SS Panel Clamps
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Re: SS Panel Clamps
A lot of good info coming out of this thread thanks guys.
Kevin Collins
1x Mark 7 - 520
2x Mark 5 - 510
1x 1956 Mark 5 - 500 in need of restoration
1x Mark 7 - 520
2x Mark 5 - 510
1x 1956 Mark 5 - 500 in need of restoration
Re: SS Panel Clamps
Oh my goodness! Someone's going to need a really, really big compass to draw that curve!BuckeyeDennis wrote: ↑Sun Jan 09, 2022 10:33 am ***
Real-world check
I just measured my own 48" Shopsmith double bar clamps. They are 2-1/8" tall in the center, and 2" tall at the ends of a 47" chord. (Beyond that they have a relief cut for the clamp hardware.)
Plugging those numbers into the curvature calculator, I get a 184' radius of curvature. That's a big difference, and I suspect that it's causing your problem. I dunno where the numbers came from on the sketch that you linked, but they definitely don't match my Shopsmith clamps.
The numbers are so huge that I keep thinking "he must mean inches not feet."
Which reminds me of the scene in Spinal Tap where their manager gives instructions to an artist to build them an 18 foot high "Stonehenge" prop but on the sketch he gives the artist (on a napkin) he writes it as 18" instead of 18', resulting "in a Stonehenge in danger of being crushed by a dwarf."
https://www.youtube.com/watch?v=zg5Ovdu6bOE
Gale's Law: The bigger the woodworking project, the less the mistakes show in any photo taken far enough away to show the entire project!
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Re: SS Panel Clamps
Thanks KCollins. Can you check the dimension on end opposite the crank end? I think it will be 1-7/8" based on Dennis and JPG's information.KCollins wrote: ↑Sun Jan 09, 2022 11:33 am Are these still needed?
Overall - 1-1/8" X 2 X 41
At the Crank End there is a recess narrowing the end to 1-5/8" for 2-3/4" - I can provide a picture if you'd like.
The holes are cut in half and are 1/2" in diameter.
On both ends there are 2 half holes that are 3-1/4 and 4-1/4" from the end.
The remaining half holes are from the end 6-1/2", 8-3/4", 11",13-1/4",15-1/2",17-3/4", 20", 22-1/4".
Larry Hargrove
Rock Island, Ok
1981 Mark V 500>510>520(98922)
19?? Mark V 500>Power Pro headstock 556176 06-17-11 factory exchange program original serial unknown
1957 Mark V 500 (350389)
1953 10ER
Another 10ER
Bandsaw 2012 Jointer 2012
Bandsaw, Jointer, other goodies
Craftsman table saw, Delta 46-460 Midi lathe
SS 6” Belt Sander w/power stand 1970’s?
Rock Island, Ok
1981 Mark V 500>510>520(98922)
19?? Mark V 500>Power Pro headstock 556176 06-17-11 factory exchange program original serial unknown
1957 Mark V 500 (350389)
1953 10ER
Another 10ER
Bandsaw 2012 Jointer 2012
Bandsaw, Jointer, other goodies
Craftsman table saw, Delta 46-460 Midi lathe
SS 6” Belt Sander w/power stand 1970’s?
- BuckeyeDennis
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- Joined: Tue Jul 24, 2012 10:03 pm
- Location: Central Ohio
Re: SS Panel Clamps
The radius of curvature on my clamps really does work out to approximately 184 feet, or 2,209 inches.
Given that a different online radius calculator reportedly gave different results than the one I linked, I checked the calculated radius using some simple trig. The results agreed. The calculator I linked also matched the results from Larry's CAD program.
Algale, I agree that a compass isn't a very practical approach to drawing the arc! (I do have a 150 foot landscape tape measure, but it would be darned hard to find a smooth flat surface that long to work on. ) I'd do it something like this:
But even if it's not the optimal profile, it's a lot better than a straight clamping edge. The Woodpeckers panel clamps are straight, and they don't draw the glue-up flat without some external persuasion. Starting at about 5:30 in this Woodpeckers Deep Dive Video, you can watch Jeff Farris explain why, and demonstrate how, he gets his board edges into vertical alignment by literally whacking them with a mallet.
Given that a different online radius calculator reportedly gave different results than the one I linked, I checked the calculated radius using some simple trig. The results agreed. The calculator I linked also matched the results from Larry's CAD program.
Algale, I agree that a compass isn't a very practical approach to drawing the arc! (I do have a 150 foot landscape tape measure, but it would be darned hard to find a smooth flat surface that long to work on. ) I'd do it something like this:
- Start with a straight edge on an MDF template.
- Use trig and a spreadsheet (or a CAD system) to calculate arc offsets from the straight edge. Generating an offset calculation every few inches along the straight edge.
- Use calipers to lay out the offset points on the template.
- Bandsaw and sand the template smoothly to the arc points.
- Use the template with a router and a pattern bit to transfer the curve to the actual cauls.
But even if it's not the optimal profile, it's a lot better than a straight clamping edge. The Woodpeckers panel clamps are straight, and they don't draw the glue-up flat without some external persuasion. Starting at about 5:30 in this Woodpeckers Deep Dive Video, you can watch Jeff Farris explain why, and demonstrate how, he gets his board edges into vertical alignment by literally whacking them with a mallet.
Re: SS Panel Clamps
The curve is there to re-direct the tension on the clamp boards 90° towards the panel being glued up. If I make my own boards I planned to sand a slight curve into them, it shouldn't take much and the shape of the curve shouldn't matter much. Cutting the board at an angle from either end and sanding down the point where the angles meet in the center will probably do the job because the curve is so slight.
Ed from Rhode Island
510 PowerPro Double Tilt:Greenie PowerPro Drill Press:500 Sanding Shorty w/Belt&Strip Sanders
Super Sawsmith 2000:Scroll Saw w/Stand:Joint-Matic:Power Station:Power Stand:Bandsaw:Joiner:Jigsaw
1961 Goldie:1960 Sawsmith RAS:10ER
510 PowerPro Double Tilt:Greenie PowerPro Drill Press:500 Sanding Shorty w/Belt&Strip Sanders
Super Sawsmith 2000:Scroll Saw w/Stand:Joint-Matic:Power Station:Power Stand:Bandsaw:Joiner:Jigsaw
1961 Goldie:1960 Sawsmith RAS:10ER
Re: SS Panel Clamps
What angle are you seeing between the two radii that form the arc?BuckeyeDennis wrote: ↑Sun Jan 09, 2022 1:55 pm The radius of curvature on my clamps really does work out to approximately 184 feet, or 2,209 inches.
Given that a different online radius calculator reportedly gave different results than the one I linked, I checked the calculated radius using some simple trig. The results agreed. The calculator I linked also matched the results from Larry's CAD program.
Algale, I agree that a compass isn't a very practical approach to drawing the arc! (I do have a 150 foot landscape tape measure, but it would be darned hard to find a smooth flat surface that long to work on. ) I'd do it something like this:
- Start with a straight edge on an MDF template.
- Use trig and a spreadsheet (or a CAD system) to calculate arc offsets from the straight edge. Generating an offset calculation every few inches along the straight edge.
- Use calipers to lay out the offset points on the template.
- Bandsaw and sand the template smoothly to the arc points.
Now here's another question: do we really know that the profile is in fact a circular arc? I suspect that it is, just because that makes it fairly easy. But I doubt that a circular arc is optimal for equalizing the vertical clamping pressure across the width of a panel.
- Use the template with a router and a pattern bit to transfer the curve to the actual cauls.
But even if it's not the optimal profile, it's a lot better than a straight clamping edge. The Woodpeckers panel clamps are straight, and they don't draw the glue-up flat without some external persuasion. Starting at about 5:30 in this Woodpeckers Deep Dive Video, you can watch Jeff Farris explain why, and demonstrate how, he gets his board edges into vertical alignment by literally whacking them with a mallet.
Gale's Law: The bigger the woodworking project, the less the mistakes show in any photo taken far enough away to show the entire project!
- BuckeyeDennis
- Platinum Member
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- Joined: Tue Jul 24, 2012 10:03 pm
- Location: Central Ohio
Re: SS Panel Clamps
1.2 degrees, for my 48" clamps.algale wrote: ↑Sun Jan 09, 2022 2:34 pmWhat angle are you seeing between the two radii that form the arc?BuckeyeDennis wrote: ↑Sun Jan 09, 2022 1:55 pm The radius of curvature on my clamps really does work out to approximately 184 feet, or 2,209 inches.
Given that a different online radius calculator reportedly gave different results than the one I linked, I checked the calculated radius using some simple trig. The results agreed. The calculator I linked also matched the results from Larry's CAD program.
Algale, I agree that a compass isn't a very practical approach to drawing the arc! (I do have a 150 foot landscape tape measure, but it would be darned hard to find a smooth flat surface that long to work on. ) I'd do it something like this:
- Start with a straight edge on an MDF template.
- Use trig and a spreadsheet (or a CAD system) to calculate arc offsets from the straight edge. Generating an offset calculation every few inches along the straight edge.
- Use calipers to lay out the offset points on the template.
- Bandsaw and sand the template smoothly to the arc points.
Now here's another question: do we really know that the profile is in fact a circular arc? I suspect that it is, just because that makes it fairly easy. But I doubt that a circular arc is optimal for equalizing the vertical clamping pressure across the width of a panel.
- Use the template with a router and a pattern bit to transfer the curve to the actual cauls.
But even if it's not the optimal profile, it's a lot better than a straight clamping edge. The Woodpeckers panel clamps are straight, and they don't draw the glue-up flat without some external persuasion. Starting at about 5:30 in this Woodpeckers Deep Dive Video, you can watch Jeff Farris explain why, and demonstrate how, he gets his board edges into vertical alignment by literally whacking them with a mallet.
- dusty
- Platinum Member
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- Joined: Wed Nov 22, 2006 6:52 am
- Location: Tucson (Wildcat Country), Arizona
Re: SS Panel Clamps
Does this represent what is being discussed here?
"Making Sawdust Safely"
Dusty
Sent from my Dell XPS using Firefox.
Dusty
Sent from my Dell XPS using Firefox.
- BuckeyeDennis
- Platinum Member
- Posts: 3683
- Joined: Tue Jul 24, 2012 10:03 pm
- Location: Central Ohio
Re: SS Panel Clamps
Close, if you're talking about the measurements that I took of my 48" clamps. The main difference is that the "height" of the arc was 1/8" on my clamps. (I actually measured a 2-1/8" total caul height in the middle, and subtracted the end height to arrive at the 1/8" arc height). It appears that you have the arc height dimensioned as 1/2".
Of little consequence, I measured the caul heights across 47" of arc, not 48". That will cause a slight difference in the calculated radius.
Of little consequence, I measured the caul heights across 47" of arc, not 48". That will cause a slight difference in the calculated radius.
Re: SS Panel Clamps
I come up with 2" on the money.larryhrockisland wrote: ↑Sun Jan 09, 2022 1:31 pmThanks KCollins. Can you check the dimension on end opposite the crank end? I think it will be 1-7/8" based on Dennis and JPG's information.KCollins wrote: ↑Sun Jan 09, 2022 11:33 am Are these still needed?
Overall - 1-1/8" X 2 X 41
At the Crank End there is a recess narrowing the end to 1-5/8" for 2-3/4" - I can provide a picture if you'd like.
The holes are cut in half and are 1/2" in diameter.
On both ends there are 2 half holes that are 3-1/4 and 4-1/4" from the end.
The remaining half holes are from the end 6-1/2", 8-3/4", 11",13-1/4",15-1/2",17-3/4", 20", 22-1/4".
Kevin Collins
1x Mark 7 - 520
2x Mark 5 - 510
1x 1956 Mark 5 - 500 in need of restoration
1x Mark 7 - 520
2x Mark 5 - 510
1x 1956 Mark 5 - 500 in need of restoration