Machine 3 - 8020 + Linear Rail + High Speed Ballscrews + GRBL

[jahnj0584]

Hey!

First thread here, and 3rd machine for me. I started with an OXBuild, then made a ballscew version, and this will hopefully be my final one for another year or two lol.
Still in design phase, I just sold my current one this week. Should ship out in a week or two.

Specs:
1500x1000 frame (40120 Y's, 80160 X, 4040 supports)
2*4 minimum cut area for sheet goods. Looks like 28x50 right now. 165mm or 6.5" of Z stroke at the moment!
20mm Genuine HIWIN rails, 12mm for Z. Dual carriages everywhere
3/4" Bed + 1/2" MDF spoiler, re-glued when faced off completely.
475 oz in Nema 23's, up to 3k rpm
48V 15A PSU
4A TB6600 drivers (2nd time, I enjoy them and the price!) + Arduino Uno + GRBL
Prox Switches
16 or 2010 Y dual screws, 20 or 2510 X screw (gives a 0.0005 resolution)
1.5kw air cooled spindle + VFD, 220V
Theoretical rapid speeds: 13.4m/min (525ipm) X, 19m/min (700ipm) Y, 10m/min (400ipm) or so Z
Welded steel tubing table (2*2, guy at work will weld it up for me + I just pin the legs on at home)

So, heres the pics for now. Ordering parts sometime soon, working on getting everything modeled and made in 3D first. Ill make my own plates and end mounts at work! (machine shop with 4 mills 7 lathes + a dozen Haas')

ANY recommendations would be appreciated, except those against the TB6600's. I get it, they are cheap and may die. Thats why I bought 5
(How do I attach photos?)


Weak points for me: Gantry plate shape + thickness (3/4 6061? Could use the inspiration!)


Mounting X Ballscrew (behind extrusion? Above? Pics again would be nice)

Prox switches off 5V supply (Enough? Use my 24V + resistors instead?)

Different style X axis? 2 Extrusions along some plate aluminum?

Ballscrew choice. I think its a matter of like 25$ to go from 16 to 20 on the Y and 20$ for 20 to 25 for X. May as well go beefy huh?

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[Biggs427]

I run my CNC using TB6600 and there's no way it can spin my stepper past 1800rpm. This is with a 195oz, 3A, 2.5 mH stepper on my desk. When attached to a ballscrews the numbers goes down to 1200.

Higher torque stepper usually mean more inductance thus reducing the max rpm.

What's the inductance of your steppers? Microstep setting you are planning to use?

The TB6600 won't handle 48v; I had to turn down the voltage to 40v on mine.

TB6600 is an ok drive, just need to adjust your expectations when using it.

[jahnj0584]

Well, my current machine drove the motors at 48V supply voltage (40V is what the driver sends out, but it will accept 48 in!) at 3k rpm (15.2m/min jog with 5mm screws = 3040rpm)

I believe they are 3.5mH or so, I specifically chose low inductance ones compared to the 6.7mH option.

Probably 1/4 stepping to get a resolution of 1 thou, but maybe even 1/8 if I want to go finer. Its impossible to stall my 170ozin motors with 5mm screws unless you hit a hard stop.

[1Jumper10]

Just a couple things I saw:
I would mount your X ball screw behind the Z, along the top of the gantry beam. Conventional wisdom says to mount it as close to the plane of the cutting bit as possible. If your gantry beam was a 2 piece design, I would suggest you mount the screw in the middle, between the top and bottom beams. Since mounting the ballscrew underneath the gantry beam is fairly impractical, not to mention making it prone to contamination, with your design and good choice of linear bearings you would be fine mounting it behind the Z axis car on top of the gantry.

For your Z axis; if you can mount the 12mm rails to the back of the plate and fix mount the bearing blocks, you gain some rigidity in the plate from the linear rails without any real penalty.

For your gantry plate, on my last router I used a 3/4" 6061 aluminum plate on the Z-axis and I feel it was stiff enough. I'm going to use the same method again on my current router but I'm going to brace the edges of the plate with angle iron.

[jahnj0584]

Yea, i was thinking along the top and adding a dust shield along the top edge of the 80160 to keep it concealed. I would aesthetically prefer it along the back edge though. I dont see how it could cause any issue, with the gantry being "framed in" with a 1/4" connector plate along the bottom (so its a "closed box" around the frame)

Why does the orientation change the ridgity? The pivot point would be the exact same location, would it not?

Changes: Y screws will be 2010, X will be 2510. Debating using 1605 for Z and maybe using 20mm rails and not need a stand off? Im sure 12mm will be fine, its just that it arrived and seems TINY.

[jahnj0584]

Lots has changed! About 300 screws, a dozen or so plates to make at work, and 4 custom ball screws.

25x50x5 cut area
600ipm rapids

[jahnj0584]

I do need suggestions on how to mount the drag chain for the X axis, Im using 18x37 inside diameter, with a 100mm rad

[wizard]

First off it is always good to know what is driving this new machine. Is it a desire to build machines or a do you have performance issues you want to correct?

Hey!

First thread here, and 3rd machine for me. I started with an OXBuild, then made a ballscew version, and this will hopefully be my final one for another year or two lol.
Still in design phase, I just sold my current one this week. Should ship out in a week or two.

Specs:
1500x1000 frame (40120 Y's, 80160 X, 4040 supports)
2*4 minimum cut area for sheet goods. Looks like 28x50 right now. 165mm or 6.5" of Z stroke at the moment!

It is good that you are looking at a bit more stroke than standard sheet goods.

20mm Genuine HIWIN rails, 12mm for Z. Dual carriages everywhere

The Z axis takes a lot of stress that is the last place to use small rails. I highly suggest the stickies where some really good threads exist that cover aspects of gantry design.

3/4" Bed + 1/2" MDF spoiler, re-glued when faced off completely.
475 oz in Nema 23's, up to 3k rpm
48V 15A PSU
4A TB6600 drivers (2nd time, I enjoy them and the price!) + Arduino Uno + GRBL

I really doubt that you will get best performance with that power supply and those drivers

Prox Switches
16 or 2010 Y dual screws, 20 or 2510 X screw (gives a 0.0005 resolution)
1.5kw air cooled spindle + VFD, 220V
Theoretical rapid speeds: 13.4m/min (525ipm) X, 19m/min (700ipm) Y, 10m/min (400ipm) or so Z

You will not get those speeds most likely.

Welded steel tubing table (2*2, guy at work will weld it up for me + I just pin the legs on at home)

The place you get the biggest pay off with steel is in the gantry. Yes you have to buy a big piece of square tubing but in the end it is a big win for rigidity.

So, heres the pics for now. Ordering parts sometime soon, working on getting everything modeled and made in 3D first. Ill make my own plates and end mounts at work! (machine shop with 4 mills 7 lathes + a dozen Haas')

That is excellent, having access to a machine shop really helps with machine construction.

ANY recommendations would be appreciated, except those against the TB6600's. I get it, they are cheap and may die. Thats why I bought 5
(How do I attach photos?)

This is one asinine statement. First off you don't start buying controls until you have a good understanding of what you will be driving. Then you have to consider your performance goals. You are also upgrading and in many respects are on your way to a nicely designed machine form the mechanical standpoint so why saddle it with crap controls? Lastly it is very possible that the TB6600's won't operate at the voltages you will need to drive the machine like you want.

Weak points for me: Gantry plate shape + thickness (3/4 6061? Could use the inspiration!)

Not sure what you mean by Gantry plate. If you mean the saddle I'd consider steel myself.

Mounting X Ballscrew (behind extrusion? Above? Pics again would be nice)

Mount the screw behind the saddle centered between the linear rails.

Prox switches off 5V supply (Enough? Use my 24V + resistors instead?)

If you are working with different power supplies make use of isolators.

Different style X axis? 2 Extrusions along some plate aluminum?

Generally I don't recommend the use of extrusions to support linear rails. I'm not sure what sort of HAAS machine you have but if you are lucky enough to have access to such machines, and they are large enough, I'd suggest using steel wherever possible.

Ballscrew choice. I think its a matter of like 25$ to go from 16 to 20 on the Y and 20$ for 20 to 25 for X. May as well go beefy huh?

It all depends upon your mechanical clearances. In short bigger ball screws are a win, but you need the physical room to install them. Don't forget about the physical size of the ball nuts. Go too big and inertia becomes a problem which comes back to not buying controls until you have the mechanical design nailed down.

In any event I look at it this way, you have access to a machine shop, this is a massive advantage over people DIY'ing a machine with almost nothing in the way of tools. As such why not take advantage of the machining capability that you have access too. With that in mind I'd seriously consider ditching the aluminum T-Slot extrusions for basic machine structure. This especially on the gantry beam and the Z axis. This is machine #3 for you and I'm assuming part of your desire here is for a machine that outclasses the previous two. Go for rigidity and precision.

[wizard]

Lots has changed! About 300 screws, a dozen or so plates to make at work, and 4 custom ball screws.

25x50x5 cut area
600ipm rapids

It looks nice but I really don't know for sure what you intend to do with the machine . It sounds like you are interested in wood based sheet goods only. What sort of results you want impact any suggestions you might get. You indicate your involvement in musical instrument making, if this machine is for that you probably what very good tolerance holding ability.

For the gantry uprights I would want to see box tubing used instead of a single plate on each side.

Getting too tired to think here.

[jahnj0584]

I just enjoy building + designing the machines, and hope to be able to do aluminum and hard wood milling easily. Last machine could almost do alu, and would've just fine with a few upgrades but I found a buyer so went from the ground up with the new knowledge.

I already have the 12mm rails, and it's 250$ USD to have 2x 330mm 20mm rails mailed to me, so unless I seriously have issues with these, I wont be upgrading them.

Those speeds are reasonable and realistic. The 1400mm long 2010 ballscrew can go 1550 rpm before reaching 80% critical, which equals 15.6m/min or 615ipm. The Y's can go 1000ipm but I doubt the machine will do that without moving itself off the table lol. We shall see when its all assembled! Anything over 250ipm is good enough for me. Resolution of a step is still 0.0005"

Controls were bought because they worked fine on my last machine. The TB6600 drivers I got can put out 3000rpm at 48V and deliver I believe 5A.

The gantry plate joins the X beam to the Y rails. I already bought the 3/4 6061 alu for it, 13lbs by itself.

One power supply now, I decided against prox switches and will use good old mechanical ones.

My Z Axis plate is also 3/4, not extrusion.

[louieatienza]

I just enjoy building + designing the machines, and hope to be able to do aluminum and hard wood milling easily. Last machine could almost do alu, and would've just fine with a few upgrades but I found a buyer so went from the ground up with the new knowledge.

I already have the 12mm rails, and it's 250$ USD to have 2x 330mm 20mm rails mailed to me, so unless I seriously have issues with these, I wont be upgrading them.

Those speeds are reasonable and realistic. The 1400mm long 2010 ballscrew can go 1550 rpm before reaching 80% critical, which equals 15.6m/min or 615ipm. The Y's can go 1000ipm but I doubt the machine will do that without moving itself off the table lol. We shall see when its all assembled! Anything over 250ipm is good enough for me. Resolution of a step is still 0.0005"

Controls were bought because they worked fine on my last machine. The TB6600 drivers I got can put out 3000rpm at 48V and deliver I believe 5A.

The gantry plate joins the X beam to the Y rails. I already bought the 3/4 6061 alu for it, 13lbs by itself.

One power supply now, I decided against prox switches and will use good old mechanical ones.

My Z Axis plate is also 3/4, not extrusion.

I too have doubts about 600ipm rapids. The motors would have to be spinning at over 1500rpm, and by then you won't have a lot of available torque. Not at 48V. At 3000rpm I doubt you have any useable torque.

Also don't get enamored with resolution. The lead error on those ballscrews is about 6 times what your resolution is, at least.

[jfong]

If you are using grbl you will probably run into the max step frequency output rate before hitting 1500rpm.

At 8microstep setting, 1500rpm is 40khz. Grbl is good for around 30khz, maybe a little bit more. I wouldn't recommend using less than 8microstep. I use atleast 10microstep on my stepper motors.

[jahnj0584]

Ive had these motors spin at 3040rpm without load so we shall see once it is all set up.

True, C7 has an error of 1.8 thou per foot. With CAM Compensation I've been able to cut within 2 thou over 3 feet though. More then enough for me.

[jahnj0584]

Started milling! Adding pics to this album as we go. About 2 hrs a night after work.

https://www.facebook.com/jahnj0584/m...9310474&type=3

[jahnj0584]

more in the album! Plan to get some more done this week, but theres a lot of OT going around the shop this month

[ger21]

The link in your previous post is bad.

[jahnj0584]

better?
https://www.facebook.com/media/set/?...1&l=41fdc2d496

[wizard]

better?
https://www.facebook.com/media/set/?...1&l=41fdc2d496

Yes this one works. Not a lot too see, looks like you are just getting started.

[jahnj0584]

Someone have 500$ for me to get a ground ball screw for my X?



Machine is ready to go. I appear to have resonance issues with the Z at 4500+mm/min (1204 screw) and 5000+ on the X (2510). It's weird because the Y is fine at 10000mm(400ipm) with a 2010 screw and same motors. Any ideas?
Do I buy digital drivers with resonance dampening? Swap for dual shaft motors and add a weight to the back?

[jahnj0584]

https://m.facebook.com/story.php?sto...5&id=609310474


Ooooh this thing is nice and rigid. The end mills are my bottle neck here for speeds. You sure can see the deflection at 500sfm(16k RPM) and 100ipm feeds. Been doing some adaptive at 15% step, 1* depth and 60ipm. It's just a single flute anyways. More testing to come!