Main Table Alignment to the Blade

charlese · Post by **charlese** » Mon Dec 23, 2013 9:38 pm

Good question, Ben!

dcottrill · Post by **dcottrill** » Tue Dec 24, 2013 9:13 am

Revised - Use the quote feature

benush26 wrote:
Anyway, decades ago when building race engines we would reinstall everything with a thread, every time that threaded piece was removed. A company called ARP had an interesting article regarding torquing and stretching the bolt (rod) which distorted the threads. I remember being amazed at just now much distortion and deformation would occur at low torques (40 foot pounds)

Be well,
Ben

When building high performance engines for performance vehicles the cost of failure is much higher than the bolts holding the SS table. The head bolts are designed to stretch to ensure that the head gasket doesn't fail with the heating and cooling of the engine and high compression forces place on the heads. It is under constant stress when in use and it is constantly undergoing expansion and contraction.

All bolts will stretch to some extent when torqued down and tightened. Even so there are many application where it is not necessary to replace the bolts every time they loosened and then tightened. The loss of strength or holding power of the bolt will not be significant enough to effect/compromise what it is holding together.

In the case of the SS table, I would not expect the bolt stretching to be a concern. Possibly; it could become a concern if you are constantly adjusting the table. I tend to only adjust alignment once a year, but check regularly.

dcottrill · Post by **dcottrill** » Tue Dec 24, 2013 9:14 am

"Anyway, decades ago when building race engines we would reinstall everything with a thread, every time that threaded piece was removed. A company called ARP had an interesting article regarding torquing and stretching the bolt (rod) which distorted the threads. I remember being amazed at just now much distortion and deformation would occur at low torques (40 foot pounds)"

When building high performance engines for performance vehicles the cost of failure is much higher than the bolts holding the SS table. The head bolts are designed to stretch to ensure that the head gasket doesn't fail with the heating and cooling of the engine and high compression forces place on the heads. It is under constant stress when in use and it is constantly undergoing expansion and contraction.

All bolts will stretch to some extent when torqued down and tightened. Even so there are many application where it is not necessary to replace the bolts every time they loosened and then tightened. The loss of strength or holding power of the bolt will not be significant enough to effect/compromise what it is holding together.

In the case of the SS table, I would not expect the bolt stretching to be a concern. Possibly; it could become a concern if you are constantly adjusting the table. I tend to only adjust alignment once a year, but check regularly.

dusty · Post by **dusty** » Tue Dec 24, 2013 9:25 am

[quote="dcottrill"]"Anyway, decades ago when building race engines we would reinstall everything with a thread, every time that threaded piece was removed. A company called ARP had an interesting article regarding torquing and stretching the bolt (rod) which distorted the threads. I remember being amazed at just now much distortion and deformation would occur at low torques (40 foot pounds)"

When building high performance engines for performance vehicles the cost of failure is much higher than the bolts holding the SS table. The head bolts are designed to stretch to ensure that the head gasket doesn't fail with the heating and cooling of the engine and high compression forces place on the heads. It is under constant stress when in use and it is constantly undergoing expansion and contraction.

All bolts will stretch to some extent when torqued down and tightened. Even so there are many application where it is not necessary to replace the bolts every time they loosened and then tightened. The loss of strength or holding power of the bolt will not be significant enough to effect/compromise what it is holding together.

In the case of the SS table, I would not expect the bolt stretching to be a concern. Possibly]

If there is anything of this nature to worry about, I would suggest that the trunnion bolt threads in the table are most vulnerable. The steel trunnion bolts are not going to be the weak link.

dcottrill · Post by **dcottrill** » Tue Dec 24, 2013 10:05 am

Dusty,

I agree that the threads in the table are the weakest link.

JPG · Post by **JPG** » Tue Dec 24, 2013 10:54 am

dcottrill wrote:Dusty,

I agree that the threads in the table are the weakest link.

Tis a no-brainer I concur!

When they do strip out, drill and tap to a larger size. Ed has some inserts that can be installed with a properly sized screwdriver!:D

dusty · Post by **dusty** » Tue Dec 24, 2013 11:28 am

JPG40504 wrote:Tis a no-brainer I concur!

When they do strip out, drill and tap to a larger size. Ed has some inserts that can be installed with a properly sized screwdriver!:D

Actually, I may considered inserts for one of my tables before they strip any further. I also thought about filling the holes with "something" (JBWeld like) and then tapping them.

billmayo · Post by **billmayo** » Tue Dec 24, 2013 2:27 pm

dusty wrote:Actually, I may considered inserts for one of my tables before they strip any further. I also thought about filling the holes with "something" (JBWeld like) and then tapping them.

JB Weld will not hold well under torque or vibration. I use heli-coils from http://www.mcmaster.com/#helicoils/=py7t3m for all my aluminum bolt hole repairs and in most new holes I bore in aluminum for jigs. They are made from 18-8 stainless steel which is mostly rust free. I am set up to do 10-24 to 3/8" thread holes. This does require a unique tap to cut the threads for the heli-coil. I used a lot of these heli-coils for repairs to aluminum racing motor parts in the 60s. I use part of unthreaded bolt that is snug inside the heli-coil and cut a notch across the bolt end for inserting the heli-coil. The heli-coil tang will break off easy when tapped on the end of the tang.

JPG · Post by **JPG** » Tue Dec 24, 2013 3:23 pm

billmayo wrote:JB Weld will not hold well under torque or vibration. I use heli-coils from http://www.mcmaster.com/#helicoils/=py7t3m for all my aluminum bolt hole repairs and in most new holes I bore in aluminum for jigs. They are made from 18-8 stainless steel which is mostly rust free. I am set up to do 10-24 to 3/8" thread holes. This does require a unique tap to cut the threads for the heli-coil. I used a lot of these heli-coils for repairs to aluminum racing motor parts in the 60s. I use part of unthreaded bolt that is snug inside the heli-coil and cut a notch across the bolt end for inserting the heli-coil. The heli-coil tang will break off easy when tapped on one side of the tang.

Do not tell Dusty the 'cost' of that 'special' tap!;)

benush26 · Post by **benush26** » Tue Dec 24, 2013 6:05 pm

Okay that settles it. No more thinking!

I still plan to laze around in bed

, but clearly I am not thinking clearly (or have WAY too much nonsense to consider while dozing

), especially early in the morning. It's probably a good thing I don't drink coffee

Bill and Dusty (if you do replace your table threads will heli-coils), I'd be curious to know if doing that keeps the table aligned (both after moving and due to use) for a longer period. My M7 made it out and when I checked it, it was well within "my" accepted tolerances, but will check it in a few month to see how well it has faired.

Thanks to all who entered in to my hi-jacking discussion!:D Common sense. What a wonderful concept. Any chance we could get more of the world to try it?:rolleyes:

Be well,

Ben

Shopsmith Forums

Main Table Alignment to the Blade

Do you consider table to blade alignment something to be avoided?