[H.O]

Hi Jerry,
There are a lot of different pull-studs available. Not only are they different according to the size of the holder 20,30,40 etc but the geometry is also different. Here's one page I found with dimensions and here's another, lot more types on the second one.

If you google pull stud dimensions I think you'll find more if you need.

Any chance of a picure, drawing or photo ? ;-)

[JerryFlyGuy]

Thanks sir..

No pictures or drawings yet.. maybe once it's pattented and up for sale on my website

J

[ger21]

The CNC Tooling catalog here might have some info. I've purchased studs from them in the past.

http://www.guhdo.com/catalogs.php

[JerryFlyGuy]

Ok couple more questions for you fellas... I'm starting fresh and trying a few new ideas.. I looked up spindle tapers in the Machinery Handbook [#26] a I can't find anything on Bt30 tapers. I find what they call "American National Standard" is that not ANSI, is this also known as ISO? I'm assuming it's not BT anyway..

[DareBee]

ISO, ISA, NMTB, ANSI - who knows

I am 99% sure (and swap tooling of the same taper myself, without issue) that the actual taper is the same (30=30, 40=40,etc). The differences come into play with where the tapers start/stop (dias), the flange configuration and the stud end configuration. Even more fun that some manufacturers make their own tools. For instance my Sodick EDM use something like SD30 tooling which is the same as other 30 taper only with a custom flange configuration.

I find that I am most confused with the holders listed through different manufacturers as ISA,NMTB & ISO because I can find ZERO difference in these holders.

I din't answer your question (just more confusion which you already knew anyway) but there HAS to be some info available on the WWW about BT config that doesn't return porn in your search.

[H.O]

Like DaraBee I'm 99.9% sure that the taper itself is the same. It's a 7:24 taper and all size 30 taper tools have the same size taper. The difference, again as DaraBee points out, is in the flange and in the internal thread for the retention knob or drawbar. BTxx have metric threads, I suspect NMTB and CAT (being Amercian) have imperial threads.

The difference in the flange is that on the BT the groove for the tool-changer fingers is centered axially on the flange where as on other types it may not be. On the BT there's two equally sized notches for the drivedogs 180° appart. On some other holders there's also a third smaller notch for locating in the tool-changer.

ISO-tools for ATC equipped machines (DIN69871 but also called SKxx) can be "converted" to a DIN2080 tool and fitted in a manual machine by replacing the retention knob with an adapter with the correct internal thread (M12, M16 etc). Obviously going the other way isn't that easy due to the extra notch in the flange mentioned earlier and also due to the fact the upper part, where the manual drawbar contacts the holder, usually isn't removable on DIN2080 holders.

But it doesn't stop there.....There's also quite a few different retention knobs that all fit the tool-holder but only one will work with the machine at hand. I believe this part has already been covered in the thread.

Let me finish by saying that I'm in no way an expert on these things. I write only from what I've read myslef as well as what I learned while designing my BT30 spindle and buying tooling for my mill which has a ISO40 spindle (DIN2080).

/Henrik.

[JerryFlyGuy]

Alrighty Guys.. thats a pretty big help. I've ended up drawing an ISO40 taper spindle [well the whole 5 axis head actually] and I've just got to put the ATC components into it.. I'll go look up some of the recommended sites for retention knobs and pick one I guess.. Machinery Handbook doesn't talk about these [as far as I can remember]..

Henrik, a question for you on your spindle. How did you plan for retaining oil at the bottom end? [also what was your Rpm range?]

So far I've been able to specify components and what not, to allow me to run up to 15k w/ this spindle[this may still get limited to some degee.. depending on some other components yet to be spec'd]. I'll end up putting a quick change Eagle PD drive belt on the motor to change ranges and then VFD the motor to control speed in that range.. [3 maybe 4 ranges at the most] This will allow me 10hp constant torque from 30rpm right to 15k.. Which is what I want.. [need??]

I passed up ~$8k worth of machining because I didn't have the spindle for it.. this last couple weeks..

Anyway, my problem?? I've yet to find a seal which will be liquid tight and stand up to 13K-fpm.. Labrinth seals would maybe help.. but they aren't liquid tight... Being as it's a vertical orientation and I need light oil for lube... I'm a bit outta my depth here, I don't know what the presedent's are... and all my bearing expert's I've contacted.. can't offer anything.. [You should see the eye widening that happens when I ask ]

Currently my only option is a slinger ring w/ a venturi oil return [air] and I'd just have to leave a timed solinoid on the valve to let it [venturi] run for an extra 10-15 minutes after shutting down the spindle.. so the extra oil can be removed from the bottom end and therefore won't drip out as it runs down..

Any idea what OEM machine tools do for this issue? I'm wondeing if I couldn't buy a seal from Mori Sekki [sp] or someone..

Thanks again guys..

[fpworks]

Hey Jerry,
On my air-oil spindle Mazaks, the oil drips out of the spindle and onto the parts. The face of the spindle is always wet. Not a big deal for us, but there are some options if you can't live with it.

First, you can specify a grease packed spindle, but the rpms are limited. (usually 10k on a 40 taper)

Alternately, they can provide a "catch can" that covers the face of the spindle to catch all the oil. It must be drained periodically, or it will slosh the captured oil when your spindle head repositions.

Take care,
Justin

[H.O]

Hi Jerry,
I'm glad I could help. I designed my spindle around a pair of SKF 7207BEGAP, these are rated at 12000rpm but that number should be derated by20%, I beleive it was, when mounting them in pair. So, 9500rpm or there about MAX. But then came the bottom seal, in the design I used a CR50X65X8 CRW 1R and I think the maximum surface speed allowed with that seal was around 17m/s which would limit the spindle to ~6500rpm.

I used a grease designed for high speed and not oil. Due to the problems I've had with the spindle I had to shorten the length of the front flange (where the seal mounts) so it no longer fits. Besides, like you, I've been told that it would never have hold up anyway.

I have a very tight gap between the spindle nose and the flange and I've added a fitting to allow the housing to be pressurized slightly to help keep debree out.

Apart from the fact the spindle doesn't work (yet) the fron seal is probably the weakst point on mine right now. If I where you I would really try to get that sorted. I was advised to use a slinger type arangement on mine but as I said earlier it's greas lubricated and not oil so....

Any chance we can have a peek at the design, please...?

/Henrik.

[JerryFlyGuy]

I'm looking at using a NSK 7016C [can't remember the rest of it..] w/ oil lube it's rated for 15k [max] It's a flush ground medium pre-load matched pair.. [nothing a $-grand-$ can't fix ]

I think at this point a slinger ring is my only option.. [not something I'm too excited about as it means more oil lines etc and on a 5 axis head, not a plus for sure..] The fit's on the spindle to housing [at the nose] will be a few thou clearance.. just enough to make sure it doesn't rub..

Here's a pic of the unit thus far.. still needs the covers for the pivot axis.. and the ATC stuff put in.. Also I realized that I'm going to have to go back and re-design my miter drive joint.. nothing that time can't fix..

I plan to build the spindle first [yellow cylinder below the blue yoke].. and mnt it as a fixed 3 axis unit and then use it to build the comp's for the 5 axis [I'll rough cast the spindle lower mnt [bright blue] and the top pivot/rotation hub[purple].. then machine them]

Lot's of work yet to do.. and I've got to be 150% convinced it can be built prior to buying any of the comp's.. so.. who know's how soon it will happen, but for now I've got time to work on the design so.. here I am

[Geof]

Anyway, my problem?? I've yet to find a seal which will be liquid tight and stand up to 13K-fpm.. Labrinth seals would maybe help.. but they aren't liquid tight... Being as it's a vertical orientation and I need light oil for lube... I'm a bit outta my depth here, I don't know what the presedent's are... and all my bearing expert's I've contacted.. can't offer anything.. [You should see the eye widening that happens when I ask ]

Currently my only option is a slinger ring w/ a venturi oil return [air] and I'd just have to leave a timed solinoid on the valve to let it [venturi] run for an extra 10-15 minutes after shutting down the spindle.. so the extra oil can be removed from the bottom end and therefore won't drip out as it runs down..

Any idea what OEM machine tools do for this issue? I'm wondeing if I couldn't buy a seal from Mori Sekki [sp] or someone..

Thanks again guys..

That is what Haas machines have; air purge that continues for a few minutes after the spindle stops, but some dripping still occurs, very little and not a problem on metalworking machines. They do mention it in the literature for their gantry machines because it can cause staining problems when doing wood.

[JerryFlyGuy]

it can cause staining problems when doing wood.

And this is my issue.. I don't plan on doing wood all the time but it would be a concern..

[H.O]

Jerry,
Very cool design, way out of my league! Please keep us updated will you....

/Henrik.

[JerryFlyGuy]

Na it's not.. I've not even built it yet.. your alot farther down the line than I am when it comes to spindles..

[JerryFlyGuy]

ok so I'm getting back into the swing of things and getting my spindle design finished. I pretty much just need to get the pull rod thing done.. and the design is done.

I was on Technik's site and they have a few different pull stud types for CAT 40. Does anyone know what the differences between these types is? They list DIN, ANSI and MAS [I, II, III]. Some of the MAS stuff has different knob 'angles' than others [45/60/75 &90]. Is it possible the MAS stuff is for those 'finger gripper' type pull rods vs the standard 'ball' type?

[dpuch]

Just one place to get commercial retention knobs http://www.commandtool.com/
Direct link to pdf http://www.commandtool.com/pdf_catal...ntionKnobs.pdf

On our commercial Cat-40 taper machines the drawbar force is 1800 lbs or more.

[jmkasunich]

Not pull-studs, but related to Jerry's 5-axis spindle design...

Forget the bearings, I want to know what you are gonna use for gears!

Do you have a source for gears that are precise enough to run at 15K RPM without sounding like a howling banshee and wearing out in minutes? Inquiring minds want to know. (I have a tilting spindle design in the back of my mind, but the gear$ have always been the main stumbling block.)

[JerryFlyGuy]

Nope, no gears as of yet.. but I'm working on it ..slowly.. I've got a few idea's but need to work through the spindle design before I can get to the gears part I suspect that if one was thinking the bearings and machining for a spindle were expensive.. then they will drop dead when they hear how much those gears are going to cost to build...

[Big_d]

Hello JerryFlyGuy
I built a spindle a few months ago that was oil filled and did 1.5~10K RPM. The only way around the spec was to use a mechanical seal. It was a simple carbon on steel arrangement that used magnets on the rotating seal component that held the carbon down on the stationary part. 80mm id 90mm od. The only drive we used for this was the inner O ring that sealed the seal against the spindle shaft. I probably should have used a titanium holder for the carbon but the steel one is still going. It took a bit of fine tuning with the internal oil pressure and O rings but it worked quite well. It does loose oil 100 ml every 1500 hours now but I believe this was due to the operator using hydraulic oil in it.
We used a hydraulic motor and a step up gearbox to run this. Nice and compact but not cheap to do. Lots of torque with the hydraulic motor, the weak link is the planetary gearbox. It only travels in one direction though, I would have no idea if the seal could handle a direction change.
Cheers
Daza

[JerryFlyGuy]

Daza, do you have any pictures? How much oil are you running them in? I'm going w/ a oil mist as at 15k the bearings just need to have oil on them.. not running in oil. The spindle design has changed radically from those pictures [yet it's still visually similar]. I'm still using a air evac to pull the oil out of the bottom of the system once it's passed through the bearings. I've changed up to a larger bearing at the top as well, this allows more room for the[larger] bellville washers I need for the ATC bits..Anyway, it's coming along very well.. now I just need to get the rest of it [above the spindle] figured out.. [a-la the gears etc]

I'm curious about your design. I would have thought that if they are 'in oil' to the point that the top bearing is also 'in oil' [I'm assuming a vertical installation here] that you'd have one heck of a heating problem at 10k?

I'd sure like to see some pic's if you've got them! Any other spec's you can share [tool holder size, bearings used etc]

Thanks