Miter Tracks and Front Rail

[dusty]

Assuming that everything is assembled correctly and has not been damaged:

Does anyone have reason to believe that the two miter tracks are not parallel to another?

Does anyone have reason to believe that the miter tracks are not perpendicular to the front rail?

NOTE: Tolerances would naturally be those appropriate for "fine wood working". We don't need to get into the third and fourth decimal position.

1/32" equals .03125"

[roy_okc]

Dusty,

Interesting questions. Are you putting them out there because you've done some extreme measuring?

I would hope that the two tracks are parallel within a few thou. Additionally, I would hope that they are in the same position and have the same separation between two tables of the same make, e.g., 510/520s the same, 500s the same.

I'd also hope that the slots/front are highly perpendicular.

Hoping you have measured some tables and can enlighten us!

[algale]

I know from experience that the manufacturing process does not guarantee that the front rail will be perpendicular to the miter slots.

As you know, the rail (at least Pro Fence system) attaches via spacers resting against machined areas on the table's edge. Those machined areas that the spacers register against have tolerances and it is possible to have an in-spec table where those machined areas are so far in opposite directions of the spec that the rail won't mount parallel to the miter slots without shimming. At least that was what was determined to be the issue with my table by Shopsmith's chief engineer a few years back.

Few of us have the capability in the shop to take sufficiently accurate measurements of the relative positions of those machined areas.

As for miter slots, I don't know. But it wouldn't be hard to check with a dial indicator mounted in one slot and a known straight edge wedged in the opposite slot to figure out how parallel they are.

Now, like Roy, I assume this isn't all theoretical. You've encountered something, maybe as a result of the move, that is making you question this?

[JPG]

I would expect the two miter gauge bar slots to be parallel.

I would expect the front of the table(Those machined spots) to be very near perpendicular to the miter gauge bar slots.

Nothing is perfect, so a few thousands or a minute or two deviation would be acceptable.

[reible]

Nick had indicated some year back that the two miter slots are milled at the same time so they should be pretty good. I have no idea on the tolerance.

As far as the front rails being perpendicular to the table is another matter. If it were perfect then the rip fence wouldn't need to be adjustable. Our best hope is that the two are uniform so one adjustment would work to get it square and stay that way.

Also keep in mind that while a machine shop would have no trouble checking all this out it is much more difficult for the home shop to do.

Ed

[garys]

My miter tracks are as close to parallel as can be measured. I don't have tools to measure closer than that.
However, I built a crosscut sled. I purposely made the rails fit closely in the tracks to eliminate any movement. The sled slides smoothly and easily from front to rear on the table. If there was any error in the miter tracks, it would show up when sliding the sled. That doesn't happen, so I can assume the tracks are parallel.

[dusty]

It has been my understanding that when the tables are manufactured the mounting pads for the front and rear rails are first milled as reference points for the remainder of the milling process. If this is correct, then I would assume that the miter slots are milled as perpendiculars to the plane of those reference points. Thus, their reference characteristics are relatively certain and can be used with confidence that they are parallel to one another and perpendicular to the plane of the front rail pads.

[dusty]

Dusty,

Interesting questions. Are you putting them out there because you've done some extreme measuring?

I would hope that the two tracks are parallel within a few thou. Additionally, I would hope that they are in the same position and have the same separation between two tables of the same make, e.g., 510/520s the same, 500s the same.

I'd also hope that the slots/front are highly perpendicular.

Hoping you have measured some tables and can enlighten us!

Not really. I was trying to bring my Mark V back into service after being stored and transported and was trying some simplified methods to make certain the table was properly oriented and the fences were still accurate.

Needless to say, I am favorably impressed with how all of my equipment came through this ordeal. My Mark V is back in service with absolutely NO adjustments needing to be tweaked. The only tools I used were the engineer's square and the Incra Miter Gauge.

Doing this in this manner necessitated my reliance on the rails being square to the miter tracks (thus my questions).

[dusty]

Dusty,

Interesting questions. Are you putting them out there because you've done some extreme measuring?

I would hope that the two tracks are parallel within a few thou. Additionally, I would hope that they are in the same position and have the same separation between two tables of the same make, e.g., 510/520s the same, 500s the same.

I'd also hope that the slots/front are highly perpendicular.

Hoping you have measured some tables and can enlighten us!

I have four tables, all originally 510 version, that I have measured. Without getting into specific numbers let me say that they are all "identical" with regard the angular measurements that come into play when doing a complete table alignment.

One of the four tables has the area either side of the blade with no ribs. That table did not come with my original 510 but it has migrated to that location now. I am unable to declare which table was my original 510.