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View Full Version : Fellow Colombo owners please respond....



bjwat@comcast.net
11-29-2002, 08:24 PM
Can any of you guys with the Colombo spindle tell me how to calculate RPM from the high frequency drive number?

The default setting is 150.00 and it says that the range is 0 to 400.00 in the book, but I haven't found a chart that tells me how to convert it to RPM.

Can anyone help me with this?

Thanks!
Brady

pjweber@tls.net
11-30-2002, 08:02 AM
The formula is in basic electrical engineering textbooks. The Colombo and Perske motors are two pole machines.

The formula is rpm = 120 x f / p

with f being the frequency output from the inverter

and with p being the number of poles on the motor

so for your case 120x150/2 = 9000 rpm

bjwat@comcast.net
11-30-2002, 01:51 PM
Thanks Harold!

I didn't expect such an 'engineered' explaination, but I understand nonetheless. ;)

So basically if I understand this correctly, it is 60RPM for every 1 diplayed frequency number, right?

150.00 X 60 = 9000RPM

Thanks again!

steve
11-30-2002, 06:30 PM
Is the columbo (or perske) spindle really much quieter than the pc router? I am thinking about changing because of the noise of the porter cable or would just changing to a makita or bosch router knock the decibles down to a more acceptable level? I mostly rout 18mm mdf cutting it through in one pass with a 7/16 inch spiral upcut bit. I realise that the actual cutting process adds to the noise but it must be nice to have less noise between cutting paths. would very much appreciate your views and experiences

bjwat@comcast.net
11-30-2002, 08:40 PM
My Colombo is MUCH quieter than the PC with or without a load. According to the book the Colombo is rated at 74 decibels at 24,000RPM (MAX RPM).

I believe that the Makita is one of the quieter ones rated at 83 decibels at 24,000 RPM. Keep in mind that decibel level is logarithmic, so an increase of just 5 decibels represents a doubling of the noise level. So taking that into consideration, the Colombo is roughly 4 times quieter than the Makita.

Aside from being quieter, the advantage of the spindle is more power, consistently maintained RPM under load (this is good if you are making straight cuts and dont want the RPM to change under load), next to no shaft play and ceramic bearings that will last a long, long time. The last thing that I want to do is have to rebuild my PC in the middle of a job after discovering that the shaft has run out so much that it is affecting my expensive stock.

Even though I haven't really put the 5 HP Colombo through all of it's paces yet, it is clear that it really makes the ShopBot a real CNC machine.

That or I just love high quality machinery


-Brady

gerald_d
12-01-2002, 01:02 PM
Steve, how many inches per second do you cut that 18mm MDF at? (PS, nice to see millimeters used here!)

ericlamoray@balsys.com
12-01-2002, 02:36 PM
We just cut a job in 5/8" particle board with a 3/8" compression spiral. Full depth, one pass at 2.5" per minute. We do have two y-axis motors which helps and I believe we could have cut it a little faster. (will try it next time on some scrap at 2.75 or more if we land the contract). Love the columbo, wouldn't have a router head for the work we do!

Eric

bjwat@comcast.net
12-02-2002, 09:27 AM
Eric,
Does it really take a MINUTE to cut 5/8 only 2.5"?

Just wondering...that seems a little on the slow side, but you do a lot more of this than I am at the moment.

Brady

elcruisr@bellsouth.net
12-02-2002, 08:52 PM
Sorry, I meant 2.5" per second! At 2.5" per minute I'd go broke for what I charged.....

Eric

sheldon@dingwallguitars.com
12-03-2002, 11:31 AM
Eric,

Are you cutting any hardwoods? Would there be a noticeable improvement in cut quality?

rgbrown@itexas.net
12-03-2002, 01:33 PM
Sheldon,

There will always be an improvement in quality when speeds and/or loads stay constant.

I visited a shop cutting over 700"/minute in 3/4"+ Whiteoak with a compression bit last year. It was impressive - and the cut was nice

Ron

elcruisr@bellsouth.net
12-03-2002, 07:56 PM
Sheldon,
We have been cutting red oak, maple, cypress, various hardwood faced plywoods, mdf, particle board, "Sintra" ( a PVC plastic product ), acrylic and plastic laminates. We can usually achieve a clean smooth cut that needs little attention except a little finish sanding for use. The only headache has been v-carving some ornery maple. Havn't found the magic combination to avoid small tearouts yet. Cut quality is a function of bit selection, rpm and feed speed as well as the runout of the spindle. We are a bit new to this ourselves but have some excellent sources for help when we need it. We have found that tooling designed and balanced for CNC work are worth the extra money. I find the unlimited RPM control on the Columbo to be very much worth the extra money if it can be afforded. The tested tolerances on mine as delivered where incredibly small. (Measured in ten thousandths) The Columbo for us means less vibration, alot more torque, lower decibles, and greater control where achieved. Coupled with the right tooling for the job the results are MUCH better. Like Ron I've seen some big equipment moving at incredible speeds with impressive results. One manufacturer even advertises over 2,000 inches a minute now in wood and 3,000 in light material. That's cutting speed not just positioning. My tooling rep said the trouble now is in supplying tools that can stand the strain without breaking! I'm a LONG way from affording or needing that level of production though!

Eric

steve
12-04-2002, 01:28 PM
Gerald I cut the 18mm mdf at 20mm per second and get a nice clean cut at that speed. I think I am sold on the idea of the columbo but have another question, shopbot offer a 3 phase unit and a single phase unit with a price difference of $500 is that because the single phase unit comes with an inverter that that makes 220v single phase into three phase? or is there another reason?
steve

steve
12-04-2002, 01:57 PM
Another question in the pictures of the jamboree there is one showing the tool changer, is that a standard spindle or is that a special? I am thinking how quick that would be to swop cutters manually or is it larger and needing a beefed up machine?

gerald_d
12-04-2002, 02:19 PM
Steve, my gut feel is that you could cut 18mm MDF at 20mm per second with 6mm bit and a much smaller, quieter, router. Also turning faster (better cut finish) and producing a lot less sawdust. Cutters are cheaper too.

It is a cheap enough test that you can do, before considering the super-expensive bulk sawdust producing beasts
. Especially if noise is your major consideration. Smaller bits are quieter.

elcruisr@bellsouth.net
12-04-2002, 07:43 PM
My experence with CNC tooling is that some smaller bits are sometimes but not very often quieter. It depends on bit deflection and feed speed. A 1/4" straight flute router bit makes alot more noise on a heavy or deep cut than a 3/8" or 1/2" compression spiral. In fact the 1/2" is the quietest tool of the lot. The 1/4" bit suffers from alot of deflection and has to be slowed down to a much slower feed rate to stop it. A 1/8 spiral bit is quiter than both but can not be fed anywhere near as fast or deep. If time dosn't matter that's one thing but for me time is money. Between the shopbot, saws, planer, jointer, sanders, etc our dust collecter has produced as many as 17 55gallon drums of dust a day so dust production is a non issue for us. At worst the 'bot has produced one barrel a day. As for tooling cost I feel a good tool that produces fast, good work with a decent life span is cheaper than a cheap bit! The tooling cost is part of the bill anyway.

Eric

rgbrown@itexas.net
12-04-2002, 09:11 PM
"shopbot offer a 3 phase unit and a single phase unit with a price difference of $500 is that because the single phase unit comes with an inverter that that makes 220v single phase into three phase? or is there another reason?"
********
Without getting real technical on this, both of the units take AC, convert it to DC current then convert it back to 3 phase at a different frequency. The Single phase current requires bigger and more expensive parts to convert the amount of current need to run the motor.

And, the manufacturers of the equipment feel they can charge more.

Ron Brown

gerald_d
12-05-2002, 12:19 AM
Eric, if your only experience with 1/4" bits was with a straight bit, then I agree with you entirely! To compare apples with apples - take the price/noise/performance of a spiral 1/4" versus a spiral 1/2" from the same supplier/product range.

Plus, the 1/4" bit should also be mounted in a decent spindle bearing to get a valid noise comparison to bigger bits in heavier spindles. We use a $200 die-grinder with a good aluminium spindle casing and a 6001ZZ bearing in the neck.

elcruiser@bellsouth.net
12-05-2002, 07:20 AM
Gerald, I was thinking of the worst extremes I've seen so far. I use mostly compresion spirals or down spirals from Onsrud and Courmat. A 1/4" spiral is still noisier than a 1/2" or 3/8" bit at the same feed rates. You have to lower the feed rate to quiet it down on the work we typically do. Yes you could send the rpms up to max rpms but then you can burn material and shorten bit life. As for a decent spindle bearing and casing we are using a 5hp Columbo spindle in a heavy aluminum case with ceramic bearings at very tight tolerances. The technical support staff at Onsrud we've talked with are not even reccomending 1/4" bits for anything except light cutting applications. Of course one of the problems here is so much depends on the material being cut, the feed rates used, the rpms, the depth of cut, and the priorities of the shop running the machine!

Eric

rgbrown@itexas.net
12-05-2002, 08:40 AM
"Of course one of the problems here is so much depends on the material being cut, the feed rates used, the rpms, the depth of cut, and the priorities of the shop running the machine!"

Damn Eric,

Now you are putting quailfiers on a statement. Are you running for a political office.

Ron

elcruisr@bellsouth.net
12-05-2002, 09:26 AM
Yup! Pesident for life Eric.....
Has a nice ring to it...!

Eric

rgbrown@itexas.net
12-05-2002, 10:38 AM
I always wanted to be Emperor of the Known Universe. And I would be Immortal, of course- No Voting, Manifest Destiny, peel a grape for me sort of a ruler.

Ron Brown

gerald_d
12-05-2002, 10:57 AM
Eric, can your Colombo turn a 1/4" bit fast enough - (double that of a 1/2" for the same material)? We run 1/4" Belin bits at 27 000 rpm cutting similar materials to Steve at around his feed rate requirement. His original concern is the noise of his 1/2" Porter Cable. I am only suggesting to him that economical noise reduction may be achievable with a 1/4 system - indeed, I suggested that he just do a simple test. If he doesn't like it, he will still have a useful small router for his shop. But I do hope that he (and others who have actually tried it) give us some feedback on noise. Granted that the Colombo will give you a heck of a lot more production (plus more sawdust and a bigger hole in the pocket
).

gerald_d
12-05-2002, 11:10 AM
For the record, this (http://www.toolhouseinc.com/products/Metabo/GSE7141.htm) is our router motor. Will the Colombo guys please refrain from laughing . . .

elcruisr@bellsouth.net
12-06-2002, 08:49 AM
Gerald, I can turn up to 24,000 with a columbo. It's just that at that rpm with the feed speed a shopbot can achieve the bits will run pretty hot and have a shorter life than at lower rpm. Remember that tooling is cooled by chips not really by air. For instance, the manufacturer of my tooling recommends at 2.5" per sec in 3/4 particle board with a 3/8" compression spiral an rpm of around 12,000 for good cooling and cut quality. I'm all for experimentation. There are often different solutions to problems in a woodshop. For a production environment though I argue that the best possible tools with high quality tooling usually result in better profits long term. After 20+ years of trying it different ways that is what has worked best for me at any rate!

Eric - contributing my share to the worlds' sawdust supply!

gerald_d
12-06-2002, 10:49 AM
*puts tongue firmly in cheek and says:*

So Eric, that's why you use a $5 000 ShopBot versus a $50 000 Multicam?

*turns around and runs away from thread*

Eric Lamoray
12-06-2002, 05:06 PM
Well, personally I know of several multicams that spend the vast amount of their time broken down. A shop near me has had 20 hours of production in one year. He has now stopped making the lease payments on it and told them to come and take it away before he goes bust. Another shop figures theirs goes down every two weeks. That is not a good bet in my estimation. For the production levels we need the shopbot fills the bill at this time. Our business plan is looking at a Komo in about two years or possibly sooner if business increases faster. We reaserched for 6 months prior to purchase and the advice we got from everything from shops with over $1,000,000 in cnc equipment to smaller shops like ours was to start small and learn the kinks on something like we purchased. It is a 5' x 11' PRT. It also set us back alot more than $5,000 the way it was built and optioned out. Slow, yes, but our production on it matches the tool. Many shops have jumped into the big machines right off and been bankrupt in under 6 months. I know of several cases. The universal advice also ran to keep the 'bot after moving up to a faster machine for small runs or larger runs that were over run from the faster machine. The best possible tool still has to fit in a sound business plan and budget. That is what the word "possible" means. If I had an unlimited budget I'd have a 3 axis and 5 axis machine capable of aerospace tolerances right now.
Shoot, one customer wants to know if I can handle graphite parts for helicopters at 5/10,000s tolerance. The answer is no, not yet. If I had several customers that needed say $500,000 gross business for that then me and my banker would be talking about the best possible tool, again, for that job. I see no tongue in cheek here,

Eric

bjwat@comcast.net
12-06-2002, 07:03 PM
Eric,
If you don't mind me asking, can you tell us what the bulk of your business has been?

I have been messing with my Bot for about 2 weeks now. Had some friends help me unload the truck and get the table together...I did the rest. It's a 5' X 16' Dual Z with Colombo and all of the options (Indexer, etc) I should be receiving the plasma setup in February after SB gets the torch controller beefed up.

I scanned a quarter (doesn't everyone?) with my Picza and cut my 1st 3D file with Millwizard...which just came yesterday! I scaled it up to 14" and cut it in about an hour, in foam...It came out OK...need to get more bits.

I would like to move into the area of custom furniture, wooden, plastic and metal. I have a few small orders now for tables.

I am wondering if I should start visiting the lumber yards and sign companies in the area to get the word out...but I am guessing that I will need at least a year to feel that I am somewhat fluent with the Bot to have the confidence to take things on.

I spent a ton of loot on this machine to begin making a transition from the rat race to my own business...I hope that I can come up with ideas that will take off besides lawn deer! LOL!

Any advice/suggestions?

Thanks!
Brady

elcruisr@bellsouth.net
12-07-2002, 09:35 AM
Brady, our primary business is building broadcast studios. We do the custom furniture and have to make up the odd control panel as well. The "other" side of our shop does all the electronics and computer work. This is a rather cyclical business so we are starting to fill in with standard wood shop fare.

For our area we actually put a salesman on commision to sell our shops capabilities. We are finding that subbing parts for other shops is working out pretty good. We've had good response from smaller sign shops, furniture shops and display companies. The big companies all pretty much have their own manufacturing capabilities. It's the growing small to medium guys who are not sure they want to invest in more people and equipment yet that you want to target.

One customer of ours just has us cutting basic particle board circles and shapes by the hundreds. He builds very cheap funiture and is concious of every penny he spends. We showed him we could free up his crew for assembly work by cutting parts for them. We were able to save him about 1.5 cents a part. Not much to some people but when you are doing thousands a year that's something. He is going to be able to increase his sales and production by giving us business. If you can develop a few relationships like this you'll stay busy!

We are also currently negotiating with a shop that builds commercial upholstered furniture. He wants basic plywood parts in huge quantities. So many that we are still questioning if we can handle the numbers. Next week should be interesting!

Another good tip is to buy the sink cutouts from you local solid surface fab shop. These can be made into high dollar cutting boards, signs, bookends, etc. if you know the basics of working with it. It's pretty easy to learn if you don't. You just have to find a few stores to sell your output. Got a flea market nearby? Cruise the stalls and see if you get ideas you could sell to some of the vendors. The profit might be a little low but it could be a start. One guy has approached us about making cord winders.

I used to think after over 20 years as a woodworker I knew a little about router bits and their ilk, I have since discovered that knowledge didn't mean much in cnc work. Try contacting your regional Onsrud rep or someone similar. Mine has spent several hours at the shop with us giving us quite an education on tooling design and application for our various types of work and materials. Courmat has been another great source for us.

Good luck!
Eric

bjwat@comcast.net
12-07-2002, 11:44 PM
Thanks for the feedback and tips, Eric!

Lots of good ideas. I have a good friend that is a designer and he was talking about creating a furniture line...one that could be fabricated with parts produced on the Bot.

I have a few contacts in the automotive high performance fabrication business that will want my cnc plasma business...but that's going to be about 6 months away.

Right now, I am trying to get a leg up on the software and confidence with using the machine. With so much invested...I am a little embarassed to admit that I am a little scared and slightly intimidated by the machine...Like what bits to use for what application, feedrates etc. I have an Onsrud catalog and there are some nice bits in there. Right now I am using some cheapies from pricecutter.com, and they're working fine with foam at the moment...going to mess with pine and plywood cuts next.

THanks again,
Brady

steve
12-08-2002, 03:30 PM
Gerald sometimes I use a 1/4" bit but have to slow the feed right down to cut in a single pass,I said I use a 7/16" I meant to write 5/16" spiral bit with 1/2" shank which I find to be less noisy and having less flex than the 1/4" shank. I also have an onsrud pin router and have been amazed at the different cutting speeds of spiral cutters from different companies, some just seem to eat through the cut very fast whilst I have had some that you have to work hard at pushing through the material.I suppose this is due to the cutting angles that the manufacturer grinds but using them on the sb I suffered some breakage so at the moment I use only the CMT spirals in the sb.

thanks for your help chaps
steve

steve
12-10-2002, 03:56 PM
Also realised today that mdf from different manufactures comes in various degrees of hardness.I had some today that was a fairly dark coloured variety and I had to use a bit more mustlepower pushing it through the pin router, being harder it also seemed to cut with louder noise.

eurocab
12-18-2002, 02:07 PM
Eric,

I am in a similar business to yours and had problems losing steps while trying to run at higher speeds, so I backed it down to about 2.25 ips and make two passes on 3/4" board. I still like the Shopbot, but have inquired about other CNC machines as well.

I recently saw the Multicam machine at the local Onsrud distributor and was very impressed. Having read your negative comments on some of your friends' experiences, I might hold off for another machine.

What exactly were the problems with the Multicam machine and which model did your friends buy?

I would have emailed you these questions, but I couldn't get your address.

Thanks in advance for the information.

Rick