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Request for Assistance.
Posted: Fri Dec 11, 2020 11:34 am
by dusty
I would sure appreciate some assistance. If you are one of those who finds that they can not interchange their extension tables and maintain alignment of those tables would you please post or email to me the diagonal measurements that you get when performing the measurements depicted in this attachment.
The numbers will likely be different than mine but the two diagonal measurements should be very, very close to the same.

- Extension Table Leg Diagonal Measurements
- Extension Table Legs Diagonal Measurements.jpg (79.84 KiB) Viewed 972 times
Re: Request for Assistance.
Posted: Fri Dec 11, 2020 1:25 pm
by JPG
I would be interested in how one measures THROUGH the headstock.
Re: Request for Assistance.
Posted: Fri Dec 11, 2020 2:00 pm
by DLB
I measured inside to inside because it is easier, so I'll normalize to your center to center. This is on a unit that I picked up cheap, needs work, so I have not aligned it, but I suspect that it has never been disassembled. This is a standard base, with a Headrest. I measured high up to clear the Headstock. I also measured the angles of the leg pairs, they vary by ~0.3 degrees between the Headrest pair and the Base pair in the axis relevant to this measurement. So, the magnitude of the difference in the diagonals would be less if I could measure just above the way tubes.
I initially measured the diagonals with a tape measure at 54-3/4" and 54-13/16". Then I used a 48" offset board and calipers and measured 54.752 and 54.803.
- David
Re: Request for Assistance.
Posted: Fri Dec 11, 2020 2:27 pm
by dusty
JPG wrote: Fri Dec 11, 2020 1:25 pm
I would be interested in how one measures THROUGH the headstock.
JPG wrote: Fri Dec 11, 2020 1:25 pm
I would be interested in how one measures THROUGH the headstock.
Doing so requires a small amount of imagination and some physical effort. To do it you really need to want it done.

- 20201211_121726.jpg (448.17 KiB) Viewed 927 times

- 20201211_121740.jpg (354.73 KiB) Viewed 927 times

- 20201211_121858.jpg (428.46 KiB) Viewed 927 times
Re: Request for Assistance.
Posted: Fri Dec 11, 2020 2:48 pm
by dusty
DLB wrote: Fri Dec 11, 2020 2:00 pm
I measured inside to inside because it is easier, so I'll normalize to your center to center. This is on a unit that I picked up cheap, needs work, so I have not aligned it, but I suspect that it has never been disassembled. This is a standard base, with a Headrest. I measured high up to clear the Headstock. I also measured the angles of the leg pairs, they vary by ~0.3 degrees between the Headrest pair and the Base pair in the axis relevant to this measurement. So, the magnitude of the difference in the diagonals would be less if I could measure just above the way tubes.
I initially measured the diagonals with a tape measure at 54-3/4" and 54-13/16". Then I used a 48" offset board and calipers and measured 54.752 and 54.803.
- David
I'll go back and measure mine to the insides as you did.
Using a tape measure and the stripped down 510 pictured in the previous post I measure 55 7/8" and 55 7/8". The carriage slides back and forth with only finger tip pressure.
Measuring center to center I get 54 11/16" by 54 11/16".
I am pleased with the consistency of my measurements. Based on this observation ( as well as yours) I would expect extension tables to be interchangeable. FWIW - This is the Shopsmith that I have been using as a router table and drill press and the one that gets rolled around (which should not be a challenge since my floors are smooth and level except for the two expansion joints).
Re: Request for Assistance.
Posted: Fri Dec 11, 2020 3:07 pm
by jsburger
dusty wrote: Fri Dec 11, 2020 2:48 pm
DLB wrote: Fri Dec 11, 2020 2:00 pm
I measured inside to inside because it is easier, so I'll normalize to your center to center. This is on a unit that I picked up cheap, needs work, so I have not aligned it, but I suspect that it has never been disassembled. This is a standard base, with a Headrest. I measured high up to clear the Headstock. I also measured the angles of the leg pairs, they vary by ~0.3 degrees between the Headrest pair and the Base pair in the axis relevant to this measurement. So, the magnitude of the difference in the diagonals would be less if I could measure just above the way tubes.
I initially measured the diagonals with a tape measure at 54-3/4" and 54-13/16". Then I used a 48" offset board and calipers and measured 54.752 and 54.803.
- David
I'll go back and measure mine to the insides as you did.
Using a tape measure and the stripped down 510 pictured in the previous post I measure 55 7/8" and 55 7/8". The carriage slides back and forth with only finger tip pressure.
Measuring with two 48" steel rules I get 53 1/2" and 53 1/2".
This is the Shopsmith that I have been using as a router table and drill press.
Did you make a typo? Your measurements are 2 3/8" different from each other.
Re: Request for Assistance.
Posted: Fri Dec 11, 2020 3:26 pm
by dusty
jsburger wrote: Fri Dec 11, 2020 3:07 pm
dusty wrote: Fri Dec 11, 2020 2:48 pm
DLB wrote: Fri Dec 11, 2020 2:00 pm
I measured inside to inside because it is easier, so I'll normalize to your center to center. This is on a unit that I picked up cheap, needs work, so I have not aligned it, but I suspect that it has never been disassembled. This is a standard base, with a Headrest. I measured high up to clear the Headstock. I also measured the angles of the leg pairs, they vary by ~0.3 degrees between the Headrest pair and the Base pair in the axis relevant to this measurement. So, the magnitude of the difference in the diagonals would be less if I could measure just above the way tubes.
I initially measured the diagonals with a tape measure at 54-3/4" and 54-13/16". Then I used a 48" offset board and calipers and measured 54.752 and 54.803.
- David
I'll go back and measure mine to the insides as you did.
Using a tape measure and the stripped down 510 pictured in the previous post I measure 55 7/8" and 55 7/8". The carriage slides back and forth with only finger tip pressure.
Measuring with two 48" steel rules I get 53 1/2" and 53 1/2".
This is the Shopsmith that I have been using as a router table and drill press.
Did you make a typo? Your measurements are 2 3/8" different from each other.
I don't think so but I'll go back and check my measurements. I think the difference is in the way we measured (outside to outside) and (inside to inside). A difference of two times the tube diameter.
Re: Request for Assistance.
Posted: Fri Dec 11, 2020 3:40 pm
by jsburger
dusty wrote: Fri Dec 11, 2020 3:26 pm
jsburger wrote: Fri Dec 11, 2020 3:07 pm
dusty wrote: Fri Dec 11, 2020 2:48 pm
I'll go back and measure mine to the insides as you did.
Using a tape measure and the stripped down 510 pictured in the previous post I measure 55 7/8" and 55 7/8". The carriage slides back and forth with only finger tip pressure.
Measuring with two 48" steel rules I get 53 1/2" and 53 1/2".
This is the Shopsmith that I have been using as a router table and drill press.
Did you make a typo? Your measurements are 2 3/8" different from each other.
I don't think so but I'll go back and check my measurements. I think the difference is in the way we measured (outside to outside) and (inside to inside). A difference of two times the tube diameter.
Sorry, your 55" dimension was from your previous measurement. I thought they were both for the inside measurement with different measuring tools.

Re: Request for Assistance.
Posted: Fri Dec 11, 2020 4:10 pm
by dusty
My next step is to replace the table legs (shown in a couple of the previous photos) with extension table legs (no tables) and take measurements.
Re: Request for Assistance.
Posted: Fri Dec 11, 2020 5:17 pm
by DLB
For clarity: My measurements were inside to inside but I added 1.25" to each when I posted them above in order to normalize them as center to center. (Because I think the sketch depicts centers.) I think Dusty and I both measured in the ~53-1/2" range inside to inside.
I did use extension table bases. But I hope it doesn't matter whether one uses those, extension tables, extra main table legs, or any combination. (All bets are off with eccentric tubes though!

) I like Dusty's use of four 510/520 main table legs because they'd be better for clearing the top of the headstock and you can measure outside to outside which is just easier. But 1) I didn't think of it, and 2) I don't have four extra main table legs laying around.
- David