Thoughts on Sorotec alu-line machine

[JAZZCNC]

What if you would compare these builds:

1. High sides, Z-axis travel 250mm. Frame made of 80x80 aluminium profiles. Gantry made of 80x160 and sat directly on the rails. Rails top mounted onto the 80x80's.

2. High gantry sides, same Z-axis travel. Gantry sides made of 30mm aluminium tooling plate. Frame made of 80x80 aluminium profiles. Gantry made of 80x160 and mounted to the gantry sides. Y-axis rails side mounted onto the 80x80's.

I understand the high sides build will always be stronger, unless you would make the gantry sides out of something much stiffer than what the frame would be made of.

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Don't know what you want me to say because you already know the answer.? #1 is stronger it's that simple.
However, 250mm is a lot of Z travel so I would ask your self do you really need that much travel as it will weaken the machine if you use a typical Z-axis design. If you don't need 250mm of travel but require the clearance for material then you may be better looking at a design with an adjustable bed so can fit tall material but still have a nice strong Z-axis.

It really does come down to how you want to use the machine and with what materials. If your thinking to cut steels then I would forget both types of moving gantry and build a Fixed gantry machine from stronger materials.

Edit: If you want a design that's in between high Gantry sides and Sat directly on rails then here's one I built. Again this machine is built for working with mostly woods, it's also got a 4th axis which is why the gantry hangs over the side. The profile is 120 x 80 Item Section and the gantry is L shape design.

[NordicCnc]

Don't know what you want me to say because you already know the answer.? #1 is stronger it's that simple.
However, 250mm is a lot of Z travel so I would ask your self do you really need that much travel as it will weaken the machine if you use a typical Z-axis design. If you don't need 250mm of travel but require the clearance for material then you may be better looking at a design with an adjustable bed so can fit tall material but still have a nice strong Z-axis.

The way I plan to solve this is whenever I am machining aluminium / very light steel, I will use a jig that I put on the table, which will then decrease the Z-clearance. This should work the same way as having an adjustable bed.

It really does come down to how you want to use the machine and with what materials. If your thinking to cut steels then I would forget both types of moving gantry and build a Fixed gantry machine from stronger materials.

The requirement is a large work area, so a moving gantry design and making it as good as possible is my goal. This of course means that it wont be as rigid and as effective for aluminium / very light steel. This is a trade-off I need to make, as I don't have the budget or space to build 2 machines right now.

Edit: If you want a design that's in between high Gantry sides and Sat directly on rails then here's one I built. Again this machine is built for working with mostly woods, it's also got a 4th axis which is why the gantry hangs over the side. The profile is 120 x 80 Item Section and the gantry is L shape design.

That is a nice looking machine you've built! Great idea with the 4th axis too.A few questions if you don't mind:

1. How does it perform in aluminium (tool, cut depth, feed rate)?
2. Do you have a build log somewhere?
3. What is the Z-axis clearance and working area?
4. Any reason why you went with L-shape design, instead of using say 90x180 box section profile?
5. Are the surfaces where the rails sit on the X-axis machined or shimmed?
6. What is the reason for having one rail top mounted and the other one front mounted on the X-axis?
7. Are the gantry sides also made of 120x80 profile? How are those mounted to the gantry?
8. The Y-axis rails appears to be top mounted. Why not side mounted?`Is it to make design simpler with the profile gantry sides?

[JAZZCNC]

The way I plan to solve this is whenever I am machining aluminium / very light steel, I will use a jig that I put on the table, which will then decrease the Z-clearance. This should work the same way as having an adjustable bed.

The requirement is a large work area, so a moving gantry design and making it as good as possible is my goal. This of course means that it wont be as rigid and as effective for aluminium / very light steel. This is a trade-off I need to make, as I don't have the budget or space to build 2 machines right now.[/QUOTE]

That's a good solution and one I'd take if building for my self with your requirements.

That is a nice looking machine you've built! Great idea with the 4th axis too.A few questions if you don't mind:

1. How does it perform in aluminium (tool, cut depth, feed rate)?
2. Do you have a build log somewhere?
3. What is the Z-axis clearance and working area?
4. Any reason why you went with L-shape design, instead of using say 90x180 box section profile?
5. Are the surfaces where the rails sit on the X-axis machined or shimmed?
6. What is the reason for having one rail top mounted and the other one front mounted on the X-axis?
7. Are the gantry sides also made of 120x80 profile? How are those mounted to the gantry?
8. The Y-axis rails appears to be top mounted. Why not side mounted?`Is it to make design simpler with the profile gantry sides?

#1 Cannot tell you this because I've never used iit myself, I only built it, and the owner only cuts woods with it as far I know.

#2 No this is a design I build and Sell.

#3 Z-clearance = 250mm Cutting dims Y1300 x X800

#4 Yes it's a much stronger design than a single piece of profile. It's my own design that I've used for years and it's well-proven on lots of machines.

#5 The surfaces are made flat and on the same plane by coating with a fine spread of Epoxy metal (not epoxy resin) and then machine frame is turned upside down and placed on precision Granite surface table.

#6 The fronted mounted rail is to give maximum clearance under the gantry and the top-mounted rail is to give greater spacing between rails and support the Z-axis rear plate.

#7 Yes 120x80. They are mounted by bolting into the lower flat profile from the top. The top profile is bolted to the flat profile from the underside, there are also aluminum keys inserted into the slots to stop any movement.

#8 It's difficult to align the rails parallel to each other when side-mounted. It's also much more difficult in regards to them being on perfectly horizontal and vertical planes. If the surface the rails mount on is not perfectly vertical then the gantry sides will form a V if viewed from front plane, likewise, if the surfaces are not parallel to each other they will form a V if viewed from Top plane.

[NordicCnc]

#4 Yes it's a much stronger design than a single piece of profile. It's my own design that I've used for years and it's well-proven on lots of machines.

#5 The surfaces are made flat and on the same plane by coating with a fine spread of Epoxy metal (not epoxy resin) and then machine frame is turned upside down and placed on precision Granite surface table.

#6 The fronted mounted rail is to give maximum clearance under the gantry and the top-mounted rail is to give greater spacing between rails and support the Z-axis rear plate.

#7 Yes 120x80. They are mounted by bolting into the lower flat profile from the top. The top profile is bolted to the flat profile from the underside, there are also aluminum keys inserted into the slots to stop any movement.

#4. Makes sense. It basically becomes an incomplete 120x200 profile shaped as an L, which has way more moment of inertia compared to a 90x180 profile. How are they mounted together? And what about using something like a 100x200 profile? I guess that would be of similar strength as the L-shape made by 80x120, but easier to use.

#5. This is interesting. So without a flat surface to rely on, you probably woulf have to go with epoxy resin levelling?

#6. Of course, why did I not think of that immediately. Oh well, it makes sense now. Is it much more difficult to get it aligned like that, compared to mounting both on the front?

#7. So you are drilling holes through the profiles for the bolts?

Bonus question: How much approximately do you sell this type of machine for? It looks really good and it sounds like a lot of fun to be making money building CNC machines!



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[JAZZCNC]

#4. How are they mounted together? And what about using something like a 100x200 profile? I guess that would be of similar strength as the L-shape made by 80x120, but easier to use.

They are bolted together from the bottom as mentioned in the last post and end plates are machined with L-shape pockets to match the profile then bolted to the ends to support the ends.

#5. This is interesting. So without a flat surface to rely on, you probably would have to go with epoxy resin leveling?

Yes, the first version I made used epoxy leveling until I aquired the large surface plate. Epoxy works ok it's just more work and takes a lot longer. The method I use now is dry within hours and can be drilled tapped the next day and rails fitted. You cannot fit rails on epoxy for at least 2 weeks.

#6. Of course, why did I not think of that immediately? Oh well, it makes sense now. Is it much more difficult to get it aligned like that, compared to mounting both on the front?

Yes and no. Yes because the rails are not on the same plane so a little more work with a dial gauge to get parallel etc. However, it does offer other advantages regards setting up the Z-axis vertical tram because you can slide the rails back n forth ever so slightly if needed, plus you the X-axis top plate which can have a little adjustment in it. More adjustments the better when it comes to building a CNC machine but Obviously within limits so as not to put a binding on the linear bearings.
Where if you have both rails on the same plane and the Vertical tram is out then you have to mess around with shims or tilting the gantry etc. Worse still if the gantry as got any twist in it because then it's not so easy to get twist out. With rails on top you can take the twist out easier.

#7. So you are drilling holes through the profiles for the bolts?

Yes, counterbore the slots to make a flat area for bolt head and then drill and tap into matching profile. Depending on profile type depends on how far into the profile I drill and counterbore.

Bonus question: How much approximately do you sell this type of machine for? It looks really good and it sounds like a lot of fun to be making money building CNC machines!

Yes, it's a lot of fun and frustration at times. As for making money that's a different matter... Not so sure I really do at times...

[NordicCnc]

Yes, the first version I made used epoxy leveling until I aquired the large surface plate. Epoxy works ok it's just more work and takes a lot longer. The method I use now is dry within hours and can be drilled tapped the next day and rails fitted. You cannot fit rails on epoxy for at least 2 weeks.

Can you specify or maybe give me a link for the epoxy metal that dries so fast? I'd like to try that.

From where/how did you aquire the large surface plate and how much did it cost? I am thinking if it would be possible to make one DIY with epoxy resin, hehe.

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[JAZZCNC]

Can you specify or maybe give me a link for the epoxy metal that dries so fast? I'd like to try that.

They have many suppliers around the world I believe but this the company and the type I use.

https://www.belzona.com/en/products/1000/1111.aspx

From where/how did you acquire the large surface plate and how much did it cost? I am thinking if it would be possible to make one DIY with epoxy resin, hehe.

It was gifted to me by a Friend. It's a massive 10" thick piece of fine-grained Granite that is precision ground to a calibrated tolerance and not something that could be replicated with epoxy.
You can buy them from any good tool supplier or meteorological supplier. However, they are expensive and very very heavy.

[NordicCnc]

I have taken some inspiration from the gantry design in your machine. What I've done differently is:

• It is far from done and many details are still missing. One gantry side is still missing completely.
  
• Y-axis linear rails are side mounted to the 160x80 item profile. This allows a larger work area and the ball screws can be mounted to the same piece of aluminium plate, with a little bit of machining.
  
• Gantry side plate is on the inside and an 80x80 item profile is mounted on the outside of the plate. The 80x80 item profile is mounted to the X-axis 200x80 item profile with a back plate and a bottom plate.
  
• The X-axis ball screw and linear rails are all on the front side. With some machining on of the aluminium plates, I am able to squeeze everything in the with custom made ball screw nut brackets.
  
• The Z-axis is made stiffer with side plates bolted onto the same plate to which the linear rails and ball screw is bolted.
  

Please let me know what you think! Are there any significant improvements I could do to make it better?

[JAZZCNC]

The main issue I see is the Z-axis and the unnecessary weight of it.!

You don't need or want the motor and ball-screw on the front plate because you are just moving around dead weight which will affect the z-axis negatively due to high inertia. Those 180W servos won't handle that weight, especially if your planning on using a large spindle or ATC spindle. You will also need a brake to stop it dropping when unpowered.

Ideally, you want a light but strong front plate with no excess baggage to affect inertia. The ball-screw could easily go on the rear plate and be shorter, the motor could mount to plate coming off slightly longer rear plate. This longer rear plate will also allow more spacing of the bearings which will stiffen things up a little.

The other thing I don't like is the ball-screw on the front. If it was me I'd mount it at the rear out fo the way of chips etc and have the ball-nut mount to the plate which the Z-axis motor mounts onto. Don't worry about the ball-nut not being in the so-called theoretical ideal central sweet spot of the front plate because in real-world the difference isn't noticeable. However, weight in the wrong place very much does affect the machine.

[NordicCnc]

The main issue I see is the Z-axis and the unnecessary weight of it.!

You don't need or want the motor and ball-screw on the front plate because you are just moving around dead weight which will affect the z-axis negatively due to high inertia. Those 180W servos won't handle that weight, especially if your planning on using a large spindle or ATC spindle. You will also need a brake to stop it dropping when unpowered.

Ideally, you want a light but strong front plate with no excess baggage to affect inertia. The ball-screw could easily go on the rear plate and be shorter, the motor could mount to plate coming off slightly longer rear plate. This longer rear plate will also allow more spacing of the bearings which will stiffen things up a little.

The other thing I don't like is the ball-screw on the front. If it was me I'd mount it at the rear out fo the way of chips etc and have the ball-nut mount to the plate which the Z-axis motor mounts onto. Don't worry about the ball-nut not being in the so-called theoretical ideal central sweet spot of the front plate because in real-world the difference isn't noticeable. However, weight in the wrong place very much does affect the machine.

Thanks man, Ill revise my design and start a build log to collect more feedback!

Do you still recommend that the linear rails stay on the Z-axis front plate? It would be significantly less weight to move if they are on the Z-axis rear plate, but not as stiff of course. Stiffness could however be increased with some aluminium strips.

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