HSD Spindles and the cold

[bill_lumley]

I am considering a 2.25 HP HSD spindle and noticed in the manual it specifies the unit can not be stored below -5 C. In my shop it can get to -25 C in the winter months . Are there any precautions one can take to use a spindle in this situation or does it put the unit at to much risk ? My primary interest at the moment is cutting the noise down as my shop is in a residential area . The Milwaukee is another option for nose reduction also . Any thoughts appreciated . Thanks

[Brady Watson]

Bill,
When I rebuilt my 5yr old Colombo 5hp unit a month or 2 ago, the motor expert that I consulted taught me a lot about bearings, specifically the ones used in my spindle. He said that it is possible to 'skid' the bearings when it is cold and advised me to start the spindle initially as low as possible. Since that time, when cold, I have started my spindle at about 1000 RPM and let it sit for a good 15 minutes. From there I will bump it up to 5000 (gradually) and finally 9000 <- What the factory recommends, until the case is warmed up. Since I don't leave the heat on in the shop overnight, it can get down to near or below freezing temps. The colder it gets, the thicker and more dense the grease in the bearings become until they essentially function as a solid glob of grease. This is not good! I have made it a habit of turning it by hand 1st, and then starting the spindle at low RPM.

I personally know very little about electric motors (engines are a different story...) and was concerned about damaging the innards of the motor by running it so slow. The motor expert assured me that it had plenty of amperage to work down that low and there is no chance of damaging the spindle's electrical guts. This guy repairs & rebuilds 150HP+ electric motors...the kind that go on big vertical lathes for machining solid carbide jet engine impellers. He knows his stuff!

To illustrate (for those interested) what happens inside a bearing when it is cold, the balls have to move around in a cold, thick mud-like grease before the spindle and grease warm up. There is a potential (although low) that you could spin the pressed in bearings in the housing when it is stone cold. When the grease is warmed, the balls move more freely and as the grease gets up to temp it slings the hot grease towards the outside through centrifugal force, clearing a spot for the balls. In doing so, the grease is hot, thin and towards the outside of the bearing...when you turn off the spindle and things begin to cool, the grease settles back down towards the center of the bearing, much like candle wax, and cools to a viscous semi-solid mass, just as it was when you 1st started it up.

The 'grease' phenomenon occurs regardless of whether it is a spindle or router. Bearings are bearings afterall, although the ones in a spindle a much larger and have a higher ABEC rating (higher precision & RPM rating). So the same would hold true for a router, except you don't have the luxury of being able to turn it on at 1000 RPM...I don't think that I have ever heard anyone tell me or anyone else that they wished that they bought a standard router in leiu of a spindle EVER! It's simply a more robust device & if your budget permits it, I highly recommend it!

-B

[bill_lumley]

Brady
When you say at or below freezing is that Centigrade or Farenheit ? So to paraphrase a test when the cold comes is to try turning by hand and if it turns it is safe to turn it on at 1000 RPM to start the warmup process . Have you ever had it not turn by hand when it is cold and what did you do then ? I am thinking of building a little cover for the unit and placing a heater in there for the really cold stuff and possible put a timer on it to come on while having breakafst so the unit has warmed up to civilized temperatures bofore going into the shop . I really just want to be sure I won't damage the unit if it freezes .

I saw a post a while back about this unit www.boatsafeheaters.com/specs.html#JR250W (http://www.boatsafeheaters.com/specs.html#JR250W)
and I am asking the company if it operates at the temperatures I need .

Thanks

[paco]

Storage and usage append for different considerations... if the unit cannot be stored under a certain point, that's problem #1... if the unit cannot bu operate under this same temperature point then it just need to be warmed back... right?

I can clearly understand why a spindle (bearings) would need a minimum temperature to be used but I can't see why it would hurt to be stored under say freezing point... but I may very well be missing something... this need clarification...

Does that make sense?

[Brady Watson]

Bill,
I've never had it where the spindle didn't turn freely, but I did notice that if you spin the collet by hand it doesn't 'freewheel' nearly as long when it is warmed up...I move it by hand just to get the grease cleared a bit before turning it on. Of course all of this is done when the temps are below 40° F. Freezing to me is 32°F -which is the same as 0°C for you.

There is absolutely no reason why you couldn't take the spindle down to crygenic temps if you wanted to IF you are only storing it. I believe the manufacturer is referring to operating the spindle at the cold temps, for no other reason than a higher potential of skidding/spinning the bearings.

A heater of sorts might be overkill, but I don't think that it is a bad idea if you are in a cold region of the world. As long as it is hooked up safely with no chance of fire, I don't see it being a problem. There's something to say about doing your own R&D without looking for approval from the masses...I say go for it!

-B

[bruce_clark]

Brady,

I am no spindle expert, but could it be possible that the bearings are such a tight fit AND that the motor case and bearings are dissimlar metals that below a certain temperature that maybe the housing will shrink or contract MORE than the bearing races, causing either a crushing force on the bearing race or cracking the bearing seat?

That would definately be a reason to store something over a certain temperature. Another might be a moisture/condensation consideration.

Bruce

[Brady Watson]

Could be Bruce, not sure. I know the Colombo has cast iron lands and the bearings are steel. I doubt that cast iron shrinks that much more than steel. Since most engines have cast iron cylinder blocks (not all), and a steel crankshaft I would say that any engine that withstands the cold is proof that a spindle will handle that cold. Only when water freezes (like in an engine block) do you have cracking of the cast iron block...or any material block for that matter due to the expansion of ice.

-B

[curtiss]

I know they make some small "heaters" that are used to keep pianos in churches at the proper temperature when the heat is turned down during the week. That might work.

Curtis J Spfd, Mo

[richards]

How about just using a light bulb? Lots of heat. Low cost. Enclosures are readily available.

[bill_lumley]

Thanks for all the input folks .

Brady I love doing R&D but not on such expensive parts


I think this (www.padheaters.com (http://www.padheaters.com)) may be the answer to warming the unit when not used . I am looking to see if they can be temporarily attached and removed while operating . So I think the cold issue is under control .

Next step for me at least is to see if the spindle noise ratings are low enough to push me in that direction . I was in a shop yesterday and got a set of measuerments for a Milwaukee router and they are very good . I have asked Shopbot to provide the same measurements for the HSD spindle to compare . When I get all the data I will post here ratings for the PC , Milwaukee and HSD. As an example the Milwaukee was only 70 db at 12,000 RPM at 6 feet which was fantastic and I think suitable for the 1/4" downcut spiral I will use quite often .

[scottcox]

Bill,

The PDS manual says "Maximum outside temperature of bearing supports is 150 deg F."

Be sure that the temperature of your heating pads don't exceed that 150 deg.

[bill_lumley]

Well I never got any numbers from Shopbot on ther HSD but here is what I have so far :

Milwaukee running in large open building mounted under open router table.
PC running in a 15x19 workshop mounted in bot with standard dust collector foot
Neither one had a bit mounted in the collet
Reading taken with Radio shack sound meter at 6'

PC
13,000 83 db
16,000 88 db
19,000 92 db
21,000 97 db

Milwaukee
12,000 70 db
16,000 80 db
18,000 82 db
20,000 84 db

Thanks to the shop and a local botter for the measurments .

[bill_lumley]

Well I never got any numbers from Shopbot on ther HSD but here is what I have so far :

Milwaukee running in large open building mounted under open router table.
PC running in a 15x19 workshop mounted in bot with standard dust collector foot
Neither one had a bit mounted in the collet
Reading taken with Radio shack sound meter at 6'

PC
13,000 83 db
16,000 88 db
19,000 92 db
21,000 97 db

Milwaukee
12,000 70 db
16,000 80 db
18,000 82 db
20,000 84 db

Thanks to the shop and a local botter for the measurments . If any of you spindle owners have a sound meter and could take a similar set of measuerments that would be great.

[gene]

Why not wrap a heating pad around it and leave it on low. you could get ona at a drug store for 10.00 or so.

[bruce_clark]

Bill,

Don't forget the actual "cutting" noise. I bet that will easily add another 5-10dB to each of those readings.

Also, little things like router bits make a huge difference in noise levels. I went from a 1/4" straight 2 flute bit to a Belin spiral O-flute and the sound level dropped by about 10dB (unofficial, but it went from me needing ear protection to being able to look at the cutting action without ear protection). This was on a Bosch 1617EVS router--which is also suppose to be a quiet router.

Bruce

[bill_lumley]

Bruce , I am aware of the extra cutting noise and thanks for the info on the bits . I will look into that .

I got info from that pad heaters folks and it is a very reasonably priced product that will fit the bill perfectly . They even have a small controller built into a plug socket that can control two units that switchs on at 2°C and turns off at 7°C to keep electrical cost at a minimum .

I should add I am new to the bot world and my main application is cabinet making so the extra precision of a spindle is not strictly speaking required . Noise is my primary concern at the moment but of course that can change later . Another concern I have with a spindle is that I want to be able to drill out my shelf pin holes and hardware holes and have heard concerns about this so my thinking was that a router can do that and even if it wears out the bearings they are at least cheap and a lot easier to replace than a spindles .

Thanks for all your help and suggestions everyone ! Bill

[bill_lumley]

To follow-up for those interested
HSD 2.25 HP noise ratings
(provided by Shopbot - distance from source unknown)
12,000 77 db
18,000 76 db
24,000 74 db

Hope this helps some folks , Bill

[jay_p]

Bill,

So the HSD spindle is only quiter than the Milwuakee at higher speeds?
How do Colombo and HSD compare in quality. If I was going to choose between a 3hp Colombo and a 4 hp HSD which way should I go? The Colombo has lower hp, but is more expensive. Is the quality really there?
I know that Brady has successfully rebuilt his Colombo. Has anyone replaced bearing on an HSD?
I am running a Milwaukee now and I like it a lot better than the PC, but I may have a chance to uprgrade to a spindle.
Any thoughts?

Jay

[Brady Watson]

Jay,
I like the HSD for the collet nut...the one on the 3HP Colombo is what I call the 'knuckle buster'. I do not however care for the VFD that ships with the HSDs since it only displays Hz and not RPM like the 3 or 5HP Colombo. I like the 5HP Colombo best because it displays RPM and has a good collet nut/wrench setup. Why is the 3HP Colombo more than the HSD? Don't know...it could be that it is Italian


Just about any spindle will be quieter than the Milwaukee (or other router), but the real bonus here is the fact that the spindle will never bog on you when you cut. Another plus is the ability to use any shank tool from 1/8 all the way up to 5/8, giving you more possibilites on cutting tools and saving you money to boot. (bits that are 1/4" shanked necked down to let's say .125 are expensive and limited)

-B

[jay_p]

Brady,

If the HSD does not display RPM how do you figure out what the cutting RPM is?

Jay

[Brady Watson]

Multiply the displayed number of Hz by 60(rpm) and you're there...You mean you don't have your '60' times table memorized??!!

EG - A displayed value of 250HZ X 60 = 15,000 RPM

-B

[jay_p]

Thanks Brady,

Luckily I have a calculator close at hand!

Jay

[harryball]

I used Excel to make a table, printed it on a UPS label and stuck it to the top of my VFD... don't tell UPS.

Robert

[thewoodcrafter]

I have found that on my 3HP Perski the multiplier is 58.25.
The spec plate states the max Hz and RPM.
RPM divided by Hz I get 58.25

[rhfurniture]

I too am currently debating spindle in my head. What interests me is the lower bearing. I suspect it is the lower bearing (together with general build mass) that has most bearing (pun intended) on cut quality. From Brady's pictures, his colombo uses twin ceramic bearings - I assume it runs at 24k, as most 18k routers use steel bearings. Fimec spindles (similar HSD/SEV) say on their website that they use a single double race thrust bearing (I don't know, but guess one race is accented to up, and one to down thrust), ceramic for 24k. My Bosch router uses a single deep vee bearing.
Any accurate and further information on this would be very useful.
Also, Brady, what was the C rating on the bearings you got for your Colombo? My bosch uses standard (C1?) fit. The very expensive hybrid ceramics advertised on the same site are rated C5 C3 (confusion? maybe it is C4..)> This indicates a much higher expected thermal expansion with ceramics (and explains further the requirement to warm them up). I am not an engineer so havn't a clue really, but would like to know more.

[Brady Watson]

Ralph,
Sounds like you've done some research & made some excellent deductions. One major hidden advantage to using ceramic bearings is that the balls are completely insulated from electrical arcing. They are steel balls w/ceramic coating. This ceramic coating really helps to insulate the balls from heat, and controls expansion better than steel ones...but takes longer to warm up because of this.

SPINDLE PEOPLE - The reason you warm up your spindle (or should be!) is because the ball bearings, when cold, fit loosely in the bearing cases. Heat expands the balls to fit more tightly and when warmed up, there is no slop in the bearings - they are at spec. When cold, to exaggerate the condition, the shaft is moving around sloppily (although you can't see it)...when it warms up, things tighten up and you are ready to cut. If you cut with a cold spindle, the shaft is 'moving all over the place', which might mean .001" runout, when the spindle is dialed in and warm it might have .0002" run out....things to think about. (numbers here used for example only)

Electricity follows the path of least resistance...and when using steel ball bearings, they are subject to galling & pitting. All it takes is one good arc & the balls are pitted and the cycle just repeats after that, killing the balls and lands as time goes on. This may be why regular router bearings die so quickly.

The original bearings (lowers) used in my 5hp Colombo were high-precision ABEC7 non-shielded steel balls. One thrusted up, the other down. They are only rated for 18,000 RPM, even though the VFD will allow you to crank it up to 400Hz (24k rpm). I believe that the ceramic bearings have a higher thrust rating and are more suitable for drilling than the steel ones...although I have drilled thousands upon thousands of holes with the steel ones. They DO need to be warmed up a bit longer than the steel ones, and are a little noisy on startup. I start running at 2,000 and let it sit for a good 10min, then graduate to 5k, 9k and then prepare for cutting & set cutting RPM (typically between 13,000 and 15,000) I was suprised that the original set of steel bearings were unshielded, but the entire case of the Colombo is completely sealed from the outside.

The top bearing is also a high-precision ABEC7 rated bearing, but it is steel. They didn't have a ceramic version. Incidentally, the top bearing is the same exact bearing used by GM for years on alternators...BUT the one for the Colombo is rated for higher tolerances, hence the ABEC7 rating. The GM one is probably ABEC1 or 2.

-B

[bcammack]

We got a full replacment set of upper and lowers for our 5-HP Colombo from Alpine Bearing.

(http://www.alpinebearing.com/ViewProdAvail.asp?AVAIL=MC-1107&IMAGE=angular-xlight-100.jpg)

They're quite knowledgable.

[scottgus]

I was able to get my VFD (Yakasawa V7-4X, running HSD 2.2hp spindle, on a PRTalpha 96x60) to read in rpm/1000, such as 15.0 for 15000rpm. Instructions were in the documentation CD for the VFD, which Shopbot shipped with the spindle. I changed setting n035 in the VFD program to the number 1180, and now I see "krpm" instead of Hz. (1180 means decimal point after the first digit, and 18 for the divider value, I think, but I don't remember exactly, I changed it several months ago.)

Also got a "poor-man's toolchanger" going, and just finished an automatic onion-skin-generating program. Lots of fun with this machine.

[jay_p]

Thanks everyone for the great input on spindles. I may be closer to getting one than I thought.

Jay