Main Table Alignment to the Blade

dcottrill · Post by **dcottrill** » Sun Dec 01, 2013 9:08 pm

Ok, When you know what to look for it seems so obvious what the problem has been all along.

See attached photo.

Holes the front Trunnion are 1/2" and holes in the rear Trunnion are 3/8". The front trunnion is on the top and the rear trunnion is on the bottom.

I need to get the micrometers out and measure the mounting bolts. Based on Dusty's bolt measurement of 0.370" there is only 0.005" of adjustment with the 3/8" hole. If it was 1/2" then there will be 0.130".

Yes it is very easy to adjust the table to within 0.001" with the rear to trunnion mounting bolts removed from the 3/8" holes. The bolts will not go back in as the trunnion holes do not line up with the corresponding holes in the table.

Now the question is: Do I send the rear trunnion back to ShopSmith to have them replace/repair or take it to a local machine shop, or try to do it myself. I'm not sure that I have the right equipment to enlarge the holes safely.

JPG · Post by **JPG** » Sun Dec 01, 2013 10:41 pm

dcottrill wrote:Ok, When you know what to look for it seems so obvious what the problem has been all along.

See attached photo.

Holes the front Trunnion are 1/2" and holes in the rear Trunnion are 3/8". The front trunnion is on the top and the rear trunnion is on the bottom.

I need to get the micrometers out and measure the mounting bolts. Based on Dusty's bolt measurement of 0.370" there is only 0.005" of adjustment with the 3/8" hole. If it was 1/2" then there will be 0.130".

Yes it is very easy to adjust the table to within 0.001" with the rear to trunnion mounting bolts removed from the 3/8" holes. The bolts will not go back in as the trunnion holes do not line up with the corresponding holes in the table.

Now the question is: Do I send the rear trunnion back to ShopSmith to have them replace/repair or take it to a local machine shop, or try to do it myself. I'm not sure that I have the right equipment to enlarge the holes safely.

Call SS CS and ask them.

dusty · Post by **dusty** » Mon Dec 02, 2013 4:59 am

dcottrill wrote:Ok, When you know what to look for it seems so obvious what the problem has been all along.

See attached photo.

Holes the front Trunnion are 1/2" and holes in the rear Trunnion are 3/8". The front trunnion is on the top and the rear trunnion is on the bottom.

I need to get the micrometers out and measure the mounting bolts. Based on Dusty's bolt measurement of 0.370" there is only 0.005" of adjustment with the 3/8" hole. If it was 1/2" then there will be 0.130".

Yes it is very easy to adjust the table to within 0.001" with the rear to trunnion mounting bolts removed from the 3/8" holes. The bolts will not go back in as the trunnion holes do not line up with the corresponding holes in the table.

Now the question is: Do I send the rear trunnion back to ShopSmith to have them replace/repair or take it to a local machine shop, or try to do it myself. I'm not sure that I have the right equipment to enlarge the holes safely.

If you do the drilling yourself, I suggest that you drill out only the rear/right hole. Leaving the other rear trunnion hole at 3/8" would make a more stable pivot point for the table.

If that does not completely resolve your alignment problem, you can then drill out the other.

Think about it. In Nick's recommended procedure he says to secure one of the bolts as a pivot point. Why drill it out and then secure it so it can't move???

If I could do mine over again, that is what I would do.

dcottrill · Post by **dcottrill** » Fri Dec 06, 2013 11:36 pm

I'm going to try to drill them myself this weekend. My real job kept me out of the shop. I did contact ShopSmith. They told me that on all the new tables the trunnions mounting holes to the table are all 1/2 inch. They would not comment on when and why. It did sound like they were making the holes different between the front and rear trunnions at one point in time.

I will try just drilling out one and then try to align it.

dusty · Post by **dusty** » Sat Dec 07, 2013 7:41 am

dcottrill wrote:I'm going to try to drill them myself this weekend. My real job kept me out of the shop. I did contact ShopSmith. They told me that on all the new tables the trunnions mounting holes to the table are all 1/2 inch. They would not comment on when and why. It did sound like they were making the holes different between the front and rear trunnions at one point in time.

I will try just drilling out one and then try to align it.

In the beginning (well, maybe not that far back) there were part numbers for two different trunnions (514620 and 514130). In addition, there was a small hand full of parts needed to create a front trunnion.

The fact that there are two trunnion numbers tells me that there was some significant physical difference between the two. Otherwise, the same trunnion (part number) would have been used to create the front trunnion (simply by adding parts) as an assembly.

Those same part numbers are available today but I don't know what size holes the rear trunnion has except that you have been told that they are 1/2".

It has been reported that the 3/8" holes were a manufacturing error and that may well be but I doubt it. I think that enlarging the holes in the rear trunnions was a design change to improve adjust-ability.

Whatever - it all works well.

beeg · Post by **beeg** » Sat Dec 07, 2013 11:18 am

dusty wrote: The fact that there are two trunnion numbers tells me that there was some significant physical difference between the two. Otherwise, the same trunnion (part number) would have been used to create the front trunnion (simply by adding parts) as an assembly.

I always thought that the change in the SKU# was due to different suppliers for the same part.

dusty · Post by **dusty** » Sat Dec 07, 2013 11:42 am

beeg wrote:I always thought that the change in the SKU# was due to different suppliers for the same part.

You may be right, beeg. Shopsmith probably does not do documentation changes near as thoroughly and frequently as I became accustomed to when working in the defense industry.

We operated under one of two different schemes depending upon whether the item had been released to production or was still in engineering.

Engineering change orders were much less frequent but when they happened were much more inclusive. Engineering change orders documented everything that was intended to be in production. An EO could involve purging an engineers notebook for work done on a particular item over a long period of time.

Once an item went to production, any change of any description was documented and resulted in a part number change. That is to say, the documentation for a part number fully described a unique item. No two part numbers were exactly same.

It made it easy when you needed to order something. All you needed to know was a number.

Just don't make a mistake in the part number. The whole thing is part of my life that I am thankful for but do not miss at all.

reddog5362 · Post by **reddog5362** » Sat Dec 07, 2013 12:45 pm

Ok maybe not the perfect thread for this question. My main table is in good alignment. I need to rip a board to 11-1/4". My extension table is close to the same alignment but obviously not perfect. I say this because my fence is good on the main table (that's the table I set it up on when I aligned it) but it's out when it's set on my extension table. How do you guys handle this? Do you re align the fence depending on which table it's on? Do you re align the extension table to get the fence closer to square? I'm finding that the position of the main table and headstock on the tubes seems to affect the relative alignment. Not sure if my tubes are not perfectly straight or what. The total variance picking worst case toe in to worst case toe out is approx 3/32". Not huge but noticeable.

wa2crk · Post by **wa2crk** » Sat Dec 07, 2013 1:03 pm

Reddog
You have to align the auxiliary table to the main table by connecting the aux table to the main table with the adjusting nuts under the aux table loosened.
Use the table tubes to connect the tables together and then carefully adjust the jacking nuts under the aux table to keep the tables in the same horizontal plane. Use a straightedge to span the two tables. There is a video by Nick Engler on the subject in the SS webpage. It is a lot easier than I made it sound.
Bill V
PS If the tubes do have a slight bend try to position the tubes with the crown up and the table should remain straight.

reddog5362 · Post by **reddog5362** » Sat Dec 07, 2013 1:13 pm

I did align the two tables. But it was done with the headstock and main table set to the far left of the machine. I assumed this would produce maximum accuracy since the distance would magnify the error. To make this rip cut I'm moving the headstock and main table to the far right since the fence has to be positioned off of the main table. This is what seems to be producing the variance.

Shopsmith Forums

Main Table Alignment to the Blade

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