How Much Horse Power is needed ??

[chopper]

I am currently running a Milwaukee 5625 rated at 3.5 hp, which is quite over rated, I have read that it is closer to 2 hp, I believe it to be less than that,
I run it at 8k for rpm I very seldom change it I would go lower if I could but it is as low as it will go, but I cut aluminum and plastic for the most part and on occasion a piece of mfd, I see others who use spindles with big hp say 5 and up
I am wondering why this much power is needed? I have never run across the need for more power than what I have, but most of the things I cut are more limited by the bit I use to cut them so my feeds and speeds are low so massive hp is not needed, are the bits that are used requiring more hp to run them?
or is it a production thing that you are trying to make a cut faster and deeper to get the job done faster? or am I missing something here?

I am also wondering about rpm, as I stated I rarely go over 8k, but it is capable of 22k, why do you run at such speeds? or do you?
I have never had the need to go over the 8K mark yet, but I do not do production wood work, I would just like to understand the reasoning behind some of the hp needs along with the rpm needs, in the future I may go to a spindle, not for hp needs but for flexibility in collet sizes and tooling choices..
and this is what sparks my questions if I change to a spindle in the future
I want to make a good choice on hp and rpm capabilities ...
thanks//chopper

[Gerald D]

Speed is the easiest topic to address . . . .

When the cutters are very small, you need to go to a very high speed to get any work done - think of a dentist drill. The guys doing fine engraving work, particularly a big 3D work of art, with say a 0.1" cutter diameter would like to go really fast.

But, the bigger the spindle (and its bearings), the less it likes high speed. When a spindle producer says their spindle can go 22 000 rpm, they don't tell you for how long it can do this before the bearings need changing. They also don't tell that the same spindle has twice as much bearing life if you reduce the speed by maybe only 20%

Horsepower . . . .

That is determined by hardness of material, diameter of cutter, depth & speed of cut and bluntness of cutter. Some have the logic that they will be safe for all these factors if they use a high power spindle. But a high power spindle needs 3-phase power, has a shorter bearing life and is more expensive to replace the bearings.

Chopper, your question is very similar to "should I buy a compact car or a SUV truck?" :)

[chopper]

Gerald,
thanks for your help I understand most of the points you made, the bearings in the higher hp spindles, I would have never thought about that,
I also know that this is kinda a loaded question and opinions will be different,
and that is what I want to know, and maybe I already know the answer to this but my reasons may be different than yours for the choices I made,
and that is what I want to get to is why you choose A over B kinda thing.
does this make sense?
//chopper

[Castone]

HP needed can be determined by tool size and chip load for a given material. Here is a link that you can plug in your speeds and feed , chip load etc and it will give you the required HP . This may help you decide on which way to go.

http://www.hougen.com/tech_tips/speeds/speed.html

[Gerald D]

I think we need to start seeing "spindles" for what they really are . . . . . . a set of very expensive bearings with a cheap motor in between them and a standard collet sticking out the one end.

It would make sense to decide which collet size is acceptable, realizing that the bigger the collet, the bigger the bearing, and the less it will like higher speed. If we want to clamp the very common 1/2" shank cutters, the collet size needs to be no bigger than ER20 (reference (http://www.sommatool.com/catalog/erickson/ER%20COLLETS.asp))

Once the collet size is decided, I would look for high horsepower available in that collet size. Extra horsepower then doesn't mean you actually have to use it, and it doesn't mean you are picking a big bearing size because you are going high horsepower. The big horsepower capacity then simply means that you get a bigger reserve and that the spindle will be electrically cooler. (to push up the horsepower, there must be more/thicker copper)

Does this make any sense? (Approaching a spindle selection from collet/bearing size viewpoint)

[chopper]

Gerald,
yes this makes complete sense to me,
I think I will go to a spindle some day in the future when my router
goes south on me, but the way you explained it by collet size is what I am looking for, and if it wasn't for the lack of collet sizes available on the router
I don't know if I would switch at all, thanks again,
and thanks castone, I will also check into the link you gave me
thanks//chopper

[ger21]

Try cutting 3/4" plywood in one pass with a 1/2" cutter @ 400ipm. Your milwaukee @ 8000 rpm would probably stall almost instantly.

[domino11]

But what HP spindle would be needed to do that then?

[Claudiu]

Try cutting 3/4" plywood in one pass with a ?1/2" cutter ? @ 400ipm....

Is this really a usual cutting routine?
I`m a newbie. Just asking:confused:

Greetings
Claus

[sailfl]

Claus,

Most people make multiple passes when cutting any thing.

[chopper]

Ger,
I understand what you are saying, and I agree that the router would more than likely stall, but what is the purpose of cutting 3/4 inch plywood in one pass?
is it a production thing?
I just want to understand why you would do this or what the application might be, as I stated I mostly cut aluminum and plastic, so I am trying to understand the wood side of things a little better
thanks//chopper

[cleyte]

I have just recently joined the Mechmate forum and plan to build in the near future. I have already ordered the lazer cut parts (from Domino11).

I plan to cut 5/8 melamine (particle core sheets 49 x 97) for cabinet box construction. I want chip free results and undertand that I should use compression cutters. Will this involve cutting in a single pass or will I make finish cuts after rough cuts? Can this be accomplished with a router or is a spindle the better option?

Fogo

[domino11]

If you are using a compression cutter, you would need to cut in one pass. This is because the bottom and top of the cutter cut in opposite directions to minimize chipping on both sides at once. If you want to cut in two passes, then use a downcut for the first pass and then use and upcut for the bottom pass. This will involve a bit change but those cutters are cheaper than the more expensive compression bits.

[chopper]

Heath,
good point I see where the compression bit could require more hose power
since you would need to cut full depth to use the bit correctly.
//chopper

[chopper]

Fogo,
I wish I had the answer for you, I think if you are going to cut heavy material in one pass you would need more hp than a router could produce, I would figure out what size bit you would be using and see how much hp it takes to cut your 5/8 inch material, I would also add that the cost of spindles have come down quite a bit in the last year or so, and when you factor in putting new bearings in your router shortly after you start using it I think it would be more cost effective to get a spindle right off the bat and be done with it.
with a spindle you will have to take into consideration that the bearings will also have to be replaced at some point, this may depend on how you use it and if you buy a cheap spindle or spend a few bucks on a better one, the reports that I have read so far on the cheaper Chinese spindles have been good but they have not been in service long enough to see how they will hold up, this link was posted by castone http://www.hougen.com/tech_tips/speeds/speed.html earlier in the thread it may help you figure out how much hp you need to run the bits you will be using,
I think there is no such thing as to much hp but budget, size, etc, will more than likely dictate how much hp you end up with.
//chopper

[ger21]

Sorry for not getting back for so long. First, I don't have a Mechmate, but work in a busy cabinet shop. When your machine is running all day long every day, you can't afford to cut in multiple passes if it's possible to do it in a single pass. Two or three passes literally will more than double or triple your machine time.

As was mentioned, compression bits are designed to cut in a single pass. If you use them for two passes, it'll result in chipped edges, which defeats the purpose of the compression bit.

With the right tooling, it's quite amazing how much wood you can remove in a single pass. Provided you have the HP. :)

[Richards]

My 3hp Colombo spindle is too light for constant one-pass work with particle board and MDF. It can handle the cut without stalling, but the bearing temperature climbs alarmingly fast.

Some of the larger shops consider their "little" 12hp spindles to be the minimum for continual one-pass cutting.

I've settled on making multiple passes, both because I usually have plenty of time and also because my vacuum system (two FEIN vacuums with a bleeder board) cannot reliably hold normal sized cabinet parts securely when making one-pass cuts.

[chopper]

Ger, Mike,
so it becomes a production thing getting the job done in one pass and also depends on the bits selected to do the job or needed for the job, this makes sense to me, as stated I am not doing much in the wood part of thing right now
but that could change, thanks for the input,
//chopper

[lunaj76]

Let's take a 1/4" compression bit and cut say 3/4" melamine. First pass is deep enough to cut the top layer of melamine with the down part of the bit while climb cutting and .03 away from the actual finished size you want. Then 2 more passes climb cutting and leave maybe .02 or the thickness of the melamine on the bottom for good vacuum hold. Final pass will be say .77 or .78 deep conventional cut and to the right size of the finished part or .30 smaller than the first 3 climb cut passes. I also think ramped entry's are required to do it like this. This is just a work around for weak routers and spindles. Also if you cut cabinet parts with a 5MM or a 1/4" bit you can do all machining and drilling of shelf pin holes without a tool change.

[liaoh75]

Hi Chopper,

I recently put in a 4hp Chinese spindle rated at 12 Amps. The highest current I've seen it pull is 3.9 Amps. That's cutting 3/4" MDF with a 1/4" strait cutter at about 2 inches per second. I brought this up in another post somewhere but I can't remember where.

Can anyone give me a conservative ball park estimate on bit life for a 1/4" compression cutter in terms of number of 4x8 sheets of standard 3/4" melamine skinned particle board and if so, recommend a particular manufacture and part number for a 1/4" bit? I'm looking for recommendations from those that have used the actual bit(s) in production if possible.

Thanks

[liaoh75]

Oh, I forgot to add that at the speed I posted, it snapped the bit about 30 seconds in!!

[Travish]

liaoh75,

How hard can you push a 1/2" bit with your 4hp Chinese spindle? How fast can you feed it at 3/4" deep in one pass? I'm just curious to see what these spindle can really handle and what is really needed. I'm still deciding on brand and hp rating I need and will use. Thanks for any info you could share.

[chopper]

David,
are you running an air cooled unit or water cooled?
thanks,
//chopper

[liaoh75]

Hi Chopper, I'm using a water cooled spindle from China - 3KW (4HP) driven by a 5HP Rich (Taiwan Brand) Inverter.

[liaoh75]

Hi Travis, I have not used a 1/2" bit due to the nature of the work I do with the machine. There are usually a lot of fancy corners that require a smaller bit. I'll try a 1/2 test in the next few days and post the results. Just a side note though, due to the nature of stepper motors not having any feedback, I would not recommend pushing to the max on speed. You will lose steps and accuracy at super high speeds. I've encountered this before where I was cutting a circle and the start and end points don't line up. I never get this problem when I'm cutting at a conservative speed for single pass work. To me, roughly 2 inches per second is a safe cutting speed for melamine sheet goods but not MDF. However, I'm using two flute strait 1/4 (6mm) carbide tipped router bits though. That's why I've been asking for a recommendation on a "real" bit for this type of material.

[ger21]

I've read of people getting between 50 and 80 sheets out of a 1/4" compression spiral, at 800 to 900 ipm. Tool life is very dependent on proper chip load. You must cut fast, or keep the rpm's low to maintain the proper chipload. I've never used a 1/4" compression, so can't recommend a part #. I've always used Vortex tools with excellent results. Onsrud should also have what you're looking for.
http://www.vortextool.com/index.cfm?fuseaction=category.display&category_id=30
http://www.vortextool.com/index.cfm?fuseaction=category.display&category_id=29
www.onsrud.com

[alan254]

hi all.

I would like to take advantage of your collective knowledge.

Since i have two columbo RV116 spinders and one ac tech vfd M 12100c controller.

The question are thev to big for the mm. If not what changes would be required other than gas shocks and wire size.

Or am i just asking for failure?

thanks

al drouin

[Gerald D]

I see you have those 2 spindles listed for sale at cnczone for $1000ea.

[domino11]

and also Here (http://www.mechmate.com/forums/showthread.php?t=3067)

[alan254]

yes i will sell if they are not compatable to the mm. But, IF, i can use i will only sell one.

thanks

al drouin

[isladelobos]

The spindles ares three phase?

You can see the 7.5Kw vfd prices. ($700 aprox.)
Normaly here in Spain the home one phase electric contract is 5.5kw.
For 7.5Kw, three phase consumption, is more cheap.

You have solutions.

1- tree phases contract in your home.
2- 7.5Kw VFD (expensive vfd and maybe need more amepres in your home electric box)
3- three phase rotary converter, you need one 15kw rotary converter for move 7.5kw spindle, (need more amperes in your home electric box)
4- connect a cable to the street lamp (free :) )

[alan254]

I have a 400 amp in my shop. it is single phase i can convert to 3. the real question is can the mm handle 10 hp and structually and still run accurately without structual changes

[Gerald D]

Can you drive a 200 HP car off the street, across your driveway and stop it before it goes through the back wall of your garage?

[alan254]

all i would like to know is, positive or negitive, will the mm structually handle a 10 hp spindle.. ? i currently have built a rolling mm, wired and ready for a spindle and drive motors and plan to use the preferred drive motors you recomened the oriental w/7.2 reduction. I am not married to the 10 hp spindles, but, I do have them and the cost is nothing if they are not compatable i just won't uses them.. if they are maby i can another mm builder out since i have 2. see thread #1 in parting out a non mm machine

thank you

[bradm]

Al, I believe that Gerald's point is that a 10 hp spindle is more power than you need, but if properly installed and operated, it will work. You'll obviously have to make the appropriate adjustments for the extra weight.

Gerald, I can normally drive a 200 or 300 HP car off the street, up my driveway, and into my narrow garage. Unless I've been manufacturing too many shims, in which case I don't drive. ;)

[Gerald D]

Alan, the point is that the horsepower rating has nothing to do with whether you can use it or not. You will have to make a judgement if it will fit in the MM.

[alan254]

thanks all