What about eBay spindles?

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DocN
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What about eBay spindles?

Post by DocN » Sun Dec 11, 2016 10:14 am

I've gotten my SO3 up and running, and have started working towards the eventual production part I hope to produce with it. Details to come later, but suffice to say that it's a somewhat larger piece (roughly 12"x1.5"x6") and while not heavily figured, there will be some contouring requiring quite a bit of material removal.

In another thread, a helpful member roughly estimated something in a circa 2hr cycle time. I'm not experienced enough with this sort of thing to know if that's a fair number or no, but really, even if it's just 20 minutes per (a number even I feel would be absurdly optimistic :) ) I may need to make upwards of 200 parts.

As such, I am, of course, looking towards some of the water-cooled spindles, most notably available off eBay. Leaving aside for the moment the usual warnings of buying Chinese hardware off eBay (lack of return policies, lack of warranty, lack of support, poor to nonexistent documentation, etc.) I've been trying to determine which one might be most suitable for my needs.

As I understand it, the default DeWalt on the SO3 is approximately 1.25HP, but I don't know how much it weighs. (I'd weigh mine, but it's thoroughly zip-tied into the wiring at the moment. :) )

So, to have a roughly equivalent spindle motor, I'd need about 1KW, 20K rpm, and ER 11, correct?

A couple of posts here in various places suggests that about 2kg or so is the upper limit of weight for the Z axis. Yet I've seen some posts from owners using 2.2kw spindles, which my rough research suggests can weigh upwards of 4+ kg. How "hard and fast" is the weight limit? I see 1.5kw spindles averaging around 3.5kg, when a weight is given.

Would slightly heavier springs help this, or is a Z-axis screw conversion the only solution?

Basically I've been looking at any one of the various 1.5KW, ER11 kits off eBay, probably one of the full kits that includes an inverter (VFD) mounting clamp, water pump, etc. The OD is generally given as 80mm (as opposed to the DeWalt's 69mm) the weight, when it's given is usually about 3-4kg (about eight pounds) and prices for a kit like that range anywhere from $350 to $550.

Now, this is not an urgent thing. It'll be a while before I'm ready to even start thinking of production, and I definitely don't want to rush into buying a bad choice. I'm wide open to options and suggestions, just keeping in mind my primary need is that the spindle lasts what might very well be many hundreds of hours of near-continuous work.

Doc.

WillAdams
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Re: What about eBay spindles?

Post by WillAdams » Sun Dec 11, 2016 11:44 am

There was one forum user who did a 1.5KW spindle conversion:

- Chinese spindle (the 2nd best thing I've done for my Shapeoko ---- http://www.shapeoko.com/forum/viewtopic.php?f=21&t=1108
- http://www.shapeoko.com/forum/viewtopic ... 89&p=15172

This was on a Shapeoko 1 or 2, so I'm sure the SO3 can handle a larger spindle --- the concern is about wear and tear on the V-wheels due to the increased mass (that was one of the arguments against mounting the machine on end or side and adding a counter-balance to the spindle carriage)

The other option would be a Kress or Ugra or other real spindle, the first listed at: http://www.shapeoko.com/wiki/index.php/ ... W_and_over
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zamp
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Re: What about eBay spindles?

Post by zamp » Sun Dec 11, 2016 3:36 pm

There's also Christian (aka the guy who wrote EstlCam) who wrote up putting a water cooled 0.8Kw spindle on his Shapeoko 3. See http://www.shapeoko.com/forum/viewtopic.php?f=21&t=7270 for Christian's writeup, including circuitry he needed to interface the VFD he purchased with the CarbideMotion controller.

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DocN
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Re: What about eBay spindles?

Post by DocN » Sun Dec 11, 2016 10:35 pm

I'd already read Christian's writeup, but he makes no mention of weight apart from the part about cutting down the rather beefy supplied clamp.

I'd also read ForgottenCNC's article on his 1.5Kw install, since that's almost the exact spindle I've been looking at (generic Chinese 1.5Kw with ER11 nose, supplied with VFD) except I'm leaning toward the water-cooled version. His build, however- I think a Shapeoko 2?- uses a screw-actuated Z, rather than the belt drive of the SO3.

Nutz95's build does note the weight, but again he has an older model, and said he had to upgrade the Z axis.

I guess, then, my main question is, can an off-the-shelf current build (Dec, '16) Shapeoko 3 Z axis accommodate a 3-4 kg/5-8lb spindle, without undue strain on the belt or stepper, and without a notable decrease in accuracy, longevity or rigidity?

Doc.

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Re: What about eBay spindles?

Post by WillAdams » Mon Dec 12, 2016 1:13 am

I don't think anyone knows that yet, except maybe Edward as a part of his design research --- try contacting him directly? Might be he'd share something privately in an e-mail he might not feel is suitable for public consumption.

Given that it all worked well enough on the SO2, I think the worst case scenario is that you would need to work up a lead screw for the Z-axis on the SO3 --- I did a rough design and have a b.o.m. here http://www.shapeoko.com/wiki/index.php/ ... dams#B.O.M.
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DocN
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Re: What about eBay spindles?

Post by DocN » Mon Dec 12, 2016 7:58 am

Okay, the supplied DeWalt 611 is about 3.5 lb, or 1.5 Kg.

The generic eBay 0.8Kw spindle (water cooled, 65mm OD) is listed as 5.2lb, or 2.4 Kg. I could only find one listing that even gave a weight, but one might assume that's fairly standard across the board. That's over half again heavier than the DeWalt.

The generic 1.5Kw spindle with a 65mm body is generally longer (about 125mm vs. about 185mm) so while I wasn't able to find a listing that gives the weight, I'd wager we could reasonably estimate it at least 3Kg, or 6.5 lb. Pretty firmly double that of the DeWalt.

I suppose I could try something like rerunning the "Hello World" program with an extra 3 lb strapped to the router, and see what happens. The preset speed is fast enough if there was going to be a skipped step somewhere, one would presume it'd show up there. I'd imagine line thickness of the Sharpie marks would be a decent indicator if the Z carriage were wanting to fall, or couldn't lift fast enough or far enough.
[...] the concern is about wear and tear on the V-wheels due to the increased mass (that was one of the arguments against mounting the machine on end or side and adding a counter-balance to the spindle carriage)
-Huh. That's actually a really interesting idea. I wonder if anyone has tried mounting one of these things vertically. There'd be less weight to lift on the Z, but more to lift on the X. You'd get pretty good chip clearance- swarf would tend to naturally fall away. (Which is why lots of industrial CNC machines run that way.)

I know keeping the cost of these kits down has always been a priority, but have you guys considered a third set of wheels- not necessarily just for the Z, but for the gantry as well? Or would they be too difficult to properly align? ('Course, both the additional two could be given those eccentric adjusters...)

Doc.

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Re: What about eBay spindles?

Post by WillAdams » Mon Dec 12, 2016 12:28 pm

My understanding is the third set of V-wheels was viewed as fiddly to adjust and not providing enough improvement to justify the effort --- ISTR someone having done this, but seem to've not recorded it on the wiki (and it's one of those concepts which is hard to search for, at least using any search engines / techniques I'm familiar with).
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atrueresistance
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Re: What about eBay spindles?

Post by atrueresistance » Fri Mar 24, 2017 1:50 am

I've done the 3 v wheel upgrade for the z axis. Deflection with the redesigned z plate is less vs the old version and 3 sets of wheels.
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