Truing, As Best You Can, Shopsmith Table Tops

[dusty]

I am just trying to see how this issue could exist (if possible) while at the same time having the bores be at 90° to one another. I just cannot bring myself to accept that sort of manufacturing error.

If the ends of the Way Tubes were not properly positioned in the casting bore, the Way Tubes could be at something other than 90°.

If I have my numbers correct, Way Tubes are 51 1/4"
long. I believe the bores for the Way Tubes on the Pivot Arm Assembly are 2" deep. If the Ways are bottomed in those bores and 2" is correct, you have approximately 47 1/4" of exposed Way Tubes. If there is more than 47 1/4", the Ways are NOT BOTTOMED in the bores which could lead to some canting of the tubes in the bore which could explain your abnormal angle.

The part number (522837) is shown in the online manual for the double-tilt base upgrade kit which I would have assumed you got when you bought the upgrade. Instructions for positioning the Pivot Arms (page 10) on the Way Tubes are rather specific and if not followed could leave too much tube embedded at one end and not enough tube embedded at the other end.

The angle formed by the inside face of the casting and the Way tubes should be 90° (at least it is on the old Base Arm Assembly). Therefore, just like the extension table tubes and the ways should be at 90°, so should the ways and the inside face of the casting. Measuring this would give you still another indication of what is not right.

PS: On my home brew double tilt 520 there is exactly 48" of exposed Way Tube between the end castings.

Sorry. I spent too much time in Manufacturing Test and Quality Control to just turn the other cheek on an issue like this without knowing the root cause. But as long as you are satisfied, I'll just butt out. I have no horse in this race.

Items in red are corrections that I made after posting.

[JPG]

Let us not overlook the 'detail' that we are critiquing a hinge. As such, the rotary positioning of the hinge will affect the angle being examined. It is not simply a matter of boring a single part with normal bores. There are two different parts with a common hinge pin(more bores!).

[jsburger]

I am just trying to see how this issue could exist (if possible) while at the same time having the bores be at 90° to one another. I just cannot bring myself to accept that sort of manufacturing error.

If the ends of the Way Tubes were not properly positioned in the casting bore, the Way Tubes could be at something other than 90°.

If I have my numbers correct, Way Tubes are 52" long. I believe the bores for the Way Tubes on the Pivot Arm Assembly are 2 3/8" deep. If the Ways are bottomed in those bores and 2 3/8" is correct, you have approximately 47 1/4" of exposed Way Tubes. If there is more than 47 1/4", the Ways are NOT BOTTOMED in the bores which could lead to some canting of the tubes in the bore which could explain your abnormal angle.

The part number (522837) is shown in the online manual for the double-tilt base upgrade kit which I would have assumed you got when you bought the upgrade. Instructions for positioning the Pivot Arms (page 10) on the Way Tubes are rather specific and if not followed could leave too much tube embedded at one end and not enough tube embedded at the other end.

The angle formed by the inside face of the casting and the Way tubes should be 90° (at least it is on the old Base Arm Assembly). Therefore, just like the extension table tubes and the ways should be at 90°, so should the ways and the inside face of the casting. Measuring this would give you still another indication of what is not right.

PS: On my home brew double tilt 520 there is exactly 48" of exposed Way Tube between the end castings.

Sorry. I spent too much time in Manufacturing Test and Quality Control to just turn the other cheek on an issue like this without knowing the root cause. But as long as you are satisfied, I'll just butt out. I have no horse in this race.

Your manufacturing process is only as good as your quality control process as I am sure you know. Here are two another SS part snafus that happened to me. When I first bought my 510 in 1994 the rubber ring on the way tube would not even come close to centering the blade in the table slot. I never worried about it. I just centered the blade by eye. Two or three years after I had bought the SS I was on the phone with them and I mentioned the problem in passing. No problem, they sent me another ring free. The new ring measures 1 15/32" wide. Maybe it should be 1 1/2" I don't know. The old ring measures 1 1/4". Huge difference. I still have that ring and it is sitting in front of me now. Another thing was the SS aluminum miter gauge fence (the extruded one). I ordered one as soon as it was advertised. When the fence came there was something wrong with it. I don't remember what it was any more but it might have had something to do with the dimensions of one of the T tracks. I called SS and they were surprised and asked me to send it back. Engineering verified the error and SS sent me a new one when the new ones were made. Seems the print was wrong and their entire inventory was bad. This was on a production item.

I think your numbers are incorrect. The way tube bore bore depth on both of my castings is 2 1/8". The way tubes (10ER Thick wall in my case) are 52". The distance between the double tilt castings is actually set by the bench castings and bench tubes. Unlike the single tilt SS both bench castings on the double tilt are the same and they both have stops for the bench tubes. Both are installed with the bench tubes against the stops.

IMAG0248.jpg (196.98 KiB) Viewed 1725 times

As far as centering the way tubes in the castings, I am not sure that it is all that important. I believe SS wrote the procedure just for completeness. At the end of the day the difference is negligible. SS says there is approximately 3/8" left right movement. If you didn't center the way tubes the most you could be off is 3/16" one way or the other. Since you are in the bore at least 2" I don't think 3/16" is going to change anything. Also there is almost no play between the way tubes and the castings before the set screws are tightened. They are a very snug fit. You can feel a little movement but you can not see it. The way tube set screws are not tightened until after you center the tubes. At that time the machine is upright with the head stock, carriage and table in place. All of that weight will register the way tubes with the bottom of the bore when the set screws are tightened.

Yes you are correct about the part number. It was staring me in the face. I was looking for an actual diagram. Operator error again. SS does need to add a link for MK 7 Bench & Base diagram to this page.

http://www.shopsmith.com/service/mark/index.htm

As for the procedure on page ten see above. I just do not believe being off at most 3/16" when you are in the casting 2" will make any difference.

As far as the inside face of the castings being 90 degrees to the way tube bores, I said it before and will say it again. That is not a reference surface and there is no guarantee where it will be with any precision. In fact it is not 90 degrees on the double tilt castings. It is 88.8 degrees and both of mine are the same. I also check the casting on my single tilt shorty and it is also 88.8 degrees. At least they are all the same but I still would not trust it as a reference surface. My guess is that the old and double tilt pivot castings are made from the same mold. The double tilt just has the bottom of the pivot pin hole machined out.

No need to butt out. I feel exactly the same as you. I would like to know the cause. I don't believe SS tolerances are that loose but we will never know since we will never see the prints. Someone could have changed a procedure slightly that results in slight errors being introduced. When I was overhauling aircraft generators for the Air Force about 90 % of what I did was trouble shooting problems with new parts from the OEM. In this the OEM was Hamilton Sundstrand. Most of the legacy aircraft have Westinghouse generators. Hamilton Sundstrand purchased the Westinghouse generator division years ago. Over the years some of Westinghouse procedures were changed mostly to save money. Some of these changes introduced problems that caused new parts to fail. The OEM did not know since the failure mode did not show up until the part was installed in a generator and tested.

[jsburger]

Let us not overlook the 'detail' that we are critiquing a hinge. As such, the rotary positioning of the hinge will affect the angle being examined. It is not simply a matter of boring a single part with normal bores. There are two different parts with a common hinge pin(more bores!).

True kind of.

In this case the two base castings are the same so should be bored on the same fixture. The same with the two pivot castings. The pivot castings don't have a hole per se although it probably started out as a bored hole and then the bottom was machined out to form a U.

Again in this case there are two hinges connected together on the opposite side of their pivot points by tubes. Unless there is a lot of slop in the tube bore diameter the rotational position of the hinges is pretty much fixed. As I stated previously there is no slop in the way tube bores.

[dusty]

A little confusing, John. If your Way Tubes are 52" long, are your Bench Tubes 52 3/4"?

With a standard Mark V, the Bench Tubes are 3/4" longer than the Way Tubes. With a standard Mark V, the left hand casting has no stops for the Bench Tubes and the casting can be sorta maneuvered to make things fit. When I exchanged castings, I lost that flexibility; I now have stops on both ends. Therefore the physical separation between the two bases is fixed at 52" (by Bench Tube length).

Since I have only 47 1/4" of exposed Bench Tube, I can then conclude that I have 2.375" buried in each casting. It is my understanding that your double tilt is the same.

I am not sure where you are hiding that extra 3/4" in Way Tubes or that 52" is the correct length.

[jsburger]

A little confusing, John. If your Way Tubes are 52" long, are your Bench Tubes 52 3/4"?

With a standard Mark V, the Bench Tubes are 3/4" longer than the Way Tubes. With a standard Mark V, the left hand casting has no stops for the Bench Tubes and the casting can be sorta maneuvered to make things fit. When I exchanged castings, I lost that flexibility; I now have stops on both ends. Therefore the physical separation between the two bases is fixed at 52" (by Bench Tube length).

Since I have only 47 1/4" of exposed Bench Tube, I can then conclude that I have 2.375" buried in each casting. It is my understanding that your double tilt is the same.

I am not sure where you are hiding that extra 3/4" in Way Tubes or that 52" is the correct length.

I am not going to disassemble my SS to confirm the bench tubes are 52 3//4 inches long. That is a given. They are OEM.

Do you have the SS double tilt upgrade??? If not how can you compare my measurements to yours?

No, my double tilt is not the same. As I said before my double tilt bores are only 2.125 NOT 2.375.

I suggest you check your measurement. There is no way one can HIDE a 3/4" difference. The distance between the end castings on the MK 7 are set by the bench tubes. That could be different than your home brew "double tilt" MK V that doesn't tilt in either direction. Please correct me if I am wrong. You are off by 1" on the length of the exposed way tubes. Operator error or not. My tubes ARE 52" and the depth of the bores in the end castings ARE 2 1/8". There is no way things are 3/4" off. How can there be a 3/4" difference as you suggest?

Again, the width of the base is set buy the bench tubes since they have stops on both ends unlike the MK V.

I have access to a Zeiss CMM machine that I used to use on T38 generator stators when we were troubleshooting problems with concentricity. Maybe I should take the pivot castings there and see how they compare.

Think about this...

The initial process has to do with establishing a reference surface on the rough casting and clamping the part in the jig. The flat surface of the casting as you suggest? The first holes are machined. Now the reference surface becomes the machined holes. The part is set up based on the first holes and the second holes are machined 90 degrees to the previous holes. However, the parts are left and right. So, You have to turn the parts 180 degrees in the jig, probably not. You have a separate jig for the left and right parts. The parts are the same but the boring jigs are different. Errors can be introduced either left or right. Also the print tolerance needs to take into account the stack up. The accumulative error of the parts that are minimum or maximum print values. In this case there is no problem with the stack up but it still needs to be considered relevant or not.

[JPG]

Dusty, double check!!!!

Both my M5 bench and way tubes have 48 1/4" exposed.

The tie bar bore is 1 7/8". That leaves 1 7/8 buried in the hinge casting.

1 7/8 + 48 1/4 + 1 7/8 = 52

Since the bench tubes are 52 3/4 that leaves 4 1/2 or 2 1/4 in each end.

My recollection is that when I modified a casting similar to the double tilt(milled out the slot below the hinge pin hole) that the bench tubes were too short to seat fully into both hinge casting bores. I do not recall the amount but was not excessive.

So 2 1/8 bores in the new double tilt castings is understandable.

I will search for that thread and determine if the 'shortness' was indeed 1/4".

I do not know where 47 1/4 or 2 3/8 came from.

[JPG]

Oh my! My 'recollection' was 'imprecise'!!!

http://www.shopsmith.com/ss_forum/viewtopic.php?t=7521

It was the way tubes that were 5/8" too short!!!

My modified hinge casting is 'not readily accessible' so this mystery will have to wait.

I believe the 'mystery' is this. The way tubes must be longer than when the tie bar was used or the new slot will not reach the hinge pin.

[dusty]

There have been some corrections but this is representative of my Mark V as modified with two Model 510 Base Arm Assemblies. It may or may not be representative of an official Double-Tilt Mark 7. Dimensions stated (by me) previously in this thread that are contradicted here were WRONG in the previous posts.

The Mark V used for this effort contains 52" long Bench Tubes and 51 1/4" long Way Tubes.

The drawings do not include the Base (504145) and therefore do not reflect the hinge pin required for tilt.

I performed this modification for the sole purpose of satisfying myself with an answer to a long time burning question. Does the 510 Tilt Lock and the Tie Bar contribute to my alignment issues and if they do does their elimination result in a more stable machine? I have not done enough wood working with this configuration to answer that question but I do believe that it will. In so doing, the official double-tilt will, in my mind, provide a great improvement over the original 505/510/520.

Furthermore, I believe I am going to be able to show that a properly assembled and aligned machine will allow the use of an aligned Extension Table on either end without concern for where it was aligned.

Shopsmith Castings with Way Tubes (corrected).png (46.37 KiB) Viewed 1648 times

[jsburger]

There have been some corrections but this is representative of my Mark V as modified with two Model 510 Base Arm Assemblies. It may or may not be representative of an official Double-Tilt Mark 7. Dimensions stated (by me) previously in this thread that are contradicted here were WRONG in the previous posts.

The Mark V used for this effort contains 52" long Bench Tubes and 51 1/4" long Way Tubes which I understand to be standard OEM.

The drawings do not include the Base (504145) and therefore do not reflect the hinge pin required for tilt.

I performed this modification for the sole purpose of satisfying myself with an answer to a long time burning question. Does the 510 Tilt Lock and the Tie Bar contribute to my alignment issues and if they do does their elimination result in a more stable machine? I have not done enough wood working with this configuration to answer that question but I do believe that it will. In so doing, the official double-tilt will, in my mind, provide a great improvement over the original 505/510/520.

Furthermore, I believe I am going to be able to show that a properly assembled and aligned machine will allow the use of an aligned Extension Table on either end without concern for where it was aligned.

Shopsmith Castings with Way Tubes (corrected).png

Where did you come up with those dimensions? Standard OEM way tubes are 52" and bench tubes are 53".

Oh, as JPG said bench tubes are 52 3/4". I tried to measure mine on the assembled machine and came up with 53 but it is hard to get an accurate measurement that way.