[Ntl]

Pretty cool, is that what you're doing with the new machine? I wonder if anyone has ever built a plastic base filled with water? You have me thinking now of different ways to make these small machines not move around. Obviously you can always just use concrete ancors and bolt them down, then the weight doesn't matter as another guy mentioned in a different thread. But it's interesting to see things done different even if it's more work than just welding up a base and bolting it down.

Looking forward to seeing the machine finished up and cutting some parts. Looking good David nice work!

Dan

[davida1234]

The gantry moves up and down instead of a Z-slide.

Alleviates the compromise with fixed tall gantry uprights for
high clearances with associated deterioration of rigidity.

Gantry is all the way down for sheet goods, with little
cantilever on the uprights and associated high rigidity.

Gantry is up only for taller materials with associated
deterioration of rigidity.

Attachment 418970

Attachment 418972

[davida1234]

Negatives for the machine:

24 (!) V-groove bearings to adjust.

5 steppers or servos needed.

Complex spring support system to
balance a 200-250 lbs gantry.

A spaghetti of stuff look on both
sides of the table.

Positives for the machine:

Works great!

Can cut 12"-16" tall material
depending on bit length.

[davida1234]

When designing the new desktop, I had to
decide if I wanted to keep the moving gantry
or the symmetrical rack and pinion drive.

The moving gantry was out early on as that
interfered with the cutting coolant setup.

The symmetrical rack and pinion is still valid
but makes the footprint 6-8" wider which I
didn't like. It also works better with vertical
Y/A carriages and low rails. Not so much
with the flat carriage system I have here.

[davida1234]

Pretty cool, is that what you're doing with the new machine?

I am intending to build a concrete block base for the machine.

[Ntl]

Pretty cool with the z gantry I've never seen one of those that I recall. I've got a question about the ballnutz, can you get 1000+ rapids out of them?

Dan

[davida1234]

Hi Dan,

According to the manufacturer, max. rpm for the
ball nuts I used here is 5000 revolutions/min.

On this machine, the ball nuts are 1204 size. 4mm lead.

Max speed would be: 5000 x 4mm = 20,000mm/min = 787 ipm.

Not quite 1000.

However, I did not test or run them at 5000 rpm as I wanted the
assembly to be as compact as possible and the servos I use
would be too small to drive them with reasonable acceleration.

I am running them at 3000 rpm which equates to about 450 ipm.
They seem to be doing just fine at that speed.

----

If I would use 1610 sized ball nuts, the max. theoretical speed
would be: 5000 x 10mm = 50,000mm/min = 1,968 ipm.

Or, you would get 1,000 ipm with a 1610 sized ball nut at 2,540 rpm.

This kind of speed is untested and I am not implying here that the
ball nuts would be able to sustain these speeds on a continuous basis.

I am also not sure if you could build this kind of assembly sturdy enough
out of 1/2" aluminum sheets and what kind of other issues would need
to be considered like lubrication, resonances, etc.

[Ntl]

So far what style do you like better the rotating nut or rotating screw? Also could you get more speed with a different reduction ratio, or does it have more to do with the screw and nut setup you're using?

Dan

[GME]

Hi Dan,

According to the manufacturer, max. rpm for the
ball nuts I used here is 5000 revolutions/min.

On this machine, the ball nuts are 1204 size. 4mm lead.

Max speed would be: 5000 x 4mm = 20,000mm/min = 787 ipm.

Not quite 1000.

However, I did not test or run them at 5000 rpm as I wanted the
assembly to be as compact as possible and the servos I use
would be too small to drive them with reasonable acceleration.

I am running them at 3000 rpm which equates to about 450 ipm.
They seem to be doing just fine at that speed.

----

If I would use 1610 sized ball nuts, the max. theoretical speed
would be: 5000 x 10mm = 50,000mm/min = 1,968 ipm.

Or, you would get 1,000 ipm with a 1610 sized ball nut at 2,540 rpm.

This kind of speed is untested and I am not implying here that the
ball nuts would be able to sustain these speeds on a continuous basis.

I am also not sure if you could build this kind of assembly sturdy enough
out of 1/2" aluminum sheets and what kind of other issues would need
to be considered like lubrication, resonances, etc.

Even if your rotating nuts could handle 1000 IPM, could you actually get to that speed on a 2 x3? Assuming you were running 3 feet in a straight line, you'd have to go from 0 to 1000 ipm and back to 0 in only 3 feet. Seems like a tall order. Correct me if I'm wrong, but I'm thinking it wouldn't be possible.

Gary

[Ntl]

Even if your rotating nuts could handle 1000 IPM, could you actually get to that speed on a 2 x3? Assuming you were running 3 feet in a straight line, you'd have to go from 0 to 1000 ipm and back to 0 in only 3 feet. Seems like a tall order. Correct me if I'm wrong, but I'm thinking it wouldn't be possible.

Gary

I just got done watching a video from Titans of CNC of a DMG milling a block of steel at 1000ipm 1963sfm 15000rpm.. I understand that it was a expensive VMC but even my router is running 940imp rapids with no problems now that I took care of the binding issues. So in my opinion it doesn't matter what the distance is since it hits top speed in under a second on my machine. I can also tell you that it definitely speeds up jobs having higher rapids especially when you have a lot of tool changes. 1000ipm rapids really isn't that fast when you think about how small the work envolpe is on even a bigger VMC and some have like 2500ipm rapids. When I think about what the industrial routers are capable of I personally think it's not asking a lot out of a well built small router to hit a 1000ipm rapid. Just my personal opinion and what I'm looking for in a machine and what my router is close to achieving now. If I ever get my liniar rails dialed in and if I dropped my microsteps down, I'm sure I could run it well over 1000ipm. Like I said it's just what I'm personally looking for in my machine and I completely understand that others don't care about it or disagree with me. Different strokes for different folks and it's one of the things I like about the diy machines everyone can make them to fit their needs.

Dan

[davida1234]

So far what style do you like better the rotating nut or rotating screw? Also could you get more speed with a different reduction ratio?

They are just two different application approaches with the same hardware.
I am not sure you could categorize one as better than the other one without
knowing what the design criteria are.

And yes, you can get different speeds with different belt pulleys.

I personally think that the rotating ball nut gives you more installation options
with the arrangement of the ball screw and has less limitations.

[davida1234]

Even if your rotating nuts could handle 1000 IPM, could you actually get to that speed on a 2 x3?

I think you can although the cutting time savings you get by
having fast rapids are proportional to the size of the machine.
A small machine will benefit less than a large machine.

As you can see in the video below, going up to 450 ipm takes a
very short portion of the run. 0-1000-0 should be easily doable:

https://youtu.be/_syh9KKP2Q8

[davida1234]

Dan and Gary,

To answer both of your inquiries, I think I will need to explain the design
intent a bit and why/how I came to the layout of the machine as it is:

• The machine will be mainly used for cutting aluminum

• I definitely wanted to go with servos. That brings the rpm range to about 3000 to 4000 rpms

• I wanted the linear drive as compact as possible and didn't want protruding motors

• The 1204 screw size seemed to offer the highest resolution with a 4mm lead

• Per Teknic's engineers, a 48" long 1204 screw is limited to about 800 rpm

• A speed of about 500 ipm seemed sufficient for the size of machine

• A 1204 sized rotating ball nut requires a 40 tooth pulley, fitting within the width of a Nema 23 motor

-----------

So, the 1204 sized PowerBallNut with a 40 tooth pulley was designed:
Attachment 419054

The servo motor also has a 40 tooth pulley, fitting within its width:
Attachment 419056

Result is a narrow mounting plate which fits between the brace and the end of gantry beam:


The selection of the servo was based on max rpm, available torque at 1000 rpm for cutting, size and cost:

[Ntl]

Dan and Gary,

To answer both of your inquiries, I think I will need to explain the design
intent a bit and why/how I came to the layout of the machine as it is:

• The machine will be mainly used for cutting aluminum

• I definitely wanted to go with servos. That brings the rpm range to about 3000 to 4000 rpms

• I wanted the linear drive as compact as possible and didn't want protruding motors

• The 1204 screw size seemed to offer the highest resolution with a 4mm lead

• Per Teknic's engineers, a 48" long 1204 screw is limited to about 800 rpm

• A speed of about 500 ipm seemed sufficient for the size of machine

• A 1204 sized rotating ball nut requires a 40 tooth pulley, fitting within the width of a Nema 23 motor

-----------

So, the 1204 sized PowerBallNut with a 40 tooth pulley was designed:
Attachment 419054

The servo motor also has a 40 tooth pulley, fitting within its width:
Attachment 419056

Result is a narrow mounting plate which fits between the brace and the end of gantry beam:


The selection of the servo was based on max rpm, available torque at 1000 rpm for cutting, size and cost:

Thanks for all the info David, I've been thinking about converting over when my rack and pinion wears out. I've been looking at different ball screws, do you have a suggestion for a vendor? There's a lot of different brands and with that comes a lot of different prices. I'm not looking for super high end high precision, just middle of the road since my router is plenty accurate with the rack and pinion. I was looking at THK, are they a decent brand?

Dan

[davida1234]

I've been thinking about converting over when my rack and pinion wears out.

It will take quite some time to wear out a R&P.

I've been looking at different ball screws, do you have a suggestion for a vendor?

I do know about most of them but I think you would have to do your own research.

[Ntl]

It will take quite some time to wear out a R&P.



I do know about most of them but I think you would have to do your own research.

No worries, looking forward to seeing the finished machine.

Dan

[teamloks1]

im using servo and my machine around your size even 400ipm is fast already that 3000 rpm while my servo can go 5000

[davida1234]

im using servo and my machine around your size even 400ipm is fast already that 3000 rpm while my servo can go 5000

Hi teamloks1,

The overall gearing determines how fast or torquey your machine runs with a particular motor.

I think 400 - 450 ipm is sufficient for this size machine.

[teamloks1]

Hi teamloks1,

The overall gearing determines how fast or torquey your machine runs with a particular motor.

I think 400 - 450 ipm is sufficient for this size machine.

yerp that good my z rapid is really scary thou haha

[mactec54]

I was looking at THK, are they a decent brand? Dan

THK are one of the high end high quality Ballscrews if you are looking at THK then NSK SKF and Bosch there are many other Ballscrew manufacturer's that make quality Ballscrews to choose from, TBI is another that is less cost and good quality worth a look at