Question about table saw alignment

[JPG]

And I'll add. Go slow on the drilling and CLAMP the table down so if ya get a catch, it won't spin the table into YOU.

Real slow feed and very gradual bit size increases.

That is not a stable setup(IIUC).

[algale]

After I enlarge the holes, do any of you think the rail bolt/nut against the left side of the trunnion will still be a problem? As it is, it certainly minimizes travel to the left.

I can also check on the hole issue with SS, but I did buy this rig 2nd hand.

Shopsmith doesn't care if it is second hand. If it is a manufacturing defect they will fix it regardless of whether you are the tenth owner.

[dusty]

After I enlarge the holes, do any of you think the rail bolt/nut against the left side of the trunnion will still be a problem? As it is, it certainly minimizes travel to the left.

I can also check on the hole issue with SS, but I did buy this rig 2nd hand.

No, I do not but then I don't believe that nut and washer are interfering with table in a manner that adversely effects "table alignment".

Yes, it gets in the way of totally free movement----but----does it prevent proper alignment? I don't think so.

I was in that camp for a short while. I too have drilled out the trunnion holes so that the table would move around more freely. After drilling out the holes, the table does move around more freely but it does not align any better than it ever did.

I have three tables with trunnions. Two have not been drilled and one has. They all are aligned to something less than .005".

BTW, Back when (during the time of Sawdust Sessios) I was one of the advocates for correcting this "manufacturing problem" but I also reversed my opinion when I got more experience with other tables.

[woodhead52]

Shopsmith doesn't care if it is second hand. If it is a manufacturing defect they will fix it regardless of whether you are the tenth owner.

Thanks, that's really good to know. I tried calling them this afternoon, but did not get through. So I sent them an email. I guess they'll get back to me tomorrow.

...I have three tables with trunnions. Two have not been drilled and one has. They all are aligned to something less than .005".

BTW, Back when (during the time of Sawdust Sessios) I was one of the advocates for correcting this "manufacturing problem" but I also reversed my opinion when I got more experience with other tables.

Dusty, Would you mind elaborating on this for me and if possible provide me with some guidance on how I can achieve a better alignment with the table as it is.

If I do decide to enlarge the holes will I require any special type of bit/s? I do have a Speed Reducer so I can use that if it would help, providing I did the horizontal boring. I do know that slower drilling speeds are recommended for metal. I haven't checked but I'm guessing the trunnions are cast aluminum. My understanding is that drilling through aluminum is not real difficult, but I haven't done much serious metal drilling since high school shop class, which was many moons ago and my memory is pretty foggy.

[dusty]

Thanks, that's really good to know. I tried calling them this afternoon, but did not get through. So I sent them an email. I guess they'll get back to me tomorrow.



Dusty, Would you mind elaborating on this for me and if possible provide me with some guidance on how I can achieve a better alignment with the table as it is.

If I do decide to enlarge the holes will I require any special type of bit/s? I do have a Speed Reducer so I can use that if it would help, providing I did the horizontal boring. I do know that slower drilling speeds are recommended for metal. I haven't checked but I'm guessing the trunnions are cast aluminum. My understanding is that drilling through aluminum is not real difficult, but I haven't done much serious metal drilling since high school shop class, which was many moons ago and my memory is pretty foggy.

I will but please remember that these are all just my opinions. Furthermore, this all depends on just how precise you believe you need to make the table alignment.

The table can be aligned to the blade with no special tools or you can make like this is a precision alignment and use the dial indicator. Repetition, using which ever method you chose, will make this alignment a simple routine experience. However, whatever method you use, once aligned the way you want it I believe you will find very little need to realign. The table maintains alignment very well.

If you have not already viewed the Sawdust Session on table alignment, I think you should. The tip regarding use of a dollar bill is a good one to follow.

If you think about how Nick uses the dial indicator in this video, you will realize that all he is doing is attempting to make the distance from the saw blade to the miter slot the same at both the infeed and outfeed side of the blade. He uses the same tooth location for these two measurements as a way of compensating for any wobble that may be in the blade.

If the blade is perfectly flat, this is an unnecessary detail. I have one blade and arbor that I treat as my "gold standard". It is nearly flat (it is flat enough) and I do not bother rotating the blade.

These images depict three different ways that this alignment can be performed with equal levels of precision.

[ATTACH]23285[/ATTACH],[ATTACH]23286[/ATTACH]

[ATTACH]23287[/ATTACH],[ATTACH]23288[/ATTACH]

Three of the images depict two of the procedures (using a dial indicator or the miter gauge and a rod).

The last picture depicts a zero clearance insert used to do the same procedure. The ZCI was cut when the table had just beed aligned using the dial indicator. If the table is properly aligned when the ZCI is dropped down over the blade it should seal into the cutout perfectly. If the table is misaligned, the ZCI will not seal into the cut out.

[dusty]

In a previous thread, this same subject was discussed with a couple other twists.

[dusty]

With a blade installed, the jig should just barely fit and when moved back and forth some drag (but no binding) should exist between the blade and the fixture..

[ATTACH]23316[/ATTACH]

Still another method..

[ATTACH]23317[/ATTACH]

[wa2crk]

I would (and do) use a broader foot on the dial indicator. The pointed foot will read variations and knicks in the surface of the blade such as rust and dirt. The broader foot will bridge over these variations and average the readings. My saw blade has a textured finish just under the teeth and that finish is actually .002 higher than the blade body. Also make sure that you measure to the same spot on the blade body in the front and the back of the cut line. I seem to recall that there were some instructions about determining the max runout. It said to measure the width of the kerf and then measure the thickness of the sawblade body. Take the difference of those measurements and then divide by two. This is supposed to be the maximum runout that is permissable before the outfeed side of the blade will start to contact the workpiece and possibly cause a kickback.
Bill V

[chris jay]

Great info guys. I appreciate it as well

[dusty]

I would (and do) use a broader foot on the dial indicator. The pointed foot will read variations and knicks in the surface of the blade such as rust and dirt. The broader foot will bridge over these variations and average the readings. My saw blade has a textured finish just under the teeth and that finish is actually .002 higher than the blade body. Also make sure that you measure to the same spot on the blade body in the front and the back of the cut line. I seem to recall that there were some instructions about determining the max runout. It said to measure the width of the kerf and then measure the thickness of the sawblade body. Take the difference of those measurements and then divide by two. This is supposed to be the maximum runout that is permissable before the outfeed side of the blade will start to contact the workpiece and possibly cause a kickback.
Bill V

Technically you are absolutely correct. Especially important when doing extreme precision work. Taking into consideration the variations in the surface gets to be "extreme precision". Tighter than my tolerance levels.

As for using a pointed tip on the dial indicator, I have chosen to use the ball tip because it slides on the reference surface. The sharp tip scatches and digs in which necessitates lifting it off when moving the dial indicator.

You make a valid point though.

Then there is "runout".

I don't understand the bolded text. The blade that was used to cut the kerf has some runout. That runout is included in the width of the kerf. What's to calculate?