MORE HP for PCNC

[johnh]

I have one of the early machines, 2007 i think, updated spindle drive years ago, I have worked it hard over the years but it has always lacked in the metal removal rate. The machine frame itself seems capable of taking out more meat from a block of aluminum.
So, I need a hotrod project and switching out the 1.5 - 2 hp motor for 5hp pullys/belt etc. and the corresponding VFD seems a fairly doable venture.
I was wondering if anyone has already done something like this and what was the experience like?

jh

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[tmarks11]

The Gates Heavy Duty V Belt Drive Design manual shows that a "A" V-belt section will transmit about 2.2 HP per belt for a minimum pulley OD of 3" at 1750 RPM.

This means you will have to replace the V belts. I would recommend a poly-v or multi-v belt, like this:

Micro-V

[Bryan Turner]

I've looked into a 3HP motor on my 770. The only immediate issue that I perceived was fitting the motor in the head, but I've found a few models that should work.

- Can the Z stepper lift the new motor?
- Can the Z stepper hold the motor in place against the cutting forces (up/down cut force)?
- Can the X/Y steppers provide enough force to properly keep a 5HP motor engaged in the cut?
- Will the (lack of) rigidity of the table translate to poor finishes or poor accuracy in the final part when using 5HP cuts?

I've sufficiently convinced myself that the 770 could take a 3HP upgrade, and it would significantly benefit roughing times. No plans to make the jump though, but would love to hear about someone trying it!
--Bryan

[shred]

As long as you don't want to use TTS it might be doable. I think TTS would have large pullout problems with more HP.

[mountaindew]

I would enjoy following a build like this. Machine mods are sometimes complex endeavors.
I'm a Jeep owner and love to do modifications. I need larger tires for more clearance. Then lift suspension so tires clear body. Looks like lower gears would fix the low power problem caused by larger tires. Darn now that I lifted the suspension the short trailing arms change geometry to much during use and cause ill handling, time for long arm suspension. Ok looks like the drive shafts are now being stressed because no longer at oem angles better swap them for some splined hd units. Brakes no longer slow down big tires and un-sprung weight, those need to be enlarged to be safe. This can turn into a never ending but interesting story,
md

[popspipes]

I would enjoy following a build like this. Machine mods are sometimes complex endeavors.
I'm a Jeep owner and love to do modifications. I need larger tires for more clearance. Then lift suspension so tires clear body. Looks like lower gears would fix the low power problem caused by larger tires. Darn now that I lifted the suspension the short trailing arms change geometry to much during use and cause ill handling, time for long arm suspension. Ok looks like the drive shafts are now being stressed because no longer at oem angles better swap them for some splined hd units. Brakes no longer slow down big tires and un-sprung weight, those need to be enlarged to be safe. This can turn into a never ending but interesting story,
md

We used to do this kind of thing with cars in the old days............

I always like to buy a bigger machine than what is needed and run it at half throttle, it will last much longer like that.

I have modded my Tormach quite a bit, but it was a matter of taking what was there and improving on it, at least in my own mind ha!

[pickled]

To be honest an extra 1/2 to 3/4 HP reserve on my PCNCs would get me over the slow drilling hump that I run into on occasion. I would assume that would not be that difficult to pull off minus mounting and drives. Someday when I have some time to tinker I might have to look at it. Until then have fun Hot Rodding! MD nailed it though...just like modifying anything you will run into design constraints that you never saw, but overcoming them is where real innovators shine through.

[LRF]

Ever wonder why the UUS Iowa with its 16" guns was so big? Because it needed to be to have 16" guns. 10 pounds of crap is about all that can fit in a 10 pound crap bag.
Lots of fun to dream but impractical and it you need the HP then buy a machine that has 5 HP spindle. IMHO
I think Shred hit the target dead center, I to don't think the TTS would hold up under 5HP and the chip load this would mean.

[Steve Seebold]

When I first got my machine, I thought 2 or 3 horsepower would be great. but now I think 3 horsepower, would just destroy the machine. It's not rigid enough for that much power.

I have learned to remove amazing amounts of material even with only 1.5 horsepower with absolutely no cutter pull out, so I'll stick with what I have.

I can use a 3/4 inch end mill to cut a 6 X 6 X 1.5 inch deep pocket and I won't have any cutter pullout, and I can do it in about 10 minutes.

[johnh]

Yes indeed it does open a can of hotrod, one thing always leads to another, yes, motor, then pulleys, then belt, drive ratios, packaging the whole thing on the spindle head, then VFD, then tuning, then a higher flow coolant pump and lines, etc. etc. but much cheaper than buying a used CNC and maintaining it. The max cut I've been able to achieve is 3/8 wide x .200 deep at 3850 rpm and 17 imp, that taxes the motor to about its foldback logic, any higher rpm and the torque goes south fast, any higher chip load and the motor bogs again, this is using a real good coolant and a Viper destiny high helix 2 flute in 6061-t6, if the cutting gets into a resonance when stepping doing a helix ramp into a deep cut the meter goes yellow and can bog down immediately but as long as the cut load begins smoothly and chips are flooded away that is all it can handle.

from experience it seems that the machine is stout enough to handle more cutter load as long as the motor can keep the endmill turning through the chip load. A bit of machine flex during roughing is tolerable because the finish cuts will cat away the sins, in theory. That and the increased rpm and HP could also equate to more feed rate. I'm sure there is a threshold where steps could be lost but I'm pretty confident there is much more material removal possible with the machine. I used to do machine design, automated type, Tormach as a manufacturer has to be conservative so that 99% of the user base will be successful which means a fair amount of reserve I imagine.

I did notice coolant makes a world of difference, I was using Cimcool Cimperial 1070 recommended to me by my CNC guru, about $130 a pail, went cheap and bought some Hangsterfers s500 the next time and I had to reduce my feed rates by 20%, that was a shock!

As far as loosing steps I'm also seriously considering upgrading to leadshines hybird steppers that have feedback
Pushing the limits will loose steps but usually the spindle motor will bog down first so these drives would be a nice insurance. My guesstimate is the z drive would be ok as z movement is typically less stressful compared to x and y
Hey, its not like it will throw a rod out of the block

So no one has tried this yet?

[johnh]

Oh, and yes, a spindle upgrade to BT30 should be in order. The only time Ive had a problem with TTS is with chatter, that yanks them out fast if not caught. So good point, the added work of the cutter would probably make the TTS the weak link here.
Oh, and the idea is not to use a 5 hp all the time, but to have a nice fat reserve when needed.

[SCzEngrgGroup]

Oh, and yes, a spindle upgrade to BT30 should be in order. The only time Ive had a problem with TTS is with chatter, that yanks them out fast if not caught. So good point, the added work of the cutter would probably make the TTS the weak link here.

FWIW, with adequate drawbar tension, you'll never get pull-out with 1.5HP. I routinely cut up to 1" deep, 0.05" width, up to 150 IPM, and have never once had pullout, even with severe chatter - bad enough I had to wear ear protection. Increase your drawbar tension, and I believe TTS will handle anything the machine frame can handle.

Regards,
Ray L.

[pickled]

No rod through a block is a very comforting thought! Man John that Leadshine closed loop set up is way sweet! To me that is going to be the Series 4 upgrade. I'd rather go that route than purchase the Series 3 when it is time to finally upgrade my Series 2 1100 mill. I can see a ton of applications that will be all over those closed loop steppers- certainly a problem solver for many applications. I also agree with you that Tormach has probably left a decent amount of performance on the table as part of their reliability safety factoring (and cost constraints). Having met Greg and the gang I can say that they are true big picture design people and definitely understand designing for reliability with data to support their decision making. The big question is at what level of power increase do you meet the inflection point in the established reliability curve.

I don't need a nitro-methane version of this machine, but I wouldn't mind having a little bit more HP (20-30%) to exploit when dealing with tough materials. When your cutter slightly bog down in 316 or grade 5 Titanium you are most likely done and may have toasted a carbide em in the process. I have machined a LOT of tough material using my Tormach mills, but the sweet spot of operations that one can exploit is not very large. If I worked in 7075 or 6061 I am thinking that everything would be fine as is. My 770 flies in aluminum and it is hard to get that machine to miss steps.

[mountaindew]

Pushing the limits will loose steps but usually the spindle motor will bog down first so these drives would be a nice insurance. My guesstimate is the z drive would be ok as z movement is typically less stressful compared to x and y
Hey, its not like it will throw a rod out of the block

So no one has tried this yet?

I don't know your methods or technics and this makes a difference. In my experience I find drilling to be by far the most violent operation I do.
Plunging a tool into material following vertical or even ramped / spiral path sounds, feels and looks like more stress on my machine. I can stall the machine for that matter any machine imho with little effort. I have broken only a few tools and they are mostly drills.
Something to consider while moding your machine! btw don't get me wrong. Im all about upgrades and mods! that's how bigger and better things are built!!!
Of course the base, head, spindle, draw bar and tool holder would have an engineered margin of some value and would allow for more spindle and axis drive power.
Im still learning a great deal about how all this works and what forces are in play and where. I found the sandvic cormorant tool training handbook a valuable resource for all the math on cutting data and the forces on each axis. This might help you push your limits a little more also. First time I read this text I was shocked at some of the forces on a cutter and machine
I am a newer user and take easy roads right now and more into learning precision and setup then production and 150 ipm cuts. Someday I bet this will change.
md

[johnh]

thanks for that observation, that's pretty extreme cutting, I think the low rpm might help dampen the problem along with the serious tension. Speaking with Greg Jackson long time ago he warned me of the pullout problem and it did but usually during chatter at higher rpm's like 2000+, chatter is never good so avoiding that usually avoids it. I have a power draw bar now and the springs limit the pull tension unfortunatly.

[johnh]

True, its all a balanced design right now and more HP will have a chain reaction. There is a bunch of IPM available I can't use, I'd like to use to speed up the removal of metal but that requires energy, IE HP.

My motor is coming, found a new 5hp for $170, 3 phase. I hope I can get it to fit the cabinet without modifying it!
Looked into belting and the Gates PowerGrip GT3 will handle the load and RPM just fine, way more compact that v belts.
I think I'm going to stick with the Emerson brand of VFD, the Tormach white paper sold me since they did so much extensive testing on drives already.
I've got to give them a call tomorrow to see what kind of RPM the spindle bearings are good for. A boost there would be good too for smaller endmills too.

[pickled]

Johnh, If you are looking at going higher RPM then you will definitely need to pursue balancing of components. My 770 vs. the 1100 goes as far as to have a ballanced R8 TTS adapter and the pulleys themselves look like they have actually been balanced (vs. my 1100). Spot on with the drive and belt. Emerson VFD's are excellent and quite reliable.

[mountaindew]

This is going to be a cool project.
Great price on motor, I picked up a baldor for a table saw the other day, single phase and it cost a tad bit more.
Using a 3 phase motor , will this require a rotary phase converter? With separate power source for motor do you rewire e-stop and other spindle controls also?

On another note, could a person use the same motor that tormach uses on sb lathe? I see in specs its 3hp single phase, that would add power and not require converter.
md

[wtopace]

This is going to be a cool project.
Great price on motor, I picked up a baldor for a table saw the other day, single phase and it cost a tad bit more.
Using a 3 phase motor , will this require a rotary phase converter? With separate power source for motor do you rewire e-stop and other spindle controls also?

On another note, could a person use the same motor that tormach uses on sb lathe? I see in specs its 3hp single phase, that would add power and not require converter.
md

I'm assuming the three phase motor will most likely be fed with a VFD, which will be fed with single phase.

[SCzEngrgGroup]

I'm assuming the three phase motor will most likely be fed with a VFD, which will be fed with single phase.

I've never seen a VFD with single-phase input that was rated more than 3HP. And if there is one, it'll require about 50A input current...

Regards,
Ray L.