30k RPM Micro Spindle

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ctwo
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Re: 30k RPM Micro Spindle

Post by ctwo »

I have ordered an ER11 collet holder in C10 size for a spindle, a pair of 10x30 AC bearings which I will back up against the collet holder, a 10x30 radial bearing to support other end of the spindle shaft.

I'll make a spindle (quill) housing for this and decide from there how to connect the motor. I think I will forego using a spindle increaser and use a DC motor or my brushless motor (I have several of each kind).

What I need to work out is how am I going to clamp the bearings for preload and hold the mess together. The ER11 spindle does not appear to be threaded at the end and I think it will be too hard (~HRC50) for me to thread, then I'll also need to figure out how to connect the motor, either belt, gear, or axially on the end with a coupling (which would be a bit long).

Anyway, it's in the mail.
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ctwo
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Re: 30k RPM Micro Spindle

Post by ctwo »

OK Guys, here's the plan, but I'm wondering if there is an easier, better way? Something about the bearings I bought make me wonder...

I've roughed out the "quill" between centers. I'll bore each end to accept 30x9 mm bearings. In the vice there are a pair of angular contact bearings. This is my setup to figure out the preload. I first clamped them up as shown and measured the axial movement of the center shaft. Then I inserted a shim (washer) on the inner race to take up that slack, plus a few tenths more (I worked it in by feel).

I'll thread the end of the spindle so I can clamp the assembly together, with a sleeve to compress all center races together. The end of the quill will have a cap that compresses the AC bearing outer races completely. The center races will be clamped by the spindle. It'll be marvelous! Well, it seems so anyway.
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30k-spindle-20160626_151217.jpg
Standards are so important that everyone must have their own...
To measure is to know - Lord Kelvin
Disclaimer: I'm just a guy with a few machines...
Magicniner
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Re: 30k RPM Micro Spindle

Post by Magicniner »

My spindle just has a pair of ball races at the bottom and one at the top, the lower two are bonded to the shaft and sleeve, the top one is bonded to the shaft only and is a sliding fit in the housing.
Your design must allow for change in length of the centre shaft, that thing will get hot and will get longer,
Regards,
- Nick
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ctwo
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Re: 30k RPM Micro Spindle

Post by ctwo »

That's a good point. I was modeling this similar to my Bridgeport spindle, and I reversed my AC bearings to spread the contact to the outsides. The upper radial bearing is allowed to float there, so I'll make some provision for that.
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WJH
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Re: 30k RPM Micro Spindle

Post by WJH »

I suppose a model gas turbine engine idling at 60,000 rpm, that goes up to 110,000 rpm would be nice for engraving, but the swarf would be hell on it :)
Magicniner
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Re: 30k RPM Micro Spindle

Post by Magicniner »

WJH wrote:but the swarf would be hell on it :)
You could have the cutter at the hot side ;-)
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ctwo
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Re: 30k RPM Micro Spindle

Post by ctwo »

I'm inching along here, just at planning the mounting. Here's my idea. My spindle housing is about 2.5" long with about an inch of the spindle shaft out the top.

I was going to make a 1/2" steel plate that would clamp to the Bridgeport quill, the quill end nut (that holds the BP spindle bearings) is just over 1/2" thinck, so I'd clamp to that and not suffer any reduced quill travel, plus not risk gouging the quill. That plate would bolt to the top of the spindle housing.

Another plate would bolt to the bottom of the spindle housing and come out to the axis of the BP spindle, where I would weld a 5/8" solid shaft to go into a regular 5/8" tool holder, so that would fix the bottom of the spindle. Except the BP spindle can rock a bit when in back gear due to the play in the splines.
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Standards are so important that everyone must have their own...
To measure is to know - Lord Kelvin
Disclaimer: I'm just a guy with a few machines...
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ctwo
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Re: 30k RPM Micro Spindle

Post by ctwo »

Magicniner wrote:Harold,
I experimented with O ring cords and found they suffered a lot of "fling" with loss of drive, the polyurethane costs pennies per metre and a with a little experimentation good welds are achievable.
Regards,
Nick
Nick, where do you find this cord? I was looking at Grainger and they sell in 100' length, 3mm diameter for $53. I calculated I'd need about 6.5" to make a 2" diameter drive belt. Or I was looking at just a standard O-ring, but they make them in poly as well, if I want to buy a 20 pack. How about nylon string? I think there is a way to weave the cut ends back together.
Standards are so important that everyone must have their own...
To measure is to know - Lord Kelvin
Disclaimer: I'm just a guy with a few machines...
Magicniner
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Re: 30k RPM Micro Spindle

Post by Magicniner »

My local bearing and seal supplier also does pulleys and belts, they keep Polyurethane round belt in rolls and sell it by the metre.
Try searching your local ebay for Round Polyurethane Belting, there are UK suppliers listing it here,
Regards,
Nick
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ctwo
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Re: 30k RPM Micro Spindle

Post by ctwo »

Will do. I really like the 3-speed pulley idea. Otherwise it's back to plan A with aluminum or plastic gears.

I discovered a high schedule steel pipe that was just a hair smaller than the end of my quill, so I lopped off a couple inches, turned, faced, and bored it just undersized. I cut out a ~4x4x1/4" inch plate and cut out a 3.75" diameter half circle to accept the pipe. I'll split that pipe, open it up some, and weld on some nuts to torque it onto the quill. After I weld the plate and pipe, I'll bore it to finish size. That will be the upper mounting. The lower is still planned to go into a 5/8" tool holder.
Standards are so important that everyone must have their own...
To measure is to know - Lord Kelvin
Disclaimer: I'm just a guy with a few machines...
Magicniner
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Re: 30k RPM Micro Spindle

Post by Magicniner »

I'm looking forward to seeing the finished project!
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ctwo
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Re: 30k RPM Micro Spindle

Post by ctwo »

Well, thanks for sticking in there. Here's a teaser.
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HSS-bored-20160703_150325.jpg
Standards are so important that everyone must have their own...
To measure is to know - Lord Kelvin
Disclaimer: I'm just a guy with a few machines...
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