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Spindle Choice: Weights, Collets, and More! (and less!)

Discussion in 'CNC Mills/Routers' started by Batcrave, Nov 25, 2018.

  1. Batcrave

    Batcrave Journeyman
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    I'm posting this for two reasons. First, obviously because I have some questions of my own that I'd really love some help with... but second, because I've seen a number of people recently asking related questions buried in other threads (and countless other lost souls over the years, who've asked their questions of the void, to be answered only by a tragic silence), and thought this might help get everyone's questions a little more attention and/or a little more focus. This also means I may be oscillating wildly between asking questions and dumping whatever details I've managed to dig up, in hopes of saving someone else the trouble.

    Like at least another 64 of you, I just ordered one of the spiffy new LEAD Machines (is that an acronym? what does it stand for? is it a secret? do I ask too many parenthetical questions?), and - like some far less obvious number of you - I still need to pick out a spindle for it. I've spent three years fighting with Harbor Freight trim routers, and that's three years too many - for the new machine I'm upgrading to the Chinese water-cooled spindle that I could never quite justify on a machine built out of scrap and plumbing supplies.

    Of course, the Chinese spindles bring with them some questions that don't arise when sticking with the default Dewalt/Bosch/Makita options - two of the biggest (or at least two of the hardest to fix after getting one home) being the type of collets they use & range of bits they'll accept, and the sheer weight of the little beasts.

    As for collets, the size chucks you're likely to find on the sort of spindle sizes that
    might be realistic on something like the Lead are ER11 (which are able - if you buy the
    appropriate size collets to put in them - to handle tool shanks of anywhere from 1/32" through
    5/16"), ER16 (up to 7/16"), and ER20 (up to 9/16" - the only one that can fit 1/2" shank router bits). If you're running on 220V *glares at most of the non-US world and everyone with spare slots in their breaker boxes* you may even be able to choose which you want.

    Of course - as someone is bound to (rightly) point out as soon as I hit 'post' - just because a tool fits in your spindle doesn't mean your spindle's up to the task of cutting with it. An 800W spindle just doesn't have the power to use most of the big 1/2" shank router bits (never mind endmills), and a 1.5kW probably isn't going to be too thrilled about it either (that didn't stop me from once running a 2" lock miter bit in a little $20 trim router, but it's really not a good idea).

    If you're happy stopping at 1/4" bits (which is probably a good idea on these spindles anyhow), then you're just fine with an ER11. Personally, I still very much want an ER20 on my little underpowered spindle. I'd like the freedom to use to use larger (1 1/2") straight/mortising bits for thin cleanup passes when surfacing wood, but even more than that, I'm just plain sick of finding that the tool/accessory I need only exists/is in stock/is on sale with a shank I can't use - both when shopping for router bits, and when looking for more traditional machining gadgets like edge & center finders. Unfortunately it's proving incredibly difficult to find anything but an ER11 on a <2.2kW 110V spindle.

    Where collet size is largely a matter of convenience & increased choice, weight (no pun intended) is a massive issue (ok, maybe just a little intended). If your spindle is too heavy, your Z-axis may not be able to lift it, or even hold it up. What's more, it may cause the long beam of the X-axis to flex or twist. This isn't a concern with light little trim routers - a bare Dewalt DWP611 weighs just under 4lbs/1.8kg, but larger & more powerful spindles can weigh significantly more. Just how much more is a fuzzier issue - since most sellers don't seem to think weight is important enough to mention - but this chart dug up by halfshavedyaks (in this thread) gives some vague indication:

    [​IMG]

    [these are only a vague guideline, btw - I've seen other sources listing 2.2kg spindles as heavy as 5.8kg]


    For those of you who are stuck living in caves in primitive backwater countries that have yet to embrace a sensible system of weights and measures (my fellow Americans, mostly), those range from 5.5lbs for the 800W and smaller 1.5kW (there are two different diameters - be sure to check which you're ordering - the larger is 8.8lbs!) up to a whopping 10.5 and 11.4lbs for the 2.2kW models. Those figures also appear to be dry weights, so the water-cooled models are going to be even heavier in operation (not having one or knowing how the cooling loop is designed, though, I don't know whether that'll be another ounce, or another pound - anyone happen to know?).

    I'm short on space where the machine will be living, so I was already planning to build my Lead with a half-length X-axis (a 500mm instead of 1000mm gantry), and conveniently, that also makes for a more rigid axis. After a lot of reading, a lot of questions, and a lot of advice from people I promise not to blame too much if I drew entirely the wrong conclusion, I've settled on either an 800W or 1.5kW spindle as probably being the sweet spot for weight/performance on my machine - with the 1.5kW only being up for consideration because of the shortened gantry. I get the impression the 500mm C-beam X-axis can probably (maybe) handle the heavier 1.5kW version without too much drooping or deflection, but after several days of searching & reading, I also have yet to stumble across anyone on Openbuilds claiming their 800W spindle didn't have enough power. The general wisdom seems to be that 2.2kW spindles, on the other hand, are pretty much out of the question for pretty much any standard Openbuilds designs - at least without taking additional measures to increase rigidity and probably upgrading Z-axis steppers and leadscrews to deal with the load. I would be curious to hear from anyone who has modified their machine to hold a monster like that, and about how they did it, but it's not something I have much interest in trying at the moment (if I'm going to have a machine that needs that much power in the spindle, then I want one that can mill steel - and I'm not likely to manage that with an aluminum frame).

    There's obviously a lot more to the topic (Air or water-cooled? Round or square? Do I have a way to mount one on my machine? Can I plug that VFD into the circuit I have available without blowing a breaker? What the hell is a VFD, anyhow, and why do I need one?), but I hope that, if I haven't actually answered anyone's questions here, I've at least provided a jumping off point for asking them. And if I've spewed out anything too horribly inaccurate or dangerously misleading, hopefully I've at leave provided a jumping off point for someone to point out what a hopeless idiot I am while everyone gathers around to laugh at my tears - I think the term is "team-building exercise".

    My remaining questions are:
    • Is there such a thing as a 110V 800W/1.5kW spindle with an ER20 or even ER16 collet, and can anyone point me towards one? I've found 600W (air-cooled DC) spindles with ER16, and 2.2kW water-cooled with ER20, but there seems to be an ER11-only dead zone in between for those of us stuck in 110land (since it would require a new sub-panel, my chances of getting a new 220 line in any time soon are looking pretty bleak)
    • If not, is it possible (or practical) to get a spindle with a bare shaft and add an ER collet of the desired size, or is that just begging for runout? What sort of tooling or shop is required to do the job right?
    • Similarly, the sellers are awfully fond of talking about bearings, but I've found very little quantitative information about them. Does the type of bearing matter? Is it practical to replace the bearings (whether as an upgrade, or due to age/wear/failure)? And, for that matter, do the bearings ever need to be replaced?

    -Bats
     
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  2. Rob Taylor

    Rob Taylor Veteran
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    All looks reasonably sensible. I've also looked a lot at these things recently on the off-chance that I might replace the mill's motor with one, but that looks somewhat unlikely now vs something like a NEMA-frame servo or brushless motor drive. I do rather like the idea of using one as a toolpost grinder on the lathe, however, so I'll probably still acquire one at some point soon. Especially if the lathe's CNC and I don't have to worry about perfectly dialling in machine tapers...

    1) Not that I've seen on any of the usual sites, personally.

    2) Again, not that I've seen, personally, and I'm not entirely sure why because that would be quite useful for me. Technically you could run a series of adaptors from a gauge pin stuck in the first ER collet, but really, adding much of anything to the chain here is begging for runout. Heat-shrink tooling would work, but I'm fairly certain it only ever comes taper-hole, rather than hole-collet chuck. Maybe float some custom tooling enquiries around some likely looking machine shops...?

    3) They seem to all be 7004/5/6/whatever angular contact bearings which appears to be a fairly standard small-size spindle bearing. I imagine they're oiled for life, I certainly wouldn't be expecting just anyone to pull apart a 24k spindle and expect it to still work well again afterward. I've never even heard of anyone relubricating them, either, never mind swapping them out. It's probably possible if you have a spindle repacking station with all the balancing jigs and tenths indicators and all that, but I likely wouldn't attempt it for the prices they are. The ones that weird me out are the ones that say 3 bearing. I get that that's two on the nose and one at the back (or certainly SHOULD be), but the idea of having one bearing just floating and not preloaded feels wrong, somehow.
     
  3. GrayUK

    GrayUK Openbuilds Team Elder
    Staff Member Moderator Builder

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    Hi Bats.
    Another entertaining read. Have you tried going to Resources and typing SPINDLE into the search area?
    There are some very useful pieces in there. Especially about Earthing checks on Spindles.
     
  4. Batcrave

    Batcrave Journeyman
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    Eep! An entire section of the site has managed to completely elude me? :eek:

    I guess I expected that it would have turned up in (what seemed to be) site-wide searches. Looking at the results, though, it clearly didn't.

    More reading for me... woo!

    -Bats

    [ edit: the Resources section doesn't seem to have anything bearing on weight or collets (or bearing on bearings, for that matter), but it does make me feel less guilty about brushing off topics like VFDs and mounting hardware, as those look to be pretty well covered ]
     
    #4 Batcrave, Nov 25, 2018
    Last edited: Nov 25, 2018
    GrayUK likes this.
  5. Batcrave

    Batcrave Journeyman
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    I've often thought a toolpost grinder (or at least some flavor of live tool - I'm a little leery of spewing clouds of abrasive over my lathe) would be a lot of fun, but it hasn't made it onto the short list yet... Especially because the lathe's not CNC.

    Yeah, I think stacking on adapters is going to be going the wrong direction for me. I've had enough trouble in the past with things like .25"->.125" reducer bushings, and those don't even hang out the end of the collet.

    I lodged a request with a friend (the one actual machinist I know), to see if he could either advise or offer a quote, but I don't know what his schedule looks like or if it's reasonable to expect an answer before I have to make a decision.

    I've also spotted some spindles like these with ER20 collets, but they don't list weights either, and, even leaving aside the additional design headaches (and trying to fabricate the required parts before having a working spindle), I can't imagine trying to hang a 60-80mm belt-drive spindle plus a 750-1500W motor on the Z-axis is going to make my life easier.

    I actually did see one video on youtube showing a guy doing exactly that... but I wasn't sure I had enough faith in my abilities to successfully replicate that sort of ultra-high precision "clamp in unmounted vise & whack with hammer & screwdriver until it comes apart" methodology. I also don't think it included any post-reassembly runout testing, which didn't do much to inspire confidence either.

    I'll file your answer on the bearings along with the blank stares (proverbial or literal) I've gotten asking similar questions elsewhere and assume that means it's just not something that people have to do. And I'll hope that it's not just because people are treating the spindles as commodity items & pitching them in the trash every x hours.


    -Bats
     

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