3hp vs 5hp Columbo single phase spindles

[Guest (Unregistered Guest)]

Does anyone have any thoughts on the pros and cons of these 2 spindles for nesting cabinet parts? Specifically,I'm wondering if the 3 hp single phase has enough jam for nesting or if I'm better off to go with the 5hp.Thanks.

[richards]

My 3hp spindle works fine when cutting MDF, particle board and plywood for cabinets. Sometimes I cut with one pass and sometimes I cut with multiple passes. In either case, the spindle is not the limiting factor. My little Fein vacuum, which does a great job, isn't big enough to cut small parts with one pass. My Alpha machine, as great as it is, might be a little too flexible to get absolutly perfectly accurate cuts when cutting 3/4-inch material full depth in one pass with a 3/8-inch cutter. It can be done and the deviation is barely measurable, but two passes generally gives smoother cuts.

The 3hp spindle, when coupled with a sharp cutter and sheet materials, usually draws 4 to 5 amps, and hardly ever goes above 6 amps. It's rated at 22 amps, so there is a lot of margin. I've had no problem keeping the spindle temperature below 140-degrees F., even on those hot summer days when the shop temperature was above 100-degrees F.

In my case, I wanted the 5hp spindle, but I have limited power available in the shop, so I bought the 3hp unit. I have not been disappointed.

[elcruisr]

It all depends on how much production you need. If you want to cut up 3/4" ply at full cutting speed all day long you need a 5 hp spindle. If you can be happy cutting a little slower a 3 hp is fine. The question you want to think about is what, exactly, do I want this machine to do. Next it is easier to define the package you need to do it. It will mean thinking about machine, spindle, hold down and software as an integrated whole.
Eric

[ron brown]

Mike,

Thanks for that bit of information on power draw. If my numbers are correct - 240VAC X 6A = ~1500W or about 2hp. I am curious to the method you used to obtain the amperage reating and if you feel it is accurate.

Ron

[richards]

Ron,

I used the figures from Shopbot's documentation, "PRTalpha Power Req - Domestic" where it lists 22 amps on the chart on page 4 for a single-phase, 3hp spindle.

(The on-line calculator that I use as a quick reference to determine hp can be found at http://www.onlineconversion.com/motor_horsepower.htm , where it calculates 14.5 amps at 240 vac to be ~ 3hp when there is 65% efficiency. I think the key word in their formula is efficiency. At 100% efficiency, ~ 9 amps equals 3hp.)

[gerald_d]

So, how would a 3HP spindle ever draw 22amp? Surely it is not mostly due to in-efficiency?

[Guest (Unregistered Guest)]

Thanks for the responses; Mike, I guess I'll stick with the 3hp. I notice you use a 3/8" cutter - have you tried the 1/4" with a full depth pass? I'm wondering if this gives too much flex for a nice cut? I intend to use 2 big Feins and tabbing so hopefully I won't get movement in that area.

P.S. Sorry about the "unregistered guest" deal, the forum won't give me an access code - I've tried 2 email addresses and nothing.

[richards]

I've used 1/4-inch with full depth a few times - and it always worked, but the noise can be intimidating. Most of the time, I try to not go deeper than the diameter of the cutter, which means 1/4-inch deep with a 1/4-inch cutter, 3/8-inch with a 3/8-inch cutter, etc. Going 2x the diameter with a 3/8-inch cutter gets me to full depth with 3/4-inch material, but that can be a loud screamer, too. A lot depends on the cutter being used and the material being cut. When things get loud, I play with the spindle speed and feed rate until the cut is as quiet as possible; however, full depth cuts will keep you awake.

A lot of my cutting is full depth in 1/2-inch material, mostly particle board. That thickness cuts quietly and quickly.

Flexing hasn't been much of a problem. I try to select cutters that are as short as possible. At one time, Eric Lamoray suggested using 3/8-inch cutters with 7/8-inch cutter length. That was excellent advice. 3/8-inch single-flute compression cutters would be my choice if I had to use only one size and style of cutters to use for all sheet goods. I use a variation of the chip-load calculator that you can download from this forum to help me select feed speeds and spindle RPM.

Gerald,
I think the 22-amp rating is kind of like the 60-amp fast blow fuse recommended by Colombo; mostly required to satisfy the lawyers. To be perfectly honest, when I started using the spindle, I expected it to draw about 22 amps. When it only pulled 4-6 amps, I just assumed that I had a large margin to use, if necessary. It wasn't until the posts today that I cross checked the Shopbot chart with the amp/hp calculator.

[gerald_d]

When I see pictures of that thick orange cable going to the SB spindles (or is it the control box?) I always wonder about the current load expectations, and what that current is supposed to be doing. If current isn't making torque, it makes heat - something just looks wrong.

[benchmark]

Hi
I am interested in a air cooled 3HP Colombo spindle ... is the air cooled version quieter than a fan cooled one and what sort of air consumption does it have.

Many thanks


Paul

[richards]

From the Colombo web site, http://www.pdscolombo.com/cool_req.htm

Cooling Requirements

Frame Size 73 = 3hp
Frame Size 90 = 5hp
RC = Compressed Air Cooled

Frame 73 = 1.5 cfm, 25 lpm
Frame 90 = 1.8 cfm, 25 lpm

The cooling fan on a Colombo makes very little noise. It's about the same as the power supply fans in a computer.

[benchmark]

Mike,

Thank you

Paul

[gerald_d]

Paul, if someone is offering you an "air-cooled" spindle without giving model numbers, then tread carefully.....

"Air-cooled" (as opposed to water-cooled) could mean two things:
- a fan mounted right near the spindle
- compressed air piped in from a compressor

"Fan at spindle" could also mean two things:
- fan has its own motor (this is the "quiet" style)
- fan is mounted on the back of the main spindle shaft (sounds like a siren!)

[benchmark]

Gerald, thanks for the info.... the model has a compressed air feed with a tool changer, but I am still unsure ??

Thanks

Paul