a 1,500 Kg minimum as suggested in post #2 is a little overkill.
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Re: NordicCNC's build log
Quote:
Originally Posted by
JAZZCNC
Thought you said wanted a good surface finish.!!. . . . Any decently built machine will give you that finish.
Hehe, seems like we have different standards! I think that finish is quite good and I would be happy with that. Of course, I will try to achieve the best finish I can with my DIY build. I will not settle with decent, if I can get good.
Quote:
Originally Posted by
JAZZCNC
Also:
If you go with 30mm rails and 25 or 32mm ball-screws then you can forget 180w or 400w servos. The extra inertia will freak a 400w servo motor when trying to stop 25mm screws from 3000rpm that are attached to a reasonably heavy Gantry which is sat on heavy bearings with a heavy ATC spindle hanging off it.
The best machines are those that have the right balance of power and weight which means getting the design and components matched. The choices you are looking at now will give you a very unbalanced machine.!
Yes, I got confused with the advice from jarjar. It seemed quite contradicting to the general advice I've seen on the forums. He mentioned that a 400W would probably be the bare minimum. Anyway I don't plan to rotate any ballscrews with 3000rpm. I will use at least a 2:1 ratio, resulting in max. 1500rpm.
Quote:
Originally Posted by
JAZZCNC
20mm screws and rails are more than enough for a machine this size. Regards the screw size and whip etc then forget whip calculators because they can't and don't account for the whole machine.
As I planned from then beginning, to use 20mm rails. Thanks for confirming!
Quote:
Originally Posted by
JAZZCNC
If you want proof if 20mm won't whip at 15mtr/min then just ask anyone who's using them on similar sized machine.! . . . .
I've seen those builds, which is why I was skeptical and questioned jarjar's advice about the huge ballscrews.
Quote:
Originally Posted by
JAZZCNC
I've built dozens and trust me they don't if properly aligned and with correct end bearings. However, I've told you how to eliminate any chance of whip and still get the speed you require.
Correct. About preloading the ballscrew with tension, using double fixed bearings. Is there any guide how to do this? I guess the applied force by tightening the fixed bearing nuts will be critical?
Quote:
Originally Posted by
JAZZCNC
Regards the weight then I think you must have got something wrong because a machine this size will easily weigh more than 200kg, even 300Kg by time it's all finished.
That is exactly what I said, that I expect it to be around the 300kg mark once finished. Probably above! :)
Quote:
Originally Posted by
JAZZCNC
Also on that note, you have to factor in the Servos and the extra resolution and power they offer over steppers. This means you can use higher pitch screws and still end up with good resolution compared to steppers. Use this along with applying a ratio and the screw speed can be lowered greatly.
My plan is now the following:
- I will build the machine with motor brackets than can be replaced. This will allow me to at least first test the 180W JMC servo motors. If they are not powerful enough even experimenting with ratios, I will have to buy new motors - probably some 400W servo motors or get stepper motors. This will be an expensive learning lesson, but that is life! I will most likely never buy any parts before design is ready again, lol.
- 20mm HIWIN linear rails on all axis's.
- 2010 ball screws on the Y-axis (base frame).
- 1610 or 2010 ball screw on the X-axis (gantry).
- 1605 ball screw on the Z-axis.
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16 Attachment(s)
Re: NordicCNC's build log
Alright first actual design post with some pictures.
Z-axis design
- 3kW ATC spindle & Ø100mm spindle bracket. The spindle alone weights about 19kg according to the supplier (RattmMotors).
Attachment 27501 Attachment 27502
- 20x200x500mm aluminium rear plate, onto which spacers, BK12/BF12 bearings and motor bracket are mounted.
- 15x50x500mm aluminium spacers to make room for BK12/BF12 bearings and 1605 ballscrew. Linear rails are mounted to the spacers.
- 20x200x171mm aluminium top plate for HIWIN narrow guide carriages that goes on top of the gantry. Gantry ballscrew nut bracket will be mounted to the same plate.
- 20x200x240mm aluminium front plate, onto which the HIWIN narrow guide carriages and ballscrew nut bracket DSG16H are mounted.
Attachment 27490 Attachment 27491 Attachment 27494 Attachment 27493 Attachment 27492 Attachment 27495
- About 200mm gantry clearance
- 146mm overhang
- Spindle can be raised about 60mm above gantry
- 1605 ballscrew, 400m long with 25mm F-length end machining for BK12 fixed bearing to allow for pulley. Floating bearing in the other end.
- 20T HTD 5M pulley on the servomotor and 40T HTD 5M pulley on the ballscrew.
- 180W JMC servo motor.
- Motor bracket with oval holes to allow belt tensioning.
Attachment 27496 Attachment 27497 Attachment 27498 Attachment 27499 Attachment 27500 Attachment 27505
- Moving weight in Z-axis direction, about 26kg - still missing cables, water pipes, proximity switches etc
- Moving weight in X-axis (gantry) direction: 40kg - still missing cables, water pipes, proximity switches etc.
Attachment 27503 Attachment 27504
I am pretty happy with the total weight of the Z-axis. I don't think it'll go over 45-50kg with everything added.
I could still trim down the X-axis direction moving weight, by removing the linear rail spacers and adding machining to the front and rear plates. But I am thinking that I will need that stiffness which the 20mm plates gives me. Would it weaken the structure a lot by adding machining of 7x60mm along the middle of the plates, to allow room for the BK/BF bearings and ballscrew nut bracket?
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Re: NordicCNC's build log
Quote:
Originally Posted by
AndyUK
Whats the maximum weight you'd expect though? I think a 1,500 Kg minimum as suggested in post #2 is a little overkill.
Think JarJar is talking about a different strength machine, esp when he's comparing to a Datron which is a big lump of epoxy Granite. Thou that's like comparing apples with pears when a Datron cost's like £100K.
I'd expect a machine this size to be around 400Kg when finished using the materials and components suggested. It's amazing just how much weight fasteners etc add.
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Re: NordicCNC's build log
Quote:
Originally Posted by
NordicCnc
- 3kW ATC spindle & Ø100mm spindle bracket. The spindle alone weights about 19kg according to the supplier (RattmMotors).
The spindle with Mount + BT30 Collet chuck weighs 19.5Kg. Don't forget if you are using dust extraction then you will need to retract the dust hood to allow access for tool change. This will mean adding pneumatic actuators and solenoid valves along with brackets etc and the dust hood its self.!... The weight creeps up fast.
Your estimate of 45-50Kg is about right. You will need a brake on the Z-axis motor to stop it dropping when not under power and i'm pretty sure your 180w motor won't handle the weight of ATC spindle.
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Re: NordicCNC's build log
Add a second spindle bracket up high on the spindle.
Add ribs on the edge of the Z axis plates. This will add a huge amount to stiffness. (Essentially make them into C channels).
Nowhere on the machine should you have a simple flat plate - everything should be box sections of at all possible, otherwise should have stiffening ribs.
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Re: NordicCNC's build log
Quote:
Originally Posted by
JAZZCNC
The spindle with Mount + BT30 Collet chuck weighs 19.5Kg. Don't forget if you are using dust extraction then you will need to retract the dust hood to allow access for tool change. This will mean adding pneumatic actuators and solenoid valves along with brackets etc and the dust hood its self.!... The weight creeps up fast.
I had not thought about retractable dust shoe. I need to investigate if I will need one!
Quote:
Originally Posted by
JAZZCNC
Your estimate of 45-50Kg is about right. You will need a brake on the Z-axis motor to stop it dropping when not under power and i'm pretty sure your 180w motor won't handle the weight of ATC spindle.
The moving weight in the Z-axis direction is 25kg and the complete Z-axis will be around 50kg. 25kg will for sure drop when the Z-motor is not under power. Could I use stepper motor brakes on these servo motors?
In the one of the YouTube videos I linked to earlier, one guy is using the same servos and he told me that his Z-axis is around 20kg (I asked). This is only about 5kg lighter than mine and he said it works very well! His axis drops when not under power too.
Anyway as I mentioned earlier, I won't let the servos I have dictate the final design. I will buy new stronger ones if it turns out that they are too weak!
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5 Attachment(s)
Re: NordicCNC's build log
Quote:
Originally Posted by
pippin88
Add a second spindle bracket up high on the spindle.
According to the spindle specification, the clamping area is defined here:
Attachment 27511
I am afraid that clamping higher up (I am at the highest allowed point already) could potentially damage the spindle. Please correct me if I am wrong? The reason why the spindle is clamped like this is for gantry clearance.
Quote:
Originally Posted by
pippin88
Add ribs on the edge of the Z axis plates. This will add a huge amount to stiffness. (Essentially make them into C channels).
Nowhere on the machine should you have a simple flat plate - everything should be box sections of at all possible, otherwise should have stiffening ribs.
Good point! While I am trying to keep the Z-axis weight low, I think adding 15mm aluminium stiffening ribs wouldn't be too harmful (only around 1.2kg added). If I understood you correctly, you means something similar to this:
Attachment 27512 Attachment 27513 Attachment 27514
Additionally I could also move the Z-axis linear rail spacers to the front plate. This would increase the moving weight by another 1kg. I am not sure fi I should keep them on the rear plate or not. I could move them to the front plate and add stiffening ribs to the back of the rear plate. The ribs would be bolted to the rear plate, top bearing plate and motor bracket, effectively forming a rigid box. Is this just adding dead weight?
Attachment 27516
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Re: NordicCNC's build log
Regarding spindle, I didn't realise it was an ATC spindle, which are a lot longer. Clamping high up may not be appropriate (though with a decent tolerance clamp I doubt you'd be crushing the spindle). The point is the longer the clamping area (or the further apart the clamping points) the better.
Yes, that's what I meant about the ribs. You don't need 15mm thick plate, even 5mm would be fine. The stiffness comes from the dimension in the direction of the force.
You should also add stiffening ribs to the carriage .
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Re: NordicCNC's build log
Quote:
Originally Posted by
NordicCnc
The ribs would be bolted to the rear plate, top bearing plate and motor bracket, effectively forming a rigid box. Is this just adding dead weight?
Machines only as strong as its weakest point. Currently what is keeping the back of your Z axis still? Its those carriages, which are attached via a 90 degree but-joint. So I'd say those two or so screws are the weakest point! That's why I created the side plates on my Z axis to give some support to the joints.
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6 Attachment(s)
Re: NordicCNC's build log
Quote:
Originally Posted by
pippin88
Regarding spindle, I didn't realise it was an ATC spindle, which are a lot longer. Clamping high up may not be appropriate (though with a decent tolerance clamp I doubt you'd be crushing the spindle). The point is the longer the clamping area (or the further apart the clamping points) the better.
Yes, that's what I meant about the ribs. You don't need 15mm thick plate, even 5mm would be fine. The stiffness comes from the dimension in the direction of the force.
You should also add stiffening ribs to the carriage .
Quote:
Originally Posted by
AndyUK
Machines only as strong as its weakest point. Currently what is keeping the back of your Z axis still? Its those carriages, which are attached via a 90 degree but-joint. So I'd say those two or so screws are the weakest point! That's why I created the side plates on my Z axis to give some support to the joints.
Thanks both of you pippin and Andy! I took your advice and now I've added 10mm aluminium ribs bolted to the front plate. I've also added 10mm side plates that are bolted to the rear plate, motor bracket and top bearing plate.
Attachment 27517 Attachment 27518
New total weights did not change much, while I think I have added quite a bit of stiffness!
Z-axis moving weight: 26.8kg -> 26.4kg
Z-axis total weight: 39.7kg -> 42.4kg
Attachment 27519 Attachment 27520
I am now debating, should I do something of the following things:
1. Remove the spacer plates used for the linear rails completely and add machining (on both the rear and front plate)? This would reduce weight (maybe 3-4kg?) and fewer parts needed. More machining though.
Attachment 27521
2. Move the spacers from the rear plate to the front plate. Linear rails would then go directly on the rear plate. Shorter spacers would be added behind the guide carriages and the front plate. This would increase the Z-axis moving weight by like 1kg, but reduce total weight by 1kg. I would gain some stiffness on the front plate, but lose some on the rear plate. Not sure where the weak point is and where the spacers are needed the most.
Attachment 27522
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Re: NordicCNC's build log
Ok well first, the ribs on the front plate add virtually nothing but weight because the plate is fastened directly to the bearings with no overhang, it's also short and strong so very little vibrations come from that area.
Regards the plates on the sides then these would help, however, I have a better suggestion. If you look at the pic and at the other machines I've built I always put a cover over the Z-axis. This isn't just to protect from debris it's also structural as it does the same job those plates. You don't need a 10mm plate, I use 3mm for the covers and it's more than strong enough.
The spindle mounting area is limited to the lower area (see the pic, it's the silver area, the black is drawbar cylinders.) However, they are steel and would easily handle another clamp.
Regards putting the spacer plates on the front plate to save weight then I wouldn't do that either because of your shifting weight to the wrong area.
To be honest I wouldn't use spacer plates as it lowers precision and makes it complicated.
Regards Motor brake then I can't answer that because I don't know those motors, but servos are not like steppers where they have a shaft sticking out the back, mostly because this is often used for the encoder.
How the motor handles the weight will depend on usage, but if you plan on doing 3D type work with lots of short moves with high acceleration then I think they 180W motors will struggle with the inertia and you'll get some following errors. Because again servos are unlike steppers where if they lose the position you visually see the lost steps, instead the encoders along with the drives close the loop and catch back up so will always return to exact same place when stopped provided they don't go outside of parameters set in the drives.
However, what you get is a following error which if it stays within following error parameters can trick people into thinking they don't have a problem because if they do a type of work which is mostly 2D the Z-axis isn't whizzing up & down so it gets missed.
Attachment 27530 Attachment 27531 Attachment 27532
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Re: NordicCNC's build log
Quote:
Originally Posted by
JAZZCNC
Ok well first, the ribs on the front plate add virtually nothing but weight because the plate is fastened directly to the bearings with no overhang, it's also short and strong so very little vibrations come from that area.
Regards the plates on the sides then these would help, however, I have a better suggestion. If you look at the pic and at the other machines I've built I always put a cover over the Z-axis. This isn't just to protect from debris it's also structural as it does the same job those plates. You don't need a 10mm plate, I use 3mm for the covers and it's more than strong enough.
The spindle mounting area is limited to the lower area (see the pic, it's the silver area, the black is drawbar cylinders.) However, they are steel and would easily handle another clamp.
Regards putting the spacer plates on the front plate to save weight then I wouldn't do that either because of your shifting weight to the wrong area.
To be honest I wouldn't use spacer plates as it lowers precision and makes it complicated.
Regards Motor brake then I can't answer that because I don't know those motors, but servos are not like steppers where they have a shaft sticking out the back, mostly because this is often used for the encoder.
How the motor handles the weight will depend on usage, but if you plan on doing 3D type work with lots of short moves with high acceleration then I think they 180W motors will struggle with the inertia and you'll get some following errors. Because again servos are unlike steppers where if they lose the position you visually see the lost steps, instead the encoders along with the drives close the loop and catch back up so will always return to exact same place when stopped provided they don't go outside of parameters set in the drives.
However, what you get is a following error which if it stays within following error parameters can trick people into thinking they don't have a problem because if they do a type of work which is mostly 2D the Z-axis isn't whizzing up & down so it gets missed.
Thanks for your advice. I think you forgot to add a picture though?
I will reply back once you have added, as I think things will make more sense to me then.
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Re: NordicCNC's build log
Quote:
Originally Posted by
NordicCnc
Thanks for your advice. I think you forgot to add a picture though?
I will reply back once you have added, as I think things will make more sense to me then.
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No didn't forget the forum is playing silly buggers again and won't let me upload the pic. I'll try again later.
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Re: NordicCNC's build log
Quote:
Originally Posted by
JAZZCNC
No didn't forget the forum is playing silly buggers again and won't let me upload the pic. I'll try again later.
Thanks man!
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2 Attachment(s)
Re: NordicCNC's build log
Here's where I throw a spanner in the works.
This is from my own way of working I think you are going way overboard with the construction of the Z axis adding more and more to it.
I made a Z axis 510mm high x 220mm wide using 12mm backing plate with cut outs to ease the weight on the Y axis with 20mm Hywin rails direct on the plate no packers and carriages direct on the spindle plate, I made a rotating ball nut and fixed 1605 screw which helps to have the very minimum of overhang and adds to the strength of the design.
Attachment 27525
It carries a German 2.2kw water cooled spindle, (I know not as heavy as yours) I do not get any drop of the Z when powered off weather this is down to the 2 to 1 reduction to the nut I am not sure but it works very well, it has cut wood, plastics, aluminium, steel plate and stone with no problems whatsoever.
Recently I setup a 4th axis to cut 2 1/2D designs around the edges of 150mm disks again works really well.
I am currently designing another machine with extended Y axis to be able to have a 4th axis running down the length of the X axis, and be able to cut around 300mm dia disks and have no problem using the same kind of design in fact I am going to use a rotating ball nut on the X & Y axis as well it is more compact and so smooth compared to turning screws.
Attachment 27526
Phill
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Re: NordicCNC's build log
Quote:
Originally Posted by
phill05
Here's where I throw a spanner in the works.
This is from my own way of working I think you are going way overboard with the construction of the Z axis adding more and more to it.
I made a Z axis 510mm high x 220mm wide using 12mm backing plate with cut outs to ease the weight on the Y axis with 20mm Hywin rails direct on the plate no packers and carriages direct on the spindle plate, I made a rotating ball nut and fixed 1605 screw which helps to have the very minimum of overhang and adds to the strength of the design.
Attachment 27525
It carries a German 2.2kw water cooled spindle, (I know not as heavy as yours) I do not get any drop of the Z when powered off weather this is down to the 2 to 1 reduction to the nut I am not sure but it works very well, it has cut wood, plastics, aluminium, steel plate and stone with no problems whatsoever.
Recently I setup a 4th axis to cut 2 1/2D designs around the edges of 150mm disks again works really well.
I am currently designing another machine with extended Y axis to be able to have a 4th axis running down the length of the X axis, and be able to cut around 300mm dia disks and have no problem using the same kind of design in fact I am going to use a rotating ball nut on the X & Y axis as well it is more compact and so smooth compared to turning screws.
Attachment 27526
Phill
Hello, looks good! Interesting with the rotating ball nut. I understand it so that you have placed the fixed bearing on the spindle plate and then the other ball screw end is lose. Does it stick up in the air or what does it look like when the Z-axis is fully retracted?
Anyway I have to say that your advice is quite contradicting compared to the advice I have received from others. I am not saying you are wrong but I try to stay open minded!
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1 Attachment(s)
Re: NordicCNC's build log
Quote:
Originally Posted by
NordicCnc
Hello, looks good! Interesting with the rotating ball nut. I understand it so that you have placed the fixed bearing on the spindle plate and then the other ball screw end is lose. Does it stick up in the air or what does it look like when the Z-axis is fully retracted?
Anyway I have to say that your advice is quite contradicting compared to the advice I have received from others. I am not saying you are wrong but I try to stay open minded!
I did say I was throwing a spanner in the works, I know it's not a conventional way of making this and yes contradicting to what has gone before but it works and works really well it is compact, less weight, and the machine cuts very well, just wanted to give you an idea of what works without going to far.
The screw is bolted tight to bottom of spindle plate (no bearing) and screw goes up with plate, attached is an image when I first put it together.
Attachment 27528
Phill
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Re: NordicCNC's build log
Quote:
Originally Posted by
phill05
I did say I was throwing a spanner in the works, I know it's not a conventional way of making this and yes contradicting to what has gone before but it works and works really well it is compact, less weight, and the machine cuts very well, just wanted to give you an idea of what works without going to far.
The screw is bolted tight to bottom of spindle plate (no bearing) and screw goes up with plate, attached is an image when I first put it together.
Attachment 27528
Phill
Oh my! You have quite some Z-axis travel height there. I can see that the screw will be sticking out in the air when Z-axis is fully retracted (at the top end position). I think you rarely use that Z-height or are you doing some custom jobs?
Looks like the gantry clearance is around 100-120mm, am I right? It would also be interesting seeing a video of its performance in aluminium/steel!
You have definitely given me something to consider, thanks for that.
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Re: NordicCNC's build log
Quote:
Originally Posted by
phill05
Here's where I throw a spanner in the works.
This is from my own way of working I think you are going way overboard with the construction of the Z-axis adding more and more to it.
You can't be serious.? You are using a rotating ball-nut on the Z-axis and you think he's going overboard with things.!
That design with the screw sticking up 400-500mm above the z-axis when at the top is just a crazy, pointless design and overly complicated for its application. Rotating ball-nuts are great on longer axis but for a Z-axis they will make no difference because the screw is so short that whipping or inertia don't factor into the equation which is the only reason to use a rotating nut, even with servo's which spin much faster than steppers.
Also regards your intended design with the L-shape Gantry that is all mixed up as well. Your design wastes Gantry clearance height because using the middle slot on the profile and misses the whole point of the "L" design. The point being the L shape is so most of the cutting forces are directed into the horizontal piece placed at the bottom where forces are highest.
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Re: NordicCNC's build log
Quote:
Originally Posted by
JAZZCNC
Ok well first, the ribs on the front plate add virtually nothing but weight because the plate is fastened directly to the bearings with no overhang, it's also short and strong so very little vibrations come from that area.
Regards the plates on the sides then these would help, however, I have a better suggestion. If you look at the pic and at the other machines I've built I always put a cover over the Z-axis. This isn't just to protect from debris it's also structural as it does the same job those plates. You don't need a 10mm plate, I use 3mm for the covers and it's more than strong enough.
The spindle mounting area is limited to the lower area (see the pic, it's the silver area, the black is drawbar cylinders.) However, they are steel and would easily handle another clamp.
Regards putting the spacer plates on the front plate to save weight then I wouldn't do that either because of your shifting weight to the wrong area.
To be honest I wouldn't use spacer plates as it lowers precision and makes it complicated.
Regards Motor brake then I can't answer that because I don't know those motors, but servos are not like steppers where they have a shaft sticking out the back, mostly because this is often used for the encoder.
How the motor handles the weight will depend on usage, but if you plan on doing 3D type work with lots of short moves with high acceleration then I think they 180W motors will struggle with the inertia and you'll get some following errors. Because again servos are unlike steppers where if they lose the position you visually see the lost steps, instead the encoders along with the drives close the loop and catch back up so will always return to exact same place when stopped provided they don't go outside of parameters set in the drives.
However, what you get is a following error which if it stays within following error parameters can trick people into thinking they don't have a problem because if they do a type of work which is mostly 2D the Z-axis isn't whizzing up & down so it gets missed.
Attachment 27530 Attachment 27531 Attachment 27532
JAZZ, I think the way you have installed the pneumatic actuators and the Z-axis cover design is great! The whole machine design is phenomenal.. I hope you don't me taking ideas and copying some features from it?
I've removed my spacer plates now and added a machining to both the rear and the front plate to make room for the bearing and ball screw nut housing. This reduced the overhang by 15mm! It also reduced the total weight a few kg's. Thanks for the tip!
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Re: NordicCNC's build log
Quote:
Originally Posted by
phill05
Here's where I throw a spanner in the works.
This is from my own way of working I think you are going way overboard with the construction of the Z axis adding more and more to it.
I made a Z axis 510mm high x 220mm wide using 12mm backing plate with cut outs to ease the weight on the Y axis with 20mm Hywin rails direct on the plate no packers and carriages direct on the spindle plate, I made a rotating ball nut and fixed 1605 screw which helps to have the very minimum of overhang and adds to the strength of the design.
Attachment 27525
It carries a German 2.2kw water cooled spindle, (I know not as heavy as yours) I do not get any drop of the Z when powered off weather this is down to the 2 to 1 reduction to the nut I am not sure but it works very well, it has cut wood, plastics, aluminium, steel plate and stone with no problems whatsoever.
Recently I setup a 4th axis to cut 2 1/2D designs around the edges of 150mm disks again works really well.
I am currently designing another machine with extended Y axis to be able to have a 4th axis running down the length of the X axis, and be able to cut around 300mm dia disks and have no problem using the same kind of design in fact I am going to use a rotating ball nut on the X & Y axis as well it is more compact and so smooth compared to turning screws.
Attachment 27526
Phill
hello, i would really like to know how you made that rotating ball nut. It looks like a flanged ball nut sandwiched in a pillow block bearing housing with a pulley holding it together. please can you share some pictures.
thanks
bob
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Re: NordicCNC's build log
Quote:
Originally Posted by
NordicCnc
JAZZ, I think the way you have installed the pneumatic actuators and the Z-axis cover design is great! The whole machine design is phenomenal.. I hope you don't me taking ideas and copying some features from it?
No don't mind at all , go for it.! . . . Thou bare in mind some of these pictures are not of the finished article, the covers, for instance, are still missing some fastenings and slot covers, etc but hopefully show what I've been saying.
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Re: NordicCNC's build log
Quote:
Originally Posted by
JAZZCNC
No don't mind at all , go for it.! . . . Thou bare in mind some of these pictures are not of the finished article, the covers, for instance, are still missing some fastenings and slot covers, etc but hopefully show what I've been saying.
Great and you have explained it very well!
By the way I have now decided that I will not use the 180W JMC servo motors that I bought in advance. I've come to realize that they are holding me back by limiting the weight of he machine. It was an expensive learning lesson but now I know that I should always wait with buying any components until the design is completed.
I've contacted the supplier and they might be willing to accept a return and I would pay a little more to get the 400W JMC servo motors in change (https://www.aliexpress.com/item/4000067490526.html). In case they don't accept the return for some reason then I have already found another use case for them, so that problem is solved - no money lost. If I then still buy the 400W JMC's, I don't know, I will have to check what you and the others here think. I saw that delta servo's were recommended as well and it was also mentioned that larger than 400W would probably be good?
Anyway the motor power issue is now out of the way and I have the money to spend on new and way more powerful motors!
So now having solved the motor power issue, do I still keep the Z-axis weight as low as possible or should I start trying to beef it up? The covers I will design to be structural, taking ideas from your machines JAZZ. The Z-axis front plate I am not so sure if I can improve much since it is already very stiff. Perhaps the Z-axis design is good as light weight and I can just stop worrying if the motor power will be enough to handle the heavy ATC spindle! :peaceful:
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10 Attachment(s)
Re: NordicCNC's build log
Short update on the Z-axis design! You might notice that the design is heavily influenced by JAZZCNC's build's (e.g. the cover and L-shape gantry), although still very different and definitely no where near his quality!
Modifications:
- Based on feedback I have now removed the stiffening ribs from the front plate. The reason is that since the front plate is directly mounted to the X-axis bearings with literally no overhang, the stiffening ribs would add nothing but weight. Instead a 3mm aluminium sheet is bent and welded, forming a cover that is structural while also protecting the components and cables from chips.
- Removed the linear rail spacer plates and added machining to both the rear and front plate, to make room for the BK12/BF12 bearings and the 1605 ball screw.
- 180W servo motors are no longer a constraint. Now I am thinking about getting Delta 400W servo motors. On the Z-axis I plan to use one with brake: https://www.aliexpress.com/item/3267...23d152a8ZJcwMZ. On the X- and Y-axis I plan to use ones without brakes: https://www.aliexpress.com/item/32671356516.html?spm. All axis with still be geared 2:1, to limit the ball screw maximum speed to 1500rpm.
- Modified the top bearing plate to account for BK15/BK15 bearings and 2010 ball screw on the X-axis (in design process).
- Preliminary positioning of proximity switches. The X-axis will only need one, but for the Z-axis I might need 2 if I can't find a location which I can use for both homing/top limit switch as well as bottom limit switch.
- New Z-axis weights are 45kg (total) and 25kg (moving).
Attachment 27538 Attachment 27539 Attachment 27540 Attachment 27541 Attachment 27542 Attachment 27543 Attachment 27544
Here is the Z-axis mounted on the draft X-axis design, made with 120x80 Item profiles (I will post a more detailed X-axis design description later):
Attachment 27545 Attachment 27546 Attachment 27547
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Re: NordicCNC's build log
Quote:
Preliminary positioning of proximity switches. The X-axis will only need one, but for the Z-axis I might need 2 if I can't find a location which I can use for both homing/top limit switch as well as bottom limit switch.
Its not easy or practical to put a bottom limit switch on the Z axis as the tool lengths will all vary .
