Ok, first off I'm sick of not knowing what spindle I should be using or can get. Like many of you out there I am using a home built unit and plan to make items I used to make by hand. It is not intended to be used in my business unless I find it's accurate and reliable. To date the table is accurate but not the spindle and it's very reliable. Those of you who have built your own know these are pretty basic machines and there's not much that can go wrong if you built it correctly with proper materials; not skimping on the linear components of course. But I still can't afford a spindle that cost twice what it cost me to build my table. Although, if it comes down to it I would put out the money so there is no question about it's accuracy. I will go into alternatives first and theories then go about explaining, with pictures, about how I tested these two routers.
As far as ready made spindles out there. Most are run using a VFD Variable Frequency Drive. This is an electrical device that uses the frequency of electricity to set the spindles RPMs. This system uses 3 phase power, but don't worry a lot of VFDs can convert single phase to 3 phase power.
As a side note never buy a static phase converter. I bought one originally when I got my Bridgeport, single phase to 3 phase, and thought it's a used mill so it might run rough already. Then I got my VFD from Automation Direct, I think, and it ran so smooth I could not believe. So static phase converters are, as my understanding, is tricking the motor into thinking it's receiving 3 phase power, but when the VDF does it, it comes out way cleaner and runs the motor a lot smoother. And it's about the same price. I bought my Phase-O-Matic for about $115 and the VFD was about $135.
As I was saying the VFD controls the RPMs. On my Bridgeport I have it set to the highest RPM on the belts and 25 on the VFD equals about 1000 RPMs. Another side note, I invest my money in measurement instruments it makes life easier. I thought I would only need a hand held tachometer to set my mill once I got the VFD installed but I actually use it quite often when I'm questioning what something is spinning at. I got my Tachometer off ebay for $40 including shipping.
Ok, as far as spindles out there. There is a rather inexpensive brand called Kress. It's hard to find in the US but it's a true cheap spindle and used metric collets, as far as I could find out. From CNC manufacturers out there and forum post some people have been having problems with them and some people think their quality has gone down, but for $150 you get what you pay for. The problem I see is the metric collets and it only goes up to 8mm. So for serious wood routing it's out because it can't accept 1/2" shank bits.
Some people love the Bosch Colt. The problem I see if for serious wood routing you can't use 1/2" bits, I know 1/4" shank 1/2" cutters, but I don't want the deflection. I want a full size router for a few reasons, one I can always go up in horsepower, they're beefier and are made for removing a lot of wood. But Bosch makes good products so for smaller CNC Routers they're fine.
Next is Colombo spindles, I know nothing about them but they are about $3000 and up.
Next is a inexpensive import spindle from homeshopcnc.com and it's $900. Again I know nothing about it.
Now I have heard good things about http://www.ekstromcarlson.com/ but again they are imports and start at $1200 for 1.34 horsepower. They also sell spindle blocks, basically a spindle without the motor. You use an outboard motor, like they do on Taig Machines and Sherline's. But those are made here in the US and cost just about the same as their import spindle that has the motor built in. So that's out.
Ok, so Taig, Sherline and MiniMills. You could buy a Taig, Sherline or MiniMill Head and use that. Good idea and cheap. I think they are all around $150 for the head with collets system, no collets of course. The only problem is for wood routing you need at least 20,000 RPM. All these spindles max out a 10,000. But still a good option for the ones not hogging out wood like I do. The MiniMill head can be had at littlemachineshop.com.
Ok, so now what, build your own. I've researched this too. So we want Angular Contact Bearings, standard is 15 degree, which are made for machine spindles. They are expensive and generally come in metric. I was going to buy a Straight Shank ER20 Collet Chuck as seen at KBC Tools Page 434, item 7-171-2009, for about $70. Then buy some spindle bearings but they don't usually come in SAE sizes and when they do they are godly expensive. So what you do is turn down a collet chuck shaft to match the 25mm ID of the bearings. Well then you get in to having to do very, very precise work. Then get a block of aluminum and mill pockets for the bearings and press everything together and hope everything is in line then mount a pulley at the top. Then go through the arduous task of finding a motor, along with stepped pulleys, to get the required 28,000 RPMs. I found a supplier near me that has the right bearings 30,000 RPMs, 15 degree contact, 25mm ID, ABEC 7, a matched set costs $250. They are all about this price on the web. He also had one that was 40 degree contact, I know the physical difference between 15 and 40 but I don't know what that equates to function as a spindle for the work we are doing. They were ABEC 5 and costs $55 each. Fine but turning down an all ready precision collet chuck to the absolute correct diameter was not going to happen with my skill, which is pretty extensive. I would try no problem if the bearings were not so expensive, because most spindles use 3, two at the collet part and one up top. That's $150 just for bearings not including the time to make everything and the collet chuck which would be useless if it didn't work because you made that shaft a different size than standard.
So what's a guy to do. Precisionbits a.k.a Think and Tinker will be coming out with a Porter Cable Precision Collet System which will include an 1/8" and 1/4" collet for about $100 in about a month. Good option if your router itself is not out. BTW Precision Bits is awesome they will spend time on the phone with you and give you any help they can even when dealing with something they don't sell. Ok, wait a month, not for me I need something now.
Bosch Colt got me thinking what about other Bosch Routers. Here's what I came up with. I've been a Porter Cable fan for a long time, but the results don't lie. Bosch makes quality products so I gave them a try.
First some notes. I tested 2 Porter Cable Router Motors a brand new one, $89 from Amazon about 3 months old very little use and only on my CNC nothing by hand model 690LR 1 3/4 Horsepower, and one I've had for 20 years original model was like 6919 or something like that, a 690 forerunner. Both Porter Cable Routers used 2 - 1/2" collets and 2 - 1/4" collets all brand new. One set came with the new router and the other set I bought before the new router to see if it was the collets which were causing the problem. Plus my bits always stuck in the router with the old collet which didn't have the bit removal feature. The Bosch I used is my brother's who doesn't take very good care of his tools at all so I figured this was a good test to see how the Bosch and it's bearings and run-out held up. It's model 1617EVS and is a few years old. All routers, collets and cup, where collets fit into on the router, were cleaned with air and a machine surface treatment. All debris was removed and inside of collet cup was checked with my finger for smoothness. All were smooth and clean.
I then used a Mill Monster 1/4" End Mill, a 1/2" Precision Drill Blank, and a Stewart MacDonald 1/4" to 1/8" brass bit adapter in conjunction with a Bits and Bits .025 bit. I made sure the bits had sufficient amount of shank in the router and used a test indicator as seen below to test the run-out on the round part of the bit shaft. I then setup the test indicator in my Bridgeport in the R8 chuck and using a bungee cord locked down the spindle so it couldn't spin. I then mounted the routers on their side in the Kurt Vice. I used enough pressure to hold the router so it didn't move but not enough to distort the frame of the router. I then setup the test indicator on the center of the various shafts rotating by hand and coming up with values listed below. After the indicator was on the shaft all gibs on the Bridgeport were locked down. Everything was solid.
First notes. I never cared for Porter Cable Collets. My first porter cable which I used for this test had bits slip out 20 years ago when I first got it. This means I'm paranoid and crank down on the collets to make sure they don't slip. I've had this problem with the new collets too, not bits coming out but a little slippage. When tightening down a porter cable collet it gets springy at the end when you're really cranking down on it. I make sure it's tight but I'm not using all my force. The Bosch collets look more like ER collets and have a very positive lock and you know it's tight enough.
So the Bosch results, first off this test indicator says .0005 on the front and I've never been super sure on how to read this, maybe someone here can help, so I'll give what I read so you can also make your own calculations. The way I look at it, it says .0005, this means every 1 on the dial equals .0005. So if the needle moves to the 5 printed on the face you take 5 and times it by .0005 equalling .0025. Right?
Bosch 1/2" Shaft 3 1/2" away from the collet: 3.65 x .0005 = .001825
Bosch 1/2" Shaft 1 1/2" away from the collet: 1.85 x .0005 = .000925
Bosch 1/4" End Mill 3/8" away from the collet: .6 x .0005 = .0003
Bosch 1/8" Adapter .025 Bit 3/8" away from the collet: 1.25 x .0005 = .000625
PC 1/2" Shaft 3 1/2" away from the collet: 9 x .0005 = .0045
PC 1/2" Shaft 1/2" away from the collet: 3 x .0005 = .0015
PC 1/4" End Mill 3/8" away from the collet: 7 x .0005 = .0035
I did the same 1/4" test again but not cranking down on the collet like I usually do.
PC 1/4" End Mill 3/8" away from the collet: 6.89 x .0005 = .003445
PC 1/8" Adapter .025 Bit 3/8" away from the collet: 6.15 x .0005 = .003075
So as you can see the results are dramatic. Bosch is head and shoulders above the rest. The best part is the body of the router is the exact same as the porter cable so you can use the existing mounts on your CNC if you use a Porter Cable now. Plus the Bosch doesn't have those annoying aluminum nubs on the body.
I will be buying the Bosch this week and checking its' run-out first, then putting it in the machine do some aggressive cutting take it out and check it again. I'll keep this post updated. Well I hope you get some use out of this post.