scmi T-110 Nova spindle nut

[David Scheckman]

Does anyone know the threading for the 1 1/4" spindle nut for an scmi T-110 shaper? My spindle has an inside and outside thread. It came with a Bolt/Washer arrangement and I'd like to be able to use a simpler nut or double nut . Checking PartsPronto, SCMI charges $91 for the nut. I'm hoping for a cheaper scheme.
Thanks,
David

[Ken Fitzgerald]

Daniel,

Is it a left-handed or right-handed thread? Do you know what the thread count is?

[David Scheckman]

I'll have to check. The bolt that goes into the spindle is a right hand thread. I would assume the nut would be too, so that it would tighten itself with conventional spindle rotation. I'll have to measure tpi. I suppose that could define the nut, 1 1/4" by tpi, right hand thread, but I was thinking it would be something metric although its an fractional spindle size.

[David Kumm]

My T130 looks to be a 1.25 but I can't tell if it is a UNC 12 or a hybrid metric 2.0 pitch. It wouldn't surprise me if SCMI adjusted the diameter but stayed with metric pitch. I'd take the spindle to a machinist and have him check it and make something to exactly match the threads. Even if you get the 1.25x12 to work, the threads might not match up exactly compromising the hold. In that application i would not take the chance. Both my 2.0 and 12 thread gauges seemed to fit but it is also about the depth and angle and with my vertigo going on I can't see well enough to say for sure. Dave

[David Scheckman]

At that point, considering my time and a machinist's time, I'd be just as well ordering the scmi nut @$90. Oh well, maybe someone will chime in who knows for sure.
Thanks,
David

[David Kumm]

At that point, considering my time and a machinist's time, I'd be just as well ordering the scmi nut @$90. Oh well, maybe someone will chime in who knows for sure.
Thanks,
David

I hear you. I have so many old machines that I need access to a machinist regularly so I get better deals but would expect to pay at least 50 for a special nut. They also need to be machined flat on the bottom or they will provide uneven pressure which may cause some runout on the cutter. More to it than just threads. Dave

[Peter Kelly]

That CEO's yacht ain't going to pay for itself..

[David Kumm]

Woodworking machinery is pretty competitive so everyone tries to make extra on parts. Good news is at least that Pete and Carissa over at parts pronto are very knowledgeable and extremely helpful. At least the overpriced stuff comes with some good people. Dave

[Rick Fisher]

$91.00

Is it shiny ?

[Casey Carr]

If it's truly 1.250" and close to 12 tpi, that's a fine thread. With a set of calipers, the thread should measure just a few thousandths smaller than 1.250, never even a thousandth over. Nominal dimensions of screws are always max dimensions also, so a .250" bolt will typically measure around .244-.246. You need to get an accurate measurement to be sure, and a tape measure isn't close enough. The metric equivalent would be 31.75, the closest thing I can find in my machinist's handbook with a pitch of 2.0 is an M33, that's just too far off to be correct unless you've estimated on the diameter. There's always the chance they did something custom, but I'd bet it's a 1.250-12UNF. Run to the hardware store and see if you can find something that size and do a fit check. If it works, you can always have the face machined off flat if necessary. There is more to consider than just whether it fits or not though, thread class being one, typically it would be 2B, but they may have a 3B on it, which is just a tighter tolerance than 2B. Doubtful, but always a possibility, we are dealing with high RPM's.

[David Kumm]

Casey, the size is definitely 1.25. My thread gauge just didn't quite seem right with the UNC fine 12 which caused me to wonder if SCMI who makes the spindle, might have used a metric pitch. Just couldn't tell enough to be sure and a nut that threads but doesn't match would scare me in that application. If SCMI would tell David the thread, life would be easier. A good machinist would too but probably not for free. Dave

[Bill Orbine]

I was trying to snoop around Parts Pronto for SCM, and my internet security software says there's a problem with the site's security certificate. Be careful!

[Jeff Duncan]

SCM is pretty expensive when it comes to replacement parts, and I'm always a fan of finding lesser costly routes. However, when talking about that one small piece of metal that's going to keep a 4"+ chunk of steel securely in place when spinning at 8k+/- rpm's….I'd pay the $91 and have peace of mind;)

good luck,
JeffD

[David Scheckman]

I think I've decided that's the route I will go, spend the bucks. I'm not one to compromise safety at this stage (latter) of my career. There's no rush, I already have the bolt and specialized washer, just wanting something more convenient to setup. After thinking it through and considering the thoughtful responses to the thread, the $90 bucks doesn't seem as bad, considering its not just a nut but a specialized, machined piece. I had been thinking perhaps a simple nut (or two) would do but now would not be comfortable with that. I have a metal lathe but don't feel confident in my machining skills for this application and per comments would not know the correct fit to machine to.
Thanks for all the comments,
David