Thoughts on buy a used Colombo spindle of unknown history?

[skrubol]

Is the stuff from Ugra any better than the run of the mill Chinese stuff that it's 50-100% more expensive than?

[ger21]

I would guess that the UGRA spindles are at the upper end quality wise of the chinese spindles. What your paying for is the fact that he actually tests them for runout, and provides an actual warranty.
But in many cases, the price is nearly 3x higher, and the warranty is only 1 year. But if the pictures are an indication of the quality, they certainly look 3x better than the spindles on Ebay.

[UgraCNC]

Yes Gerry you are right.

Our spindles are in the upper end. They are still Chinese spindles tho.

You realize the difference when you actually hold in hands a GMT or KEN spindle and the cheap one you can find on eBay.

When I was looking for a spindle suppler when we started our business I got a few samples from different Chinese factories.

Most of them were never listed for sale. They had so poor quality that I was not brave enough to introduce them to the market under our name.

What about GMT? I love them so I think you customers will love them. That's it.

Out of thousands sold spindles only 5-7 pieces were bad. And most of them were caught while performing the tests.

I would easily give a 2 or 3 year warranty even though the factory gives only one year.

The thing is the customers kill spindles sometimes It takes a lot of energy to solve such customer's problems

And sure our prices are quite high.

I think we will try to get some cheap spindles to give our customers more options but most likely we will never drop prices for GMT or KEN.

Regards,

Andy

[louieatienza]

Is the stuff from Ugra any better than the run of the mill Chinese stuff that it's 50-100% more expensive than?

Dunno... just Google search....

[Goemon]

Really, if time is truly not of an issue, then why even bother with ATC? It's not like you're going into full scale production making these molds. If you go about using your spindle to power an ATC spindle cartridge - keep in mind by the time you procure a pulley and shaft for the Colombo spindle (and have that assembly balanced if you want to spin it at 18krpm), get an air cylinder, fabricate a "floating plate" unit so your air cylinder isn't mashing your spindle bearings every time you make a tool change, fabricate your Z axis plate to hold all this, including the fact that you'll either have the ATC spindle far away from the gantry or have the Colombo spindle mounted to the side of the Z carriage to accommodate the belt... it gets pretty kludge. You're better off getting one of these...

https://ugracnc.com/store/cnc-spindl...v-iso30-detail

I have no intention of buying an ATC capability right now. As you said, the time saving is imaterial to me. I would prefer to spend any extra cash available on more power, more precision and more range. My interest in asking if people switched out spindle ends or added mechanical spindles with gear reductions is only about the vertastility of using larger tools and getting more low speed torque if the need arose. I'm a big fan of tools that are modular and upgradable.

Those GMT ATC spindles are as unaffordable to me as every other ATC spindle. I did look at some of their MTC spindles but I couldn't find much info from people who own them and they are too expensive to take a leap of faith on. They kinda sit in no-man's-land at the price level they are at for me. They are too expensive to accept the compromises found on cheap Chinese spindles and not that much less than some deals you find on new or refurbished European brands.

Once I got over the mental barrier around spending more than $1,000 on a spindle, I started looking at what else I could get for the money. You start to see very good deals on Colombo, HSD, ELTE, Perske and PSD in that range. There is lots of user review info for these brands out there.

I would like to hear what people who have experience with some of those European brands think of those GMT spindles and how they compare. They could be an option in the future once some of you guys have put them to the test. They should send two or three test models to some of the more experienced members here for testing and review.

[Goemon]

I'm having a "should have looked before I leaped" feeling. I was planning on buying a 7.5hp VFD to power the 7.5hp spindle I ordered but someone just told me that I will need a 22.5hp VFD if I'm using it as a phase converter. Is this right?

I will be using a 230v 1 phase outlet with one of those 1 phase input / 3 phase output VFD's. I was assuming I was ok to use 7.5hp VFD with a 7.5hp 3 phase spindle because they are typical packaged together like that when vendors sell them togeather. Have I made a big mistake?

[wizard]

Wow one busy thread.

The mold in that thread was not for one of my products. It was just an example to show the desired quality of the finish. A number of the cf stocks I make now have flat sides and corners. Being able to mill flat surfaces in mold cavities is a must.

It's true that a mirror smooth mold cavity makes parts release easier but you are correct that primary motivation is to achieve a high quality part. The qaulity of finish on the part can only be as good as the mold.

For making cosmetic carbon fiber parts with exposed glossy woven cf, you need a glossy smooth mold surface. It's a very different process to injection molding. I find that any texture in the mold surface is a recipe for problems. You get more trapped air voids, more part release issues and a build up of mold release products where the wax gets stuck in the textured surface.

You'd never be able to get away with adding a checkering pattern in the mold with any repeatability. You also can't mill fine (or any) patterns into the surface of cf parts. They aren't like wood or plastic. The fiber's need to remain intact. I won't be using any end mills smaller than 1/4' for anything I currently make.

The thought wasn't so much fine texturing like one sees with hand cut checkering in wood. I was think more along the lines of scalloping a 1/4" ball mill might make cutting maybe 0.050" deep. This is actually something I'm concerned about as a stock user no so much a manufacture because slippery is bad. I can't suggest much for retained air other than to do the lay up in a vacuum.

I had been leaving the textured surfaces for the grip areas in the mold but recently, I even decided to remove those and add any texture after the parts have cured because they caused me so many problems.

That is too bad to hear. That might explain injection molded plastic panels seen on some stocks though.

There are some people who sandblast their mold surfaces to create matte instead of gloss finishes but I find it is easier to spray on matte clear coats when they are needed. Hunters usually want matte finish stocks, target shooters often like glossy.

It is most definitely possible to tidy up the surface of a part afterwards with extra sanding and clear coat but for a business making multiple parts, it makes more sense to spend the time upfront making the mold perfect to avoid time consuming handwork on every part. Sanding carbon fiber is dangerous and best kept to a minimum.

3d printing the stocks would make no sense for what I do.

This is not what I was trying to get past you. Rather I meant seeing if 3D printing the mold is cheaper than having someone machine the molds. I'm not sure if they could do the mold in one shot so the idea of making the mold in sections and bolting it together. I bring this up because 3D printing is becoming cost effective for many things, especially one offs.

The point on using carbon fiber is that it's incredibly strong, stiff and light with excellent thermal stability. This is why the best stocks in the world are made of carbon fiber. There are no 3D printing alternatives that could produce anything close to comparable results. CF stocks are superior to any known wood, plastic or aluminum. It also looks great when done right.

Well looks are determined by the beholder. But again the 3D printing is about building molds.

Using a third party CNC shop to make my molds is the first thing I considered but there are no companies anywhere on earth offering genuinely affordabld aluminum molds in the sizes I need. The price for a single mold starts in the thousands. it's just not worth it for me. Plus, even the high end mold makers have to spend a lot of time polishing their molds. It can take them weeks. There is no way around it.

I understand that the costs are high but so will be the costs of building a machine that can do what you want (which seems to be a moving target). As for the sizes needed, like with the idea of 3D printing your molds consider a multi piece mold to lower the costs. This can be applied to your machine build too, as you can build a small extremely stiff machine far cheaper than a large one that can handle a very long mold. Yeah I understand the challenges in getting the parting line to disappear, but if costs for a full sized die are getting out of hand then you need to consider alternatives.

It is worth noting that this isn't something I aspire to do or an unrealistic future goal. I am already doing it. I make my own molds with glossy smooth surfaces now out of carbon fiber. The only thing I am looking to change is that I want a machine to make molds while I make product.

To an extent I can understand this. But the more I read of this thread the more I'm concerned that you are looking for a $5000 machine that can replace a $50,000 ($500,000) machine. That will be difficult to do to say the least. You will either need to make compromises or invest in a mold making VMC.

Also, I'm too far down the road of investing in building my own CNC capability to switch paths now. I am going to finish my CNC machine. I am going to make aluminum molds with it and if there are some issues that come up, I'll fix them. if I can't I'll just sell the machine and carry on doing what I do now.

[wizard]

I'm having a "should have looked before I leaped" feeling. I was planning on buying a 7.5hp VFD to power the 7.5hp spindle I ordered but someone just told me that I will need a 22.5hp VFD if I'm using it as a phase converter. Is this right?

It is hard to tell. Your best bet is to check with the drives support center. In general the problem with using the larger VFD's that are designed for 3 phase in, is that the rectifier at the front end of the VFD is too small to handle the single phase current involved. There may also be issues with filtering capacitance. In any event the applications engineer can usually tell you if the drive can handle single phase input.

I will be using a 230v 1 phase outlet with one of those 1 phase input / 3 phase output VFD's. I was assuming I was ok to use 7.5hp VFD with a 7.5hp 3 phase spindle because they are typical packaged together like that when vendors sell them togeather. Have I made a big mistake?

Only the vendor can answer that. If the drive is documented to work on single phase you have no problem. If it isn't you can't be sure if it will or won't work on single phase. Basically you would need a drive with a rectifier that can handle at least 25 amps. As for that AC outlet it would be best if it was at least a thirty amp circuit maybe more depending upon other machine demands.

A little background, the vast majority of VFD's work by rectifying AC input to a DC voltage. That DC voltage is then hoped by the output circuitry to create your variable frequency output. It is in the rectification that we end up having problems as obviously you end up with pretty huge single phase currents compare to 3 phase power input. There is a newer drive topology that requires three phase input but those drives so far a fairly large and far less common.

[skrubol]

I'm having a "should have looked before I leaped" feeling. I was planning on buying a 7.5hp VFD to power the 7.5hp spindle I ordered but someone just told me that I will need a 22.5hp VFD if I'm using it as a phase converter. Is this right?

I will be using a 230v 1 phase outlet with one of those 1 phase input / 3 phase output VFD's. I was assuming I was ok to use 7.5hp VFD with a 7.5hp 3 phase spindle because they are typical packaged together like that when vendors sell them togeather. Have I made a big mistake?

You can't really use a VFD as a general purpose phase converter, they only work with motors. I think your 3:1 confusion is if you are using a motor as a phase converter, then you need some significant overhead for the motor.
If you're using a single phase input VFD to power a 7.5 HP motor, you need a 7.5 HP VFD. For larger motors (heavier with more thermal mass,) some go up to the next sized VFD as the overload ratings of motors are typically quite a bit higher than those of VFD's (50% overload of a VFD is typically for 10 seconds, for a motor it's usually 1+ minute.) For high speed spindles I don't think that really applies as they don't have the thermal mass/power ratio of 50/60 Hz motors.
If you end up with a 3-phase input VFD, you will need to oversize by about 1.8x to get full power. Some 3 phase VFD's refuse to work on single phase at all, so it's a risk trying to go that route. You should still be able to get full torque on a 7.5 HP, 3-phase VFD, but only up to 55% of the rated speed, where you would hit about 4 HP (if it's rated 7.5 HP at 18k you would have full torque up to about 10k RPM and be limited to around 4HP from there on up.)

[ger21]

I can't recall if you need to derate the VFD by 50%, or if you need a 50% larger VFD? So you'd need either an 11HP, or 15HP VFD, if you are powering it with single phase power. As Wizard said, check with the drive manufacturer.

I'd probably buy one of these, and see how it works.

https://www.ebay.com/itm/VARIABLE-FR...cAAOSwjVVVnhP6

[Goemon]

You can't really use a VFD as a general purpose phase converter, they only work with motors. I think your 3:1 confusion is if you are using a motor as a phase converter, then you need some significant overhead for the motor.
If you're using a single phase input VFD to power a 7.5 HP motor, you need a 7.5 HP VFD. For larger motors (heavier with more thermal mass,) some go up to the next sized VFD as the overload ratings of motors are typically quite a bit higher than those of VFD's (50% overload of a VFD is typically for 10 seconds, for a motor it's usually 1+ minute.) For high speed spindles I don't think that really applies as they don't have the thermal mass/power ratio of 50/60 Hz motors.
If you end up with a 3-phase input VFD, you will need to oversize by about 1.8x to get full power. Some 3 phase VFD's refuse to work on single phase at all, so it's a risk trying to go that route. You should still be able to get full torque on a 7.5 HP, 3-phase VFD, but only up to 55% of the rated speed, where you would hit about 4 HP (if it's rated 7.5 HP at 18k you would have full torque up to about 10k RPM and be limited to around 4HP from there on up.)

Ok good. That's what I thought but this vendor got me worried. I guess he's either wrong or doesn't understand what I'm doing. I did tell him that I was looking to run a 3 phase 7.5hp CNC spindle though. I only asked the question because there was confusing info in his listing. It stated "phase converter" as part of the features of the Fuji VFDs he sells but, in the details, it stated 3 phase input / 3 phase output. The others that I saw specifically stated "1 phase input / 3 phase output". I'm not sure how it's a "phase converter" if it uses 3 phase 230v input / 3 phase 230v output. I hate confusing product info....

Thanks for putting my mind at rest. That vendor had me worried that I wasn't going to be able to use my new spindle and that I was going to be stuck with it. I spent a lot of time looking at the used spindle market lately so I have serious doubts that I would even be able to sell my one if it didn't work out.... I've seen the same spindles on eBay for months. Even the ones that look like really good deals hardly sell, even if they are new and half the retail price.

- - - Updated - - -

You can't really use a VFD as a general purpose phase converter, they only work with motors. I think your 3:1 confusion is if you are using a motor as a phase converter, then you need some significant overhead for the motor.
If you're using a single phase input VFD to power a 7.5 HP motor, you need a 7.5 HP VFD. For larger motors (heavier with more thermal mass,) some go up to the next sized VFD as the overload ratings of motors are typically quite a bit higher than those of VFD's (50% overload of a VFD is typically for 10 seconds, for a motor it's usually 1+ minute.) For high speed spindles I don't think that really applies as they don't have the thermal mass/power ratio of 50/60 Hz motors.
If you end up with a 3-phase input VFD, you will need to oversize by about 1.8x to get full power. Some 3 phase VFD's refuse to work on single phase at all, so it's a risk trying to go that route. You should still be able to get full torque on a 7.5 HP, 3-phase VFD, but only up to 55% of the rated speed, where you would hit about 4 HP (if it's rated 7.5 HP at 18k you would have full torque up to about 10k RPM and be limited to around 4HP from there on up.)

Ok good. That's what I thought but this vendor got me worried. I guess he's either wrong or doesn't understand what I'm doing. I did tell him that I was looking to run a 3 phase 7.5hp CNC spindle though. I only asked the question because there was confusing info in his listing. It stated "phase converter" as part of the features of the Fuji VFDs he sells but, in the details, it stated 3 phase input / 3 phase output. The others that I saw specifically stated "1 phase input / 3 phase output". I'm not sure how it's a "phase converter" if it uses 3 phase 230v input / 3 phase 230v output. I hate confusing product info....

Thanks for putting my mind at rest. That vendor had me worried that I wasn't going to be able to use my new spindle and that I was going to be stuck with it. I spent a lot of time looking at the used spindle market lately so I have serious doubts that I would even be able to sell my one if it didn't work out.... I've seen the same spindles on eBay for months. Even the ones that look like really good deals hardly sell, even if they are new and half the retail price.

[Goemon]

Wow one busy thread.


The thought wasn't so much fine texturing like one sees with hand cut checkering in wood. I was think more along the lines of scalloping a 1/4" ball mill might make cutting maybe 0.050" deep. This is actually something I'm concerned about as a stock user no so much a manufacture because slippery is bad. I can't suggest much for retained air other than to do the lay up in a vacuum.

That is too bad to hear. That might explain injection molded plastic panels seen on some stocks though.

This is not what I was trying to get past you. Rather I meant seeing if 3D printing the mold is cheaper than having someone machine the molds. I'm not sure if they could do the mold in one shot so the idea of making the mold in sections and bolting it together. I bring this up because 3D printing is becoming cost effective for many things, especially one offs.

Well looks are determined by the beholder. But again the 3D printing is about building molds.

I understand that the costs are high but so will be the costs of building a machine that can do what you want (which seems to be a moving target). As for the sizes needed, like with the idea of 3D printing your molds consider a multi piece mold to lower the costs. This can be applied to your machine build too, as you can build a small extremely stiff machine far cheaper than a large one that can handle a very long mold. Yeah I understand the challenges in getting the parting line to disappear, but if costs for a full sized die are getting out of hand then you need to consider alternatives.

To an extent I can understand this. But the more I read of this thread the more I'm concerned that you are looking for a $5000 machine that can replace a $50,000 ($500,000) machine. That will be difficult to do to say the least. You will either need to make compromises or invest in a mold making VMC.

I did look into 3d printing for molds a while ago but the technology is just not there yet.

The molds I use need to be able to withstand heat and pressure. They spend many hours in the oven under vacuum. They have to last for many cycles without warping. It's a challenge to make longer 3d printed parts retain dimensional stability over time even at room temp.

The reason I use carbon fiber to make my molds now is because I had terrible warping and indexing issues when I used fiberglass and plastics. I also got fed up of having to redo weeks of work when molds snapped when I pulled parts out. My carbon fiber molds never break and they index perfectly even after 12 months of daily use.

The only alternative (to my cf molds) that I would consider using (for what I do) is aluminum molds. They won't be as strong as my cf molds but I need metal for a new compression molding process I am designing.

As far as I can tell, even the six figure machining centers are not capable of delivering ready to use molds. My expectation is that there will be weeks of hand finishing required to get the mold surface where I want after the CNC machine has finished. I am sure that my machine will take a lot longer than a high end machining center but that's no issue to me and I have to work with what I have.

Anyway, the time for all that doubt and negative thinking has long past. I have nearly finished making my machine and I have already bought most of the components. No matter what, I'll finish the project. If it turns out that it's not up to what I need then I just sell it for what I can get and move on. I think it is going to work though.

I ask around on composites forums before I started this project and it's fairly common for people there to build CNC machines to make aluminum molds. I'm not exactly breaking new ground here. I am walking a well beaten path.

The only concern I have is if there will be any time efficiency from using a CNC machine compared to what I do now.

[Goemon]

I can't recall if you need to derate the VFD by 50%, or if you need a 50% larger VFD? So you'd need either an 11HP, or 15HP VFD, if you are powering it with single phase power. As Wizard said, check with the drive manufacturer.

I'd probably buy one of these, and see how it works.

https://www.ebay.com/itm/VARIABLE-FR...cAAOSwjVVVnhP6

These are pretty much my only option for what I need. If I go with the 10hp model in the link then I should be well covered for a 7.5hp spindle. I don't even know if I'll use it at 24,000 rpm. It only reaches 4.2kw at 18,000 but I like the idea of having spare capacity. The 10hp VFD is only $15 more than the 7.5hp model too.

[skrubol]

These are pretty much my only option for what I need. If I go with the 10hp model in the link then I should be well covered for a 7.5hp spindle. I don't even know if I'll use it at 24,000 rpm. It only reaches 4.2kw at 18,000 but I like the idea of having spare capacity. The 10hp VFD is only $15 more than the 7.5hp model too.

Just looked back at your post about the spindle you got, wasn't it a 7.5kw/10HP unit? Definitely go with a 10+ HP VFD. You mentioned it was rated for 300/400 Hz, which in Colombo terminology means it hits full power at 300Hz/18kRPM, so you should have 7.5kw at 18k. Given the price difference it's a no brainer to get a 10 HP VFD.
I do think there are other options in the used market for single phase it's just tricky to find one for a reasonable price (used).
Here's a new Fuji that's a bit pricey, but shows they are out there.
https://www.ebay.com/itm/FUJI-ELECTR...AAAOSwmCVY-PC3

[Goemon]

Just looked back at your post about the spindle you got, wasn't it a 7.5kw/10HP unit? Definitely go with a 10+ HP VFD. You mentioned it was rated for 300/400 Hz, which in Colombo terminology means it hits full power at 300Hz/18kRPM, so you should have 7.5kw at 18k. Given the price difference it's a no brainer to get a 10 HP VFD.
I do think there are other options in the used market for single phase it's just tricky to find one for a reasonable price (used).
Here's a new Fuji that's a bit pricey, but shows they are out there.
https://www.ebay.com/itm/FUJI-ELECTR...AAAOSwmCVY-PC3

I didn't end up getting the one I mentioned. I apparently missed out by a few days. They were just slow at updating their website. Once I had my heart set on a higher quality spindle like that though, I couldn't go back to browsing the Chinese stuff so I ended up ordering a 7.5hp PSD brand. I went with the electric fan version which is rated for a far broader range. It can operate from 0 up to 24,000 rpm (although it's a little asthmatic below 2000 rpm). It also has the ceramic front bearings.

It's not quite a powerful as the Colombo but I am hoping it will make up for it other areas. I know that 7.5hp is not that much for a 24,000rpm unit but hopefully it will be enough.

- - - Updated - - -

Just looked back at your post about the spindle you got, wasn't it a 7.5kw/10HP unit? Definitely go with a 10+ HP VFD. You mentioned it was rated for 300/400 Hz, which in Colombo terminology means it hits full power at 300Hz/18kRPM, so you should have 7.5kw at 18k. Given the price difference it's a no brainer to get a 10 HP VFD.
I do think there are other options in the used market for single phase it's just tricky to find one for a reasonable price (used).
Here's a new Fuji that's a bit pricey, but shows they are out there.
https://www.ebay.com/itm/FUJI-ELECTR...AAAOSwmCVY-PC3

I didn't end up getting the one I mentioned. I apparently missed out by a few days. They were just slow at updating their website. Once I had my heart set on a higher quality spindle like that though, I couldn't go back to browsing the Chinese stuff so I ended up ordering a 7.5hp PSD brand. I went with the electric fan version which is rated for a far broader range. It can operate from 0 up to 24,000 rpm (although it's a little asthmatic below 2000 rpm). It also has the ceramic front bearings.

It's not quite a powerful as the Colombo but I am hoping it will make up for it other areas. I know that 7.5hp is not that much for a 24,000rpm unit but hopefully it will be enough.