Rubber Baby Bumpers

[reible]

Here is mine. Mark 7, March 2015

Mine could well be that as well, only used a rule to measure so 1-7/16 is quite close.....

Do we want to do it that way? I'll redo mine tomorrow with the caliper if so.


Ed

[Skizzity]

Here is mine. Mark 7, March 2015

Mine could well be that as well, only used a rule to measure so 1-7/16 is quite close.....

Do we want to do it that way? I'll redo mine tomorrow with the caliper if so.


Ed

I eyeballed my 32nd rule and saw 15/32. I was just trying to be as precise as I could for you guys with the calipers.

[reible]

And the caliper says 1-29/64. And that is my final answer.

Ed

[robinson46176]

I measured mine using an old brick and a wide marker pen...
My 510 came up as 1 7/16".
One refurb regular Mark V unit with an original SS rubber baby buggy bumper ring is 7/16".
On another refurb regular Mark V I had cut rings for both way tubes and I had cut them at 7/16" from a piece of new straight radiator hose I had in stock in the farm shop (Picture attached). Any time I work on any SS from now on it will get a ring installed on each way tube. Since having the Push-me Pull-me double drill press means that I will seldom raise one to vertical the rings may be even more important for protection as my sometimes absent mind may forget to lock the headstock well before lifting it... (Sometimes I forget stuff ).
The Old Mark VII of course uses a special rod that can be used to lock the carriage and headstock together at a couple of spacings and the old Mark VII originally controlled the headstock location with the rack & pinion gears on the back of the front way tube. If it had a ring it would have to be on the rear tube. I have no idea if it came new with a ring.

I consider the rings more important as protective cushions than spacers, especially since I don't use them as table saws that much. All of this super accurate measuring of the rings is of little value when you look at them and realize that neither surface that they butt against is even flat a flat surface and contact is only at the bottom of each side of the ring. The headstock face and the carriage face both slant back at the top. Even light hand pressure pushing the carriage toward the headstock can compress the limited contact area at the bottom of the rings enough to toss these fine measurements to the wind... You might as well use a micrometer to measure a block of Jello...
The rings do make a reasonable starting point when setting the carriage to the headstock but if you use the guard or splitter you need to always make a final adjustment with the quill to get the splitter exactly aligned with the blade.

Shopsmith homemade rubber baby buggy bumpers 7-16 inch - 2.jpg (151.49 KiB) Viewed 8246 times

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[wa2crk]

I don!'the know what mine measures but my blade always comes through the slot when I use my zero clearance table insert. So what difference at this point does it make?!!!
Bill V

[dusty]

The two that I have installed measure a nominal 1.479" (1 15/32"). The one that I replaced (but will not discard) measures 1.376" (1 3/8"). A 3/32" difference. That is definitely "close enough for Government work" but if you are striving for precision during alignment that is a huge gap.

This would explain to me why so many users are willing to say that moving the carriage tight against the bumper does not result in the blade being centered in the table cutout. Mine used to be very close to dead center. With the new bumpers it is no more. One side of the blade to the edge of the opening now measures 1 5/8" while the other side measures 1 3/4".

This, in itself, clearly indicates that the manufacturing objective (of the rubber bumper) was NOT to create a spacing that would locate the blade in the center of the opening.

[algale]

The two that I have installed measure a nominal 1.479" (1 15/32"). The one that I replaced (but will not discard) measures 1.376" (1 3/8"). A 3/32" difference. That is definitely "close enough for Government work" but if you are striving for precision during alignment that is a huge gap.

This would explain to me why so many users are willing to say that moving the carriage tight against the bumper does not result in the blade being centered in the table cutout. Mine used to be very close to dead center. With the new bumpers it is no more. One side of the blade to the edge of the opening now measures 1 5/8" while the other side measures 1 3/4".

This, in itself, clearly indicates that the manufacturing objective (of the rubber bumper) was NOT to create a spacing that would locate the blade in the center of the opening.

Isn't that somewhat dependent on where the table is aligned relative to the oversized trunion holes? In other words, with the bumper in place, could you loosen the trunion bolts and slide the table left or right to get it centered and aligned?

[dusty]

The two that I have installed measure a nominal 1.479" (1 15/32"). The one that I replaced (but will not discard) measures 1.376" (1 3/8"). A 3/32" difference. That is definitely "close enough for Government work" but if you are striving for precision during alignment that is a huge gap.

This would explain to me why so many users are willing to say that moving the carriage tight against the bumper does not result in the blade being centered in the table cutout. Mine used to be very close to dead center. With the new bumpers it is no more. One side of the blade to the edge of the opening now measures 1 5/8" while the other side measures 1 3/4".

This, in itself, clearly indicates that the manufacturing objective (of the rubber bumper) was NOT to create a spacing that would locate the blade in the center of the opening.

Isn't that somewhat dependent on where the table is aligned relative to the oversized trunion holes? In other words, with the bumper in place, could you loosen the trunion bolts and slide the table left or right to get it centered and aligned?

Maybe but aligning the table while centering it in the cutout may be more tedious than some users are willing to tolerate. How much movement is available with the enlarged holes. I don't believe that much.

Love the search function.

The trunion bolts are 3/8" and the trunion holes, if enlarged, are 1/2". The 1/8" movement is certainly not enough to compensate for the change in bumper dimension and at the same time achieve table alignment.

[dgreen810]

Several years ago when I upgraded from 500 to 510 they included a rubber spacer to replace the hard spacer that was on the 500. I too ran into the problem of jacking around trying to locate the saw blade in the approximate center of the insert. Didn't like the idea of adjusting it with the quill. So I cut a piece of aluminum tube to the correct length, split it one side, opened it up to slide on the way bar and closed it back up with a hose clamp. PVC would work as well. Been using it for probably 15 20 years. I have a free standing Delta drill press so rarely use the SS in drill press mode.

Don G

[JPG]

If the 'true' purpose of the 'ring' was a bumper, why was it originally very hard 'plastic'?

The blade insert has a wide center(front to rear) so persnickity accuracy was not a goal. ZCI came later. Rubber tubing is cheaper than plastic. Dimensional accuracy is not easy with rubber tubing(so not attempted).

Just the way I see all this confusion.

In a half century using the original Mark 5 ring, I have never been dissatisfied with the centering(but then I did not use a ZCI). Only when I needed the narrow neck to be closer to the blade(sorta to mimick a ZCI) did I alter the spacing with the quill.

Guess the purpose is in the mind of the user. I believe the parts description as referred to above tells the tale. No mention of 'bumper', but rather 'stop ring'.