Spindles ... HSD and Columbo

[pfulghum]

I called Shopbot this morning about the spindles they offer. Here is what I heard that I thought others would have have interest in.

Both the Columbo and HSD have electric fans and are very quiet. Some spindle have the cooling fan driven directly from the bit shaft.

Horsepower = Torgue X RPM * (some constant)

Spindles are know for constant torque, but there is a power curve to get to that constant torque. In other words you will not have full toque until some specified rpm is reached.

The HSD spindle is limited to 18,000 rpm.
The HSD spindle will build max torgue at 13,000 rpm

The Columbo spindle is limited to 24,000rpm
The Columbo spindle will build max torgue at 18,000 rpm.

Taking into account the power curves, comparing a 3HP PC router and HSD 2.2 spindle both at 13,000, the HSD spindle will have about 2x the HP (and torque) of the PC router.

I usually cut at about 13,000 with my PC. When would I ever run at greater than 18K rpm?


-- pat

[bcammack]

Well, after a year's heavy slogging, our 5hp Columbo spindle has munched a bearing.

Considering we run at around 7k RPM for tool life considerations, it seems like the 4.5hp HSD would be more suitable with it's lower peak torque RPM than the 5hp Colombo, no?

Logic is a way to go wrong with confidence, though...


We need to choose a replacement ASAP. Will the VFD that ships with the Colombo work with the HSD?

[richards]

I was under the impression that the Colombo spindle, configured as ordered through Shopbot and delivered by PDS Colombo, had the power curve set to be at maximum power between 12,000 and 18,000 RPM. I was also under the impression that the power curve settings depended on settings within the Delta VFD, meaning that the user could change the settings to match the power required to the type of work he/she did.

And the last impression (all impressions are possible misconceptions on my part) is that the speed of my Colombo should be limited to 18,000 RPM because the spindles that are sold through Shopbot, are not equipped with ceramic bearings (which are required for 24,000 RPM operation).

I believe that the VDF is the key element in making a spindle behave properly. On other forums, (CNCZone, Gecko, Mach, etc.), when do-it-yourselfers comment on various brands of VFDs, all of the various brands of VFD's seem to work (if properly sized and properly configured).

Here's a quote from the tech support section of www.pdscolombo.com (http://www.pdscolombo.com) about the power curve:

Power Curve

Colombo Electric Spindles are available in either Constant Power or Constant Torque. Both types offer advantages depending upon the operating speed for the cutter(s) used in your application.

Constant Torque electric spindles suit applications where maximum cutting power is required near maximum spindle speed. Their torque is constant so power increases steadily from zero at zero speed to full power at full speed.

Constant Power electric spindles provide flexibility for a wider variety of cutting tasks. They deliver more power at mid-range speeds but less power at maximum speed than constant torque spindles. Typical constant power ranges are 9000 - 18000 rpm, 12000 - 18000 rpm or 18000 - 24000 rpm. The selection depends upon the operating speed for the cutter range & material type.

[patricktoomey]

Must be something in the air, our 5hp Colombo bearings also went bye-bye yesterday.

I am also struggling with whether to pay the 800-1300 estimated price for the bearings and possibly the shaft or look at an HSD optimized for lower speeds. I would actually like to go to a tool changer at some point so I'm wondering what the price difference is to get the HSD with the quick change head instead of the ER-25 collet. Anybody have a clue?

[carlcnc]

re Colombo bearings
Hi Guys,
I have been running a 5hp Colombo for about 5 years
I have cut miles of aluminum,plex,dibond,plywood etc etc. and have no bearing problems
after the bearings in my first Perske went out THEN I found notes about warming up the spindle for several minutes before cutting [even light cuts]
if you need bearings it isn't too difficult to locate ,buy and install your self.
The ones for my 71/2 perske were 185$ and took less than an hour till I was back to cutting.
by the way, I have a new 5hp Elte 30 taper ATC spindle motor for sale but please contact me off the forum if interested

Carl

[patricktoomey]

I got about 5,000 hours out my Colombo bearings which is about the upper limit of what you can expect. I am religious about warming up and cooling down according to factory specs which is probably how I got that many hours out of it. I was curious about changing bearings myself but based on the fact that the factory changes them in a humidity and temperature controlled clean room and gives it back to you with a new warranty, I'm a little worried about trying it myself in my dirty shop with aftermarket parts and lube. Has anyone out there actually tried doing Colombo bearings themselves? What were the results?

[elcruisr]

I've been through one set of bearings in five years on my Colombo 5 hp spindle. The first set went after a year and a half of full time operation. The last set gets run just as much but gets warmed up and cooled down every time. It makes a big difference folks!

I know of some big operations that do their bearing changes in house. They figure they get about half the lifespan over getting it done by a factory tech but that the savings are worth it. Just shop it around as well. There are a number of shops around that work on spindles, not just PDS. I would avoid commercial electric motor shops who rarely work on 'em though. Seen a few disasters there.

Brett, what are you running for feeds and speeds at 7,000? You may be loading the heck out of any spindle if you are running any kind of good feed speeds.

[bcammack]

We run anywhere from .5 to 1.0 IPS when cutting. 1/2" carbide bit. We are cutting faucet holes and sink basin cutouts out of 1-1/4" thick acrylic-modified polymer resin and alumina trihydrate composite. (vanity countertops) The stuff is very dense and rather abrasive. (completely unlike standard solid surface)

We are on the very edge of the machine's capacity as this process borders on milling instead of routing. I wish we could put a 2:1 geardrive on it and spin the spindle at 15K RPM.

I need to check with the manager to know for certain, but we must've cut a couple thousand sinks out with this spindle over the last 9-10 months. The policy is for rigorous compliance with warm-up and cool-down guidelines. Presumably these are followed.

I'm just trying to deduce the best choice for our operation that will give the best results and equipment life-span.

[harold_weber]

Carl, or anyone else, could you please give us sources for Perske, HSD, and Colombo bearings? I see that McMaster carries ABEC-7 bearings and they are around $180 each. Is ABEC-7 the right quality?

[elcruisr]

Brett, now it makes sense! I know the stuff you're talking about. It might be worth looking into diamond tooling even. Might work out better cost wise or might not. Would be worth a call to a tooling rep to see what others in that industry are running!

[carlcnc]

Brett
get in touch with Courmat[t?]
they seem to have an answer/tool for any material,tool/speed/rpm question. I would bet they can come up with a 1flute tool design that would allow you to do higher rpm and feed rates.
good luck
Carl

[Brady Watson]

Harold,
'ABEC-n' ratings typically refer to the tolerances of the bearing, allowing for higher RPM and reduced runout as the ABEC rating increases. A standard ABEC-1 bearing has a lower max RPM rating than an ABEC-5 or ABEC-7. The ABEC-7 spec bearings are the proper replacement bearings for spindles. My Bridgeport CNC Mill also uses ABEC-7 rated bearings in the spindle head.

In general 'ABEC' is analogous to SAE or any number of 'association approved' ratings.

-B

[patricktoomey]

I decided to go for it and I tore my Colombo apart and pulled the bearings off. Well, to be fair, I got the top bearing off. I need to get another tool to let me get the bottom end apart and pull those bearings out. In the meantime I got a price quote from these guys...
http://www.ekstromcarlson.com/
of $89 for the top bearing (6203)
and $398 for a pair of bottom bearings (7007) I didn't know there were two in the bottom but as soon as I get it pulled apart I'll verify that. I'm assuming the rep is right as they do replacements on Colombos. I have heard of much cheaper steel bearings being sold out there but these are ceramic which I would think would be the way to go. I'll keep shopping around to see if I find any better prices. I'll take some pics of the dismembered spindle so that if anyone else has the guts they can try it too. Better wait till I'm done and we see if this thing runs again though ;-)

[jhicks]

I thought we had lost the bearings in our 5HP Calumbo and called their Texas office to see what they recommended. They made it sound quite exotic and highly sensitive, clean room, ultra precision allignment, burn in testing and calibration, etc. They quoted $1,100.00 for the change plus freight.
Fortunately they were not shot and we're still running fine but I'm interested in the ability to change out yourself. Are they just blowing smoke or is it a dangerous adventure to change ceramic bearings? I would love to know so when it does happen I have a bit more intelligence.

[thewoodcrafter]

I just pulled apart my 3HP Perske for bearing replacement.
I found standard SKF brand steel bearings. I took them to the local bearing supplier. They had them on the shelf, 2 bearings for $30.
Now maybe they had been replaced before I don't know but for $30 vers $300 or $1100 I will replace them myself ounce every 3 years if I have to.

[Brady Watson]

Jerry,
If you can change wheel hub bearings on a Chevy, you can change spindle bearings on a Columbo. Now...I would not advise changing spindle bearings in the driveway though...


'Ceramic' bearings are not as exotic as you would think. Just the steel balls are coated in ceramic (and possibly the race it rides on)...So as you can imagine, this is not a 'hammer & socket' type removal & replacement job. To do it properly, you will want to visit a friend with a hydraulic press or buy a 20T unit from Harbor Freight. Press the old ones out. Press the new ones in...all the while keeping things surgically clean.

From what I recall, the Columbo rep told me tha the spindles are dynamically balanced, so if you buy a new collet nut, it is already balanced. I would put a dial indicator on it when you were through just for piece of mind to make sure that there is no run out. AND...Treat the main shaft with care avoiding nicks etc.

-B

[jhicks]

Thanks, great to hear its not the rocket science they portrayed it as.

[gene]

The reason some people make things sound tough is there is alot of markup from 30.00 to 1100.00
Just about 1070.00 plus the downtime. The biggest reason alot of people can't do alot of stuff is the fear factor , Fearing they cant do it, they dont even try.

[patricktoomey]

Fear is the reason I didn't want to try it but now that I've pulled it apart I'm not too worried. As Brady said you just press the old ones out and press the new ones in, so far it doesn't look like a big deal. I still have not found a quote much less than $500 for the three ceramic bearings though. It looks like I could get regular steel ones for maybe $200 but I'm going to keep looking.

[Brady Watson]

The ceramic ones are not cheap...but if you think about it, their's where the rubber meets the road when you chuck ANY tool in your spindle on EVERY job. I've got hours upon hours on my 5HP Columbo and it's still very tight.

-B

[bcammack]

We've ordered a replacement/spare Colombo 5-hp as the ShopBot is the critical path in our production process and there are already some 60 tops sitting waiting for a sink cutout.

Jaime at ShopBot has been extremely helpful in directing us in this process. One thing I learned is that these spindles can be rewound by PDS to place the torque peak into a more suitable range.

We'll be sending our original spindle back for, hopefully, warranty replacement of the bearings and for a rewind to get the peak down around 10k RPM.

Quick question: Does the electric fan exhaust air from the spindle or force air into the spindle to cool it? Obviously, ours is down, so I can't check for myself right now.

[Brady Watson]

Brett,
The cooling fan at the top blows air around the spindle through the casing to cool it. The fan should ALWAYS be running (for those that also have spindles)

-B

[bcammack]

Long ago, I was told, "Turbulence cools better than laminar flow. That's why people stand in front of fans, not behind them, to cool off."

I never like to assume, though.

I wasn't saying the fan was down, but the entire spindle is off the machine so I couldn't just mosey out on the shop floor and check it myself.


Looks like I could put some prefiltration on the air getting to that spindle fan. I wonder if I could meter dried, compressed air in to a plenum feeding that fan, hmmm.

The dust from this material is somewhat abrasive, so I'm thinking it might improve bearing life.

[patricktoomey]

Brett, the spindle is completely sealed so there is no dust that can get to the spindle bearings. The case has channels in it that guide the air from the fan down through the case and out the bottom. Since the inner case is totally sealed though, there is no issue with dirt. A little filtration on top of the fan should be fine as long as you never let it get dirty and restrict the airflow through the fan.

[bcammack]

Interesting. I was counselled by ShopBot that abrasive dust contamination could be an issue in bearing life. Conflicting information troubles me.

[patricktoomey]

Brett, that is interesting. Were they talking about bearing life inside the spindle? Having disassembled the Colombo I can safely say that there is no way anything is getting inside there. I would assume other spindles are similar. Now a router would have big issues with abrasive dust flying around since they can suck dirty air right in the top where the brushes and everything are exposed. I would be interested to hear from ShopBot if there is indeed some sort of abrasive issue with any particular spindles. I am getting closer to needing another 'bot and I may not go with a Colombo next time so I want to make sure there are not other brands with issues like that.

[paul60]

http://www.larkencnc.com/purchase.htm

[paco]

So, should one go with a Columbo or a HSD?

What are the pros and cons?

[pfulghum]

My original question also remains unanswered...

I usually cut at about 13,000 with my PC. When would I ever run at greater than 18K rpm?

-- pat

[richards]

Pat,

Here's a link to www.moldmakingtechnology.com (http://www.moldmakingtechnology.com/articles/010204.html) that has an article on using high speed spindles (30,000 RPM with small cutters to make molds.

Personally, I usually run my Colombo around 12,000 RPM for almost everything that I cut. At times I go as fast as 15,000, but very rarely any faster than that.

[fleinbach]

Pat,

I rarely run more the 15,000 with my 3HP Colombo. But I am in the process of cutting some Azek and after much experimentation found I got the cleanest cut by increasing to 18,000 rpm. I was sort of amazed since I thought Azek being a plastic composition would require lower speed to keep from melting. Also I actually cut as low as 5,000 rpm and it cuts like butter even at that speed but it was leaving lots of burrs. The increase to 18,000 minimized them significantly though not entirely. I did try cutting even as high as 22,000 but got no better results then at 18,000

[elcruisr]

With the feed / speed combo's you're likely to use on a Shopbot in normal runs you'll not need more than 18,000. A big consideration for your purchase might be which one has the closest service shop / best turnaround times if you need repairs? Colombo used to have a big share of the market but HSD has really made a strong move in the CNC world the last 5 years or so. I've seen many pieces of equipment switching to them. Both will work and cut material all day for you. Sort of a Ford or Chevy choice....

Even more important is matching horsepower and torque to your anticipated work. I panel process tons of work in 3/4" ply and MDF. Drilling at 6,000 and cutting at 18,000 / 8 to 10 inches per second. I can push a 5 hp spindle up to it's limit. A 3 hp spindle probably isn't up to what we do from my experience. For other shops a 3hp spindle would be perfect. Talk to the tech people at both places and tell them what you want to cut and see what they have to say.