Taig Headstock Improvements??

[scubasteve_911]

Hello everyone,

First of all, I must admit my admiration for this site and everyone in it, I love browsing around and checking out everyone's ingenious ideas!

I'm on a quest to improve the taig cnc mill. There has been a lot wrong with the design and now that I have a means to improve it, I am trying my best to fix it up. My first modification that I am currently doing is replacing the huge induction motor with a 400W servo I scored off of ebay. I am using an ION drive to control it with great precision. I'm driving it through a timing belt for a full speed range of 0-10000RPM. I will be sure to post pictures when I am finished..

I'm planning on stiffening the vertical column up, since it has a way of moving under load and leveraging vibrations down to the workpiece. I'm still thinking of an easy way to do this. I actually found some concrete slabs at Home Depot and bolted the machine down, hoping to damping vibrations. Then, I lined carpet damping material underneath the block. Then, I added another layer of concrete and carpet foam. The result is the machine is very secure and it doesnt vibrate the floor anymore.

My question is, can I replace the Taig bearings for better performance? I was thinking of using some Abec5-Abec7 ceramic bearings to do the job. I know that the bearings are 17mm ID and 40mm OD, but how deep are they? Furthermore, are these angular contacts? I am assuming they are preloaded because the shaft has zero play that I can feel. Hopefully they didn't preload regular deep-groove bearings for this. If they are angular contact, I am guessing the dimensions are 17X40X17.5mm. Can anyone verify this?

I would really like to run the taig at 10000RPM without the headstock getting too hot, which I think the ceramic bearings would handle a bit better. Does anyone have experience with this???

Thanks a lot!,

Steve

[askman]

ceramics are really bad for any place where it can chatter. they are very brittle and can't recommend it for spindle.

I am doing a similiar thing. instead of servo, I scored some brushless bicycle motor (400watt) that has built in controller and was affordable. weighs 5lb and runs 2800rpm at 24v. I am planning on keeping the belt drive (and by adding a 4" pulley, I want to hit 13000rpm) with my broken in spindle (which has been running 10k for over 6month and runs just slightly warm at 10k), I think I can get it up to 13000 without it heating up too bad. generally, by replacing the grease with oil, you can usually gain 2-3k rpm anyway, but require regular oiling)

if you want to make your own higher speed spindle, you can get just the er16 spindle with 1/2" diameter, which would allow you to run 17k bearings(abec5) you will need different spindle body though. I think I can be happy with 12-3k with variable speed and keeping the 6 speed belt drive.

[scubasteve_911]

Yes, I agree with the chatter and catastrophic failure mode of ceramic bearings. It would be a bit risky to attempt that one..

Brushless is really the way to go with these things, much more power density due to permanent magnets and control of speed are the two desirable attributes that I wanted. We have the ability to specify an exact velocity to the headstock, which is excellent for getting the right finish on the part. Mastercam calculates the spindle speed and feedrate, which I am going to stick to since they probably have a lot better idea than I when it comes to machining.

I'm purchasing the 9"X19" Grizzly lathe in a few weeks, so I might consider making a new spindle. I'm trying to find an outside stator brushless motor kit that I can use, but they all seem ridiculously expensive. Danaher Motion makes these kit motors, but they cost around 600-700$US for even a modest one. I have some silicon steel lying around, so I technically could machine one given I have the design. I really wanted to stay away from cartridge-type spindles and come up with my own direct drive.

I have the Taig ER16 spindle already, do you know what type of bearings they take? I know that they are 17mm ID and 40mm OD, but I don't know what type.. Dual-row angular contacts? Single row deep groove? If nobody knows on here, I might have to give them a call on Monday to see. I would like to search for some upgraded bearings, maybe preload a bit more to get less runout. If I can get the bearings cheap enough, I don't care if I have to go through a set every 2 months, as long as they're accurate.

Thanks for your input and I am welcoming anyone else's suggestions.

Steve

[askman]

kelinginc.net has a nema 34 brushless servo motor for decent price. (I believe they are 48v, 3000rpm , 800watt for 150 bucks or so) I do have some nema 23, 200watt ones (36v,4000rpm) which I was thinking of using on my taig, untill I found these bicycle motors. (save me the cost of controllers)

I believe it is just standard cartridge bearing on the taig. you can get it off by heating the body, as it is press fit. or contact cartertools, and he will let you know. for precision spindles, they are available from MSC or others if you look. only thing you would need to make is a body.

[scubasteve_911]

Wow, not bad for an 800W motor... We're very happy with our 400W, since it seems to be powerful enough for the job. I hope to have it all mounted and ready by tomorrow night, so I will post pictures ASAP.

I'm just going to have to give them a call, I wonder why they don't post solid specifications on the bearing in the parts list.

On another note, I measured the headstock squareness and was thrown by how much it has moved. We had it aligned within 0.001" across the table after about 30mins with a dial indicator. A week later, it's out visibly by what it looks to be around 0.01".. I gotta get on stiffening that headstock, it's quite a silly design when you don't need to tilt the head.

Steve

[askman]

I got the nema 23 200watt brushless for under 50 bucks. so it is great price.

anyway, looking forward to your work. since I run my spindle in router, they are fixed. don't have to worry about tilting. great spindle for the money.

[scubasteve_911]

Well, I completely messed up my spindle conversion.. Something went wrong when I went to bore out my timing pulley and it was a bit off of center. This gave a bit of vibration that I am not happy with.

I really need that lathe Getting one in a month!

I am thinking of making an integrated motor spindle for all the trouble this is giving me. I have a new stator from a 400W motor that has nine slots. It originally is supposed to use 4 pole pairs on the rotor, but I want to change these 8 magnets to a single neodymium ring magnet. I found some magnets that will work perfectly.

I guess I will wait and see how good I am with a lathe. I have always wanted to snag a pair of off diameter super precision angular contacts off of ebay for a good price and make them work in a one-off solution. Eventhough, I will be kicking myself down the road if I crash the spindle or wear it out over time.

Steve