Parallel Extension Tables

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RFGuy
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Re: Parallel Extension Tables

Post by RFGuy »

DLB wrote: Wed Dec 09, 2020 3:43 pm
dusty wrote: Wed Dec 09, 2020 3:10 pm ...the only conceivable explanation for me is that the four bores (for the extension table legs) are not properly oriented with respect to one another.
It seems like everyone agrees on this point. Or at least that no one has disagreed.

I'm much less sure about doing the alignment on a flat surface, but if it works for you that's great. I follow the intent of the manual, but I do deviate in several areas.

- David
While I don't disagree with this as a possible explanation, I certainly wouldn't say it is the ONLY explanation. I have found it is helpful to always question one's assumptions. In this regard, the elephant in the room, so to speak, are the waytubes, trunion/auxiliary table tubes are perfectly straight and do NOT flex at all? The latter being the bigger question mark for me in this scenario. Not trying to detour the conversation, but just pointing out there could be several unknowns to account for as to why the alignment is off between right and left.
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dusty
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Re: Parallel Extension Tables

Post by dusty »

algale wrote: Wed Dec 09, 2020 4:12 pm Dusty: Don't get me wrong, I wish you nothing but success in this endeavor. If I thought I could achieve this on my 520 and that the alignment would last at least as long as my main table alignment, I'd probably do it just for the sake of doing it. But I tried and failed.

But the need for a second extension table on the left side is, for me, pretty much non-existent. If I want a table to the left of the head stock, I simply mount a floating table to the left of the head stock using the tubes that go through my 520 fence rails. I usually use my 3 foot tubes which came standard. But if I want to go crazy, or need really wide support, I've got a set of six foot connecting tubes.

Those six foot connecting tubes will go all the way through the right side extension table, through the main table and through the floating table and permit a wider variety of support settings than a second extension table mounted on the left side because the floating table can be moved anywhere along the connecting tubes. With or without adding the adjustable legs that can go on the ends of the connecting tubes, I find this setup quite solid. And if I choose to rip from the left side floating table, which I have done a handful of times, I have no rip fence alignment issues with the floating table set up this way.
I have done the same but if the tables are all in line with one another and the floating table bolts to secure to the extension legs, do those bolts line up with the holes in the extension table legs. An exercise for tomorrow.
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Re: Parallel Extension Tables

Post by DLB »

RFGuy wrote: Wed Dec 09, 2020 4:13 pm
DLB wrote: Wed Dec 09, 2020 3:43 pm
dusty wrote: Wed Dec 09, 2020 3:10 pm ...the only conceivable explanation for me is that the four bores (for the extension table legs) are not properly oriented with respect to one another.
It seems like everyone agrees on this point. Or at least that no one has disagreed.
While I don't disagree with this as a possible explanation, I certainly wouldn't say it is the ONLY explanation. I have found it is helpful to always question one's assumptions. In this regard, the elephant in the room, so to speak, are the waytubes, trunion/auxiliary table tubes are perfectly straight and do NOT flex at all? The latter being the bigger question mark for me in this scenario. Not trying to detour the conversation, but just pointing out there could be several unknowns to account for as to why the alignment is off between right and left.
Agreed. Every mechanical piece and interface has tolerances that are unknown and may or may not be met by a given set of hardware that may range from brand new to almost 70 years old. BUT, wouldn't the result of all present errors combined be that the four bores are not precisely oriented with respect to one another? (In other words, I don't think those bores have to be correct with respect to the plane of rotation, but all must have the same error to be corrected by one table alignment.)

- David
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Re: Parallel Extension Tables

Post by JPG »

DLB wrote: Wed Dec 09, 2020 5:49 pm
RFGuy wrote: Wed Dec 09, 2020 4:13 pm
DLB wrote: Wed Dec 09, 2020 3:43 pm It seems like everyone agrees on this point. Or at least that no one has disagreed.[/b][/color]
While I don't disagree with this as a possible explanation, I certainly wouldn't say it is the ONLY explanation. I have found it is helpful to always question one's assumptions. In this regard, the elephant in the room, so to speak, are the waytubes, trunion/auxiliary table tubes are perfectly straight and do NOT flex at all? The latter being the bigger question mark for me in this scenario. Not trying to detour the conversation, but just pointing out there could be several unknowns to account for as to why the alignment is off between right and left.
Agreed. Every mechanical piece and interface has tolerances that are unknown and may or may not be met by a given set of hardware that may range from brand new to almost 70 years old. BUT, wouldn't the result of all present errors combined be that the four bores are not precisely oriented with respect to one another? (In other words, I don't think those bores have to be correct with respect to the plane of rotation, but all must have the same error to be corrected by one table alignment.)

- David
YEP!
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Re: Parallel Extension Tables

Post by BuckeyeDennis »

A couple of years ago, I asked an eBay seller what he would charge for an extension table base only. The answer was $20, including shipping. It was from a Mark V 500 extension table, for which there is very little demand. But the base is still the same, and it’s less expensive to ship than the entire table. So I bought it and mounted it to one of my 520 floating tables, and now I have two 520 extension tables. Of course I’m also down to just one floating table that can be used above the way tubes, but so far I haven’t found that to be a problem.

My main objective here was to be able to use my 520 as a miter-saw stand, without taking up any extra space in my shop. The miter saw sits on the main table, and the extensions tables serve as outboard workpiece supports. But the extra extension table also renders the ambidextrous alignment issue moot.
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Re: Parallel Extension Tables

Post by JPG »

One 'detail' that has sorta slipped through the cracks is that all this perfect aligning at both ends only matters IF one intends to mount a rip fence upon it. If one does not intend to use a rip fence on it than only the horizontal adjustments(lr,fr) are relevant(i.e coplaner to the main table(maybe)). If only vertical support is required much preciseness can be ignored.
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Re: Parallel Extension Tables

Post by dusty »

JPG wrote: Wed Dec 09, 2020 7:37 pm
DLB wrote: Wed Dec 09, 2020 5:49 pm
RFGuy wrote: Wed Dec 09, 2020 4:13 pm
While I don't disagree with this as a possible explanation, I certainly wouldn't say it is the ONLY explanation. I have found it is helpful to always question one's assumptions. In this regard, the elephant in the room, so to speak, are the waytubes, trunion/auxiliary table tubes are perfectly straight and do NOT flex at all? The latter being the bigger question mark for me in this scenario. Not trying to detour the conversation, but just pointing out there could be several unknowns to account for as to why the alignment is off between right and left.
Agreed. Every mechanical piece and interface has tolerances that are unknown and may or may not be met by a given set of hardware that may range from brand new to almost 70 years old. BUT, wouldn't the result of all present errors combined be that the four bores are not precisely oriented with respect to one another? (In other words, I don't think those bores have to be correct with respect to the plane of rotation, but all must have the same error to be corrected by one table alignment.)

- David
YEP!
Really! When you set out to do an alignment do you just square the main table to the blade and call it done? What about Miter Gauge, Rip Fence, and Extension Tables, Table Tilt?
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Re: Parallel Extension Tables

Post by JPG »

Maybe rearranging the words will help communicate the intent.

All the multitudinous variations between the two ends of the ss are likely not the same, so adjusting ONE table to correctly be aligned with the rest of the ss parts and accessories at ONE end will not likely be adequate to achieve the same worldly alignment at the other end.
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Re: Parallel Extension Tables

Post by dusty »

JPG wrote: Thu Dec 10, 2020 8:45 am Maybe rearranging the words will help communicate the intent.

All the multitudinous variations between the two ends of the ss are likely not the same, so adjusting ONE table to correctly be aligned with the rest of the ss parts and accessories at ONE end will not likely be adequate to achieve the same worldly alignment at the other end.
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Re: Parallel Extension Tables

Post by dusty »

Anatomy of Two Extension Tables.jpg
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