adaptling ISO30 pull studs to BT30?

[Andrew HutchinsonParticipant @andrewhutchinson12802]

Hi folks,

 

I errantly purchased a ten pack of Emco compatible ISO30 pullstuds off ebay for an F1 I'm trying to stick together thinking they were BT30. Of course when I got around to sticking them in my collet chucks I saw the mistake. They don't fit my National, Briney, BP, off-brand, etc – the cylindrical portion above the thread being .010 or so thou too large for the BT "hole". They thread very nicely but as soon as the locating features touch it's game over.

Being very new to the BT spindle set-up I'm not sure what is what. In practice how critical is the locating diameter (the part that disappears into the collet chuck) on the pull stud? If I try hardturning it and get a little deep or screw up the finish by accident will there be an issue? And second, if hardturning doesn't work and I end up making my own, what (tool) steel is best to use for a stud? I don't have a surface grinder to rig something up on and definitely not a cylindrical grinder so I'm kind of left leaving them in a soft state or praying they don't warp badly.

Now that I've written the above I'm curious if the ISO stud head is even in the right place height wise for a BT. I'll have to go check that off line but I guess my question regarding what steel to use for the studs is still applicable.

 

Thanks for your time

Andrew Hutchinson

 

 

Edited By Andrew Hutchinson on 22/02/2017 01:24:46

Edited By Andrew Hutchinson on 22/02/2017 01:36:38

[Andrew HutchinsonParticipant @andrewhutchinson12802]

[MuzzerParticipant @muzzer]

There's an enormous amount of confusion and mislabelling of taper tooling. I can only go by the published DIN etc stds but of course, the suppliers may have different ideas.

As far as I can tell, ISO30 (DIN2080) has a parallel shank at the end of the taper, BT30 (JIS B 6339) is just a tapered body, as is SK30 (DIN69871). So apart from the pullstud not fitting the hole, it could well be in the wrong place by 15-20mm or so.

Did you notice that APT-tools in Glasgow sell taper tooling in 30 size? That may be where you went…

Murray

[EmgeeParticipant @emgee]

Hi Andrew

Chart below gives details of the BT range of pull studs, note the spigot diameter is 12,50mm diameter for the BT30. The pull contact angle on these is 45 deg whereas the Emco studs have a 3.50mm radius at the pull contact point. I have several with the 45 deg angle and have no problem in use on an F1.

Emgee

[Clive FosterParticipant @clivefoster55965]

On a small machine like that Emco you should be safe if the stud flange has decent metal to metal contact with the end of the taper. Bigger question then is whether the overall length is such that the stud is gripped properly and pulls up hard when inserted. There is some tolerance for variations but probably not much. Cutwell tools do a pull stud identifier matrix which might help sort what differences you are left with once you have modified them to screw in.

If the ball is a bit low when screwed in one wonders if a spacer washer would be acceptable given that its a small machine.

Spigot is a nominal size so a touch under or over won't hurt. Just needs to be close enough for the gripping parts to work Obviously if its too small bits will try to drop out and if too large the innards won't close up enough to work but within a thou or three should be fine.

Not really DIY material proposition if you want them to last Needs to have the right combination of hardness and toughness. Even professional grade ones get seriously marked up in time. In pro shops considered a consumable item.

Clive

[EmgeeParticipant @emgee]

Hi Andrew

The point of correct length mentioned by Clive is important and can be checked by feel on the toolchange lever, if the stud provides the correct gripping length the opening force feel on the change handle will be at the same degree of downward travel as with an Emco original toolholder. There may in any case be a small difference because of the std tool contact point being a radius. Small differences will make little or no difference to the retention force on the tool.

Emgee

[MuzzerParticipant @muzzer]

This is how I got around the problem. My machine is NMTB30 (imperial version of ISO30) yet BT30 is more readily available. So I got 2 sets of pullstuds made. The longer one is for BT30. The parallel shank on the top tool is not consistently defined in length from tool to tool but is easy enough to turn back. This style of holder was probably designed for drawbar so the length was less critical, whereas the BT etc style was designed for pullstuds.

If the pull stud head is not in the right place, it won't do a lot of pulling…

Dunno if this clarifies matters!

[Andrew HutchinsonParticipant @andrewhutchinson12802]

AHHH!

My post didn't go through… I was logged in and then it told me to log in again. Serves me right for not typing it out on wp first.

Anyways I've got a bunch of work to do so I'll keep it short second time around but thanks to all three of you who responded. You've given me some informed opinions to work off of. I noticed the same thing that Emgee did about 45 degree pull studs pulling up Ok but I wasn't sure what OK was at the time. I'll make an Emco one to test with since I don't have any of there chucks. There's a drawing or file on the yahoo F1 users group back on my box at home.

For the record they were IFT ISO30 pull studs I got out of Michigan. My own stupidity plain and simple.

Thanks!

Andrew Hutchinson

Surrey BC Canada

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