ISO30 Spindle > BT30 Tool Holder = Adapter Pullstud?

I’m looking to use BT30 tool holders with an ISO30 spindle, was told this could be accomplished by replacing the tool holder pullstud. Machining the part is not in the cards- anybody know of a vendor for the adapted pullstud?

Why? Some BT30 tool holders feature narrower profiles along a longer gauge length than I’ve been able to source in ISO30. Shrink-fit may ultimately be a better solution, with a DIY holder heater, as seen here:

Usual preface: I’m with PreciseBits, so while I try to only post general information take everything I say with the understanding that I have a bias.

Best bet would probably be Techniks. You can find the studs on page 234 here (Link). Don’t know if those will solve the issue for you between the other differences.

In general, while they are both 7/24 tapers be careful with this regardless of if those studs will work. Usually BT holders are not balanced for as high speed. I’d look for something that was 2.5G @ 20KRPM or better. The lower the G at the same RPM or the higher the RPM at the same G the better the balance. The worse the balance gets the more load and wear you are putting on the spindle bearings.

Might be able to help more if I knew what you were actually looking for. Have examples of the profile and gauges you want or the type of studs you are looking for?

1 Like

As to the type of studs, I’m ignorant- at this moment, just trying educate myself as to the specific stud that both the holder and spindle will be happy with together. I very much appreciate the reference- it may be I can use the included measurements and images to eventually determine potential candidates.

I take all the balance/RPM caution to heart. I will attempt some deep carves- ~7", if the vibration can be managed -into HDPE, and reckoned the least obstructive holder that could provide extended support would enable the use of non-custom tooling in most circumstances.

The stud depends on the spindle. Only thing I can really tell you otherwise is the ones we supply on ISO30 are the ones the Techniks catalog marks “for HSD spindles”. I know those work in HSD and Hiteco spindles.

If the goal is to reduce vibration and deflection from the tool holder you want the shortest gauge possible. The gauge is basically adding more stickout, admittedly with a much greater mass but it’s still better to have less.

Another thing you could try is to get a dual contact or dual “marketing name here” tool holder. You need a good manufacturer both on the spindle and tool holder side as the point is to get rid of the gap from the spindle face to the tool holder flange. Any real error and you can end up in a worse position where you don’t have good taper contact or aren’t closing the gap.

Let me know if there’s something I can help with.

“The stud depends on the spindle.”

The context is an adapter stud for joining an ISO30 spindle to a BT30 tool holder, right?

“The gauge is basically adding more stickout, admittedly with a much greater mass but it’s still better to have less.”

I appreciate that. (It may be that the expense of the tool holder and tool aren’t any more economic than having a custom carbide tool cut, anyway. Of course, that would be for just one tool- an array of tools might justify the expense… but again, only if wieldy.)

Not just for that. Even inside of ISO tool holders different spindles use different studs for their different drawbars. You can see in the Techniks catalog they have a few different versions listed. e.g. for ISO30 they have “RS”, “HSD”, and “Columbo” these have different end styles and lengths. RS, HSD, and Columbo are big spindle brands or models. Those studs don’t just work on them but the end style and lengths need to match the spindle they are used with. In switching from a ISO to BT there could be other things that need to be accounted for like overall length.

I guess I’m confused here. If you are wanting to cut 7" deep in a material than you need a bit that will cut that. You can’t use the tool holder’s gauge to reach that deep unless you are willing to offset cuts deeper than the bit’s cutting length. This is because you can never have a toolholder the same size or smaller than than the bit as it wouldn’t have anything to grip the bit. This is true even for shrink fit as you still need extra diameter for the bit to fit into.

So as an example, if I have a bit that will cut 3" and a 120mm gauge tool holder I could only cut 3" straight down. If I was making a pocket I could then step into that pocket by the extra width of the toolholder and cut another 3" deep. But I would crash the tool holder if I tried to cut deeper straight down. From the sounds of your previous thread this method wouldn’t work.

The only way you could get a tool holder to help here would be with a step shank tooling (cutting diameter bigger than shank). Those are pricey, fragile, and balance / force nightmares.

Thanks for the clarification of spindle-specific needs. As to gauge and reach, I appreciate tool holder interference would preclude many operations, such as perpendicular pockets, and does not represent a universal substitution for tooling of suitable length. The questions were mindful of diverse needs.