I'm kind of in a jam right now. I need a spindle motor for my machine. The machine of made from a ton of taig lathe parts and a 12"x5" xy table. The headstock is from my old taig lathe. I'm looking for a DC motor with variable control. I like the sherline set up, but I figured there must be a cheaper alternative to the same thing. I have limited experiance with electronics and almost no understanding of how the motor controller works. What other motors and controllers are out there that are suitable for a bench top mill? I would like a motor in the 250-400 watt range.
thanks for any help

mike g

I needed a simple, cheap, powerful option to drive a Taig spindle, and after digging around I came up with an interesting solution that might work for you as well. I wanted variable speed as well, so DC was a necessity, but I wanted less cost and more power than the Sherline head. I also don't like thier spindle and belt setup as much. I just wanted to use the stock Taig spindle.
After looking at servo motors and other brushless DC options, I found the cost was pretty large, especially for the controllers. Then on Ebay I found a 400 watt brushless DC motor with the right speed range - with the speed controller built right in! It is one of those Kollmorgen 24v 400W electric moped motors of all things. They had to cost a bundle to originally build, but as no one ever bought those silly electric bikes someone wound up with a warehouse full of the motors and no use for them, so they are selling them off as new surplus for like $40 or less.

The motor is easy to fit in the same space as it is about the same diameter of the Taigs original AC motor, but only half the height. They are also somewhat lighter, never a bad thing. They put out about twice the power though!

Since the controller is built in, they have two cables coming out of the case - one cable with two connections for power, and one cable with three connections for a 5k ohm pot to control speed and two more for the "brake" circuit (or E-stop for our purposes). For the electrical it is literally hook it up and run.

The only real downside is that the shaft only sticks about half an inch out of the motor, so you can't use the stock Taig six-step pulley as it requires a longer shaft. No big deal, as you should probably change pulleys to go over to sturdier belting anyway to handle the new power output. You also have use a metric bore pulley, or alter one, as the shaft is metric. Minor issue, but still annoying.

If you can get past that you have a really cheap and simple 1/2 hp brushless spindle motor with a crapload of torque! Don't know how they hold up for really long term use yet, but they look sturdy enough, and mine is still going with no trouble. For the price you can't really go wrong.

ok, everyone duck!

i was having a thought the other night when i broke off a 1/32 endmill... i really need to increase the spindle speed on my x3... so heres my thoughts.

1) i have a 2 1/2 or so HP porter cable router, lets call it brandnew cause i've only had it on for maby 15min max, could a person make this into a reliable spindle motor.. one thought was to replace the existing spindle motor, but i really dont think that the x3's spindle bearings would live at 10k-30k rpm for long.. plus theres gears in that head that i question as well.. so along came thought #2

2) make something, that would chuck up in the existing spindle, maby using a 3/4" collet, that would have its own high speed bearings, that could hold an endmill, maby one of thoes little quick change jobby's that use the little er20 spring collets or something of that sort... then have the router motor hang off to the side of the existing head, and belt drive to this new "sub spindle"

the router that i have has variable speed from 10k to 30k RPM, so that should be plenty enough, and at 2-1/2HP plenty powerfull.. my thinking was to use this for say my 1/4" and smaller endmills, and then if i need to do something large, slide out the sub spindle and use the original..

another aspect of all of this that i had thought about, what if the sub spindle weren't straight, well i suppose a person could turn on the original and have the base of the sub spinning, this would take out the not straightness and possibly cause a wobble effect, tho i really dont think that it would be an issue, as i cant see any kind of a wobble when i run end mills in it now..

i still need to setup my coolant system, and that will help at these faster rpm's, but help me out, if i turn the endmill faster, and cool it, then cant i cut at higher IPM's?

the last thought that i had, was also an attachment that would "chuck up" in the original spindle, something like a small gearbox, that would double or more the rpm's of these wee tiny endmills that i need to use.. it would be something like a sun and planetary gearset, and would have to have some sort of a zero arm or somethhing that would contact the outside of the head to hold one of the 3 gears stationary, either the sun, planets, or outter ring, depending on the design...

i know that running the original spindle wide open fast on high speed for a while (30+ min) causes it to get quite warm... just wondering if the router or gearset would help get what i want and reduce this some...

hanging the router motor off to the side of the existing head and using it alone as the spindle would seem to reduce the useable travel of the table, thats why i was thinking of the hole chucking up part...

thoughts?

Don't even consider running the stock x3 bearings above 5k for any length of time! Been there.......
HOT! after 15mins.
Runout is terrible on the wood routers and any of the cheap air grinders.
This will wear endmills quickly since the flutes will not all be cutting evenly. Best budget bet is to use a router but make a new small adjustable chuck for the endmills to adjust out most of the runout and be left with what is in the bearings. The chucks are not high accuracy as they are made for wood bits. I have found from .003"- .005" on most routers and die grinders that I have measured. Now .001" maybe even .003" is no big deal on a 1/2" endmill. But on tiny engraving endmills it will have an effect. And to put that into perspective the x3 would be a big pile of crap if it came with a spindle of .001" runout for instance.
But the router is a cheap way to go.
High speed and low runout spindles are not cheap. Some low power / high rpm with very low runout spindles can be had cheaply for engraving duties. Check Ebay.
I have run 1/64" endmills on my x3. Broke most of them but have done good work with very slow turtle like feeds.
A high speed spindle is on my list of must haves for the x3. I'm still looking for an affordable answer.

Steve

It is certainly a rather pedestrian option, and not a panacea, but just the basic Sherline and Taig spindle cartridge inserts are sold separately, are easy to install into a simple to make mounting block, and are really cheap. They will take decent power (up to 1/2 hp), at decent speeds (12k or so), with minimal runout (a few ten-thousandths), and take some pretty reasonable abuse without complaint.
After that it seems you are stuck with either engraving spindles that while scary accurate and run up to 25k-40k or more only run at low power and 1/8" or smaller bits, or a WHOLE lot of really stupid money for an industrial spindle that will handle big shanks and real power at those same speeds.

the runout on the router wouldnt really be that big of an issue if it were just used to belt drive the sub spindle... but i can definately see where using it directly might be an issue..

thats why i suggested a bearing head that would go into the x3 and turn freely and sepperately from the x3 spindle.. use some good bearings and i would think that it would live at 10k+ on 1/8 and smaller endmills..

tell me more about these shearline inserts.. i'm not sure i'm picturing what your telling me correctly.

and maby the big router is too much, perhaps something more like a trim router as the motor to belt drive the actual spindle...

i just found an air spindle on harbor freight thats on sale for $10, i'm gonna go grab a couple and try them out.. if it works, awesome, if not, at 10 each, i can afford to blow it up and not loose the farm.

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=47869

thats why i suggested a bearing head that would go into the x3 and turn freely and sepperately from the x3 spindle.. use some good bearings and i would think that it would live at 10k+ on 1/8 and smaller endmills..

tell me more about these shearline inserts.. i'm not sure i'm picturing what your telling me correctly.

http://www.sherlineipd.com/images/6505.JPG

This is what I had in mind. It is a complete self contained spindle housed in a simple flanged sleeve, or cartridge, for easy mounting. The ER collet and closer fits there on the bottom. The pulley fits on the top, this drawing showing a toothed pulley installed, obviously others can be fitted as well.

You simply drill a hole in a block and drop it in, or put it into a linear shaft clamp, and you now have a mounted spindle, or sub-spindle in your case. More pics at http://www.sherlineipd.com/spindles.htm if you are interested. They are cheap and rated for 10k, hobbyist web pages show people getting them to run higher. ER16 means mills of up to at least 3/8". Sherline are certainly not the only people making generic cartridge-style spindles if you need more speed.

that would work, just have to figure out how to make it work so that its not to the side of the existing spindle and thus loosing some usable table trravel...

i shot a video of my new $10 air spindle, the bracket i made, and so forth.. the videos are at: http://www.jpcustomcrafts.com/cnc_videos.htm

they are shakey, poor quality, and were shot using a webcam with a cord that i just handheld.. sorry for the quality, but i think you'll get the idea.. i was really surprised as to how loud the little air spindle was.. but it seems to cut well, and the little endmills didnt seem to walk out of the collet like i thought they would... kinda like they do when i use a dremel...

If a subspindle is set up off to the side, you don't actually lose any table travel, just available table directly under the spindle. The table still moves the same amount. Center a tooling plate or similar under the spindle to gain all that area back, in other words offset the plate to hang a few inches over the free end of the table if it is a problem.

yea, i realize this, but as for right now i really dont have the materials for it.

i wonder if some 1" thick t6061 would hold up as a new table top if i were to slot it for my tnuts. (i'm not using a vice to hold my work as of yet.

maby theres a better way, some sort of extruded profile that i could just bolt down rather than having to slot it myself.

yea, i realize this, but as for right now i really dont have the materials for it.

i wonder if some 1" thick t6061 would hold up as a new table top if i were to slot it for my tnuts. (i'm not using a vice to hold my work as of yet.

maby theres a better way, some sort of extruded profile that i could just bolt down rather than having to slot it myself.

I bought some T-slot profile on eBay UK from MarchantDice - I'm sure there's something similar available on your part of the globe.

That said, I think you might be better off simply driling and tapping a matrix of holes onto a piece of cast-tooling plate.It's not expensive, and is mega flat on the front and back.

it just so happens that i have some 1/2" tp t6061 around here, i was planning on using it to make the spindle mounts for my 3x3 router... i dont remember the dimentions, but maby i should check to see if it fits for this application before i cut it up for the router... thats a really easy fix, thanks... i could just chuck up a drill in the mill, draw out the hole pattern and let it drill all the holes, then i'll have to tap em.. or maby, drill it from the backside, countersink em bit, and use some threaded inserts... hmm that sounds like the way to go rather than tapping 100's of holes...

it just so happens that i have some 1/2" tp t6061 around here, i was planning on using it to make the spindle mounts for my 3x3 router... i dont remember the dimentions, but maby i should check to see if it fits for this application before i cut it up for the router... thats a really easy fix, thanks... i could just chuck up a drill in the mill, draw out the hole pattern and let it drill all the holes, then i'll have to tap em.. or maby, drill it from the backside, countersink em bit, and use some threaded inserts... hmm that sounds like the way to go rather than tapping 100's of holes...

I'm sure I saw a table on here that had a matrix of holes that were drilled through, countersunk on the rear side, and then had flange-nuts press fitted into each hole - simple, cheap and effective. If you have a pile of threaded inserts, I suppose they'd be even better.

well i cant imagine that thier that expensive, might even pick them up for around $.25 each or less, i havent looked, but surely the big orange box or my local nut and bolt shop can get me what i need at a price i'm willing to pay.. just have to go and ask the questions and look around.. but i'm thinking that this just might be the way to go.. time to do more research.