Can I Drill a Hole in a Pull Stud to Make it a CTS Pull Stud?

Nerdlinger · Apr 10, 2020

Hi Everyone!

I have like 10,000 new (non-CTS) pull studs but all I need is a CTS one. Ironic, don't cha think? Can I just drill a hole in one and be done with it or are there differences in the CTS ones (like hardness?) that allow them to hold up even with a hole going through the center? I don't even know how hard they are...CAN they be drilled with a carbide drill or are they too hard?

I have the following non-CTS studs from Mari:

PS-25084A-HTHS (BT30 high-strength)
PS-31109A (BT30 regular-strength)

Thank you!

Milland · Apr 10, 2020

Get an opinion from Frank, it's in his interest to make sure you're on the best footing.

boosted · Apr 10, 2020

Nobody is going to tell you that it is okay to do this. 30 taper pull studs are already a weak link.

How desperate are you? I'd be tempted to get the job done, and then throw it away.

DavidScott · Apr 10, 2020

Drawbar retention is the weak link, the pull studs break when the tool holder is pulled out of the taper a little. Not sure but I think pull studs are case hardened so you should be able to drill one out. IMO the strength is there but I would only do it in an emergency and remove the pull stud from use as soon as possible. Is the machine it will be used on dual contact? Dual contact spindles have significantly more drawbar force.

thermite · Apr 10, 2020

boosted said:
Nobody is going to tell you that it is okay to do this. 30 taper pull studs are already a weak link.

How desperate are you? I'd be tempted to get the job done, and then throw it away.

Seems so.

There would still be 9,999 left to mess with.

Or exaggerate less about?

Go for it!

Nerdlinger · Apr 10, 2020

I figured this Q would end up going to Frank eventually but I wanted to make my question public in case someone asked the same question on this forum in the future. He said don't do it. I know he's working hard so I won't bug him with my compulsory, "Why not?" I suppose the hole is not the only difference, otherwise I think it would be fine. I certainly won't want to trash my spindle to try to save $40 or whatever on a new pull stud, so I'll get a new one. I just didn't know if it was common practice to do it if you wanted to. Oh, it is a dual contact spindle, by the way. Thanks!

thermite · Apr 10, 2020

Nerdlinger said:
I figured this Q would end up going to Frank eventually but I wanted to make my question public in case someone asked the same question on this forum in the future. He said don't do it. I know he's working hard so I won't bug him with my compulsory, "Why not?" I suppose the hole is not the only difference, otherwise I think it would be fine. I certainly won't want to trash my spindle to try to save $40 or whatever on a new pull stud, so I'll get a new one. I just didn't know if it was common practice to do it if you wanted to. Oh, it is a dual contact spindle, by the way. Thanks!

Frank sez don't? His rice-bowl, and he's GOOD at it.

Waste of time to try to learn 1 percent of what he already knowed before ever you asked, then, ain't it? He's had a "head start". Bigtime.

It'd be about as dumb a risk to save small money, then, as a blowout patch on $250 200 MPH rated tire already under serious stress, yah? Save $190, trash the motorcar, damage yer health? Why wudja?

theperfessor · Apr 10, 2020

Don't have a CTS system but it was my impression that the top of the pull stud made a rotating seal. I could be wrong, like I said I don't have that system on my mill.

trochoidalpath · Apr 10, 2020

Nerdlinger said:
Can I just drill a hole in one and be done with it or are there differences in the CTS ones (like hardness?) that allow them to hold up even with a hole going through the center?

The exterior dimensions are the same, so you are talking about drilling a 0.098" 18.6xD through. Ouch. Also CTS studs are slightly softer — non-CTS are 52-56rc, CTS are 48-52rc.

It sure seems like with BT30, the pull stud is the weakest link in the chain... and spindles are much more expensive than an overnighted 25084AC pull stud.

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Can I Drill a Hole in a Pull Stud to Make it a CTS Pull Stud?

Nerdlinger

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Milland

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boosted

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DavidScott

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thermite

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Nerdlinger

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thermite

Diamond

theperfessor

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trochoidalpath

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