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Shopsmith Saw Arbor Set Screw (222458)

dusty

The Shopsmith Saw Arbor should be out fitted with a 1/4" flat point set screw (222458).

If a longer set screw is used, does this increase the propensity for the set screw to work loose?

I so wish that questions like this could be directed to the engineering staff at Shopsmith.

polycarp

I can't answer that question with any certainty but i wonder how safe it would be using a longer set screw there?

JPG

One thing I am certain of is that the excess length outside the arbor threads do nothing to help.;)

However you would be assured of having as much as possible in thar.

As mentioned it would be prudent to have as little as possible protruding.

As a 'suggestion', grind one too long so it sits flush to minimally proud. The miter gauge with the SS tool kit in the stop gauge holes makes a good jig for grinding a square end against a sanding disk.

No I do not want to get into a discussion re the shaft taper here!:D But if that is bothersome(love that 'medical' term[them folks are the only ones I have heard use it]), grind with the miter gauge set to that angle and rotate the tool kit.:rolleyes:

dusty

Let me repeat the question.

If a longer set screw is used (as an arbor set screw), does this increase the propensity for the set screw to work loose?

charlese

I thought your question was answered! Do you have the answer? Was this a trick question?

JPG

dusty wroteLet me repeat the question.

If a longer set screw is used (as an arbor set screw), does this increase the propensity for the set screw to work loose?

OK! Guilty! Missed 'increase'! Since your previous concerns re set screw involved retention, I totally missed that subtle directional alteration!

Only thing I can come up with is, it depends upon what it snags on. I do not think flying in the breeze will cause it to work loose. I do not think increased centrifugal force due to increased mass will either. Increased mass may alter any sympathetic vibration, but that is pretty far fetched.

Nor do I think it will help other than that already stated above.;)

Gene Howe

OK, I'll answer.

No.

polycarp

Is this just a matter of curiosity or is there a problem needing to be solved with the arbor?

JPG

polycarp wroteIs this just a matter of curiosity or is there a problem needing to be solved with the arbor?

Only the sha . . er . . ah . . Dusty knows!

Dusty has gone broke replacing saw arbor screws.

No that is not snarky, just bending the truth slightly!;)

He and I differ greatly as to the significance of this. I have yet to replace a set screw because it worked loose.:)

dusty

charlese wroteI thought your question was answered! Do you have the answer? Was this a trick question?

If my question was answered, I missed it. What is the answer?

No, this is not a trick question. It is a real honest to goodness question.

If a longer set screw is used, does this increase the propensity for the set screw to work loose?

JPG

See post # 7.;)

dusty

Gene Howe wroteOK, I'll answer.

No.

OKAY. What then is the most likely cause of a properly selected and properly secured set screw coming loose?

JPG

dusty wroteOKAY. What then is the most likely cause of a properly selected and properly secured set screw coming loose?

Loose(sloppy) threads. Insufficient torque when tightening. Improper alignment of the arbor to the shaft.

But then you properly excluded two of those causes.

Sure that was a good idea?;)

I just have not experienced this problem. Yes at times the arbors come loose, but, I attribute that to improper alignment and tightening when it occurs. More careful exercise of same prevents recurrence.

benush26

Dusty,

Regarding set screws coming loose.....

Is it one specific arbor? Or possibly arbors for 1 1/4 rather than 5/8 ?

Why? Because one time I thought I remembered seeing a picture of a blade holder in your shop and each blade had a separate arbor. Just trying to narrow down the selection if possible. If it is one specific arbor then maybe it's tapped hole is worn out and time for SS to give you another or if it's all the standard or all the 5/8, then that might point to a common tapping problem versus a set screw problem.

Be well,

Ben

dusty

benush26 wroteDusty,

Regarding set screws coming loose.....

Is it one specific arbor? Or possibly arbors for 1 1/4 rather than 5/8 ?

Why? Because one time I thought I remembered seeing a picture of a blade holder in your shop and each blade had a separate arbor. Just trying to narrow down the selection if possible. If it is one specific arbor then maybe it's tapped hole is worn out and time for SS to give you another or if it's all the standard or all the 5/8, then that might point to a common tapping problem versus a set screw problem.

Be well,

Ben

Thank you for inquiring, Ben but I don't have a problem. Yes, I have several blades mounted on arbors. This makes blade change real convenient.

The initial post was intended to be a simple question.

If a longer set screw is used, does this increase the propensity for the set screw to work loose?

wa2crk

If it is an older arbor that has rust removed removed from the set screw and the arbor then enough metal may have been removed resulting in a sloppy fit.

More to the point, if the set srew has come from a inferior manufacturer such as one in a country whose name is similar to the kind of dishes my wife likes to use when we have company :D the threads may not have proper contact area to do the job properly.

As an example for a 5/16 X 18TPI set screw the hole could be drilled with a letter drill "G" for a 70-80% thread contact. This would be for cast steel, drop forged, or tool steel.

In most cases a 53% contact area will break the bolt before the threads strip. A 100% thread is only 5% stronger than a 75% thread but it takes three times the power to tap the hole

This information was taken from the "Machinist's Practical Guide" published by the Morse Twist Drill & Machine Co. and was copyrighted in 1950 but I don't think these specs have changed much.

Bill V

PS. I don't think the length of the set screw will have an effect but the precision that the threads have been machined to probably will. If the pitch of the threads on the screw are a poor match to the threads in the hole all bets are off. Bestsolution is to put a small drop of RTV on the threads and it will act as a thread locker and still permit the set screw to be removed easily.

dusty

wa2crk wroteIf it is an older arbor that has rust removed removed from the set screw and the arbor then enough metal may have been removed resulting in a sloppy fit.

More to the point, if the set srew has come from a inferior manufacturer such as one in a country whose name is similar to the kind of dishes my wife likes to use when we have company :D the threads may not have proper contact area to do the job properly.

As an example for a 5/16 X 18TPI set screw the hole could be drilled with a letter drill "G" for a 70-80% thread contact. This would be for cast steel, drop forged, or tool steel.

In most cases a 53% contact area will break the bolt before the threads strip. A 100% thread is only 5% stronger than a 75% thread but it takes three times the power to tap the hole

This information was taken from the "Machinist's Practical Guide" published by the Morse Twist Drill & Machine Co. and was copyrighted in 1950 but I don't think these specs have changed much.

Bill V

PS. I don't think the length of the set screw will have an effect but the precision that the threads have been machined to probably will. If the pitch of the threads on the screw are a poor match to the threads in the hole all bets are off. Bestsolution is to put a small drop of RTV on the threads and it will act as a thread locker and still permit the set screw to be removed easily.

A lot of good information here. Thanks for the response.

A am going to try to find that reference document and do some more reading.

BTW I have gotten all of my set screws from either Fastenal or from Shopsmith. Knowing that I have very little concern that they might have come from China or any other questionable source.:rolleyes:

wa2crk

Dusty

I don't think that you will be able to find the reference that I quoted. It is a small notebook that my Grandfather gave me shortly after he retired and I was working a summer job in a manufacturing facility. There is no Library of Congress info and it is about 3" by 5" so that someone could carry it in a shirt pocket.

Bill V

lightnin

wa2crk wroteDusty

I don't think that you will be able to find the reference that I quoted. It is a small notebook that my Grandfather gave me shortly after he retired and I was working a summer job in a manufacturing facility. There is no Library of Congress info and it is about 3" by 5" so that someone could carry it in a shirt pocket.

Bill V

Well lookie here ... right now there is one for ten bucks if you hurry

JPG

http://www.morsecuttingtools.com/cgi/CGP2SRIM?PMITEM=20402&PARTPG=CGP2SRFC&PAMENU=Content-type:%20text/html