Need Advice about Table Alignment

[dusty]

Well Guys You are helping the biggest dope there is i don't know why i didn't so this in the first place maybe it was because i wasn't felling the best or my mind is on my vacation to the beach any way. As you can see from the pictures I was able to do a rough alignment of the table i need to do a more precise alignment but at least the table is straight

I might at some time drill out the rear trunnions but for now I'll work with this.

When you did this, did you rotate the sanding disk so that you are measuring from the tables edge to the same spot on the sanding disk. Do not just move the ruler to the other side. Rotate the disk as well.

You might want to measure, rather than to the edge of the table, to the edge of the nearest miter track. The tables edges are far from perfectly straight and smooth.

[reible]

I haven't been following this thread but caught up tonight. A couple of quick comments, first the drilling can be done and a few of us here have done it. For me it was a major improvement and I'm glad I did it. But if I recall someone here managed to damage themselves while do the operation. So if you are going to do it make sure you have it well clamped and fingers out of the way.

Second, I hope you are doing your alignment differently then pictured. Maybe you already know this but for the sake of people who do not.... You need to have a method that will allow you to accurately adjust your table and it will not be using the sanding disk and ruler. I find a saw blade with a tooth marked so it the same tooth can be use in the front and the rear is a good way to go. I would also say you need to align to the miter slot not the edge of the table. In the good old days clamping the long allen wrench to the miter gauge to use as a gauge worked well. If you need more details a lot of us here can provide many many ways to do it besides the tried and true.

Ed

[joe_cool]

Dusty i used my combination square from the miter slot and i did rotate the disk. again it was just rough to see if i could close the gap. i'll me doing a more precise alignment later with my dial indicator

[joe_cool]

Ed i was just trying to remove the gap sorry the pictures we close up. i should have zoom out. I plan on doing a precise alignment to my saw blade later with my dial indicator. When i started this thread i was worried that there was something major wrong with the gap i had. I'm just glad there is a simple fix.

[JPG]

Are the mounting screws not 3/8"? If so there is no way the table is adjustable with both holes in the rear trunion equal to 3/8".

Be careful there. That is an awfully hard position to take. My trunnions were not redrilled until just a few years ago and I have always been able to align the table.

If you haven't attempted to move a table around on the trunnions with the rear trunnion holes drilled to 3/8", you need to try it before you take such a hard stance.

If every thing else is properly installed, the main table does not have to move very much to zero it in.

Am I to understand BOTH holes in the rear trunion were 0.375"? If so your screws were less than 0.375". Perhaps the holes were slightly larger than 0.375".

EDIT - After reviewing the 'original' thread it seems both Are indeed '3/8'.

Must be some slop in the trunion pivot also.

Also rediscovered this.
http://www.shopsmith.com/ss_forum/viewt ... p=756#p756

Here we are almosty 8 years later!

[joe_cool]

JPG yes the rear holes were .375 and the screws were .375 as well. no play in the rear holes

[JPG]

JPG yes the rear holes were .375 and the screws were .375 as well. no play in the rear holes

I added what I think allows some alignment motion - trunion pivot to the previous post. Also a quote from Nick 7 plus years ago.

[BuckeyeDennis]

I don't know how much clearance Shopsmith allowed in the 3/8" clearance holes, but standard mechanical design practice is to make the hole diameter larger than the nominal machine-screw size. Here's a table of standard hole clearances. For a 3/8" screw, a "close fit" clearance hole is 0.386", and a "free fit" hole is 0.397". Which allows a nominal lateral adjustment of about +/- 0.005" and 0.016" respectively.

[dusty]

JPG yes the rear holes were .375 and the screws were .375 as well. no play in the rear holes

joe, you say there is no play in the rear holes. Is that statement made based on empirical observation or based on 3/8" bolt in a 3/8" hole.

A perfect 3/8" hole measures .373". The bolts that I have measure .368"-.369". This would allow some movement (.004"+). That much movement, measured at the bolt would be even more measured at the tables edge.

I can't tell you how much because I can't go to the shop and mount a table with 3/8" trunnion holes. I am on a medical restriction that prevents me from lifting over 10 pounds.

[JPG]

Using a hole size of 0.375 and a screw size of 0.369, and 'guessing' the trunion hole spacing is 4", the hole/screw slop allows about 1/10" movement at 18" from the trunion which amounts to less than 0.4 degree range. That is less than the amount allowed by the 3/8\1/2 front trunion screw/hole.

No question that increasing that 0.006 slop to 0.131 will greatly increase the range. That may be too much. Perhaps 7/16 is a better choice for the rear trunion holes.

Consider there is other 'slop' that will affect blade to table alignment(trunion mounting tubes\holes\clamp and headstock lock and quill runout.

Considering all that, the use of dial gauges is likely folly.

Question remsains, was Nick correct or Gail/Gale?