Not Just a Coincidence

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dusty
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Not Just a Coincidence

Post by dusty »

If, after having done all of your table/blade related alignments, you find that with the carriage slid left and the headstock slid right against the rubber bumper that the left face of a mounted saw blade is not at dead center in the table insert...you should investigate as to why. Something is not right.
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everettdavis
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Re: Not Just a Coincidence

Post by everettdavis »

How far off is it?

There is a difference between early vs late saw arbors, there is a difference in the width of carriage positioning bumper, there is a possibility the quill is not retracing fully.

Everett
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dusty
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Re: Not Just a Coincidence

Post by dusty »

everettdavis wrote:How far off is it?

There is a difference between early vs late saw arbors, there is a difference in the width of carriage positioning bumper, there is a possibility the quill is not retracing fully.

Everett
Mine is fine. The left face of the saw blade is about 1/62" to the left of table insert center line. Whenever I do a table alignment I check for that relationship. If it is not there, I realign unless I know I have trunnions with enlarged bolt holes. I think I have retired those trunnions to the spare parts shelf. I should never have drilled those out.
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algale
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Re: Not Just a Coincidence

Post by algale »

I generally shoot to have the blade roughly in the center of the slot but I don't obsess over dead center -- unlike when I align my table and rip fence when I routinely obsess over a few thousandth of an inch in trying to achieve parallelism. I obsess over those parallelism measurements because I know they can affect quality of cut and safety since a table or rip fence that is out of parallel can cause burning or, worst case scenario, a kickback. In contrast, ensuring the blade is dead center in the slot really affects nothing as long as the table is able to drop over it without interference.

If the centering of the blade does affect some essential function or affects safety in some way I'm overlooking, then in my opinion the spacer is inadequate for the job! Sure, it gets you in the zip code, but I'd not rely on it to give me repeatable dead center alignment if for some reason safety or performance depended on that. That rubber ring has just got too much slop, which allows it to "rack" on the way tube, and the material is just too soft to get a reliable reference surface for repeatable set ups.

What am I missing?
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Re: Not Just a Coincidence

Post by DLB »

I don't really use the bumpers myself. But I have two in my shop, both for 510/520 machines. They differ by a bit over 3/16" (1.25" and 1.45") in just those two samples. I don't know if that is by design (offsetting for something else?), manufacturing variation, or change over time. I don't know a correct dimension or what machines that would apply to.

The only adjustment that I can think of off hand that changes this relationship is where the table mounts to the trunnions. I don't look at absolute position when I make that adjustment, but I can see that it might be important to others. If you used the bumper as a stop, always fully retracted the quill when setting up, and wanted consistent alignment with a ZCI, I can see that during this adjustment is when you need to make that happen if possible. I don't think I could make that happen on both of my machines with this much variance between the bumpers because I don't think there is close to that much play in the bolt holes.

I can't explain the difference in bumpers, and I'm only looking at two. I think the smaller is early 90's and the other is early 2000's. Different tables, different quills, I guess it could be a deliberate change.

- David
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jsburger
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Re: Not Just a Coincidence

Post by jsburger »

algale wrote:I generally shoot to have the blade roughly in the center of the slot but I don't obsess over dead center -- unlike when I align my table and rip fence when I routinely obsess over a few thousandth of an inch in trying to achieve parallelism. I obsess over those parallelism measurements because I know they can affect quality of cut and safety since a table or rip fence that is out of parallel can cause burning or, worst case scenario, a kickback. In contrast, ensuring the blade is dead center in the slot really affects nothing as long as the table is able to drop over it without interference.

If the centering of the blade does affect some essential function or affects safety in some way I'm overlooking, then in my opinion the spacer is inadequate for the job! Sure, it gets you in the zip code, but I'd not rely on it to give me repeatable dead center alignment if for some reason safety or performance depended on that. That rubber ring has just got too much slop, which allows it to "rack" on the way tube, and the material is just too soft to get a reliable reference surface for repeatable set ups.

What am I missing?
I don't think you are missing anything. It is there for exactly the purpose you stated. Get the table close enough so the blade goes through the insert with out hitting.

However, with zero clearance inserts all bets are off. As you say the rubber bumper is not that accurate.
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jsburger
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Re: Not Just a Coincidence

Post by jsburger »

DLB wrote: Thu Oct 29, 2020 4:06 pm I don't really use the bumpers myself. But I have two in my shop, both for 510/520 machines. They differ by a bit over 3/16" (1.25" and 1.45") in just those two samples. I don't know if that is by design (offsetting for something else?), manufacturing variation, or change over time. I don't know a correct dimension or what machines that would apply to.

The only adjustment that I can think of off hand that changes this relationship is where the table mounts to the trunnions. I don't look at absolute position when I make that adjustment, but I can see that it might be important to others. If you used the bumper as a stop, always fully retracted the quill when setting up, and wanted consistent alignment with a ZCI, I can see that during this adjustment is when you need to make that happen if possible. I don't think I could make that happen on both of my machines with this much variance between the bumpers because I don't think there is close to that much play in the bolt holes.

I can't explain the difference in bumpers, and I'm only looking at two. I think the smaller is early 90's and the other is early 2000's. Different tables, different quills, I guess it could be a deliberate change.

- David
My new early 90's 510 (94) came with a bumper that was too short. It would not let the blade enter the insert slot without adjusting the table. I lived with it for a few years and then mentioned it to SS one day on the phone. CS didn't hesitate to send me another one. Like they knew they had a problem at one time. The new one was about 3/16" wider as I remember. I still have it so I can measure it but it fixed the issue.
John & Mary Burger
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Hooper, UT
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dusty
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Re: Not Just a Coincidence

Post by dusty »

jsburger wrote: Mon Nov 02, 2020 1:37 pm
DLB wrote: Thu Oct 29, 2020 4:06 pm I don't really use the bumpers myself. But I have two in my shop, both for 510/520 machines. They differ by a bit over 3/16" (1.25" and 1.45") in just those two samples. I don't know if that is by design (offsetting for something else?), manufacturing variation, or change over time. I don't know a correct dimension or what machines that would apply to.

The only adjustment that I can think of off hand that changes this relationship is where the table mounts to the trunnions. I don't look at absolute position when I make that adjustment, but I can see that it might be important to others. If you used the bumper as a stop, always fully retracted the quill when setting up, and wanted consistent alignment with a ZCI, I can see that during this adjustment is when you need to make that happen if possible. I don't think I could make that happen on both of my machines with this much variance between the bumpers because I don't think there is close to that much play in the bolt holes.

I can't explain the difference in bumpers, and I'm only looking at two. I think the smaller is early 90's and the other is early 2000's. Different tables, different quills, I guess it could be a deliberate change.

- David
My new early 90's 510 (94) came with a bumper that was too short. It would not let the blade enter the insert slot without adjusting the table. I lived with it for a few years and then mentioned it to SS one day on the phone. CS didn't hesitate to send me another one. Like they knew they had a problem at one time. The new one was about 3/16" wider as I remember. I still have it so I can measure it but it fixed the issue.
3/16" made that much difference?? The bumper on my 520 measures 1 3/8" and with the quill fully retracted the blade hits almost dead center in the cutout. The cut out is 3" wide. If I removed the rubber bumper completely the blade would still be within the cutout (I think).
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jsburger
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Re: Not Just a Coincidence

Post by jsburger »

dusty wrote: Mon Nov 02, 2020 1:57 pm
jsburger wrote: Mon Nov 02, 2020 1:37 pm
DLB wrote: Thu Oct 29, 2020 4:06 pm I don't really use the bumpers myself. But I have two in my shop, both for 510/520 machines. They differ by a bit over 3/16" (1.25" and 1.45") in just those two samples. I don't know if that is by design (offsetting for something else?), manufacturing variation, or change over time. I don't know a correct dimension or what machines that would apply to.

The only adjustment that I can think of off hand that changes this relationship is where the table mounts to the trunnions. I don't look at absolute position when I make that adjustment, but I can see that it might be important to others. If you used the bumper as a stop, always fully retracted the quill when setting up, and wanted consistent alignment with a ZCI, I can see that during this adjustment is when you need to make that happen if possible. I don't think I could make that happen on both of my machines with this much variance between the bumpers because I don't think there is close to that much play in the bolt holes.

I can't explain the difference in bumpers, and I'm only looking at two. I think the smaller is early 90's and the other is early 2000's. Different tables, different quills, I guess it could be a deliberate change.

- David
My new early 90's 510 (94) came with a bumper that was too short. It would not let the blade enter the insert slot without adjusting the table. I lived with it for a few years and then mentioned it to SS one day on the phone. CS didn't hesitate to send me another one. Like they knew they had a problem at one time. The new one was about 3/16" wider as I remember. I still have it so I can measure it but it fixed the issue.
3/16" made that much difference?? The bumper on my 520 measures 1 3/8" and with the quill fully retracted the blade hits almost dead center in the cutout. The cut out is 3" wide. If I removed the rubber bumper completely the blade would still be within the cutout (I think).
:confused: :confused: :confused: What does the 3" cut out in the table have to do with it? I am talking about the slot in the saw insert. Yes I know the cutout positions the saw insert, but...

I will let you do the math. The replacement bumper SS sent is 1 3/8" wide. The slot in the saw blade insert is 5/8" wide except it has those two little tabs in the center on each side. That makes the insert slot effectively 1/2" wide. The original bumper on my new 1994 510 is 1 1/4" wide. I just measured it. Don't forget you have to take into account 1/16" for half of the blade width. So yes, with a 1 1/4" bumper vs a 1 3/8" bumper the saw blade will hit the insert enough that you can not lower the table.

Also any varience in the head stock and table carriage castings will affect all of this also.
John & Mary Burger
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dusty
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Re: Not Just a Coincidence

Post by dusty »

dusty wrote: Mon Nov 02, 2020 4:34 pmThanks, John.
Main Table Insert, Insert Cutout and Blade Slot.jpg
Main Table Insert, Insert Cutout and Blade Slot.jpg (271.34 KiB) Viewed 1611 times
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