Rauno's CNC router

[Rauno]

Hi, CNC enthusiast!

I would like to start with the reason why I started this thread. I started designing my first CNC router and googled like crazy to reach the best possible design. I felt I am quite at the optimal point already and thought about starting to ordering parts. Actually I already ordered one motion parts kit, and then I found this forum, specifically the DIY routers section and all the hell broke loose. I realized I have a lot of research to do.

So thanks to everyone for sharing their builds in this forum!

My goal

I would like to build a quite universal CNC router, so I could cut aluminum, wood, plastic. I know universal things are very good for nothing, but I would like to try to make the best out of it. I don’t want to make (small scale) series production. My main interest is to make prototypes, both functional and aesthetical. Therefore a rigid design is a must for the machine in order to make nice looking aluminum parts.

Current design

Size: Rail lengths 1000x1500x400 mm. Maybe it’s reasonable to make the router smaller so it could be more rigid with same ball screws and frame design. The 1500 mm could be changed to 1000 mm for example. Mainly considering this due the lower price of 1605 ball screws.


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Custom parts (plates): Surface milled (mainly 20 mm) aluminum plates, I plan to order water cutting of the parts. Where needed I could make counterbores for the hex socket bolts using special counterbore drill.

Base frame: Rectangular tube steel, design is yet not final. I am able to weld it by myself.

Gantry beam: 4080 aluminum profile with sheet metal reinforcement. I know the 45x90 design recommendation, but it would cost me 60€ more, yet I am open to your opinion - is the 45x90 L design gantry worth this money?

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Linear rails: HGR20

Ball screws:

Two options:
X, Y, Z 1605
X, Y 1610 or 2010 and Z 1605

1605 ball screws are cheaper 400€ for all axes. If I go for the 1610 or 2010 it would cost 300€ extra for me. The numbers include linear rails because 1605 are cheaper in kit with linear rails.

Few links:

HGR20+1605 kits: https://www.aliexpress.com/item/1005002977089308.html?spm=a2g0o.store_pc_groupList .8148356.13.3cef5171eAfjgA

1610 and 2010 could be offered mainly from BST: https://www.aliexpress.com/item/32887382899.html?spm=a2g0o.productlist.0.0.63fe30c crFB03a&algo_pvid=5f8412e1-f172-44cc-863c-1b2cad5b83fa&algo_exp_id=5f8412e1-f172-44cc-863c-1b2cad5b83fa-0&pdp_ext_f=%7B%22sku_id%22%3A%2265625355885%22%7D

Spindle

2.2kw water cooled + VFD

Motors:

Lichuan LCDA86H+LC60H21 Set of 4 500€ from Aliexpress https://www.aliexpress.com/item/1005001700902044.html?spm=a2g0o.productlist.0.0.7a 87635fuamd69&algo_pvid=ffc3bcc3-e8f6-4d32-acae-e8befa747921&algo_exp_id=ffc3bcc3-e8f6-4d32-acae-e8befa747921-1&pdp_ext_f=%7B%22sku_id%22%3A%2212000017208626891%2 2%7D

Do I need that expensive motor+driver for Z axis?

Belt drive: HTD 5m closed loop timing belt, pulley size 20T

Controller:

AXBB-E running UCCNC

Power supply:

230VAC for VFD
230VAC -> 55VAC toroidal transformer for drivers

If I understand correctly the toroidal transformer could power those VAC capable Lichuan drivers directly with AC current. One thing to consider is the input grid voltage, as my place has solar panels and this could cause bigger voltage fluctuations than the grid itself has.


I am open for comments, suggestions. Main questions are:

1. If I continue with this size is it reasonable to use 1610/2010 ballscrews for Z and Y axis. Is it worth the extra 300€. And if I don't spend extra money should I downsize the router?

2. Is the gantry stiff enough?

[JAZZCNC]

Therefore a rigid design is a must for the machine in order to make nice looking aluminum parts.

If your main goal is to cut aluminum then you need a stronger base and gantry along with a ridged Z-axis.


Mainly considering this due the lower price of 1605 ball screws.

It would be a mistake to go for RM1605 for a machine this size, I wouldn't even use 1605 on a smaller router because you still need a certain amount of speed to cut materials like wood and MDF correctly, and using 1605 means your motors are always spinning fast when cutting at higher feeds so torque is low and often very near the stall point.
RM1610 gives you all the speed you require while allowing the motor to spin slower with higher torque while cutting. Careful not to get caught up in the resolution trap either because you don't actually need high resolution for the type of materials you are looking to cut and a 10mm pitch with micro-stepping drives will give you more than enough resolution for most types of cutting.




I plan to order water cutting of the parts.

Careful with water jet cutting because unless it's cut very slowly you will get a tapered edge.


Gantry beam: 4080 aluminum profile with sheet metal reinforcement. I know the 45x90 design recommendation, but it would cost me 60€ more, yet I am open to your opinion - is the 45x90 L design gantry worth this money?

I've built literally 100's of machines now using the 45x90 with my "L" design gantry so I'm probably a little biased, but it just works and pound for pound it's the strongest arrangement I've ever used. Yes, I've built and still do build machines with stronger gantry's but they are much much more expensive and complicated to build and can only be done if you have a CNC machine to start with.



Do I need that expensive motor+driver for Z axis?

Yes, don't underestimate the Z-axis, it's THE most important part of the machine, if the Z-axis is weak or underpowered it doesn't matter how good the rest of the machine. Also, if you plan on doing 3D type work or V-carving which has lots of Z-axis movement then you will need plenty of power with a reasonably heavy spindle like a 2.2Kw.



If I understand correctly the toroidal transformer could power those VAC capable Lichuan drivers directly with AC current. One thing to consider is the input grid voltage, as my place has solar panels and this could cause bigger voltage fluctuations than the grid itself has.

We fit 55Vac transformers on the machines we build using these Lichuan drives and with a 230V - 55Vac transformer on a UK grid which runs around 240Vac the output usually runs around 60Vac so I would expect you'll be ok because I think your grid will be more like 220/230Vac and the Lichuan drives will handle 70Vac and I know from experience because of a transformer sizing error that they will take 72Vac without damage.

[Rauno]

If your main goal is to cut aluminum then you need a stronger base and gantry along with a ridged Z-axis.

Recommendations for stronger design are welcome. I made a base frame design, larger rectangular tubes are 80x80x4 and smaller ones 50x50x4.

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It would be a mistake to go for RM1605 for a machine this size, I wouldn't even use 1605 on a smaller router, because you still need a certain amount of speed to cut materials like wood and MDF correctly. Using 1605 means your motors are always spinning fast when cutting at higher feeds so torque is low and often very near the stall point.
RM1610 gives you all the speed you require while allowing the motor to spin slower with higher torque while cutting. Careful not to get caught up in the resolution trap either, because you don't actually need high resolution for the type of materials you are looking to cut and a 10mm pitch with micro-stepping drives will give you more than enough resolution for most types of cutting.

I choose RM1610 for the X and Y axis.



Careful with water jet cutting because unless it's cut very slowly you will get a tapered edge.

I am aware of this problem, maybe it's reasonable to mill over the important surfaces. Let's see.



I've built literally 100's of machines now using the 45x90 with my "L" design gantry so I'm probably a little biased, but it just works and pound for pound it's the strongest arrangement I've ever used. Yes, I've built and still do build machines with stronger gantry's but they are much much more expensive and complicated to build and can only be done if you have a CNC machine to start with.

I actually had the 45x90 already made in 3D model, now I can show it. I also added reinforcement plates for the Z axis sides. Yes, I got the idea from your webpage, JazzCNC :)

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Yes, don't underestimate the Z-axis, it's THE most important part of the machine, if the Z-axis is weak or underpowered it doesn't matter how good the rest of the machine. Also, if you plan on doing 3D type work or V-carving which has lots of Z-axis movement then you will need plenty of power with a reasonably heavy spindle like a 2.2Kw.

Roger that.



We fit 55Vac transformers on the machines we build using these Lichuan drives and with a 230V - 55Vac transformer on a UK grid which runs around 240Vac the output usually runs around 60Vac so I would expect you'll be ok because I think your grid will be more like 220/230Vac and the Lichuan drives will handle 70Vac and I know from experience because of a transformer sizing error that they will take 72Vac without damage.

Then I'll go with 55Vac transformer, thanks for the info.