ISO 30 Spindle

[IndHobby]

Take the R8 pin out, it makes tool changes a lot faster.

[BobWarfield]

Originally Posted by IndHobby Take the R8 pin out, it makes tool changes a lot faster.

I was hoping someone would say that!

FWIW, on another site, a fellow seems to have figured out how to do this without even removing the spindle:

http://finance.groups.yahoo.com/grou...r/message/2777

I'm sure Aaron can do this blindfolded with one hand tied behind his back, but the rest can look to the link for details, or, here is the salient paragraph:

I had recalled from earlier inspections a slot in the quill that was exposed when I lowered the spindle. I wondered if it was placed such that I could gain access to the spindle pin from the outside. Sure enough, it was. I had to rotate the spindle to expose the pin but the slot was perfectly positioned axially so that I could effect my repair.

Best,

BW

[krymis]

so we can take the r8 pin out and it will still tighten properly on the drawbar? I just added the same power drawbar that bob did. I gotta say I will be doing another with a better base plate for the ih mill and I will be doing a couple for the minimills that are going on ebay. If i could get rid of this then my toolchanger will work out perfectly. That along with two other issues were holding me back.

[Loadedagain]

does anyone have the bearing part numbers for this spindle? looks like aaron took them off his web site when he shut down the shop.

[Loadedagain]

never mind... found the link is still active on the ih site. here it is copied (so i don't lose it again).

Originally Posted by ind hobbies web site http://www.industrialhobbies.com/Products/spindle.htm A 30 taper spindle goes by a few names: * ISO 30 * National 30 * NMTB 30 * Erickson Quickchange 30 * Some catalogs will just say 30 taper A CAT 30 taper is the same taper angle, but a slightly different design but I hear it too will work properly. It is NOT BT 30. The top bearing is must have an ID of 30mm, for angular bearings this would be a 7206 (McMaster PN 6680K17) The lower bearing is must have an ID of 35mm, for angular bearings this would be a 7207 (McMaster PN 6680K18) Although the McMaster catalog states they are ABEC 1 we have found them to be ABEC 3.

[kimoyo]

Does anyone know if there would be enough room to mount a duplex pair of angular bearings in the sleeve and on the new spindle? I've looked at the diagram but haven't taken it apart yet.

These would be for the lower bearings, http://bearingsdirect.com/products/i...=4&prevstart=0

and these for the top, http://bearingsdirect.com/products/i...=4&prevstart=0

But since there are two I guess they would be twice the width.

[Loadedagain]

not sure about adding bearings, but isn't abec7 a little excessive? what do you feel the benefits are as opposed to the abec1/3 is? they're $20... and the 7's are almost $600 for a pair.

[BobWarfield]

ABEC7 probably is excessive, but it depends on what other bearing sources you have available. This is a duplex pair, so you don't need 2 of these, just 1 at least.

Kimoyo, it does look to me like there is room for a duplex pair. The next question will be, "Where is a cheaper 7207 duplex pair?"

Failing a duplex pair, you'll have to create the preload with a spacer, which is a pretty finicky operation. A pair has a much higher likelihood for success.

Best,

BW

[kimoyo]

Originally Posted by Loadedagain not sure about adding bearings, but isn't abec7 a little excessive? what do you feel the benefits are as opposed to the abec1/3 is? they're $20... and the 7's are almost $600 for a pair.

A pair is $300 which is still alot. But after reading this thread, http://www.cnczone.com/forums/showth...=abec7+nc+cams, I realized that it would probably be money well spent. I would only get the pair for the lower bearings but I'm am concerned if the spindle housing is toleranced well enough for the bearings.

Bob -

Where are you getting your pulley to fit the spindle shape? Any ideas how your going to tension the belts yet?

[BobWarfield]

RE pulleys, many different suppliers have them. I've just looked at McMaster Carr for design purposes to see their dimensions. Before beginning the project I would need to find who has the best deal. As I've mentioned, for me this project is behind a few other things in the queue, so I won't expect to get started on it for quite a few months.

RE tensioning, I intend to build a new housing for this spindle, rather than trying to reuse the old one. I'll be milling some slots for the motor so it can slide to provide that tension. I could also mount the motor on a plate in a slideway with a threaded bolt to provide the tension. We will see.

One design issue I'm still pondering is speed ranges. I would like to get 6K to 8K rpm for aluminum, but steel wants to run a lot slower. If I cover that whole range with just the VFD, there is not going to be much torque available for steel. It seems inevitable that the system wants a Hi/Lo range for best performance over a broad range of spindle speeds. Still contemplating the best way to go about providing that.

I may investigate a tumbler back gear arrangement at the motor end that can halve the motor speed for cutting tougher materials. I hate the thought of changing pulleys, but that is another simpler possibility.

If any of us actually get the silly thing to work well for $300 in bearings and a $65 spindle, it will be a lifetime achievement award and very cheap for a decent spindle. Try not to think too hard about what it'll be like if you get the preload wrong and burnup a few sets of those bearing--Doh!

Spindles have to be one of the more finicky and difficult projects one could tackle.

Best,

BW

[philbur]

NC Cams last words in the last post of the thread you identify were:

..................................quote....................................
Sherline example is this: the abec 1's worked fine in a commercially built/tolearnced item. Do NOTHING more than replace 1/s with 7's and abject misery sets in. Yet, in an ABEC 7 toleranced housing (worked on some of them too) the thing "fell" together.

Morale: you can't take a sow's ear housing, install rocket ship quality bearings and expect it to work. The converse should also be true although I haven't wasted the time trying to prove it...
...................................end quote...................................................

Kinda sums it all up. If the bearing tolerances are specified in microns then so are the tolerances for the housing and the spindle. So when you upgrade to ABEC 7's what to do about upgrading the housing. Also what about the tolerance on concentricity of the spindle taper to the spindle bearing seats and the seat diameteres themselves, microns as well I guess.

Regards
Phil

Originally Posted by kimoyo A pair is $300 which is still alot. But after reading this thread, http://www.cnczone.com/forums/showth...=abec7+nc+cams, I realized that it would probably be money well spent. I would only get the pair for the lower bearings but I'm am concerned if the spindle housing is toleranced well enough for the bearings. Bob - Where are you getting your pulley to fit the spindle shape? Any ideas how your going to tension the belts yet?

[BobWarfield]

Originally Posted by philbur Kinda sums it all up. If the bearing tolerances are specified in microns then so are the tolerances for the housing and the spindle. So when you upgrade to ABEC 7's what to do about upgrading the housing. Also what about the tolerance on concentricity of the spindle taper to the spindle bearing seats and the seat diameteres themselves, microns as well I guess. Regards Phil

First, recall I intend to make a cartridge spindle and not reuse the original housing. I'll also eliminate the quill function altogether, as this will be a CNC only spindle. That means I have to build it all anyway, and can do the housing as a piece of DOM tubing, which simplifies the task of fitting bearings.

Per Fafnir (Timken if you prefer), we need an OD fit within 2.5 tenths, and the same ID fit on their ABEC7 AC bearings for machine tool spindles. These are doable numbers in a home shop, but the easy answer is you take it to a grinding shop and let them worry about it. This would include regrinding the taper with the bearings installed to ensure concentricity, OD grinding the spindle/bearing mating surface, and ID grinding the DOM spindle cartridge. The bearing catalogs, as NC Cams is wont to point out many times, have all the info you need. p202 of the Fafnir Super Precision Bearings catalog walks through these considerations, for example.

For the more ambitious, you can have a go at tolerances yourself. Again, 2.5 tenths ought to be very feasible. A toolpost grinder is the likely approach, though one could also investigate the techniques of the turbine building crowd or the build your own tool grinder crowd. 5Bears, for example, has a nice treatise on accurately fitting shafts and bearings to precise tolerances. There are a lot of techniques available to help sneak up on the accuracy successfully, but it still won't be an easy job. As I mention above, getting it all done without blowing up at least one set of bearings on the learning curve will be a major achievement.

I have collected quite a list of resources on this in my research. Even came across a guy who rebuild a Haas spindle, which was pretty interesting. That was definitely an ABEC-7 situation and he managed to get it done in home shop level environment and never having done it before. Those bearings were a lot more than $300 a pair too! He checked his taper to see if it would need to be reground, but ultimately decided not to.

I would check the taper last, after the spindle has been run on the bench for a bit to ensure all else is well, and in particular, that the bearings aren't running too hot, and that your lubrication system is working for your application. The latter cannot be underestimated!

Best,

BW