-
A new hope: Epoxy granite and steel.
Hey,
Preface.
I've done a fair bit of research over the last few months and I decided to open a build thread. There's a bunch of things I haven't read about yet, hopefully I'll have a clearer picture of everything in the coming months.
Materials.
I'm gonna limit myself to 2 materials. Epoxy granite and toolsteel sheet up to 30mm thick.
Structural.
There are 2 options I'm considering:
A. Epoxy granite bed(Y-axis) and steel welded gantry(X-axis). Z-axis steel.
B. Epoxy granite bed(Y-axis) and epoxy granite gantry(X-axis). Z-axis steel. I'd prefer this option due to the free
form advantage of casting epoxy granite.
Motors.
Lichuan's A4ST 80's.
Linear Rails.
Hoping to snipe some mint Rexroth roller rails from ebay. I've seen a bunch of them come and go over the last few months so there seems to be a somewhat steady supply out there.
Size 35 for Y, 25 for X and Z
Belt driven ballscrews.
Hiwin 2510 on x_axis and y_axis(2x), Isel 2510 on z. For backlash 2x screw nuts on each ballscrew. 25mm Gates GT3 5M belt. 18 teeth on the motor and 36 teeth on the ballscrew,
Spindle.(max. 2x380V)
BT30 with a custom 'hydraulic' drawbar pushed be an axial pump driven by a 40/60 servo, mounted to the side.
driven by a servo size 130/140. RPM up to 5500.
alternative Teknomotor C60/67-D-DB-P-ER32. It's a 6000-9000RPM 3.3kW spindle for EUR 1000,00 https://www.damencnc.com/userdata/ar...24513-en-G.jpg
EDIT 2.
Some pics as promised.
Spindle
BT30 cartridge.
Thanks!
-
Re: A new hope: Epoxy granite and steel.
Hi,
That sounds like a heavy build!
But you are missing some crucial informations: what would be the working area and what do you plan to make with it??
Quote:
Originally Posted by
hardenum
- There are also holes on the side of the carriages, is that so that I can move the lubrication port from the front to the sides?
Yes but you have to pierce a hole with a needle and tap the thread.
Quote:
Originally Posted by
hardenum
I'm thinking of a BT30 and a size 130 servo(180 might be too heavy for a moving gantry), something at the range 12-24Nm and able to get to 9000RPM. I got a google problem with this though, I'm not getting any matches for "spindle servo" or even "spindle cartridge", the results almost always show up regular router spindles.
Check out CTB servo in China. They make nice spindle servos, but they are quite bulky.
Quote:
Originally Posted by
hardenum
Alignment:
- aligning ballscrew with the rails, I know how to do rail-to-rail alignment, but how do I do it for the ballscrew ?, the old fashioned way of moving the carriage and then tightening the ballscrew mount? Is there a more foolproof way of doing it? How do I make sure there are no forces acting perpendicularily on the ballscrew?
https://www.youtube.com/watch?v=mLCHT2ywk5A
-
Re: A new hope: Epoxy granite and steel.
Quote:
Originally Posted by
hardenum
Motors.
Lichuan's A4ST 60's or 80's. Probably 60's due to lower inductance.
These are AC Servo's not DC steppers so inductance doesn't play such a large part in the performance as your using mains AC voltages so pushing volts/current through them isn't a problem, it's the rotor inertia you are more concerned with when it comes to Servo's.
-
Re: A new hope: Epoxy granite and steel.
Quote:
Originally Posted by
JAZZCNC
These are AC Servo's not DC steppers so inductance doesn't play such a large part in the performance as your using mains AC voltages so pushing volts/current through them isn't a problem, it's the rotor inertia you are more concerned with when it comes to Servo's.
Duly noted.
Quote:
Originally Posted by
jarjar
That sounds like a heavy build!
But you are missing some crucial informations: what would be the working area and what do you plan to make with it??
Target build volume 320(Y)640(X)180(Z). Primarily aluminium(AW-6060 / AW-6082 / AW-2007/ AW-1050A/ AW-5754/ AW-5083/ AW-7075), occasionally mild steel. Mostly sheet metal, sometimes a mold for silicone injection(low pressure).
Quote:
Originally Posted by
jarjar
Check out CTB servo in China. They make nice spindle servos, but they are quite bulky.
Thanks for the tip, I found one that I like. https://ctbservo.com/product/servo-s...75x175x360-mm/
I'm really not an EE guy, despite many attempts. What's the deal with Rated Speed and Max Speed.
Does this mean I can run any servo over it's Rated Speed or are "spindle motors" a different motor type that allows it?
ie. synchronous for positioning, asynchronous for spindle? Or can I take a eg. an oversized servo and use it to drive the spindle cartridge?
-
Re: A new hope: Epoxy granite and steel.
Quote:
Originally Posted by
hardenum
Does this mean I can run any servo over it's Rated Speed or are "spindle motors" a different motor type that allows it?
ie. synchronous for positioning, asynchronous for spindle?
Both types of motor can be run above their rated speed however the difference is how long for.? An Axis servo can typically be run 100-200% above rated speed and torque but only for a few seconds. A spindle Servo motor is nearly always running above its rated speed but with a loss in torque.
How does it work.?
Now, I'm no Motor expert so don't quote me, but I think it comes down to the Motor type and how it's constructed.
An axis servo motor type is (synchronous) and uses permanent magnets to drive the Rotor, this is why it can give constant torque through its speed range.
The Spindle Servo type is (Asynchronous) which has no permanent magnets and relies on the rotating field to produce a magnetic field. This means it can run at higher than rated speeds constantly but at the cost of lower torque than at rated speeds.
There are other differences in how they work regards the drive. An Axis servo is typically run using POSITION mode whereas a Servo Spindle is run in SPEED Mode. (There is also TORQUE mode but POSITION and SPEED are the most commonly used.)
This is why you can rotate the shaft of the Servo Spindle motor when powered up but you cannot spin the shaft of an Axis servo motor. The Axis servo drive is constantly monitoring the rotor position and applying corrections to keep it POSITION, if you turn it by hand too far it will fault the drive.
Now, if you ran the Axis servo in Torque mode then this is similar to POSITION but now the drive monitors the TORQUE and tries to maintain it and if the torque falls below a set range it will fault.
SPEED mode you can probably guess by now.! The rotor position isn't monitored at all and is free to spin without any faults in the drive but the Speed is monitored and the drive will try to maintain this speed and again if it falls below a preset threshold the drive will go into a fault.
Now Servo spindles can position the rotor shaft for things like tool changing, they do this by switching into POSITION mode, and using the encoder they can rotate the shaft to an angular position.
So in Recap, Axis Servo can run above rated speed/torque for limited time periods without loss of torque. Spindle Servo, mostly, constantly run above rated but with some loss in torque as speed increases. This due to motor construction, (synchronous) and (Asynchronous)
Hope this helps.
-
Re: A new hope: Epoxy granite and steel.
There generally isn't that much difference between an axis servo motor, and a spindle servo motor. The main difference is in how they're utilised.
A servo motor rated speed/torque is what it should be able to happily produce 100% off the time without any overheating problems.
In terms of an axis, you're never likely to sustain using 100% of that continually, so you can intermittently drive the servo harder, which is where the instantaneous torque figures come in.
The rated speed is where the laws of physics really kicks in.
Regardless of being AC or DC, motor torque is directly proportional to current. More current = more torque.
In the case of DC, motor speed is proportional to voltage. More voltage = more speed.
In the case of AC, motor speed is proportional to frequency. Higher frequency = more speed.
As a motors speed increases, the back emf (electromotive force) increases. Think of emf as if the motor was acting like a dynamo/alternator being spun, in that it produces power, aka emf. The faster the motor spins, the more emf it produces. Now this emf fights 'back' against the voltage being applied to the motor, so the faster you spin the motor, the more voltage you need to maintain a given current through the motor. This applies to both DC and AC motors.
At a motors rated speed, this is the point the rated supply voltage can still overcome the back emf to provide the rated current.
Above this point, with an AC servo, as speed is not reliant on voltage, you can continue to increase the frequency, but you then start to lose torque, as you don't have the voltage to force enough current through the motor.
The motor essentially goes from being a constant torque source, with power proportionally increasing as motor speed increases to the rated speed, to a constant power source, with torque proportionally dropping as speed increases.
This applies to pretty much all electric motors.
In terms of a standard servo, and a spindle servo. The main difference is likely to be the spindle servo is derated, with better cooling to reduce the risk of overheating. There is nothing stopping you from using a standard servo, and running it above it's rated speed, to drive a spindle. Most servo manufacturers will list a rated speed, but they'll also produce speed/torque graphs that show motors performance above the rated speed, up to the speed they deem possible to run the servo.
In terms of drives.
Torque mode is the most basic, and gives the most responsive control over the servo. The big downside is torque mode is inherently unstable. Anytime the load on the servo changes, the servo speed also changes, so the controller has to be very responsive and tuned very well to maintain position.
Speed mode gives almost as much control over the servo, but due to the additional filtering involved, it's not quite as responsive. Speed mode was the mode any old school DC servo with a tacho fitted used, as at the time, controllers just weren't responsive enough to use torque mode. The tacho and servo drive (well technically amplifier) essentially acted as a damper to reduce the responsiveness needed from the controller to maintain position.
Position mode sits on top of speed and torque modes. It's basically a closed loop controller within the servo drive.
How any servo and drive responds, is entirely down to settings.
I'll just correct Jazz on torque mode. If you set a servo to torque mode, and command it to produce say 50% torque. With no load it'll spin up to it's rated speed. Stall it, it'll sit and produce 50% torque against that stall. Load it so it spins the opposite way, and it'll still happily sit producing that 50% torque against how it's being spun.
The servo drive doesn't care how the motor is turning/being turned, as long as it can produce the request torque without triggering a fault, it'll continue to do so.
Servo tuning does vary between axis and spindle though.
In an axis you want positional accuracy, so they get tuned to hold that position as best as possible. The downside is you end up working the motor harder, as it continually changes output trying to hold position, and you'll often find what works well at low speed/stationary, doesn't work so well at high speed, so you need to compromise to minimise following error under all conditions.
With a spindle, you're not as concerned about position, so you can tune them to be far more sluggish to respond to changes. A spindle being a few turns from position at 3000rpm isn't a major issue, as long as the speed remains constant. The last thing you want is a spindle that surges when it encounters a sudden load change, so you'll generally tune them to be more sluggish to respond.
As somebody asked me when tuning the servo spindle on my little mill, why do you need a spindle that only has a 20 count position error?
Even when rigid tapping, all you need is a stable spindle that you can reliably stop, it doesn't have to be on position to achieve that. It's up to the Z axis is ensure the thread is where it should be.
Although I still love playing with the servo spindle on my lathe, but it highlights how sluggish it's tuned. Put it in C-axis mode, and you can rock the chuck, before the drive just sluggishly pulls it back to where it should be. It could probably be tuned to respond faster, but it wouldn't make any difference to the parts it's makes.
You have to consider the loads the spindle actually sees. My lathe has a 5.5KW 3000rpm spindle servo, so it only produces 17Nm of continuous torque at the chuck. Given it's got a 8" chuck fitted, that means it only takes 170N pull at the edge of the chuck to overcome the spindle. Doesn't sound a lot, but when you're drilling/milling within the capacity of the lathe, it's more than enough to keep things where they need to be.
-
Re: A new hope: Epoxy granite and steel.
Again many thanks to JAZZCNC and m_c!
A dedicated direct drive spindle is too long for my build, the shortest I found is 385mm (https://sc02.alicdn.com/kf/HTB1l9RHX...XXaC.jpg_.webp) with a motor that puts me at almost 700mm Z axis and that's just too long, so unless I design my own spindle I don't see how I can fit in max 500mm length. I guess that's off the table then.
-
Re: A new hope: Epoxy granite and steel.
-
Re: A new hope: Epoxy granite and steel.
-
Re: A new hope: Epoxy granite and steel.
Is the "Attachment 29166" not clickable?
-
Re: A new hope: Epoxy granite and steel.
It links to "invalid attachment"
-
Re: A new hope: Epoxy granite and steel.
Quote:
Originally Posted by
jarjar
It links to "invalid attachment"
I tried opening it in edge and it also didn't work, I do not know how attachments work here so I changed the host. it should be visible now.
-
Re: A new hope: Epoxy granite and steel.
Why the big cutout for the motor? Looks like a big waste of material and it certainly won't help with the stiffness of the fixed ballscrew bearing block.
For the gantry I would make a much bigger section, ideally square. EG is not very stiff at about 30 GPa.
-
Re: A new hope: Epoxy granite and steel.
Quote:
Originally Posted by
jarjar
Why the big cutout for the motor? Looks like a big waste of material and it certainly won't help with the stiffness of the fixed ballscrew bearing block.
For the gantry I would make a much bigger section, ideally square. EG is not very stiff at about 30 GPa.
Actually that's because I wanted to make a universal casting for the belt assembly, and that meant all axes would have the same belt config, belt length etc. like this: https://i.imgur.com/5XeRLwY.png
The x_axis actually sits on a structural steel plate that provides the necessary stiffness and connects the x_axis with the supports.
-
Re: A new hope: Epoxy granite and steel.
Did I miss it, what is the gantry section size?
Sent from my SM-G970F using Tapatalk
-
Re: A new hope: Epoxy granite and steel.
Quote:
Originally Posted by
Nikolaguca
Did I miss it, what is the gantry section size?
Sent from my SM-G970F using Tapatalk
it's 280x140mm
-
Re: A new hope: Epoxy granite and steel.
I'm building a steel gantry router and I wanted to go with 200x100 steel tube but was given the advice to go with 200x200 because you're not just fighting gravity but cutting forces as well (and torsional forces when the z axis is lowered down)...
I'm using 250x250x10mm steel tubing for the gantry at 1300mm lenght to get the stifness I need.
Sent from my SM-G970F using Tapatalk
-
Re: A new hope: Epoxy granite and steel.
Power supply
I've seen a toroidal PSU is a popular choice. I've also read that it can be quite dangerous to work with, as in getting electrocuted. I have octopus fingers, they get into all sorts of places without my permission, which usually results in cuts and wounds, I'd rather avoid any potential dangers, I'm quite clumsy in general. What are my options here?
AC/DC
I'm also confused about the fact that these (eg. https://www.cnc4pc.com/unregulated-l...oidal-psu.html) output DC, if I got AC servos, how does that work? Do I convert it back to AC?
Thanks!
-
Re: A new hope: Epoxy granite and steel.
There's nothing any more dangerous about a toroidal PSU versus any other PSU of similar voltage and wattage. However, I think you might be slightly confused though - I'd expect that you'd be buying the servo with a matching servo driver. Looking at lt Lichuan 60's on Aliexpress - that's certainly a common bundle. In which case - check the datasheet, but the servo drivers would likely be 220VAC mains driven, and in which case you wouldn't need the high power, high voltage toroidal PSU. Or maybe I'm too tired and I've missed a point in your post?
-
Re: A new hope: Epoxy granite and steel.
Quote:
Originally Posted by
Doddy
There's nothing any more dangerous about a toroidal PSU versus any other PSU of similar voltage and wattage. However, I think you might be slightly confused though - I'd expect that you'd be buying the servo with a matching servo driver. Looking at lt Lichuan 60's on Aliexpress - that's certainly a common bundle. In which case - check the datasheet, but the servo drivers would likely be 220VAC mains driven, and in which case you wouldn't need the high power, high voltage toroidal PSU. Or maybe I'm too tired and I've missed a point in your post?
I will definitely be buying a matching driver(amplifier) from lichuan. I really have no idea about powering electronics, I probably don't even know the questions I should ask. What's confusing me is that the servo's are AC and the recommended PSU outputs in DC.
-
Re: A new hope: Epoxy granite and steel.
Link to information that recommends a DC power supply for the servo driver?
-
Re: A new hope: Epoxy granite and steel.
Quote:
Originally Posted by
Doddy
Link to information that recommends a DC power supply for the servo driver?
No such thing, it was my assumption, so in other words I don't need any PSU at all, just plug the drivers directly to mains?
-
Re: A new hope: Epoxy granite and steel.
Read the specification for you selected drivers.
You will always need part for control logic, switching etc., but if you have mains driven servo drivers then this would be a much smaller power supply, at lower voltage and power.
-
Re: A new hope: Epoxy granite and steel.
Quote:
Originally Posted by
Doddy
You will always need part for control logic, switching etc., but if you have mains driven servo drivers then this would be a much smaller power supply, at lower voltage and power.
ah, that makes sense, okay, thanks.
-
Re: A new hope: Epoxy granite and steel.
Some servo drives need only a AC supply, others need AC + 24V DC for the control logic.
In all cases you will still need a DC supply for the motion controller and other things. Basically a small switching PSU like this: https://uk.rs-online.com/web/p/din-r...plies/0428477/
-
Re: A new hope: Epoxy granite and steel.
-
Re: A new hope: Epoxy granite and steel.
Why direct drive?
Won't it be much harder regarding drawbar etc?
-
Re: A new hope: Epoxy granite and steel.
-
Re: A new hope: Epoxy granite and steel.
The Z looks complex. I assume you have a complete machine shop to build it. Ideally it should be as wide as the gantry carriage.
I would go fixed gantry for the relatively small working area you planned.
Maybe also consider simplifying the shape of the columns, but in the end you'll be the one to build the molds :)
-
Re: A new hope: Epoxy granite and steel.
Quote:
Originally Posted by
jarjar
The Z looks complex. I assume you have a complete machine shop to build it. Ideally it should be as wide as the gantry carriage.
I would go fixed gantry for the relatively small working area you planned.
Maybe also consider simplifying the shape of the columns, but in the end you'll be the one to build the molds :)
I do not, all I have is a hand drill and a dremel, I'm outsourcing it. The sheet metal cutting and welding. It's not more complex then a straight or a C plate. It's just a square steel tubing in the end. I've actually received a quote for the whole piece from the local shop EUR600 total for the thing.
Besides the Z, nothing is final yet. I'd go with a fixed gantry but I haven't got a clue yet as to how I'd deal with the bed. What I mean by that is I want to be able to mount the 640x320 work piece vertically. With a moving bed, I don't have any ideas how to do that though.
-
Re: A new hope: Epoxy granite and steel.
Quote:
Originally Posted by
hardenum
I do not, all I have is a hand drill and a dremel, I'm outsourcing it. The sheet metal cutting and welding. It's not more complex then a straight or a C plate. It's just a square steel tubing in the end. I've actually received a quote for the whole piece from the local shop EUR600 total for the thing.
What about the pretty much mandatory stress-relieving after welding, the precision milling/grinding for the rails, boring for the spindle body, milling for the spindle flange?
-
Re: A new hope: Epoxy granite and steel.
Quote:
Originally Posted by
jarjar
What about the pretty much mandatory stress-relieving after welding, the precision milling/grinding for the rails
stress-relieving is in the quote. No under-rail machining, epoxy leveling them. If I were to have them machine all the required surfaces on it, might as well find a different hobby. Machining prices in germany are off the charts. One time I wanted to bring my 300x200mm aluminum heatsink for a shop to mill 3x 10mm wide 200mm long cannals on the underside for heat pipes, the quote was EUR2000.
Quote:
Originally Posted by
jarjar
boring for the spindle body, milling for the spindle flange?
You mean the cartridge? I'm not doing it from scratch. I'll be (or rather the shop will be) making a different drawbar for one of these https://ae01.alicdn.com/kf/H06429625...c015c524f3.jpg, and slightly modifying the spinning part on their lathe. You are right though, that is not a part of the quote above.
-
Re: A new hope: Epoxy granite and steel.
Steel-filled epoxy molding against a surface plate, yes, that can work. But not epoxy leveling.
I meant the bore to fit the spindle and milling the mounting surface flat and perpendicular to the rails where the spindle flange will be bolted.
-
Re: A new hope: Epoxy granite and steel.
Quote:
Originally Posted by
jarjar
I meant the bore to fit the spindle and milling the mounting surface flat and perpendicular to the rails where the spindle flange will be bolted.
This sounds overcomplicating? The mounting surface that will be touching the cartridge will be cut with a saw so pretty straight to me if you ask. I mean I'm not making swiss watches, I don't need that kind of precision.
Quote:
Originally Posted by
jarjar
Maybe also consider simplifying the shape of the columns, but in the end you'll be the one to build the molds.
A smart man once said "people should put more work into molds".
-
Re: A new hope: Epoxy granite and steel.
Quote:
Originally Posted by
hardenum
I don't understand why you cant have a belt driven spindle. Just put the motor beside or in front of the spindle instead of behind.
I'm not saying direct drive is a bad idea. I just suspect it will be difficult dealing with drawbar issues etc
-
Re: A new hope: Epoxy granite and steel.
Quote:
Originally Posted by
jarjar
Steel-filled epoxy molding against a surface plate, yes, that can work.
This, thanks for this, another piece of puzzle for my project. Really cool idea, having a hardness gradient on the cast piece.
-
Re: A new hope: Epoxy granite and steel.
Jar Jar and Pippin are making some very valid points and If you are not careful you are going to waste a lot of euros.
You are over complicating the design around the spindle and underestimating the importance of precision required in surfaces, etc. The fact you haven't even considered or looked into Fixed gantry design or even understand how it works tells me that you haven't done enough research into what is required for the machine you require.
I suggest you STOP and go take a look at fixed gantry designs because it's the BEST design for the size of the machine you are planning to build.
-
Re: A new hope: Epoxy granite and steel.
Quote:
Originally Posted by
JAZZCNC
Jar Jar and Pippin are making some very valid points and If you are not careful you are going to waste a lot of euros.
You are over complicating the design around the spindle and underestimating the importance of precision required in surfaces, etc. The fact you haven't even considered or looked into Fixed gantry design or even understand how it works tells me that you haven't done enough research into what is required for the machine you require.
I suggest you STOP and go take a look at fixed gantry designs because it's the BEST design for the size of the machine you are planning to build.
I cannot build a fixed gantry, there is no way for me to mount the workpiece vertically if I went with a moving table. There would be no point in building any cnc if I can't mill all 6 sides of the work piece.
I have looked over hundreds of designs over the past half a year and only a moving gantry with a fixed bed with a cutout ala Datron allows me to mount the workpiece in all orientations.
There is another design, a horizontal cnc mill, that would allow me to mount the workpiece so that I can mill all 6 surfaces. But to be honest it looks quite daunting to go down that route.
The spindle choice is pretty easy though. One day your bank account is full, the next day it's empty. If I went with a motorized spindle, I'd be screwed if either of the components broke. Cartridge + motor is far safer if something were to brake and needs replacing.
I'm happy to be proved wrong though.
I was thinking of having the front mold piece machined instead of plates that are cast into the casting. Cast it after having everything aligned to the machined front mold piece. There is no way for me to transport the casting to a shop for machining after it's been cast.
By the way, I'm months, if not years, away from actually starting doing any of this work, so I really appreciate any and all insights!
-
Re: A new hope: Epoxy granite and steel.
Quote:
Originally Posted by
hardenum
I cannot build a fixed gantry, there is no way for me to mount the workpiece vertically if I went with a moving table. There would be no point in building any cnc if I can't mill all 6 sides of the work piece.
I have looked over hundreds of designs over the past half a year and only a moving gantry with a fixed bed with a cutout ala Datron allows me to mount the workpiece in all orientations.
Only a 5 Axis machine can allow you to cut on all 6 sides in one operation. If your meaning to re-fixture and cut the other 2 sides then that's easily fixed, it's called an Angle plate bolted to the bed. Because that's all the Datron is providing with it's cut out, it's just an inverted angle plate built onto the end of the bed.
Other than that there is no difference between Fixed or Moving gantry other than Strength and size, Both have their own strengths and weakness but in your working envelope then the Fixed gantry wins hands down if you are wanting a strong machine.
If you want to work on 5 sides in one operation then Bolt a 4th axis to the table, again this would work on both designs but the Fixed gantry will do it better because it's stronger.
Quote:
Originally Posted by
hardenum
The spindle choice is pretty easy though. One day your bank account is full, the next day it's empty. If I went with a motorized spindle, I'd be screwed if either of the components broke. Cartridge + motor is far safer if something were to brake and needs replacing.
I'm happy to be proved wrong though.
I wasn't meaning the choice of separate Spindle + motor, that works good, but more your implementation of it is too complicated. Also, the Z-axis design is narrow and weak which will make all the trouble you'll be going to a pointless exercise.
There are plenty of examples of ATC spindle setups, just about every Milling machine with ATC uses the same setup. You just need the same setup and just rotate it 90deg so it's at the side if you don't have the room behind the spindle.
Also, I'm not sure your choice of Servo motor is correct as it looks just like an axis Servo rather than a Servo spindle motor.?
These are just some of the things I'm meaning when I say you are going to waste lots of Euros because none of them is cheap and easily done wrong if you haven't thought about and planned every last detail.
Theory and Cad are great, however, Reality is a Mother - F@~ing -Bitch just waiting to slap your face and kick you in the Nuts who never plays by theory's rules and changes them to suit Her whenever she wants.
-
Re: A new hope: Epoxy granite and steel.
Quote:
Originally Posted by
JAZZCNC
If your meaning to re-fixture and cut the other 2 sides then that's easily fixed, it's called an Angle plate bolted to the bed. Because that's all the Datron is providing with it's cut out, it's just an inverted angle plate built onto the end of the bed.
I can see how this would be problematic if you want to mill on the side of long pieces that won't fit under the gantry. With a fixed bed the cutout allows the work piece to extend below the bed. If OP wants to do a lot of those pieces then the moving gantry seems indeed the way to go.
About the sawn surface to bolt the spindle on, I think this is a big no-no. I'm not talking about precision watch making, just basic good practice for mating surfaces. If the contact area is bad, you will lose most of the stiffness and also distort the spindle housing, possibly damaging the bearings very quickly.